Journal of Animal Science

Myer, R., O.;Gorbet, D., W.;Combs, G., E.

doi: 10.2527/jas1986.6251290xpmid: N/A

Abstract Two 2 × 2 randomized, complete-block trials were conducted in consecutive years to evaluate effects of storage method (high-moisture vs dry) and tannin level (high variety vs low variety) on nutritional value of grain sorghum for growing-finishing swine. High-moisture (HM) grains were harvested and anaerobically stored at 24 to 26% moisture. After 6 mo storage, HM grains were dried (35 C) to 11 to 12% moisture before incorporation into diets. Dry grains were harvested at 18 to 20% moisture, dried (40 C) to 11 to 12% moisture and stored in aerated bins. For each trial, 48 crossbred pigs (28 kg) were used for a total of three pens of four pigs each per treatment. Level of dietary grain was constant within grower or finisher diets. During the grower phase, apparent digestibilities of dry matter (DM), crude protein (CP) and gross energy were determing using chromic oxide as an indigestible indicator. The HM storage reduced tannin content of high-tannin grain sorghum by 27 and 30%, respectively, for the two crops. Over both trials, daily weight gain was not affected (P>.05) by treatment. Feed efficiency (P<.01) and DM (P<.01), energy (P<.05) and CP (P< .01) digestibilities were improved by HM storage of the grain sorghums; however, feed consumption was decreased (P<.01). Pigs fed diets containing high-tannin grain sorghum had poorer (P<.01) feed efficiency than did those fed low-tannin diets but feed consumption was similar (P>.05). Diets containing high-tannin grain sorghum had lower (P<.01) energy, CP and DM digestibilities than did diets containing low-tannin grain. High-moisture storage of high-tannin grain sorghum was not (P>.05) particularly beneficial for improving feed efficiency or DM, energy or protein digestibilities over that of pigs fed diets containing low-tannin grain sorghum stored in the high-moisture state. This content is only available as a PDF. Author notes 3 Agr. Res. and Educ. Center, Marianna 32446. 4 Dept. of Anim. Sci., Univ. of Florida, Gainesville 32611. 5 Inst. of Food and Agr. Sci., Agr. Res. and Educ. Center. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Lindemann, M., D.;Cornelius, S., G.;El Kandelgy, S., M.;Moser, R., L.;Pettigrew, J., E.

doi: 10.2527/jas1986.6251298xpmid: 2424884

Abstract Thirty-seven pigs were used to evaluate the effects of age and weaning on the level of protease in the gastric mucosa and trypsin, chymotrypsin, amylase and lipase in the pancreas. There was a positive allometry of the pancreas and gastric mucosa associated with age and with weaning to a solid diet. Increases with age in total activity of chymotrypsin. trypsin, amylase and gastric proteases were due to increases in both tissue weight and enzyme activity per gram of tissue. A general depression in pancreatic enzymatic activities, but not in gastric proteolytic activity, was found during the first week following weaning. Forty pigs were used in a second trial to evaluate the effects of age and weaning diet on the same digestive enzymes. Total activity of all enzymes assayed increased with time postweaning. Increases in total activity of lipase and chymotrypsin were due primarily to increased pancreatic weight postweaning. Amylase trypsin and gastric protease increases were due both to increased tissue weight and increased activity per gram of tissue. There were no effects of diet on the weight of gastric mucosa or the level of activity of the gastric proteases. Pigs fed a diet containing 20% whey had larger pancreases (P<.10) at slaughter and a greater, but nonsignificant, mean activity per gram of pancreas for all pancreatic enzymes. It appears that the pig has sufficient pancreatic and gastric enzyme activity so that performance should not be limited, with the possible exception of the period shortly after weaning. However diet digestibility and subsequent pig performance may be more directly related to the extent of release of these enzymes into the intestine and the conditions that exist therein. This content is only available as a PDF. Author notes 3 Present address: Virginia Polytechnic Inst. and State Univ., Tidewater Res. Center, Suffolk 23437. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Galitzer, S., J.;Oehme, F., W.;Bartley, E., E.;Dayton, A., D.

