TY - JOUR
AU1 - Peine, Jena L
AU2 - Neville, Tammi L
AU3 - Jia, Guangquiang
AU4 - Van Emon, Megan L
AU5 - Kirsch, James D
AU6 - Hammer, Carolyn J
AU7 - Meyer, Allison M
AU8 - O’Rourke, Stephen T
AU9 - Reynolds, Lawrence P
AU1 - Caton, Joel S
AB - Abstract Multiparous Rambouillet ewes (n = 32) were allocated in a completely randomized design to determine if rumen-protected L-arginine (RP-Arg) supplementation during mid- and late gestation would 1) alter maternal carotid artery hemodynamics and 2) affect circulating amino acids associated with arginine metabolism in dams from day 54 of gestation to parturition and in their offspring from birth to 54 d of age. Ewes were assigned to one of three treatments from day 54 ± 3.9 to parturition: control (CON; 100% nutrient requirements), restricted (RES; 60% of CON), and RES plus 180 mg RP-Arg•kg BW-1•d1 (RES-ARG). Ewes were penned individually in a temperature-controlled facility. Carotid artery hemodynamics was measured via Doppler ultrasound at day 50 and 130 of gestation. Maternal serum was collected at day 54 and 138 of gestation and at parturition. At parturition, lambs were immediately removed from their dams and reared independently. Lamb serum samples were collected at birth and 1, 3, 7, 33, and 54 d of age. Pulsatility index was the only hemodynamic measurement altered by dietary treatment, where day 130 measurements were greater (P ≤ 0.04) for RES and RES-ARG compared with CON. The change in pulsatility index was greater (P < 0.01) for RES compared with CON but tended to be intermediate (P ≥ 0.12) for RES-ARG. Maternal serum Arg, Cit, and Asp at day 138 were greater (P < 0.01) for CON compared with RES and RES-ARG; serum Orn at day 138 was greater (P = 0.04) for CON compared with RES. Maternal serum Cit at parturition was greater (P ≤ 0.03) for CON and RES-ARG compared with RES. Offspring serum Arg was affected by a maternal treatment by day of age interaction (P = 0.03), where at day 3, CON and RES-ARG had greater (P ≤ 0.03) serum Arg concentrations than RES, and at day 54, RES-ARG was greater than (P = 0.002) CON and RES was intermediate and did not differ from (P ≥ 0.09) CON and RES-ARG. Offspring serum Orn and Cit were less (P ≤ 0.03) for RES and RES-ARG compared with CON. Results indicate that distal tissue blood perfusion decreased due to maternal RES, and RES-ARG was able to improve perfusion but not to the level of CON ewes. Further, maternal RP-Arg altered offspring Arg and related amino acid concentrations during the postnatal period. Introduction The amino acid L-arginine is the direct precursor for production of the endogenous vasodilator, nitric oxide. Arginine administration causes increased NO synthesis in endothelial cells that leads to a reduction in vascular tone (Martin et al., 2001) and increased blood flow (Morris, 2007; Wu et al., 2009; Wu et al., 2013). Peine et al. (2020) and Meyer et al. (2011b) found supplementation of 180 mg of rumen-protected L-Arg (RP-Arg)•kg body weight (BW)-1•d-1 improved carotid artery hemodynamics through increased distal tissue perfusion and decreased arterial resistance. These blood flow effects may be beneficial during gestation because increased blood flow improves transport of nutrients and respiratory gases to the developing fetus. At-risk pregnancies that result in fetal growth restriction can be induced by poor maternal nutrition during gestation (Wu et al., 2006) and are often associated with impaired hemodynamics during gestation (Reynolds and Redmer, 1995; Reynolds et al., 2006). Therapeutic targeting of the nitric oxide system to increase blood flow could help rescue these pregnancies (Reynolds et al., 2006). Jugular Arg infusions (81 mg L-Arg•kg BW-1•d-1) during mid to late gestation rescued birth weights in nutrient restricted ewes (Lassala et al., 2010). Peine et al. (2018) reported increased lamb fetal and postnatal and growth when nutrient-restricted ewes were supplemented with 180 mg RP-Arg•kg BW-1•d-1 from day 54 to parturition. Taken together, these studies suggest Arg supplementation during gestation may rescue the fetus from the deleterious effects that result from poor maternal nutrition. Numerous Arg supplementation studies have delivered Arg to ruminants by intravenous infusion to prevent ruminal microbe catabolism (Luther et al., 2009; Lassala et al., 2010; Lassala et al., 2011; McCoard et al., 2013; Satterfield et al., 2013; Crane et al., 2016; Zhang et al., 2016), but this strategy is not practical for livestock production. Meyer et al. (2018) reported forage-fed steers consuming RP-Arg had increased delivery of Arg to the small intestine and increased intestinal Arg uptake, demonstrating that rumen protection provides an effective and practical approach for Arg supplementation to ruminants. The supply of specific amino acids is critical not only for normal embryonic and fetal development during gestation but also during the rapid postnatal growth period (Bell et al., 1987; Thureen et al., 2003; Wu and Morris Jr., 2004; Regnault et al., 2005; Wu et al., 2009; Wu et al., 2013; Lin et al., 2014; Wu et al., 2018). Because Arg interacts with key amino acids in specific ways, RP-Arg supplementation has restored the concentration of many circulating amino acids in restricted ewes to that of control-fed ewes (Zhang et al., 2016). Previous work in our lab demonstrated that RP-Arg (180 mg•kg-1 BW•d-1) increased serum Arg, Orn, Asp, and Glu compared with 90 mg RP-Arg•kg-1 BW•d-1 in non-pregnant ewes (Peine et al., 2020). Furthermore, for offspring serum amino acid concentrations, several Arg supplementation studies have provided insight into fetal amino acid status during gestation or shortly after parturition (Kwon et al., 2004; McCoard et al., 2013; Satterfield et al., 2013; Zhang et al., 2016); however, few studies have followed the offspring during the postnatal period. Gootwine et al. (2020) reported increased circulating maternal Arg, but no changes in pregnancy outcomes or lamb growth rates in response to protected Arg supplementation. Unfortunately, these authors (Gootwine et al., 2020) reported no measures of maternal hemodynamics, and their offspring responses to maternal treatment during pregnancy were partially confounded by lactation as lambs remained with the ewes. In the current study, we assessed maternal hemodynamics, and offspring were reared independent of ewes, providing novel insights into the effects of maternal RP-Arg on both ewe and lamb responses. Furthermore, the RP-ARG used in the current study altered carotid artery hemodynamics and concentration of amino acids associated with Arg metabolism in non-pregnant ewe lambs (Peine et al., 2020). The objectives of this study were to evaluate the impact of maternal RP-Arg supplementation to nutrient-restricted ewes on carotid artery hemodynamics and circulating serum amino acids of pregnant dams from mid-gestation to parturition as well as circulating serum amino acids of their offspring from birth to day 54 of age. We hypothesized RP-Arg would improve carotid artery hemodynamics from days 50 to 130 of gestation. We further hypothesized RP-Arg would increase circulating Arg and amino acids associated with Arg metabolism and decrease circulating amino acids that compete with Arg for intracellular transport (Lys and His) in gestating ewes from days 54 to 138 and immediately postpartum and for offspring from birth to day 54 of age. Materials and Methods This research was approved by the North Dakota Institutional Animal Care and Use Committee protocol number A12071. Animals and facility Pregnant multiparous Rambouillet-cross ewes (n = 32; 67.7 ± 6.2 kg initial BW) were transported from the NDSU Hettinger Research Extension Center to the Animal Nutrition Physiology Center at Fargo, ND and housed individually in a temperature-controlled facility (12 to 21°C) with free access to water. The lighting was timed to mimic normal daylight patterns for late summer through late fall in North Dakota. Experimental design and treatments These procedures are described in more detail by Peine et al. (2018). Briefly, ewes were fed a complete pelleted diet at 0800 daily (Table 1). Ewe BW was determined weekly to make dietary adjustments as needed. Individual ewe dietary intake was calculated based on BW and ME requirements and adjusted for dietary treatment. Diets were analyzed for dry matter and crude protein following AOAC (1990) procedures