Journal of Animal Science

Rumsey, T., S.;Hammond, A., C.;McMurtry, J., P.

doi: 10.2527/1992.704995xpmid: 1582959

Abstract This study determined the influence of the estrogenic ear implant Synovex-S® on feedlot performance, tissue deposition, and thyroid status of growing-finishing beef steers implanted either once or reimplanted. The pattern of implant absorption was also determined. Two 112-d feeding trials were used with 48 Hereford steers per trial. Each trial was a randomized block design with eight groups (lots) of six steers each assigned to four treatments (two lots/treatment). Treatments were 1) no implant or control, 2) implanted on d 0 and reimplanted at 60 d on trial, 3) implanted at 30 d on trial, and 4) implanted on d 0 only. These implant treatments resulted in withdrawal periods before slaughter of approximately 60, 90 and 120 d for Treatments 2, 3, and 4, respectively. All steers were given ad libitum access to water and a 60% concentrate diet. Group intakes were determined daily, BW weekly, estimated body composition every 28 d, plasma thyroid hormone concentrations at 112 d and at slaughter, and carcass measurements and liver tissue deiodinase at slaughter. Approximately 25% of the original implant dose remained in the ear 60 d after implanting and this residual amount was absorbed linearly at the rate of approximately .15% of the original dose per day. Implant treatments increased (P < .05) DMI, BW gain, feed conversion, and empty body gains for water and protein. Carcass measurements suggested a nonsignificant trend (P > .10) for leaner carcasses for implanted steers. An immediate shift toward greater protein and less fat deposition occurred within 28 d after initial implanting (Treatment 3).(ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Author notes 1 Subtropical Agric. Res. Sta., P. O. Box 46, Brooksville, FL 34605. Copyright © 1992 by American Society of Animal Science

Perkins, T., L.;Green, R., D.;Hamlin, K., E.

doi: 10.2527/1992.7041002xpmid: 1582927

Abstract Yearling crossbred feedlot steers (n = 495) and heifers (n = 151) were ultrasonically measured at the 12-13th rib interface 24 h before slaughter to evaluate the accuracy of ultrasonic measurements of fat thickness (BFU) and longissimus muscle area (LMAU) for prediction of actual carcass measures. Isonification was with an Aloka 210DX ultrasound unit equipped with a 12.5-cm, 3.0-MHz, linear array transducer by two technicians. Carcass fat thickness (BFO and longissimus muscle area (LMAC) were measured 48 h postmortem. Differences between ultrasonic and actual carcass measures were expressed in actual (BFDIFF and LMADIFF) and in absolute (|BFDIFF| and |LMADIFF|) terms for backfat and longissimus muscle area, respectively. When expressed as percentages of the actual carcass measures, the average absolute differences indicated error rates of 20.6% for backfat and 9.4% for longissimus muscle area. Average actual differences (BFDIFF and LMADIFF) indicated that underprediction occurred more often than overprediction for both measures. The BFU was within .25 cm of BFC 70% of the time, and LMAU was within 6.5 cm2 of LMAC 53% of the time. Ultrasound measurements BFU and LMAU more accurately predicted BFC and LMAC in thinner and more lightly muscled cattle, respectively. Simple correlation coefficients between ultrasonic and carcass measures were .75 (P < .01) for BF and .60 (P < .01) for LMA. Analyses of variance of absolute differences between ultrasonic and carcass measures indicated no significant differences to exist between technicians. Predictive accuracy of ultrasonic measures did not change as the level of experience of technicians increased during the study.(ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Copyright © 1992 by American Society of Animal Science

Pond, K., R.;Holladay, S., D.;Luginbuhl,, J.-M.

doi: 10.2527/1992.7041011xpmid: 1582928

Abstract Two methods to preserve gastrointestinal tract (GIT) organs and tissues, plastic coating (PC) and plastination (PN), were investigated and compared. Specimens to be preserved were removed from animals within 2 h of death and immediately cleaned with water. Digesta contents were removed by flushing desired portions of GIT with water until the exiting water was clear. In the PC method, cleaned specimens were dehydrated by immersion in an isopropanol solution, dried with forced air after positioning and orientation as in situ, and finally coated on the outer and inner surfaces with a clear plastic material. In the PN procedure, specimens were filled with, and submerged in, a low-formaldehyde fixative, then dehydrated by immersion in a cold acetone solution. Dehydrated specimens were immersed in silicone and placed in a freeze drier for impregnation under low vacuum, followed by overnight gas curing with a silicone crosslinker. Finally, viewing windows were cut out with a scalpel in GIT preserved by both methods. Preserved GIT and tissues had an appearance similar to their appearance in vivo. The PC method was simple and inexpensive. Plastinated specimens were more flexible, durable, and lifelike than those preserved by the PC method. In addition, many body parts, such as muscles, nerves, bones, ligaments, and central nervous system specimens, were preserved by PN. Both methods were found to be useful tools for postmortem studies of tissues and GIT organs. This content is only available as a PDF. Copyright © 1992 by American Society of Animal Science

Turner, S., C.;McKissick, J., C.;McCann, M., A.;Dykes, N., S.