doi: 10.2527/jas1986.6251308xpmid: 3722021

Abstract Thirty-six steers (148 to 500 kg) divided into six equal groups were used in a toxic syndrome study of lasalocid and monensin given as a single oral dose. One group was given a placebo, a second group received monensin (25 mg/kg body weight) and the other four groups received lasalocid at 1, 10, 50 or 100 mg/kg body weight (bw). No toxic signs developed in cattle given placebo or lasalocid at 1 or 10 mg/kg bw dose. The earliest toxic signs were muscle tremors, tachycardia and rumen atony. After 24 h, the cattle were dehydrated, anorectic and had diarrhea. Deaths occurred between d 1 and 22.5 in the groups receiving lasalocid at 50 and 100 mg/kg bw and monensin. Altered values in blood leucocytes, erythrocytes, hemoglobin, hematocrit, total protein, albumin, creatinine, urea nitrogen, total bilirubin, creatine kinase, lactic dehydrogenase, calcium, chloride and inorganic phosphate occurred 1 d after dosing; urine pH and specific gravity also changed 1 d after dosing. Maximum changes occurred at d 3. Most of the changes were indicative of dehydration rather than specific organ damage. This content is only available as a PDF. Author notes 2 The authors are grateful to Mr. Lloyd Manthe for his invaluable assistance. 3 This study was one of the last projects Dr. Bartley completed before his death. 4 Present address: Pfizer, Inc., Anim. Health Res., P.O. Box 88, Terre Haute, IN 47808. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Spicer, L., J.;Convey, E., M.;Tucker, H., A.;Echternkamp, S., E.

doi: 10.2527/jas1986.6251317xpmid: 3087926

Abstract Changes in numbers of ovarian follicles and coincident secretion of pituitary gonadotropins were characterized in suckled, anovulatory beef cows injected iv with 500 ng of luteinizing hormone-releasing hormone (LHRH) every 2 h for 48 or 96 h, starting 21.4 ± .4 d after parturition. Two hours after the last injection, all cows were ovariectomized. Compared with saline-injected controls, LHRH had no effect on baseline or overall concentrations of luteinizing hormone (LH) in serum (P>.10), but increased (P<.05) frequency and decreased (P<.05) amplitude of LH pulses. Luteinizing hormone-releasing hormone increased (P<.05) baseline concentration of follicle stimulating hormone (FSH) in serum and frequency of FSH pulses, but decreased (P<.05) pulse amplitude. Overall concentrations of FSH increased 20% (P<.10). Exogenous LHRH did not affect diameter of the two largest follicles or numbers of follicles 1.0 to 3.9 mm, 4.0 to 7.9 mm or ≥8.0 mm in diameter. These data suggest that increasing the frequency of episodic LH and FSH pulses in postpartum cattle by intermittent administration of LHRH did not increase mean circulating levels of LH, or alter size and numbers of ovarian follicles within the 96-h period of injections. Thus, induction of ovulation in anovulatory cows treated with low-dose injections of LHRH cannot be explained on the basis of an increase in mean concentrations of LH or numbers of antral follicles within 96 h after initiation of injections. This content is only available as a PDF. Author notes 3 Present address: M. S. Hershey Medical Center, Pennsylvania State Univ., Hershey, PA 17033. 4 Present address: Merck, Sharp and Dohme Res. Lab., Merck & Co., Inc., Rahway, NJ 07065. 6 Roman L. Hruska U. S. Meat Anim. Res. Center. 7 Dept. of Anim. Sci. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Spicer, L., J.;Convey, E., M.;Tucker, H., A.;Echternkamp, S., E.