and neutral and acid detergent fibers using an Ankom Fiber Analyzer (Ankom Technology, Fairport, NY). Table 1. Ingredient and nutrient composition of pelleted diet fed to ewes Item . % . Ingredient  Alfalfa meal, dehydrated 34.0  Beet pulp, dehydrated 27.0  Wheat middlings 25.0  Ground corn 8.4  Soybean meal 5.0  Trace mineral premix1 0.6 Nutrient composition  Dry matter 89.9  Crude protein 15.5  Neutral detergent fiber 37.2  Acid detergent fiber 21.5 Item . % . Ingredient  Alfalfa meal, dehydrated 34.0  Beet pulp, dehydrated 27.0  Wheat middlings 25.0  Ground corn 8.4  Soybean meal 5.0  Trace mineral premix1 0.6 Nutrient composition  Dry matter 89.9  Crude protein 15.5  Neutral detergent fiber 37.2  Acid detergent fiber 21.5 Table obtained from Peine et al. (2018). Diets administered to ewes daily at 0800h. 1Premix: 18 to 21% Ca, 9% P, 10 to 11% NaCl, 49.3 mg/kg Se, 700,000IU/kg Vitamin A, 200,000 IU/kg Vitamin D, 400 IU/kg Vitamin E. Open in new tab Table 1. Ingredient and nutrient composition of pelleted diet fed to ewes Item . % . Ingredient  Alfalfa meal, dehydrated 34.0  Beet pulp, dehydrated 27.0  Wheat middlings 25.0  Ground corn 8.4  Soybean meal 5.0  Trace mineral premix1 0.6 Nutrient composition  Dry matter 89.9  Crude protein 15.5  Neutral detergent fiber 37.2  Acid detergent fiber 21.5 Item . % . Ingredient  Alfalfa meal, dehydrated 34.0  Beet pulp, dehydrated 27.0  Wheat middlings 25.0  Ground corn 8.4  Soybean meal 5.0  Trace mineral premix1 0.6 Nutrient composition  Dry matter 89.9  Crude protein 15.5  Neutral detergent fiber 37.2  Acid detergent fiber 21.5 Table obtained from Peine et al. (2018). Diets administered to ewes daily at 0800h. 1Premix: 18 to 21% Ca, 9% P, 10 to 11% NaCl, 49.3 mg/kg Se, 700,000IU/kg Vitamin A, 200,000 IU/kg Vitamin D, 400 IU/kg Vitamin E. Open in new tab Ewes were randomly assigned to one of three dietary treatments. Dietary treatments included control (CON) fed at 100% of requirements based on NRC (2007) recommendations, restricted (RES; fed 60% of CON), and RES supplemented with 180 mg RP-Arg•kg BW-1•d-1 (RES-ARG). Rumen-protected Arg (Kemin Industries, Des Moines, IA) dose was based on previous research conducted by our laboratories (Meyer et al., 2011a; Meyer et al., 2011b; Peine et al., 2020) and intended to improve hemodynamic measurements and amino acid concentrations without interfering with the transport of competitive amino acids (Lys and His). The RP-Arg was delivered in 50 g of a fine ground corn carrier that was fed daily before the pelleted feed. The RP-Arg supplement was only fed to the RES-ARG ewes; however, 50 g of fine ground corn was fed to all ewes, regardless of treatment. Parturition and lamb management Lambing was closely monitored 24 h per day so lambs could be separated from their dams immediately post-birth to eliminate any developmental bias due to suckling. Lambs were reared independent of the dams for the remainder of the study. These procedures were described in more detail by Peine et al. (2018). Briefly, lambs were group housed and received artificial colostrum (Lifeline Rescue Colostrum, APC, Ankeny, IA) for the first 20 h after birth and then received milk replacer (Super Lamb Milk Replacer, Merrick’s Inc., Middleton, WI) via bottle until they could be transitioned to a teat bucket system. In addition to milk replacer, a mixture of long stem mid-bloom alfalfa hay and creep feed (DM basis: 20% CP, 6% fat, 8% crude fiber, 1.4 to 1.9% Ca, 0.4% P, 0.5% to 1.5% NaCl, 0.3 ppm Se, 11,000 IU/kg vitamin A, 6,000 IU/kg vitamin D, and 100 IU/kg vitamin E) were available ad libitum, and lambs had free access to water. Doppler ultrasonography The Doppler ultrasonography procedure used for this experiment followed the same procedures as Peine et al. (2020). Briefly, carotid artery hemodynamics were evaluated using duplex B-mode and D-mode programs of the color Doppler ultrasound instrument (model SSD-4000; Aloka America, Wallingford, CT) with an attached 7.5-MHz finger transducer probe (Aloka UST-995). Ultrasound assessments were obtained without the use of anesthesia, beginning with a baseline measurement at day 50 of gestation followed by final measurements at day 130 of gestation. All scans were performed approximately 10 cm below the mandible on the lateral carotid artery after shearing wool and cleaning the area of interest, using Aquasonic transmission gel as needed (Parker Laboratories, Fairfield, NJ). A cross-sectional view of the carotid artery was visualized first using B mode, and arterial pulsatility was confirmed using a duplex view of B-mode and D-mode. The transducer probe was manually turned to obtain a longitudinal section of the carotid artery. The probe was aligned to the carotid artery at an average angle of insonation of 70.8 ± 0.5°. Duplex view allowed B-mode to be used for visualization while simultaneously using D-mode to record pulsatile waves, and duplex mode was used to obtain final hemodynamic measurements. As described by Lemley et al. (2012) and Peine et al. (2020), three separate ultrasonography assessments yielding three analogous cardiac cycle waveforms were used to obtain average hemodynamics for each ewe within a gestational day (i.e., 9 waveform measurements per day). Hemodynamic measurements were calculated using peak systolic velocity (PSV; cm/s), end-diastolic velocity (EDV; cm/s), mean velocity (MnV; cm/s), and cross-sectional area of the vessel (cm2). These parameters were used to calculate pulsatility index (PI; PI = [PSV - EDV]/ MnV), an indicator of tissue blood perfusion; resistance index (RI; RI = [PSV - EDV]/ PSV), an indicator of vascular resistance; and flow volume (MnV × cross-sectional area × 60 sec; mL/min). Additionally, heart rate (beats/min), stroke volume (velocity-time interval × cross-sectional area; mL), and cardiac output (stroke volume × heart rate; L/min) were recorded. All of the above calculations were performed by the preprogrammed Doppler software. Change in hemodynamic measurements was calculated as day 130 measurement – day 50 measurement. Blood sample collection and analysis Blood samples were obtained from dams via medial jugular venipuncture (to avoid puncturing the lateral carotid artery, which was used for Doppler ultrasonography) before feeding at 0700 on days 54 and 138 of gestation and immediately following parturition. Blood was collected from lambs via jugular venipuncture immediately post-birth, at 24 h (1 d), and at 3, 7, 33, and 54 d of age. All blood samples were collected in 10-mL Corvac serum separator vacuum tubes with thrombin (Tyco Healthcare, Mansfield, MA) and placed on ice immediately after sample collection for a minimum of 45 min. Whole blood samples were centrifuged for 30 min at 1,500 × g at 4°C. Following centrifugation, the serum supernatant was pipetted into 2-mL screw-cap vials and stored at -20°C. Serum amino acid concentrations were evaluated using ultra-performance liquid chromatography methods similar to Crouse et al. (2019). For ewes, change in amino acid concentration was calculated as day 138 concentration – day 54 concentration. Statistical analysis Two ewes, one CON and one RES, were removed from the current analysis because they died of causes unrelated to dietary treatment before the final amino acid and hemodynamic data could be collected resulting in 10 ewes per treatment for these parameters. A third ewe, in the CON treatment, died prior to parturition of causes unrelated to dietary treatment; however, her data remained within the initial, final, and change hemodynamic and amino acid analyses because she died after collection of the final hemodynamic and amino acid data, and the data fell well within the standard error of the treatment mean. Her data were not included in the parturition amino acid data set because she died before parturition; therefore, for the parturition data set, there were 9 CON, 10 RES, and 10 RES-ARG ewes. For the offspring, initially there were 11 lambs per treatment. There were four sets of twins (2 CON, 1 RES, and 1 RES-ARG). Two lambs died during the experiment due to non-treatment related causes, one male at 7 d (RES-ARG) and another male at 45 d (RES). Their data were included in the analyses up to removal from the study; therefore, for RES-ARG there were 11 lambs per treatment for birth and days 1 and 7 and 10 lambs per treatment for days 33 and 54, and for RES there were 11 lambs per treatment for birth and