doi: 10.2527/1992.7041015xpmid: 1582929

Abstract Data from feeder cattle teleauction sales in Georgia from 1977 to 1988 were analyzed using least squares analysis of variance to detect significant (P < .05) influential factors on price. The sample was divided into two periods, 1977 to 1982 and 1983 to 1988, to test whether the influence of factors had changed over the time periods. The test of equality was rejected (P < .01) using a Chow test, thus suggesting a change had occurred. Hereford breeds were discounted in the latter period whereas Angus breeds generated a premium in the earlier period. Treatment for specific diseases resulted in premium prices, as did preconditioning, during the 1983 to 1988 period. The effect of seasonality on prices decreased over the two time periods. The optimal lot size increased from 228 to 280 cattle during the time periods. This content is only available as a PDF. Author notes 2 FAS, U.S. Dept. of Agric. Copyright © 1992 by American Society of Animal Science

Comerford, J., W.;House, R., B.;Harpster, H., W.;Henning, W., R.;Cooper, J., B.

doi: 10.2527/1992.7041022xpmid: 1582930

Abstract Fifty-eight Holstein and 58 crossbred beef steers were individually fed one of four isonitrogenous diets to evaluate the effects of forage source (corn silage and alfalfa haylage) and protein source (soybean meal and fish meal) on feedlot performance. Phase 1 diets (up to 354 kg of BW) were 40% forage and 60% concentrates and were fed for 70 to 136 d (depending on diet and breed group). Phase 2 diets (354 kg of BW until slaughter) were 20% forage and 80% concentrates and were fed for 127 to 150 d (depending on diet and breed group). Slaughter end points were .6 cm of 12th rib fat for Holsteins and 1.0 cm of rib fat for crossbreds using real-time ultrasonic estimates. The steers were fed for a maximum of 330 d each year. Forage source was a significant component of variation for most growth, efficiency, and carcass traits. Holstein and crossbred steers fed alfalfa haylage had significantly lower average daily gain, feed efficiency, dressing percentage, and empty body fat and required more days on feed to reach slaughter end points, but had higher total feed energy intake available for production. Steers fed corn silage diets had significantly greater energetic efficiency (P < .05) than those fed alfalfa haylage, due to increased use of ME to produce fat in the carcass. Protein type did not influence gain, feed or energetic efficiency, energy intake, or most carcass traits. A significant protein system × forage source interaction among the four diets was detected for crossbred steers fed corn silage and fish meal, for which there was significantly greater feed conversion with lower energy intake above maintenance, possibly due to better fiber digestion and(or) amino acid flow to the lower tract. Alfalfa haylage plus soybean meal diets decreased (P < .05) the percentage of Holsteins grading USDA Choice or higher. These results indicate that corn silage, because of greater energy concentration, was a more desirable forage in feedlot diets composed of ≤ 40% forage and that protein type (soybean meal and fish meal) in growing diets is not an important factor in feedlot performance or carcass traits of Holstein or crossbred steers that are fed these diets. This content is only available as a PDF. Author notes 1 Supported by Hatch Project 3116 and funded by the Pennsylvania Dept. of Agric., Agway, Inc., and Century Farms, Inc. The authors thank Don Nichols, Eric Lorenz, Jerry Smeal, and Don Butts (deceased) for their assistance in conducting this trial. Copyright © 1992 by American Society of Animal Science

Winder, J., A.;Rankin, B., J.;Bailey, C., C.

doi: 10.2527/1992.7041032xpmid: 1582931

Abstract Maternal performance of 134 Hereford (H), Brangus (B), and reciprocal crossbred (H × B and B × H) cows from 2 to 7 yr of age was evaluated tinder semidesert conditions in this study. Calves produced by 2- and 3-yr-old cows were sired by Brangus and Hereford bulls. Calves produced by 4- to 7-yr-old cows were sired by Charolais bulls. Breed of sire and breed of dam of cow affected kilograms of weaning weight, 205-d weight, weaning weight as a percentage of cow weight, and 205-d weight as a percentage of cow weight produced annually. Brangus (either as sire or dam of cow) was superior to Hereford in all cases. Observed maternal heterosis on 2- to 3-yr-old cows was 23.0, 20.1, 30.0, 29.1, 23.9, and 23.0% for calf birth date, weaning percentage, weaning weight per year, 205-d weight per year, weaning weight as a percentage of cow weight per year, and 205-d weight as a percentage of cow weight per year, respectively (P < .01). Observed maternal heterosis from mature cows was 19.8, 12.8, 21.0, 18.7, 17.4, and 15.4% for calf birth date, weaning percentage, weaning weight per year, 205-d weight per year, weaning weight as a percentage of cow weight per year, and 205-d weight as a percentage of cow weight per year, respectively (P < .01). Results indicate large heterotic effects on annual cow productivity and an adaptive advantage for cows with Brangus sires and(or) dams under semidesert conditions. This content is only available as a PDF. Copyright © 1992 by American Society of Animal Science

Brethour, J., R.