doi: 10.2527/jas1986.6251324xpmid: 3522520

Abstract To examine ovarian follicular response to low-dose injections of luteinizing hormone-releasing hormone (LHRH), 32 anovulatory, suckled beef cows were allotted to one of four treatment groups and injected with either saline or 500 ng LHRH every 2 h for 48 or 96 h, starting 21.4 ± .4 d after parturition. Two hours after the last injection of LHRH, cows were ovariectomized and 10 to 15 ovarian follicles per pair of ovaries were removed and categorized by diameter as small (1.0 to 3.9 mm), medium (4.0 to 7.9 mm) or large (≥8.0 mm). Injections of LHRH did not affect (P>.10) steroid levels in small follicles or numbers of gonadotropin receptors in small and medium follicles. Concentrations of progesterone in fluid of medium follicles increased 1.5-fold (P<.05) after 96 h of LHRH, whereas concentrations of estradiol and andros-tenedione were unchanged. In fluid of large follicles, concentrations of progesterone were fourfold greater (P<.05) in LHRH-treated than in control cows at 48 h, but by 96 h progesterone was twofold greater (P<.05) in control than LHRH-treated cows. In large follicles, concentrations of estradiol were unchanged (P>.10) after 48 h of LHRH injections but after 96 h estradiol was twofold greater (P<.05) in LHRH-treated than control cows. Increased concentrations of estradiol in large follicles coincided with increased numbers of binding sites for human chorionic gonadotropin (hCG) but not follicle stimulating hormone (FSH) in granulosa and theca. At 96 h, a greater proportion (P<.05) of LHRH-treated than control cows had at least one large follicle with concentrations of estradiol greater than progesterone (estrogen-active). The high concentrations of estradiol in estrogen-active follicles in LHRH-treated cows were associated with greater binding capacity of FSH to granulosa cells than found in estrogen-inactive (progesterone > estradiol in fluid) follicles. We suggest that increased capacity of large follicles to produce initially progesterone and bind hCG, then produce subsequently greater amounts of estradiol and bind FSH may be important steps in initiating ovulation in anovulatory cows treated with low-dose injections of LHRH. This content is only available as a PDF. Author notes 3 Present address: M. S. Hershey Medical Center, Pennsylvania State Univ., Hershey, PA 17033. 4 Present address: Merck, Sharp and Dohme Res. Lab., Merck and Co., Inc., Rahway, NJ 07065. 6 Roman L. Hruska U. S. Meat Anim. Res. Center. 7 Dept. of Anim. Sci. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Miller, C., J.;Amann, R., P.

doi: 10.2527/jas1986.6251332xpmid: 3522521

Abstract With the goal of hastening puberty, we evaluated the effects of dose of gonadotropin releasing hormone (GnRH) during pulsatile injection on luteinizing hormone (LH) secretion in bulls 6, 10 or 14 wk old, and of pulsatile administration of GnRH every 2 h to bulls from 6 to 12 wk of age on reproductive development. Based on response to the last three of 12 bihourly injections of 20, 200 or 2,000 ng GnRH/kg, only the two higher doses of GnRH induced secretion of LH at 6 wk. At all ages, 200 ng GnRH/kg induced maximal discharges of LH. Based on comparisons between seven treated bulls and their identical twins, bihourly injections of GnRH starting on d 42 elicited discharge of LH for ≤4 d in progeny of one sire and >28 d but <42 d in progeny of another sire. After 14 d of treatment, both elicited and spontaneous discharges of LH were smaller in all treated bulls. Within 2 d after cessation of GnRH injections on d 84, LH discharges were similar in frequency and amplitude in treated and control twins. Testicular and body growth were similar in treated and control bulls, but puberty was delayed (P<.05) in bulls in which exogenous GnRH suppressed endogenous discharges of LH. This content is only available as a PDF. Author notes 2 Anim. Reprod. Lab. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Whisnant, C., S.;Thompson, F., N.;Kiser, T., E.;Barb, C., R.

doi: 10.2527/jas1986.6251340xpmid: 3013825

Abstract Two experiments were conducted with the opioid antagonist naloxone to determine the effect of opioid receptor blockade on hormone secretion in postpartum beef cows. In Exp. 1, nine anestrous postpartum beef cows were used to measure the effect of naloxone on serum luteinizing hormone (LH), Cortisol and prolactin concentrations. Cows received either saline (n = 4) or 200 mg naloxone in saline (n = 5) iv. Blood samples were collected at 15-min intervals for 2 h before and after naloxone administration. Serum LH concentrations increased (P<.01) in naloxone-treated cows from 1.8 ± .04 ng/ml before treatment to 3.9 ± .7 ng/ml and 4.2 ± .5 ng/ml at 15 and 30 min, respectively, after naloxone administration. In contrast, LH remained unchanged in saline-treated cows (1.6 ± .3 ng/ml). Serum Cortisol and prolactin concentrations were not different between groups. In Exp. 2, 12 anestrous postpartum beef cows were used to examine the influence of days postpartum on the serum LH response to naloxone. Four cows each at 14 ± 1.2, 28 ± .3 and 42 ± 1.5 d postpartum received 200 mg of naloxone in saline iv. Blood samples were taken as in the previous experiment. A second dose of naloxone was administered 2 h after the first, and blood samples were collected for a further 2 h. Serum LH concentrations increased (P<.01) only in cows at 42 d postpartum. Serum LH concentrations in cows at 42 d postpartum increased from 2.1 ± .4 to 3.6 ± .6 ng/ml and from 2.2 ± .3 to 3.4 ± .5 ng/ml after the first and second administrations of naloxone, respectively. These results suggest that endogenous opioids influence LH secretion in the postpartum beef cow, and that the ability of naloxone to increase serum LH concentrations changes during the postpartum period. This content is only available as a PDF. Author notes 1 The research was conducted with State, Hatch and USDA funds. The authors wish to thank Dr. George Rampacek, Univ. of Georgia, Dr. Robert R. Kraeling, USDA-ARS and Dr. John Stuedeman, USDA-ARS for their advice and help in conducting this research. LH for iodination was donated by Dr. L. E. Reichert, Jr. Albany Medical College. 2 Dept. of Anim. and Dairy Sci., College of Agr. 3 Dept. of Physiol. and Pharmacol., College of Vet. Med., Univ. of Georgia, Athens, GA 30602. 4 USDA-ARS, Russell Res. Center, Athens, GA 30613. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Pratt, B., R.;Wettemann, R., P.