days 1, 7, and 33, and 10 lambs per treatment for day 54. Offspring sex was balanced across treatments (Peine et al., 2018). All data were analyzed using the general linear models procedure of SAS (SAS Inst. Inc, Cary, NC). Hemodynamics and maternal serum amino acid concentrations at day 50 or day 54, respectively, for initial baseline measurements, at day 130 or day 138, respectively, for final measurements, and for change in measurement (final – initial) were analyzed for the effect of maternal dietary treatment. For maternal serum amino acid concentrations, samples collected immediately post-parturition were analyzed using the general linear models procedure of SAS for effect of maternal dietary treatment. For lamb serum amino acid concentrations, the main effects of maternal dietary treatment and day of age and the interaction of maternal dietary treatment × day of age were analyzed using the general linear models procedure of SAS. Means were separated using the least squares means procedure of SAS, with P-values ≤ 0.05 considered significant and P-values > 0.05 but ≤ 0.10 considered tendencies. Results Ewe Doppler measurements There were no differences between maternal dietary treatments (P ≥ 0.12) for initial (day 50 of gestation) carotid artery hemodynamic data (Table 2). For final hemodynamic data (day 130 of gestation), PSV, EDV, MnV, cross-sectional area, RI, heart rate, and stroke volume did not differ (P ≥ 0.24) between dietary treatments. There was a tendency (P = 0.06) for treatment to alter final flow volume and cardiac output. Final flow volume was greater (P = 0.03) for CON compared with RES-ARG, while RES ewes were intermediate and similar to (P ≥ 0.06) to both CON and RES-ARG. For final cardiac output, CON was greater (P ≤ 0.05) than RES and RES-ARG, which were similar (P = 0.86). There was a main effect of treatment (P = 0.03) for final PI, where PI was greater (P ≤ 0.04) for RES and RES-ARG compared with CON. Rumen-protected Arg supplementation did not alter (P = 0.50) final PI compared with RES. There was a main effect of treatment (P = 0.02) for change (final – initial) of PI, with the least (P = 0.006) change for CON compared with RES, while RES-ARG was intermediate and equal to CON and RES (P ≥ 0.12). All other changes of hemodynamic measurements from day 50 to day 130 of gestation were not altered (P ≥ 0.30). Table 2. Influence of nutrient restriction and rumen-protected L-Arg (RP-Arg) supplementation on maternal carotid artery hemodynamics at day 50 (initial) and 130 (final) . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Peak systolic velocity, cm/s  Initial 136.2 115.4 120.7 8.4 0.21  Final 151.0 168.7 136.8 22.6 0.61  Change2 14.9 53.3 16.1 24.4 0.46 End diastolic velocity, cm/s  Initial 41.4 34.9 34.4 2.6 0.12  Final 52.0 57.0 48.3 7.8 0.73  Change2 10.6 22.2 13.9 8.9 0.64 Mean velocity3, cm/s  Initial 69.2 59.4 57.3 5.0 0.22  Final 51.1 44.8 38.5 5.1 0.24  Change2 -18.1 -14.5 -18.7 7.4 0.91 Cross-sectional area, cm2  Initial 0.246 0.278 0.270 0.019 0.48  Final 0.271 0.284 0.266 0.023 0.84  Change2 0.024 0.006 -0.005 0.021 0.62 Pulsatility index4  Initial 1.4 1.4 1.6 0.1 0.39  Final 2.0a 2.5b 2.3b 0.1 0.03  Change2 0.5a 1.1b 0.8ab 0.1 0.02 Resistance index5  Initial 0.69 0.70 0.71 0.01 0.65  Final 0.65 0.79 0.64 0.08 0.35  Change2 -0.04 0.09 -0.07 0.08 0.30 Flow volume6, mL/min  Initial 985.8 983.7 929.5 99.9 0.90  Final 818.6 631.2 608.1 66.2 0.06  Change2 -167.2 -352.5 -321.4 96.8 0.36 Heart rate, beats/min  Initial 99.4 90.3 91.1 4.2 0.25  Final 92.4 97.5 79.0 9.7 0.40  Change2 -7.0 7.2 -12.0 10.8 0.43 Stroke volume7, mL  Initial 10.0 11.0 10.3 1.2 0.84  Final 9.0 7.9 7.8 0.9 0.57  Change2 -1.1 -3.1 -2.5 1.2 0.48 Cardiac output8, liter/m  Initial 1.0 1.0 0.9 0.1 0.89  Final 0.8 0.6 0.6 0.1 0.06  Change2 -0.2 -0.4 -0.3 0.1 0.39 . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Peak systolic velocity, cm/s  Initial 136.2 115.4 120.7 8.4 0.21  Final 151.0 168.7 136.8 22.6 0.61  Change2 14.9 53.3 16.1 24.4 0.46 End diastolic velocity, cm/s  Initial 41.4 34.9 34.4 2.6 0.12  Final 52.0 57.0 48.3 7.8 0.73  Change2 10.6 22.2 13.9 8.9 0.64 Mean velocity3, cm/s  Initial 69.2 59.4 57.3 5.0 0.22  Final 51.1 44.8 38.5 5.1 0.24  Change2 -18.1 -14.5 -18.7 7.4 0.91 Cross-sectional area, cm2  Initial 0.246 0.278 0.270 0.019 0.48  Final 0.271 0.284 0.266 0.023 0.84  Change2 0.024 0.006 -0.005 0.021 0.62 Pulsatility index4  Initial 1.4 1.4 1.6 0.1 0.39  Final 2.0a 2.5b 2.3b 0.1 0.03  Change2 0.5a 1.1b 0.8ab 0.1 0.02 Resistance index5  Initial 0.69 0.70 0.71 0.01 0.65  Final 0.65 0.79 0.64 0.08 0.35  Change2 -0.04 0.09 -0.07 0.08 0.30 Flow volume6, mL/min  Initial 985.8 983.7 929.5 99.9 0.90  Final 818.6 631.2 608.1 66.2 0.06  Change2 -167.2 -352.5 -321.4 96.8 0.36 Heart rate, beats/min  Initial 99.4 90.3 91.1 4.2 0.25  Final 92.4 97.5 79.0 9.7 0.40  Change2 -7.0 7.2 -12.0 10.8 0.43 Stroke volume7, mL  Initial 10.0 11.0 10.3 1.2 0.84  Final 9.0 7.9 7.8 0.9 0.57  Change2 -1.1 -3.1 -2.5 1.2 0.48 Cardiac output8, liter/m  Initial 1.0 1.0 0.9 0.1 0.89  Final 0.8 0.6 0.6 0.1 0.06  Change2 -0.2 -0.4 -0.3 0.1 0.39 1Control (CON) fed at 100% NRC requirements and received 50 g fine ground corn (n = 10); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 10); nutrient-restricted Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 10). 2Change = final - initial. 3Mean velocity = Velocity time integral (cm)/ Flow time (ms). 4Pulsatility index = (Peak systolic velocity ˗ End diastolic velocity)/ Mean velocity. 5Resistance index = (Peak systolic velocity ˗ End diastolic velocity)/ Peak systolic velocity. 6Flow volume = Mean velocity × Cross-sectional area × 60 s. 7Stroke volume = Velocity time integral (cm) × Cross-sectional area (cm2). 8Cardiac output = Stroke output × Heart rate. a, bMeans with differing superscripts differ P ≤ 0.05. Open in new tab Table 2. Influence of nutrient restriction and rumen-protected L-Arg (RP-Arg) supplementation on maternal carotid artery hemodynamics at day 50 (initial) and 130 (final) . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Peak systolic velocity, cm/s  Initial 136.2 115.4 120.7 8.4 0.21  Final 151.0 168.7 136.8 22.6 0.61  Change2 14.9 53.3 16.1 24.4 0.46 End diastolic velocity, cm/s  Initial 41.4 34.9 34.4 2.6 0.12  Final 52.0 57.0 48.3 7.8 0.73  Change2 10.6 22.2 13.9 8.9 0.64 Mean velocity3, cm/s  Initial 69.2 59.4 57.3 5.0 0.22  Final 51.1 44.8 38.5 5.1 0.24  Change2 -18.1 -14.5 -18.7 7.4 0.91 Cross-sectional area, cm2  Initial 0.246 0.278 0.270 0.019 0.48  Final 0.271 0.284 0.266 0.023 0.84  Change2 0.024 0.006 -0.005 0.021 0.62 Pulsatility index4  Initial 1.4 1.4 1.6 0.1 0.39  Final 2.0a 2.5b 2.3b 0.1 0.03  Change2 0.5a 1.1b 0.8ab 0.1 0.02 Resistance index5  Initial 0.69 0.70 0.71 0.01 0.65  Final 0.65 0.79 0.64 0.08 0.35  Change2 -0.04 0.09 -0.07 0.08 0.30 Flow volume6, mL/min  Initial 985.8 983.7 929.5 99.9 0.90  Final 818.6 631.2 608.1 66.2 0.06  Change2 -167.2 -352.5 -321.4 96.8 0.36 Heart rate, beats/min  Initial 99.4 90.3 91.1 4.2 0.25  Final 92.4 97.5 79.0 9.7 0.40  Change2 -7.0 7.2 -12.0 10.8 0.43 Stroke volume7, mL  Initial 10.0 11.0 10.3 1.2 0.84  Final 9.0 7.9 7.8 0.9 0.57  Change2 -1.1 -3.1 -2.5 1.2 0.48 Cardiac output8, liter/m  Initial 1.0 1.0 0.9 0.1 0.89  Final 0.8 0.6 0.6 0.1 0.06  Change2 -0.2 -0.4 -0.3 0.1 0.39 . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Peak systolic velocity, cm/s  Initial 136.2 115.4 120.7 8.4 0.21  Final 151.0 168.7 136.8 22.6 0.61  Change2 14.9 53.3 16.1 24.4 0.46 End diastolic velocity, cm/s  Initial 41.4 34.9 34.4 2.6 0.12  Final 52.0 57.0 48.3 7.8 0.73  Change2 10.6 22.2 13.9 8.9 0.64 Mean velocity3, cm/s  Initial 69.2 59.4 57.3 5.0 0.22  Final 51.1 44.8 38.5 5.1 0.24  Change2 -18.1 -14.5 -18.7 7.4 0.91 Cross-sectional area, cm2  Initial 0.246 0.278 0.270 0.019 0.48  Final 0.271 0.284 0.266 0.023 0.84  Change2 0.024 0.006 -0.005 0.021 0.62 Pulsatility index4  Initial 1.4 1.4 1.6 0.1 0.39  Final 2.0a 2.5b 2.3b 0.1 0.03  Change2 0.5a 1.1b 0.8ab 0.1 0.02 Resistance index5  Initial 0.69 0.70 0.71 0.01 0.65  Final 0.65 0.79 0.64 0.08 0.35  Change2 -0.04 0.09 -0.07 0.08 0.30 Flow volume6, mL/min  Initial 985.8 983.7 929.5 99.9 0.90  Final 818.6 631.2 608.1 66.2 0.06  Change2 -167.2 -352.5 -321.4 96.8 0.36 Heart rate, beats/min  Initial 99.4 90.3 91.1 4.2 0.25  Final 92.4 97.5 79.0 9.7 0.40  Change2 -7.0 7.2 -12.0 10.8 0.43 Stroke volume7, mL  Initial 10.0 11.0 10.3 1.2 0.84  Final 9.0 7.9 7.8 0.9 0.57  Change2 -1.1 -3.1 -2.5 1.2 0.48 Cardiac output8, liter/m  Initial 1.0 1.0 0.9 0.1 0.89  Final 0.8 0.6 0.6 0.1 0.06  Change2 -0.2 -0.4 -0.3 0.1 0.39 1Control (CON) fed at 100% NRC requirements and received 50 g fine ground corn (n = 10); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 10); nutrient-restricted Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 10). 