doi: 10.2527/1992.7041039xpmid: 1582932

Abstract Repeatability of ultrasound backfat measurements was determined on 217 cattle, and the association of ultrasound and carcass backfat measurements was evaluated with 580 animals. The correlation (repeatability) between consecutive ultrasound measurements was .975. Average difference between two ultrasound measures was .72 mm and error size was directly related (P < .001) to the amount of backfat. Ultrasound measures averaged 8% (P < .001) less than carcass measures. The average absolute difference between these two measures was 1.57 mm. Discrepancies were (P < .001) larger when backfat was thicker; cattle with backfat measuring < 10 mm averaged 1.43 mm absolute difference, whereas those with backfat > 10 mm averaged 1.89 mm. The variance of the discrepancies was partitioned into three components: ultrasound measurement error (14%), drift related to intercept and slope (15%), and residual (71%). The residual component may have represented errors in carcass measurement. In a subsequent trial with 175 cattle, average difference between ultrasound and carcass backfat measurements was reduced to 1.19 mm. Also, the slope and intercept virtually mimicked the isopach. Ultrasound measures can be more precise (minutely exact) and accurate (close to the true value) than carcass measures for assessing absolute backfat thickness in cattle. Elements of measurement protocol that may improve ultrasound technique are imparted in the manuscript. This content is only available as a PDF. Copyright © 1992 by American Society of Animal Science

Famula, T., R.

doi: 10.2527/1992.7041045xpmid: 1582933

Abstract Animals bred in pastoral systems are often part of multiple-sire groups, introducing uncertainty into pedigrees. Genetic evaluation of sires and dams in such instances is complicated by the uncertainty of parenthood. This article defines a simple and rapid algorithm to compute the inverse of a numerator relationship matrix under uncertain parenthood. The algorithm can accommodate inbreeding and uncertainty of parenthood on both paternal and maternal sides of the pedigree. This content is only available as a PDF. Copyright © 1992 by American Society of Animal Science

Woltmann, M., D.;Clutter, A., C.;Buchanan, D., S.;Dolezal, H., G.

doi: 10.2527/1992.7041049xpmid: 1582934

Abstract Selection in pigs for either fast line F) or slow (line S) postweaning gain was replicated in spring (SREP) and fall (FREP) farrowing groups. Littermate barrows were sampled from F and S during Generations 2, 3, and 4 of the SREP and Generation 3 of the FREP. Beginning at approximately 35 kg (OTWT), barrows were either allowed ad libitum access to feed (AL) or limited to a standard total feed intake CLIM). Blocks of the line × intake level factorial were removed from test and carcass data collected when the average weight of barrows in the block was approximately 110 kg. Carcass data were also collected on an additional barrow from each litter at OTWT to allow estimation of lean tissue gain per unit of feed consumed (LTFC) of tested barrows. In Generations 3 and 4 of the SREP, F-AL was greater (P < .01) than S-AL for average daily intake and ADG; carcass backfat was greater (P < .01) but LTFC tended to be less (P < .10) for F-AL than for S-AL. When LIM was imposed in the SREP, F barrows gained faster (P < .05) than S barrows in Generation 4, but across generation the lines did not differ for carcass backfat and LTFC was greater (P < .01) for F than for S. In the FREP, F-AL was greater (P < .05) than S-AL for average daily intake and ADG and was less (P < .05) for LTFC, but F and S did not differ for these traits when LIM was imposed; carcass backfat of F was greater (P < .01) than that of S by .46 cm under AL and .38 cm under LIM. Most of the response in ADG could be attributed to changes in intake, but results in Generation 4 of the SREP indicated that changes in efficiency had also contributed. Most of the additional intake in F vs S resulted in deposition of fat, probably due in part to the heavier weight of F-AL vs S-AL barrows. This content is only available as a PDF. Copyright © 1992 by American Society of Animal Science

Quinton,, M.;Smith,, C.;Goddard, M., E.

doi: 10.2527/1992.7041060xpmid: 1582935

Abstract Animal geneticists predict higher genetic responses to selection by increasing the accuracy of selection using BLUP with information on relatives. Comparison of different selection methods is usually made with the same total number tested and with the same number of parents and mating structure so as to give some acceptable (low) level of inbreeding. Use of family information by BLUP results in the individuals selected being more closely related, and the levels of inbreeding are increased, thereby breaking the original restriction on inbreeding. An alternative is to compare methods at the same level of inbreeding. This would allow more intense selection (fewer males selected) with the less accurate methods. Stochastic simulation shows that, at the same level of inbreeding, differences between the methods are much smaller than if inbreeding is unrestricted. If low to moderate inbreeding levels are targeted, as in a closed line of limited size, then selection on phenotype can yield higher genetic responses than selection on BLUP. Extra responses by BLUP are at the expense of extra inbreeding. The results derived here show that selection on BLUP of breeding values may not be optimal in all cases. Thus, current theory and teaching on selection methods are queried. Revision of the methodology and a reappraisal of the optimization results of selection theory are required. This content is only available as a PDF. Author notes 2 Victoria Dept. of Agric, E. Melbourne, Australia. Copyright © 1992 by American Society of Animal Science