doi: 10.2527/jas1986.6251346xpmid: 3087927

Abstract Twenty-four Angus × Hereford steers (155 ±4 kg) were used to examine thyroid function during exposure to ambient temperatures of 4, 18 and 32 C. Jugular cannulae were inserted after steers were acclimated to individual stalls in environmentally controlled chambers at 18 C for 3 d. The day following cannulation. ambient temperatures were changed 2 C/h for 7 h and serum samples were collected hourly. After steers were exposed to either 4, 18 or 32 C for 1 and 72 h, thyrotropin releasing hormone (TRH; 50 µg. iv) was rapidly infused. Serum samples were collected hourly for 8 h after each treatment with TRH and every 8 h for 3 d between treatments. Rectal temperatures and respiratory were greater (P<05) in steers exposed to 32 C compared with steers at 4 C. During the change in environmental temperature, the concentrations of thyroxine (T4) and triiodothyronine (T3) over time tended (P<10) to decrease in steers exposed to 32 C compared with those at 4 C. Concentrations of T4 and T3 after the second treatment with TRH were significantly less in steers exposed to 32 C compared with those at 4 C. The response of T4 to TRH was reduced (P<.01) after the second treatment with TRH compared with the first for steers exposed to all three temperatures, whereas, the response of T0 was reduced (P<.05) after the second treatment with TRH only in steers exposed to 32 C. These data suggest that exposure of steers to elevated temperature for 3 d reduces the response of T3 and T4 to treatment with TRH and that the response of T4 is reduced after a second injection of TRH 3 d after the first treatment. This content is only available as a PDF. Author notes 2 Present address: Dept. of Anim. and Vet. Sci., Univ. of Maine, Orono 04469. 3 Anim. Sci. Dept., Oklahoma State Univ., Stillwater 74078. Copyright 1986 by American Society of Animal Science American Society of Animal Science

Garcia-Winder,, M.;Lewis, P., E.;Deaver, D., R.;Smith, V., G.;Lewis, G., S.;Inskeep, E., K.

doi: 10.2527/jas1986.6251353xpmid: 3087928

Abstract Two experiments were designed to examine whether hormonal profiles were related to luteal life span in pluriparous postpartum anestrous beef cows. Cows (Exp. 1, n = 34; Exp. 2, n = 23) received norgestomet (N) for 9 d or served as controls (C). Each cow received 1,000 IU human chorionic gonadotropin (hCG) 48 h after removal of N (d 0). Blood samples collected every 15 min for 8 h on d −5, 3 and 5 (Exp. 1) or on d −10 and −1 (Exp. 2) were assayed for luteinizing hormone (LH) and follicle stimulating hormone (FSH). Cortisol was determined in hourly samples collected on d −5 and in samples collected every 2 min during suckling on the same day (Exp. 1). Concentrations of 15-keto-13,14-dihydro-PGF2α (PGFM) were determined in samples collected at 15-min intervals for 2 h on d −5, 3, 5 and 10 (Exp. 1). EstradioI-I7β was measured in samples collected on d −5 (Exp. 1) or on d −10 and −1 (Exp. 2). Life span of induced corpora lutea was longer (P<.05) in N than C cows. Percentages of N cows in which corpora lutea, formed in response to hCG, exhibited a normal life span were 83% on farm 1 and 25% on farm 2 (Exp. 1), and 90% (Exp. 2), compared with 0% in C cows. Concentrations of FSH were not affected by N but were lower (P<.05) on d −5 in cows on farm 2 (.6 ± .1 ng/ml) than in cows on farm 1 (.8 ± .1 ng/ml). On d −5, a treatment × farm interaction (P<.05) for mean LH was observed and frequency of pulses of LH was higher (P<.01) in N than C cows (2.7 ± .4 vs .8 ± .8 pulses/8 h). Neither Cortisol nor PGFM was affected by N. Estradiol was increased in d −1 (6.1 ± .5 vs 2.6 ±.8 pg/ml; P<.01) by N. It is suggested that pre-treatment with N enhanced life span of induced corpora lutea, in part, by influencing secretion of LH and development of follicles, but a threshold concentration of FSH was required for N to exert this effect. This content is only available as a PDF. Author notes 3 The Upjohn Co., Kalamazoo, MI 49001. 4 Beltsville Agr. Res. Center-East, USDA, Beltsville, MD 20705 Copyright 1986 by American Society of Animal Science American Society of Animal Science