2Change = final - initial. 3Mean velocity = Velocity time integral (cm)/ Flow time (ms). 4Pulsatility index = (Peak systolic velocity ˗ End diastolic velocity)/ Mean velocity. 5Resistance index = (Peak systolic velocity ˗ End diastolic velocity)/ Peak systolic velocity. 6Flow volume = Mean velocity × Cross-sectional area × 60 s. 7Stroke volume = Velocity time integral (cm) × Cross-sectional area (cm2). 8Cardiac output = Stroke output × Heart rate. a, bMeans with differing superscripts differ P ≤ 0.05. Open in new tab Ewe circulating amino acids As expected, there were no differences (P ≥ 0.18) for maternal initial (day 54 of gestation) serum concentrations of the amino acids of interest (Table 3). Final (day 138 of gestation) maternal Arg, Orn, Cit, and Asp serum concentrations were altered (P ≤ 0.05) by treatment. Final maternal Arg, Cit, and Asp serum concentrations were greatest (P ≤ 0.007) for CON compared with RES and RES-ARG, which were similar (P ≥ 0.28). Final maternal serum concentrations of Orn were greater (P = 0.02) for CON compared with RES, while RES-ARG dams were intermediate and equal to CON and RES (P ≥ 0.06). Final maternal Met serum concentrations tended to be altered (P = 0.08) by treatment, where concentrations were greater (P = 0.03) for CON compared with RES-ARG, while RES ewes were intermediate and equal to (P ≥ 0.09) CON and RES-ARG. Table 3. Influence of nutrient restriction and rumen-protected L-Arg (RP-Arg) supplementation on maternal serum amino acid concentrations (µmol/liter) at day 54 (initial) and day 138 (final) and immediately following parturition . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Arg  Initial 199.3 202.5 208.4 15.3 0.91  Final 183.9a 144.9b 148.1b 8.3 0.004  Change2 -15.4 -57.7 -60.3 17.2 0.14  Parturition 125.7 106.2 125.6 9.9 0.26 Orn  Initial 58.2 61.2 59.1 4.7 0.90  Final 35.6a 23.8b 26.2ab 3.4 0.05  Change2 -22.6 -37.4 -32.9 4.7 0.10  Parturition 19.9 18.2 26.2 2.7 0.08 Cit  Initial 228.5 219.4 232.4 17.9 0.87  Final 162.9a 119.6b 131.3b 7.5 0.001  Change2 -65.6 -99.8 -101.2 19.7 0.37  Parturition 117.2a 91.4b 127.7a 8.0 0.007 Asp  Initial 12.8 14.8 14.9 1.3 0.44  Final 9.7a 7.1b 6.9b 0.6 0.003  Change2 -3.1a -7.7b -8.0b 1.1 0.007  Parturition 6.9 5.2 6.3 0.6 0.14 Pro  Initial 92.0 89.8 91.8 6.2 0.96  Final 96.0 87.6 83.0 4.3 0.11  Change2 4.0 -2.2 -8.8 6.9 0.44  Parturition 64.0 56.6 61.0 4.1 0.43 Glu  Initial 68.1 88.9 76.4 9.0 0.28  Final 74.7 81.5 66.1 6.7 0.28  Change2 6.6 -7.4 -10.3 11.0 0.51  Parturition 119.8 114.6 94.3 9.1 0.11 Gln  Initial 261.3 297.1 327.4 24.4 0.18  Final 244.3 250.5 263.7 12.9 0.56  Change2 -17.0 -46.6 -63.7 23.9 0.39  Parturition 188.9 190.5 213.5 14.4 0.38 Met  Initial 11.6 12.8 14.3 1.3 0.36  Final 20.0 16.6 15.7 1.4 0.08  Change2 8.4a 3.9b 1.4b 1.5 0.009  Parturition 15.0 11.0 11.4 1.3 0.06 Lys  Initial 113.7 114.5 112.8 9.5 0.99  Final 157.2 159.3 171.4 11.1 0.63  Change2 43.5 44.8 58.7 14.9 0.73  Parturition 82.1 90.2 109.2 9.7 0.13 His  Initial 52.5 59.2 60.6 3.8 0.29  Final 54.8 49.5 54.4 2.8 0.36  Change2 2.3 -9.7 -6.2 4.6 0.19  Parturition 45.8 42.9 45.7 2.7 0.67 . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Arg  Initial 199.3 202.5 208.4 15.3 0.91  Final 183.9a 144.9b 148.1b 8.3 0.004  Change2 -15.4 -57.7 -60.3 17.2 0.14  Parturition 125.7 106.2 125.6 9.9 0.26 Orn  Initial 58.2 61.2 59.1 4.7 0.90  Final 35.6a 23.8b 26.2ab 3.4 0.05  Change2 -22.6 -37.4 -32.9 4.7 0.10  Parturition 19.9 18.2 26.2 2.7 0.08 Cit  Initial 228.5 219.4 232.4 17.9 0.87  Final 162.9a 119.6b 131.3b 7.5 0.001  Change2 -65.6 -99.8 -101.2 19.7 0.37  Parturition 117.2a 91.4b 127.7a 8.0 0.007 Asp  Initial 12.8 14.8 14.9 1.3 0.44  Final 9.7a 7.1b 6.9b 0.6 0.003  Change2 -3.1a -7.7b -8.0b 1.1 0.007  Parturition 6.9 5.2 6.3 0.6 0.14 Pro  Initial 92.0 89.8 91.8 6.2 0.96  Final 96.0 87.6 83.0 4.3 0.11  Change2 4.0 -2.2 -8.8 6.9 0.44  Parturition 64.0 56.6 61.0 4.1 0.43 Glu  Initial 68.1 88.9 76.4 9.0 0.28  Final 74.7 81.5 66.1 6.7 0.28  Change2 6.6 -7.4 -10.3 11.0 0.51  Parturition 119.8 114.6 94.3 9.1 0.11 Gln  Initial 261.3 297.1 327.4 24.4 0.18  Final 244.3 250.5 263.7 12.9 0.56  Change2 -17.0 -46.6 -63.7 23.9 0.39  Parturition 188.9 190.5 213.5 14.4 0.38 Met  Initial 11.6 12.8 14.3 1.3 0.36  Final 20.0 16.6 15.7 1.4 0.08  Change2 8.4a 3.9b 1.4b 1.5 0.009  Parturition 15.0 11.0 11.4 1.3 0.06 Lys  Initial 113.7 114.5 112.8 9.5 0.99  Final 157.2 159.3 171.4 11.1 0.63  Change2 43.5 44.8 58.7 14.9 0.73  Parturition 82.1 90.2 109.2 9.7 0.13 His  Initial 52.5 59.2 60.6 3.8 0.29  Final 54.8 49.5 54.4 2.8 0.36  Change2 2.3 -9.7 -6.2 4.6 0.19  Parturition 45.8 42.9 45.7 2.7 0.67 1Control (CON) fed at 100% NRC requirements and received 50 g fine ground corn (n = 10 for initial, final, and change; n = 9 for parturition); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 10); nutrient-restricted RP-Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 10). 2Change = final amino acid concentration- initial amino acid concentration. a, bMeans with differing superscripts differ P ≤ 0.05. Open in new tab Table 3. Influence of nutrient restriction and rumen-protected L-Arg (RP-Arg) supplementation on maternal serum amino acid concentrations (µmol/liter) at day 54 (initial) and day 138 (final) and immediately following parturition . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Arg  Initial 199.3 202.5 208.4 15.3 0.91  Final 183.9a 144.9b 148.1b 8.3 0.004  Change2 -15.4 -57.7 -60.3 17.2 0.14  Parturition 125.7 106.2 125.6 9.9 0.26 Orn  Initial 58.2 61.2 59.1 4.7 0.90  Final 35.6a 23.8b 26.2ab 3.4 0.05  Change2 -22.6 -37.4 -32.9 4.7 0.10  Parturition 19.9 18.2 26.2 2.7 0.08 Cit  Initial 228.5 219.4 232.4 17.9 0.87  Final 162.9a 119.6b 131.3b 7.5 0.001  Change2 -65.6 -99.8 -101.2 19.7 0.37  Parturition 117.2a 91.4b 127.7a 8.0 0.007 Asp  Initial 12.8 14.8 14.9 1.3 0.44  Final 9.7a 7.1b 6.9b 0.6 0.003  Change2 -3.1a -7.7b -8.0b 1.1 0.007  Parturition 6.9 5.2 6.3 0.6 0.14 Pro  Initial 92.0 89.8 91.8 6.2 0.96  Final 96.0 87.6 83.0 4.3 0.11  Change2 4.0 -2.2 -8.8 6.9 0.44  Parturition 64.0 56.6 61.0 4.1 0.43 Glu  Initial 68.1 88.9 76.4 9.0 0.28  Final 74.7 81.5 66.1 6.7 0.28  Change2 6.6 -7.4 -10.3 11.0 0.51  Parturition 119.8 114.6 94.3 9.1 0.11 Gln  Initial 261.3 297.1 327.4 24.4 0.18  Final 244.3 250.5 263.7 12.9 0.56  Change2 -17.0 -46.6 -63.7 23.9 0.39  Parturition 188.9 190.5 213.5 14.4 0.38 Met  Initial 11.6 12.8 14.3 1.3 0.36  Final 20.0 16.6 15.7 1.4 0.08  Change2 8.4a 3.9b 1.4b 1.5 0.009  Parturition 15.0 11.0 11.4 1.3 0.06 Lys  Initial 113.7 114.5 112.8 9.5 0.99  Final 157.2 159.3 171.4 11.1 0.63  Change2 43.5 44.8 58.7 14.9 0.73  Parturition 82.1 90.2 109.2 9.7 0.13 His  Initial 52.5 59.2 60.6 3.8 0.29  Final 54.8 49.5 54.4 2.8 0.36  Change2 2.3 -9.7 -6.2 4.6 0.19  Parturition 45.8 42.9 45.7 2.7 0.67 . Treatment1 . . . . . . CON . RES . RES-ARG . SEM . TRT P-value . Arg  Initial 199.3 202.5 208.4 15.3 0.91  Final 183.9a 144.9b 148.1b 8.3 0.004  Change2 -15.4 -57.7 -60.3 17.2 0.14  Parturition 125.7 106.2 125.6 9.9 0.26 Orn  Initial 58.2 61.2 59.1 4.7 0.90  Final 35.6a 23.8b 26.2ab 3.4 0.05  Change2 -22.6 -37.4 -32.9 4.7 0.10  Parturition 19.9 18.2 26.2 2.7 0.08 Cit  Initial 228.5 219.4 232.4 17.9 0.87  Final 162.9a 119.6b 131.3b 7.5 0.001  Change2 -65.6 -99.8 -101.2 19.7 0.37  Parturition 117.2a 91.4b 127.7a 8.0 0.007 Asp  Initial 12.8 14.8 14.9 1.3 0.44  Final 9.7a 7.1b 6.9b 0.6 0.003  Change2 -3.1a -7.7b -8.0b 1.1 0.007  Parturition 6.9 5.2 6.3 0.6 0.14 Pro  Initial 92.0 89.8 91.8 6.2 0.96  Final 96.0 87.6 83.0 4.3 0.11  Change2 4.0 -2.2 -8.8 6.9 0.44  Parturition 64.0 56.6 61.0 4.1 0.43 Glu  Initial 68.1 88.9 76.4 9.0 0.28  Final 74.7 81.5 66.1 6.7 0.28  Change2 6.6 -7.4 -10.3 11.0 0.51  Parturition 119.8 114.6 94.3 9.1 0.11 Gln  Initial 261.3 297.1 327.4 24.4 0.18  Final 244.3 250.5 263.7 12.9 0.56  Change2 -17.0 -46.6 -63.7 23.9 0.39  Parturition 188.9 190.5 213.5 14.4 0.38 Met  Initial 11.6 12.8 14.3 1.3 0.36  Final 20.0 16.6 15.7 1.4 0.08  Change2 8.4a 3.9b 1.4b 1.5 0.009  Parturition 15.0 11.0 11.4 1.3 0.06 Lys  Initial 113.7 114.5 112.8 9.5 0.99  Final 157.2 159.3 171.4 11.1 0.63  Change2 43.5 44.8 58.7 14.9 0.73  Parturition 82.1 90.2 109.2 9.7 0.13 His  Initial 52.5 59.2 60.6 3.8 0.29  Final 54.8 49.5 54.4 2.8 0.36  Change2 2.3 -9.7 -6.2 4.6 0.19  Parturition 45.8 42.9 45.7 2.7 0.67 1Control (CON) fed at 100% NRC requirements and received 50 g fine ground corn (n = 10 for initial, final, and change; n = 9 for parturition); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 10); nutrient-restricted RP-Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 10). 2Change = final amino acid concentration- initial amino acid concentration. a, bMeans with differing superscripts differ P ≤ 0.05. Open in new tab Change (final – initial) in maternal Asp and Met serum concentrations were altered (P ≤ 0.007) by treatment (Table 3). Change in maternal Asp was least (P ≤ 0.007) for CON compared with RES and RES-ARG, which did not differ (P = 0.84). Change in maternal Met was greatest (P ≤ 0.04) for CON compared with RES and RES-ARG, which did not differ (P = 0.25). Change in maternal Orn tended to be altered (P = 0.10) by treatment, where the change was greater (P = 0.04) for RES compared with CON and intermediate (P ≥ 0.14) for RES-ARG ewes. Immediately following parturition, maternal Cit serum concentrations were altered (P = 0.007) by treatment (Table 3). Maternal Cit immediately following parturition was least (P ≤ 0.03) for RES compared with CON and RES-ARG, which did not differ (P = 0.35). Maternal serum concentrations of Orn and Met immediately following parturition tended (P = 0.08 and 0.06, respectively) to be altered by treatment. Immediately following parturition, maternal Orn serum concentrations were greater (P = 0.03) for RES-ARG compared with RES and intermediate (P ≥ 0.10) for CON. Maternal Met serum concentrations immediately following parturition were greatest (P ≤ 0.05) for CON compared with RES and RES-ARG, which did not differ (P = 0.83). Lamb circulating amino acids Lamb serum Arg concentrations were the only amino acid of interest affected by a maternal treatment by day of age interaction (P = 0.03; Figure 1). At birth and 1 d of age, all lambs had similar (P ≥ 0.19) serum Arg concentrations. At day 3 of age, lambs from CON and RES-ARG ewes had similar (P = 0.76) serum Arg concentrations that were greater (P ≤ 0.03) than lambs from RES ewes. At days 7 and 33 of age, there were no differences among maternal dietary treatments (P ≥ 0.09) for lamb serum Arg concentrations. At day 54 of age, lambs from RES-ARG ewes had greater (P = 0.002) serum Arg concentrations than lambs from CON ewes while lambs from RES ewes were intermediate (P ≥ 0.09). Figure 1. Open in new tabDownload slide Influence of maternal nutrient restriction and rumen-protected L-Arg supplementation on offspring serum Arg concentration (µmol/liter). Dams were fed control (CON) at 100% NRC requirements and received 50 g fine ground corn (n = 11 lambs for days 0 to 54); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 11 lambs for days 0 to 33; n = 10 lambs for day 54); nutrient-restricted RP-Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 11 lambs for days 0 to 7; n = 10 lambs for days 33 and 54). *At day 3, CON and RES-ARG are greater than (P ≤ 0.03) RES but equal to one another (P = 0.76). **At day 54, RES-ARG is greater than (P = 0.002) CON while RES is intermediate and equal to (P ≥ 0.09) CON and RES-ARG. Figure 1. Open in new tabDownload slide Influence of maternal nutrient restriction and rumen-protected L-Arg supplementation on offspring serum Arg concentration (µmol/liter). Dams were fed control (CON) at 100% NRC requirements and received 50 g fine ground corn (n = 11 lambs for days 0 to 54); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 11 lambs for days 0 to 33; n = 10 lambs for day 54); nutrient-restricted RP-Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 11 lambs for days 0 to 7; n = 10 lambs for days 33 and 54). *At day 3, CON and RES-ARG are greater than (P ≤ 0.03) RES but equal to one another (P = 0.76). **At day 54, RES-ARG is greater than (P = 0.002) CON while RES is intermediate and equal to (P ≥ 0.09) CON and RES-ARG. The main effect of maternal dietary treatment altered (P ≤ 0.03) lamb Orn and Cit serum concentrations (Table 4). Lambs from CON ewes had the greatest (P ≤ 0.05) Orn and Cit serum concentrations compared with lambs from RES and RES-ARG ewes, which were similar (P ≥ 0.14). Maternal dietary treatment tended (P = 0.07) to alter lamb Asp serum concentration, where lambs from CON ewes had greater (P = 0.03) serum Asp concentrations compared with lambs from RES ewes while lambs from RES-ARG ewes were intermediate (P ≥ 0.06). Table 4. Influence of maternal nutrient restriction and rumen-protected L-Arg (RP-Arg) supplementation on offspring serum amino acid concentrations (µmol/liter)1 . Treatment2 . . . . . Item . CON . RES . RES-ARG . SEM . TRT P-value . Arg3 178.0 168.8 186.9 5.9 0.09 Orn 67.0a 59.2b 56.7b 2.8 0.03 Cit 281.8a 231.5b 251.0b 9.4 <0.001 Asp 13.6 11.9 13.5 0.6 0.07 Pro 153.9 148.3 148.2 3.8 0.48 Glu 138.9 136.6 138.6 4.3 0.92 Gln 166.8 180.3 174.1 6.9 0.38 Met 23.6 21.5 22.6 0.8 0.17 Lys 97.1 93.8 94.6 3.8 0.80 His 63.3 61.1 62.6 2.1 0.76 . Treatment2 . . . . . Item . CON . RES . RES-ARG . SEM . TRT P-value . Arg3 178.0 168.8 186.9 5.9 0.09 Orn 67.0a 59.2b 56.7b 2.8 0.03 Cit 281.8a 231.5b 251.0b 9.4 <0.001 Asp 13.6 11.9 13.5 0.6 0.07 Pro 153.9 148.3 148.2 3.8 0.48 Glu 138.9 136.6 138.6 4.3 0.92 Gln 166.8 180.3 174.1 6.9 0.38 Met 23.6 21.5 22.6 0.8 0.17 Lys 97.1 93.8 94.6 3.8 0.80 His 63.3 61.1 62.6 2.1 0.76 1Offspring serum samples were collected at birth and days 1, 3, 7, 33, and 54 of age. 2Dams were fed control (CON) at 100% NRC requirements and received 50 g fine ground corn (n = 66); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 65); nutrient-restricted RP-Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 64). 3Arginine was the only amino acid concentration that had a significant maternal treatment x day of age interaction (P = 0.03). Interactive means are presented in Figure 1. All other interactive P-values ≥ 0.30. a, bMeans with differing superscripts differ P ≤ 0.05. Open in new tab Table 4. Influence of maternal nutrient restriction and rumen-protected L-Arg (RP-Arg) supplementation on offspring serum amino acid concentrations (µmol/liter)1 . Treatment2 . . . . . Item . CON . RES . RES-ARG . SEM . TRT P-value . Arg3 178.0 168.8 186.9 5.9 0.09 Orn 67.0a 59.2b 56.7b 2.8 0.03 Cit 281.8a 231.5b 251.0b 9.4 <0.001 Asp 13.6 11.9 13.5 0.6 0.07 Pro 153.9 148.3 148.2 3.8 0.48 Glu 138.9 136.6 138.6 4.3 0.92 Gln 166.8 180.3 174.1 6.9 0.38 Met 23.6 21.5 22.6 0.8 0.17 Lys 97.1 93.8 94.6 3.8 0.80 His 63.3 61.1 62.6 2.1 0.76 . Treatment2 . . . . . Item . CON . RES . RES-ARG . SEM . TRT P-value . Arg3 178.0 168.8 186.9 5.9 0.09 Orn 67.0a 59.2b 56.7b 2.8 0.03 Cit 281.8a 231.5b 251.0b 9.4 <0.001 Asp 13.6 11.9 13.5 0.6 0.07 Pro 153.9 148.3 148.2 3.8 0.48 Glu 138.9 136.6 138.6 4.3 0.92 Gln 166.8 180.3 174.1 6.9 0.38 Met 23.6 21.5 22.6 0.8 0.17 Lys 97.1 93.8 94.6 3.8 0.80 His 63.3 61.1 62.6 2.1 0.76 1Offspring serum samples were collected at birth and days 1, 3, 7, 33, and 54 of age. 2Dams were fed control (CON) at 100% NRC requirements and received 50 g fine ground corn (n = 66); nutrient-restricted (RES) fed at 60% CON diet and received 50 g fine ground corn (n = 65); nutrient-restricted RP-Arg supplemented (RES-ARG) fed at 60% CON diet with 180 mg RP-Arg •kg BW-1•d-1 mixed in 50 g of fine ground corn (n = 64). 