Anthony, R., V.;Bellows, R., A.;Short, R., E.;Staigmiller, R., B.;Kaltenbach, C., C.;Dunn, T., G.

doi: 10.2527/jas1986.6251363xpmid: 3722022

Abstract Fifty-nine crossbred heifers (427 kg) bred to one Hereford sire were randomly assigned at 75 d prepartum to two diets. Heifers were individually fed, and diets were isocaloric but contained either a low (LP = 81% NRC, .56 kg/d) or high (HP = 141% NRC, .98 kg/d) level of crude protein. Jugular vein cannulae were inserted into 16 LP and 16 HP heifers at 10 d prepartum. Daily preprandial blood samples that were collected until parturition were analyzed for serum estradiol-17ß (E2), progesterone (P4), glucose (G) and urea nitrogen (UN). Heifers fed LP gained slower than HP-fed heifers before calving (.73 vs 1.02 kg/d; P<.01); immediate post-calving weights and condition scores were 418 vs 444 kg (P<.01) and 5.4 vs 6.1 (P<.01; LP vs HP, respectively). Calf birth weights (35.3 vs 36.1 kg), average calving difficulty score (1.6 vs 1.6) and percent assisted births (35.5 vs 35.7%) did not differ (P>.10; LP vs HP, respectively). Prepartum concentrations of UN (6.2 vs 13.5 mg/dl) and G (52.9 vs 58.2 mg/dl) were lower (P<.05) and P4 (5.94 vs 4.26 ng/ml) was higher (P=.07) in LP heifers. Prepartum concentration profiles were related to calving difficulty score (CD, 1 = no assistance to 3 = hard pull) for E2 (CD1 vs CD2 + CD3, P<.01; CD2 vs CD3, P=.01), P4 (CD1 vs CD2 + CD3, P<.05), G (CD1 vs CD2 + CD3, P<.05) and UN (CD2 vs CD3, P<.05). After calving, all dams were maintained together on pasture and supplemented with alfalfa hay and grain mix until adequate range forage was available to maintain weight gains. Dams that were fed LP prepartum gained faster than HP dams during this period (.49 vs .15 kg/d; P<.01). Prebreeding weights (443 vs 453 kg; LP vs HP) and condition scores (5.1 vs 5.1) did not differ, nor was the postpartum interval affected (44 vs 40 d; LP vs HP). There was no effect of dietary protein on dystocia or postpartum interval, although there were diet-induced differences in body weight and condition of the dams at calving. Results indicate that differences in prepartum profiles of serum steroid hormones and metabolites may be related to dystocia, in addition to relative fetal oversize. This content is only available as a PDF. Author notes 2 Research completed as partial requirement for the Ph.D. degree at the Univ. of Wyoming, Laramie. Present address: Dept. of Biochem., J. Hillis Miller Health Center, Box J-245, Univ. of Florida, Gainesville 32610. 3 Fort Keogh Livestock and Range Res. Lab. USDA-Agr. Res. Serv. 4 Division of Anim. Sci., Univ. of Wyoming, Laramie 82071. 6 The cooperation of the Montana Agr. Exp. Sta. is appreciated and acknowledged. Copyright 1986 by American Society of Animal Science American Society of Animal Science