3Arginine was the only amino acid concentration that had a significant maternal treatment x day of age interaction (P = 0.03). Interactive means are presented in Figure 1. All other interactive P-values ≥ 0.30. a, bMeans with differing superscripts differ P ≤ 0.05. Open in new tab The assessment of circulating amino acids in lambs from birth to weaning (Table 5) in response to maternal nutrition is novel. These data show that from the postnatal phase through day 54 of age, all serum concentrations of amino acids of interest were affected (P < 0.001) by day of age. Lamb serum Arg concentrations increased from birth to day 7 (P ≤ 0.02) and then decreased to levels similar (P ≥ 0.12) to day 3 at days 33 and 54. Interaction means for serum Arg are discussed above and shown in Fig 1. Serum Orn concentrations of lambs decreased (P < 0.001) from birth to day 1 then began to increase to intermediate levels at days 3 and 7 that were similar (P = 0.61) to the highest concentration (P ≤ 0.03) at day 33 of age. At day 54, lamb serum Orn concentrations were similar to concentrations at birth and day 33 (P ≥ 0.09). Lamb serum Cit decreased (P = 0.001) from birth to day 1 then rose to its greatest (P ≤ 0.04) concentration at day 3 and remained at a steady state (P ≥ 0.28) from days 7 to 54 of age. Serum Asp concentrations in lambs were similar (P = 0.64) at birth and day 1 then increased to the greatest (P < 0.001) concentration at day 7. At days 33 and 54, lamb serum Asp concentrations were similar (P = 0.74) and less than (P < 0.001) day 7 Asp concentrations. Lamb serum Pro concentrations decreased from birth to day 1 of age to their lowest concentration (P < 0.001); at day 3 and 7, the concentrations rose to levels similar (P ≥ 0.56) to at birth before decreasing at days 33 and 54 to intermediate and equivalent (P = 0.22) concentrations. Lamb serum Glu concentrations were similar (P = 0.90) at birth and day 1, increased (P < 0.001) to intermediate but equivalent (P = 0.17) concentrations at days 3 and 7, and then increased (P < 0.001) to equivalent (P = 0.25) concentrations at days 33 and 54. Lamb serum Gln concentrations were greatest (P < 0.001) at birth and decreased (P < 0.001) from birth to day 1 then increased (P < 0.001) to intermediate but equivalent (P = 0.73) concentrations at days 3 and 7 before decreasing (P < 0.001) at days 33 and 54 to levels similar (P ≥ 0.12) to those at day 1. At birth and 1 d of age, lamb serum Met concentrations were similar (P = 0.36); Met increased to its greatest (P ≤ 0.02) concentration at day 7 of age, then decreased at day 33 to concentrations similar (P ≥ 0.08) to those at birth and day 3, and then increased again at day 54 to concentrations similar (P = 0.59) to day 7 concentrations. Lamb serum Lys concentrations were equivalent (P = 0.86) at birth and day 1, increased (P < 0.001) to intermediate and equivalent (P = 0.25) concentrations at days 3 and 7, and then increased (P < 0.001) at day 54. Offspring serum His concentrations increased (P ≤ 0.001) from birth to their greatest (P < 0.001) concentrations at day 3 of age then decreased at days 7 and 33 to concentrations similar (P ≥ 0.94) to those at birth before increasing at day 54 to concentrations similar (P = 0.84) to day 1 of age. Table 5. Influence of offspring day of age on serum amino acid concentrations (µmol/liter) . Day . . . . . . . . Item . 0 . 1 . 3 . 7 . 33 . 54 . SEM1 . Day P-value . Arg2 51.1a 79.6b 230.3c 259.3d 214.4c 232.6c 8.6 <0.001 Orn 71.7a 28.1b 51.7c 48.8c 84.3d 81.3ad 4.1 <0.001 Cit 140.8a 80.1b 361.4c 322.1d 301.8d 322.5d 13.6 <0.001 Asp 6.6a 7.1a 17.3b 21.9c 12.4d 12.8d 0.8 <0.001 Pro 166.4ab 106.6c 170.4a 162.1ab 142.8d 152.3bd 5.5 <0.001 Glu 78.9a 77.8a 115.5b 127.1b 219.5c 209.4c 6.2 <0.001 Gln 275.8a 134.4b 186.0c 190.8c 117.0b 138.5b 9.9 <0.001 Met 18.0ab 16.6a 21.9c 29.5d 20.9bc 28.6d 1.2 <0.001 Lys 37.5a 38.7a 87.2b 95.7b 142.9c 169.0d 5.4 <0.001 His 53.3a 66.9b 81.4c 53.0a 53.4a 66.1b 3.0 <0.001 . Day . . . . . . . . Item . 0 . 1 . 3 . 7 . 33 . 54 . SEM1 . Day P-value . Arg2 51.1a 79.6b 230.3c 259.3d 214.4c 232.6c 8.6 <0.001 Orn 71.7a 28.1b 51.7c 48.8c 84.3d 81.3ad 4.1 <0.001 Cit 140.8a 80.1b 361.4c 322.1d 301.8d 322.5d 13.6 <0.001 Asp 6.6a 7.1a 17.3b 21.9c 12.4d 12.8d 0.8 <0.001 Pro 166.4ab 106.6c 170.4a 162.1ab 142.8d 152.3bd 5.5 <0.001 Glu 78.9a 77.8a 115.5b 127.1b 219.5c 209.4c 6.2 <0.001 Gln 275.8a 134.4b 186.0c 190.8c 117.0b 138.5b 9.9 <0.001 Met 18.0ab 16.6a 21.9c 29.5d 20.9bc 28.6d 1.2 <0.001 Lys 37.5a 38.7a 87.2b 95.7b 142.9c 169.0d 5.4 <0.001 His 53.3a 66.9b 81.4c 53.0a 53.4a 66.1b 3.0 <0.001 1SEM = 33 for days 0, 1, 3, and 7; SEM = 32 for days 33; SEM = 31 for day 54. 2Arginine concentration had a significant maternal treatment × day of age interaction (P = 0.03). Interactive means are presented in Figure 1. a, b, c, dMeans with differing superscripts differ P ≤ 0.05. Open in new tab Table 5. Influence of offspring day of age on serum amino acid concentrations (µmol/liter) . Day . . . . . . . . Item . 0 . 1 . 3 . 7 . 33 . 54 . SEM1 . Day P-value . Arg2 51.1a 79.6b 230.3c 259.3d 214.4c 232.6c 8.6 <0.001 Orn 71.7a 28.1b 51.7c 48.8c 84.3d 81.3ad 4.1 <0.001 Cit 140.8a 80.1b 361.4c 322.1d 301.8d 322.5d 13.6 <0.001 Asp 6.6a 7.1a 17.3b 21.9c 12.4d 12.8d 0.8 <0.001 Pro 166.4ab 106.6c 170.4a 162.1ab 142.8d 152.3bd 5.5 <0.001 Glu 78.9a 77.8a 115.5b 127.1b 219.5c 209.4c 6.2 <0.001 Gln 275.8a 134.4b 186.0c 190.8c 117.0b 138.5b 9.9 <0.001 Met 18.0ab 16.6a 21.9c 29.5d 20.9bc 28.6d 1.2 <0.001 Lys 37.5a 38.7a 87.2b 95.7b 142.9c 169.0d 5.4 <0.001 His 53.3a 66.9b 81.4c 53.0a 53.4a 66.1b 3.0 <0.001 . Day . . . . . . . . Item . 0 . 1 . 3 . 7 . 33 . 54 . SEM1 . Day P-value . Arg2 51.1a 79.6b 230.3c 259.3d 214.4c 232.6c 8.6 <0.001 Orn 71.7a 28.1b 51.7c 48.8c 84.3d 81.3ad 4.1 <0.001 Cit 140.8a 80.1b 361.4c 322.1d 301.8d 322.5d 13.6 <0.001 Asp 6.6a 7.1a 17.3b 21.9c 12.4d 12.8d 0.8 <0.001 Pro 166.4ab 106.6c 170.4a 162.1ab 142.8d 152.3bd 5.5 <0.001 Glu 78.9a 77.8a 115.5b 127.1b 219.5c 209.4c 6.2 <0.001 Gln 275.8a 134.4b 186.0c 190.8c 117.0b 138.5b 9.9 <0.001 Met 18.0ab 16.6a 21.9c 29.5d 20.9bc 28.6d 1.2 <0.001 Lys 37.5a 38.7a 87.2b 95.7b 142.9c 169.0d 5.4 <0.001 His 53.3a 66.9b 81.4c 53.0a 53.4a 66.1b 3.0 <0.001 1SEM = 33 for days 0, 1, 3, and 7; SEM = 32 for days 33; SEM = 31 for day 54. 2Arginine concentration had a significant maternal treatment × day of age interaction (P = 0.03). Interactive means are presented in Figure 1. a, b, c, dMeans with differing superscripts differ P ≤ 0.05. Open in new tab Discussion Ewe Doppler measurements We anticipated RP-Arg would improve carotid artery hemodynamics during gestation, and RES-ARG ewes would present similarly to CON ewes, with RES ewes having poor hemodynamic measurements. However, the RES and RES-ARG ewes presented with similar carotid hemodynamics. The lower final PI for the CON ewes indicates CON ewes had greater distal tissue perfusion than RES and RES-ARG ewes. The final flow volume measurements further reflect this same pattern of perfusion to distal tissues. However, when PI was expressed as change across the duration of the study, which is likely more reflective of the biology, the intermediate change in perfusion of distal tissue for the RES-ARG ewes indicated RP-Arg supplementation was able to lessen the impact of maternal nutrient restriction on PI and distal tissue perfusion. Previous studies noted that for at-risk pregnancies, similar to those of the RES ewes, normal blood flow alterations during gestation may not occur, and fetuses and offspring may suffer as a result (Reynolds et al., 2006). However, rumen-protected Arg supplementation during late gestation partially restored maternal systemic pulsatility index to control levels during at-risk pregnancies. Meyer et al. (2011b) reported steers consuming 180 mg of RP-Arg/kg BW had lower carotid and caudal PI and RI compared with steers receiving no supplemental Arg. Additional data from our laboratory in nulliparous ewe lambs reported a quadratic decrease for PI and RI due to increasing Arg supplementation from 90 to 180 to 360 mg of RP-Arg•kg BW-1•d-1, with the lowest PI and RI for the 180 mg RP-Arg/kg BW ewes (Peine et al., 2020). The major difference between the previous nulliparous ewe study (Peine et al., 2020) and the current study is pregnancy status of the ewes and maternal nutrient restriction. In the current study, the RP-Arg supplement could not fully restore the hemodynamic changes associated with nutrient restriction in pregnant ewes compared with controls. Others have also reported poor hemodynamic responses to Arg in pregnant ruminants (Yunta et al., 2015). Specifically, they (Yunta et al., 2015) reported no differences for PI, RI, uterine artery diameter, or uterine flow volume in response to intraperitoneal infusion of 40 mg L-Arg/kg BW from days 41 to 146 of gestation in dairy cows. Rosenfeld (1977) reported blood flow and change in distribution of cardiac output from non-pregnant and pregnant ewes from mid- and late gestation. Though blood flow to the brain was not different due to pregnancy status or stage of gestation, the change in distribution of cardiac output to the brain of pregnant ewes decreased as pregnancy progressed (Rosenfeld, 1977). In contrast, blood flow and distribution of cardiac output to the uterus and mammary gland of ewes increased markedly as pregnancy progressed (Rosenfeld, 1977). This remarkable shift in tissue perfusion during pregnancy (Rosenfeld et al., 1974; Rosenfeld, 1977; Reynolds et al., 2006) may overshadow responses from the RP-Arg supplement in the current study. Although uterine and mammary blood flows were not measured in the current study, they may have been impacted by RP-Arg supplementation of nutrient restricted ewes. In the current study, there is a tendency for decreased cardiac output due to nutrient restriction, but not RP-Arg supplementation. This agrees with previous work from our laboratory that demonstrated no change in cardiac output due to RP-Arg supplementation (Meyer et al., 2011b; Peine et al., 2020). Other researchers reported a marked reduction in cardiac output and blood flow to the uterus, ovary, and placenta at 21 d of gestation in rat dams that were fed 50% of control intake beginning at day 5 of gestation (Rosso and Kava, 1980). However, when expressed as distribution of cardiac output, there was no change for the whole uterus, ovary, and placenta due to maternal intake (Rosso and Kava, 1980), and these authors concluded nutrient restriction interfered with expansion of reproductive organ blood flow by interfering with the normal expansion of cardiac output during gestation. Ewe circulating amino acids We hypothesized that the RP-Arg supplementation would elevate circulating Arg concentrations above the RES ewes and potentially even the CON ewes, and many of the amino acids associated with Arg metabolism would respond similarly. In the current study, concentrations of the amino acids directly associated with the urea cycle and polyamine synthesis, including Arg, decreased due to nutrient restriction at day 138 of gestation, and the change in amino acid concentrations across the duration of the study showed the same pattern. In most cases, supplementation of RP-Arg did not ameliorate this effect. In previous studies, regardless of supplementation route, oral RP-Arg or Arg-HCl infusion, and with or without nutrient restriction, Arg concentrations increased to levels similar to or above the control ewes (Lassala et al., 2010; McCoard et al., 2013; Satterfield et al., 2013; Zhang et al., 2016; Gootwine et al., 2020). However, the remaining urea cycle- and polyamine synthesis-related amino acids were not consistently altered based on supplementation or restriction methods. Zhang et al. (2016) reported maternal concentrations of Orn, Cit, and Met for twin-bearing ewes that were fed a control (100% NRC) diet were greater than ewes fed a 50% restricted diet that received a RP-Arg supplement (20 g RP-Arg/d to equal 10 g L-Arg/d) from days 35 to 110 of gestation, but the Arg-supplemented ewes had greater concentrations compared with the 50% restricted ewes. Ornithine concentrations were elevated above the control-saline and restricted-saline ewes in ewes from a non-nutrient-restricted or nutrient-restricted model with Arg-HCl infusion (McCoard et al., 2013; Satterfield et al., 2013). In a different nutrient restriction model, Arg-HCl infusion (81 mg L-Arg•kg BW-1•d-1) resulted in intermediate Orn and Met concentrations compared with control-saline or restricted-saline ewes (Lassala et al., 2010). Jugular Arg-HCl infusion (81 mg L-Arg•kg BW-1•d-1) in a nutrient restriction model resulted in Cit concentrations less than controls but similar to restricted ewes (Lassala et al., 2010; Satterfield et al., 2013). Regardless of supplementation method, RP-Arg or jugular Arg-HCl infusion, Asp concentrations were less for 50% nutrient-restricted ewes compared with controls and intermediate when Arg supplementation was provided to restricted ewes (Satterfield et al., 2013; Zhang et al., 2016). McCoard et al. (2013) reported Met concentrations decreased with tarsal vein infusion of 180 mg L-Arg HCl•kg BW-1•d-1. Some studies have reported no change for Cit, Asp, and Met concentrations (McCoard et al., 2013; Satterfield et al., 2013) with intravenous Arg-HCl infusions of 81 or 180 mg L-Arg HCl•kg BW-1•d-1. Zhang et al. (2016) reported 21 of 24 amino acids analyzed were decreased due to ewes that were nutrient-restricted during gestation compared with control-fed ewes. In contrast to the current study, Zhang et al. (2016) reported many differences for amino acid concentrations, where Arg supplementation restored concentrations of amino acids involved in the urea cycle and polyamine synthesis to levels above the nutrient-restricted, saline-infused ewes and sometimes to levels similar to the control-fed ewes. In the current study, all amino acids related to the urea cycle were present at lower levels for RES ewes. For RES ewes, less nitrogen was consumed as part of the nutrient restriction model, so this result was expected. A global decrease of amino acids that participate in polyamine synthesis has the potential to alter cellular growth and apoptosis, modify polyamine ion channels, and alter membrane permeability. Because polyamines are upregulated in rapidly proliferating cells, in gestating ewes, decreased polyamine synthesis would be expected to negatively affect angiogenesis and placental and embryonic development (Kwon et al., 2003; Wu and Morris Jr., 2004), which could explain why reductions of birth weight were noted for offspring from RES compared with CON ewes of the current study (Peine et al., 2018). Other amino acids related to Arg metabolism, Pro, Glu, and Gln, were not altered in the current study; however, other researchers have noted differences in the concentrations of these amino acids. Proline concentrations were intermediate to control or nutrient-restricted ewes regardless of Arg supplementation method, whether by infusion of Arg-HCl or feeding RP-Arg (Lassala et al., 2010; Zhang et al., 2016). Satterfield et al. (2013) reported Gln concentrations from Arg-HCl-infused ewes were intermediate but equal to both control- and restricted-fed ewes. Rumen-protected Arg supplementation did not elevate Gln concentrations of restricted ewes, which were less than control ewes (Zhang et al., 2016). Additionally, no differences for circulating Pro, Glu, and Gln concentrations have been reported (Lassala et al., 2010; McCoard et al., 2013; Satterfield et al., 2013; Zhang et al., 2016). When examining the cationic amino acids that compete with Arg for transport (Lys and His), mixed results have been reported due to Arg supplementation. In the current study, neither Lys nor His were affected by nutrient restriction or RP-Arg supplementation. In other research, Lys and His were elevated for control ewes compared with restricted and restricted, Arg-supplemented ewes, regardless of supplementation method, whether by infusion of Arg-HCl or feeding RP-Arg. (Lassala et al., 2010; Zhang et al., 2016). Satterfield et al. (2013) reported Arg-HCl-infused restricted ewes and restricted ewes had greater Lys concentrations than control fed, saline-infused ewes, while His concentrations were greater for control compared with restricted, Arg-HCl-infused ewes, and restricted, saline-infused ewes were intermediate. McCoard et al. (2013) reported no differences for Lys and His concentrations with Arg infusion. Ewe amino acids immediately following parturition Similar to cohort two from the McCoard et al. (2013) study, where Arg was intravenously infused at 180 mg L-Arg•kg BW-1•d to ewes that were allowed to lamb and maternal blood samples at 2 h post-birth were analyzed for amino acid concentrations, Cit concentrations were similar between control and Arg-supplemented ewes. However, McCoard et al. (2013) did not implement a nutrient restriction model for which we report elevated Cit and Orn for the RES-ARG ewes compared with the RES ewes. For Met, both the current study and McCoard et al. (2013) reported similar decreases for the Arg-supplemented ewes. McCoard et al. (2013) further reported decreased His concentrations for Arg-infused ewes. Lamb circulating amino acids When evaluating the amino acids directly involved in the urea cycle, our lamb circulating Arg, Orn, and Cit concentration data agree with previous data from Kwon et al. (2004), where fetal plasma from ewes fed 50% of requirements from day 28 to day 78 but realimented from days 78 to 135 and from ewes nutrient-restricted from days 28 to 135 of gestation had reduced amino acid concentrations at days 78 and 135 of gestation compared with fetuses from ewes fed 100% of requirements throughout gestation. When Arg was infused, no change for fetal Arg, Cit, or Asp concentrations have been reported from fetuses at day 125 (Satterfield et al., 2013) or day 140 of gestation or from lambs at 2 h post-birth (McCoard et al., 2013). Ornithine concentrations were greater at day 140 of gestation and tended to be greater at 2 h post-birth when ewes were infused with L-Arg-HCl (180 mg•kg BW-1•d-1; McCoard et al., 2013). However, when a nutrient restriction model was used, Satterfield et al. (2013) reported the greatest fetal Orn concentrations at day 125 of gestation from nutrient-restricted, Arg-infused (50% nutrient restriction; 81 mg L-Arg-HCl•kg BW-1•d-1) dams compared with all other fetuses. Zhang et al. (2016) supplemented nutrient-restricted ewes with RP-Arg (20 g RP-Arg/d to equal 10 g L-Arg/d) and reported elevated serum Arg concentrations, similar to concentrations for control-fed, from the umbilical vein at day 110 of gestation compared with fetuses from nutrient-restricted ewes. Ornithine and Cit concentrations for day 110 fetuses increased due to RP-Arg supplementation to nutrient-restricted dams compared with nutrient-restricted fetuses but were less than fetuses from control-fed dams (Zhang et al., 2016). Fetal plasma or serum Asp concentrations were not altered due to nutrient restriction or realimentation at day 78 or day 135 of gestation (Kwon et al., 2004) or RP-Arg supplementation at day 110 of gestation (Zhang et al., 2016). Citrulline and Asp produce Arg for metabolism into nitric oxide via nitric oxide synthase. Aspartate joins Cit to produce argininosuccinate and then Arg. The Arg produced can interact with NADPH, H+, and O2 in a reaction catalyzed by nitric oxide synthase to produce Cit, nitric oxide, H2O, and NADP+. In the current study, while Cit concentrations from RES-ARG offspring were similar to RES, Asp concentrations tended to be similar between the CON and RES-ARG offspring, and Arg concentrations at day 54 were greater for RES-ARG compared with CON offspring with RES intermediate and equal to both. Other amino acids of interest associated with Arg metabolism, Pro, Glu, Gln, and Met, provide inconsistent results with Arg supplementation. For their nutrient-restricted model, Kwon et al. (2004) reported no changes due to nutrient restriction for day 78 Glu and Met, but day 78 Pro and Gln and day 135 Pro, Glu, Gln, and Met were reduced for fetuses from nutrient-restricted dams, and realimentation from days 78 to 135 increased concentrations of Pro, Glu, and Met at day 135 of gestation to intermediate concentrations. Maternal Arg infusion tended to increase Pro concentrations of lambs 2 h post-birth, and Met concentrations for fetuses at day 140 of gestation decreased when ewes were infused with Arg (McCoard et al., 2013) while at day 140 of gestation fetal plasma Pro, Glu, and Gln and at 2 h post-birth lamb plasma Glu, Gln, and Met were not different due to maternal Arg infusion. Maternal RP-Arg resulted in similar concentrations of Pro as control fetuses at day 110 that were greater than fetuses from restricted ewes, Glu and Gln concentrations from maternal RP-Arg fetuses were similar to fetuses from restricted ewes and less than fetuses from control-fed ewes, Met concentrations for fetuses from RP-Arg ewes were less than fetuses from control-fed ewes and greater than fetuses from restricted ewes (Zhang et al., 2016). For the current study, there were no differences between the cationic amino acids (Lys or His) that compete for similar transport systems as Arg due to maternal RP-Arg supplementation. Similarly, Satterfield et al. (2013) and Zhang et al. (2016) reported no differences for fetal plasma Lys or His concentrations at day 125 due to maternal arginine infusion (81 mg L-Arg HCl•kg BW-1•d-1) or at day 110 due to maternal RP-Arg supplementation (20 g RP-Arg/d to equal 10 g L-Arg/d), respectively. McCoard et al. (2013) reported no change for fetal Lys at day 140 of gestation, but fetal His concentrations decreased due to maternal Arg supplementation (180 mg L-Arg HCl•kg BW-1•d-1); however, at 2 h after birth, lambs born in the second cohort of the study had opposite results where there was no change for His concentrations, but there was a tendency for increased Lys concentrations due to maternal Arg supplementation. In a nutrient-restricted model, Kwon et al. (2004) reported no change for fetal Lys and His concentrations at day 78 of gestation; however, at day 135 of gestation, fetuses from control ewes had the greatest Lys concentrations, restricted were intermediate, and fetuses from realimented ewes had the least circulating Lys, and for His, fetuses from control and realimented ewes had similar concentrations that were greater than fetuses from restricted ewes. Amino acids are important not only for fetal and placental growth during gestation but also for growth of young mammals. Several studies have provided insight into fetal amino acid status during gestation with or without maternal restriction dietary treatments (Kwon et al., 2004; McCoard et al., 2013; Satterfield et al., 2013; Zhang et al., 2016). However, very few studies of amino acid profiles have been reported for the postnatal to weaning phase of growing mammals. Tatara et al. (2014) reported amino acid profiles of 22 amino acids from ram lambs at 21 and 150 d of age (early post-natal life and after development of the rumen) where five essential (Arg, Trp, Thr, Lys, and His) and five non-essential (Pro, Tyr, Cit, Glu, and Ser) amino acids had decreased concentrations of 21.9% to 70.2% from days 21 to 150 of age, Phe showed a strong tendency to be reduced for 150-d-old lambs, nine amino acids (Cys, Tau, Asp, Gln, Gly, Ala, Val, Leu, and Orn) showed no differences between the age groups, and Ile and one non-essential amino acid had a 36.9% and 119.6% increase when lambs had functioning rumens. While the current study did not evaluate offspring to 150 d of age, the current study did evaluate 10 circulating amino acids associated with Arg metabolism from birth until day 54 of age. In the current study, the most notable changes were increased concentrations of Arg, Orn, Cit, Asp, Glu, and Lys. Arginine had a 406.9% increase from birth to day 7 of age. Concentrations of Orn had a 189.7% increase from days 1 to 54 of age. A 351.4% increase for Cit concentrations occurred form days 1 to 3 of age. From birth to day 7 of age, Asp concentrations increased by 231.2%. Glutamate and Lys concentrations increased by 165.4% and 351.3%, respectively, from birth to day 54 of age. Other concentration changes ranged from a 10.3% to 60.9% decrease and a 24.5% to 59.9% increase. The notable increases of Glu, Orn, Cit, Asp, and Arg make for an interesting picture. The increased Glu can increase α-ketoglutarate that can feed into the TCA cycle or increase Orn concentrations. Increased Orn can increase polyamine synthesis or Pro concentrations that result in increased levels of either hydroxyproline or Arg that result in increased urea or Cit. The elevated Asp concentrations can join with the elevated Cit to produce arginosuccinate and ultimately, Arg. In contrast, the elevated Cit concentrations may indicate increased production of nitric oxide from Arg. Offspring from the current study from ewes that received RP-Arg were reported to have increased lamb birth weight, average daily gain from days 14 to 19 of age, girth measurements at birth and days 19 and 54 of age, and curved crown rump measurements at day 54 of age (Peine et al., 2018), and the elevated amino acids may have contributed to the postnatal growth changes. Conclusion Data from this study demonstrate maternal RP-Arg supplementation during the last two-thirds of gestation has the potential to alter offspring metabolism of Arg and related amino acids. However, for the current study, we reject the hypothesis that RP-Arg supplementation during gestation will restore maternal carotid artery hemodynamics to control levels in at-risk pregnancies. 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TI - Effects of maternal nutrition and rumen-protected arginine supplementation on maternal carotid artery hemodynamics and circulating amino acids of ewes and offspring
JF - Journal of Animal Science
DO - 10.1093/jas/skab201
DA - 2021-11-01
UR - https://www.deepdyve.com/lp/oxford-university-press/effects-of-maternal-nutrition-and-rumen-protected-arginine-fe4pJOG4oK
VL - 99
IS - 11
DP - DeepDyve
ER -