Journal of Animal Science

Baker,, J.F.;Stewart, T., S.;Long, C., R.;Cartwright, T., C.

doi: 10.2527/jas1988.6692147xpmid: 3170369

Abstract Multiple regression and principal components analyses were employed to examine relationships among pubertal and growth characters. Records used were from 424 bulls and 475 heifers produced by a diallel mating of Angus, Brahman, Hereford, Holstein and Jersey breeds. Characters studied were age, weight and height at puberty and measurements of weight and hip height from 9 to 21 mo of age; pelvic measurements of heifers also were included. Measurements of weight and height near 1 yr of age were related most highly to pubertal age, weight and height. Larger size near 1 yr of age was associated with younger, larger animals at puberty. Growth rate was associated with pubertal characters before, but not after, adjustment for effects of breed-type. Principal components of the variation of pubertal and growth characters among animals were strongly related to both weight and height. The majority of the variation among breed-types was due to height. Characteristic vectors of principal components describing the variation of bulls and heifers were strikingly similar. The variance-covariance structure of pubertal characters was essentially the same for both sexes even though the mean values of the characters differed. This content is only available as a PDF. Author notes 1 Dept. of Anim. Sci. 2 Present address: Dept. of Anim. Sci., Purdue University, West Lafayette, IN 47907. 3 Present address: Texas A&M Univ. Agric. Res. and Ext. Center, Overton 75684. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Houpt, K., A.;Houpt, T., R.

doi: 10.2527/jas1988.6692159xpmid: N/A

Abstract The social and physical environmental preferences of horses were studied using preference testing, changes in behavior with changes in the social environment and operant conditioning. The preference of 10 mares for visual contact with other mares was determined by measuring the time spent in a position where they could watch other horses vs a position where they could not. Although horses spent slightly over half their time in a position where they could watch other horses, the time spent where they could watch other horses was not significantly greater than the time spent in the position where they could not. When the behaviors of the same 10 mares in three different social environments were compared, horses with no other horses present were three times more active and spent 10% less time eating than those that could make visual, auditory and physical contact with other horses. Using an operant conditioning technique, each of five horses in a dark environment learned to turn on lights, indicating a preference for a lighted environment. This content is only available as a PDF. Author notes 1 Dept. of Physiol., New York State College of Vet. Med. 2 The authors gratefully acknowledge the assistance of Soroya Juarbe-Diaze, Warren Rivera and Heidi Johnson. We also are grateful to Ellis Loew for measuring the illumination. 3 Supported by a grant from Humane Information Serv., Inc., St. Petersburg, FL. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Rohde Parfet, K., A.;Gonyou, H., W.

doi: 10.2527/jas1988.6692165xpmid: 3170370

Abstract In the first of two studies on teat-seeking behavior of newborn pigs, latencies from birth to first mammary contact (LMC) and to first suckle (LS) were recorded by live observation (n = 66). LMC accounted for 66% of LS and variances were similar between these two measures, suggesting that LMC is a good predictor of time to first suckle. In a second experiment, 32 litters of pigs were farrowed in crates equipped with either solid, vertically slatted, horizontally slatted or diamond mesh creep partitions. Piglet behavior following parturition was recorded via time-lapse videotape. LMC was determined for each piglet and movements were plotted for four focal pigs/litter. Partition type did not affect LMC (mean = 34 min). LMC was significantly affected by number of littermates present during teat-seeking (P < .001), birth order (P < .001) and frequency of position changes by the sow (r = .26, P < .01). Neither sex nor birth weight affected LMC on a within-litter basis, but across litters smaller pigs had greater contact latencies (r = −.38, P < .001). Partition type did not affect distance traveled or time spent in contact with the sow, in contact with the creep partitions, free standing or the total of these. LMC was positively correlated (P < .05) with contact time with the sow (r = .34) and time behind the sow's back (r = .38) and negatively correlated with time spent free standing (r = −.35, P < .05) and in contact with the sow's rear legs (r = −.29; P < .10). This content is only available as a PDF. Author notes 1 The authors express their appreciation to D. Alexander for construction of the experimental crates, the staff of the Swine Research Center, and C. Edfors for assisting in viewing videotapes. 2 Current address: Dept. of Anim. Sci., Univ. of Missouri, Columbia. 3 Dept. of Anim. Sci. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Jenkins, T., G.;Leymaster, K., A.;Turlington, L., M.

doi: 10.2527/jas1988.6692174xpmid: N/A

Abstract Equations for estimating kilograms of fat-free soft tissue (sum of chemical protein and water) were developed from data collected on 40 crossbred lamb carcasses (½ Columbia-¼ Suffolk-¼ Hampshire). Estimative traits were chilled carcass weight, longissimus area, fat depth at the 12th rib and the fourth sacral vertebra, carcass length and resistive impedance. Resistive impedance estimates body composition by measuring the reduction in current as electricity passes through a carcass. The significance of fitting estimators individually or in combination was determined after statistical adjustment for variation in carcass weight. Mean slaughter weight of the lambs was 43.9 kg and mean chilled carcass weight was 20.8 kg. Fat-free soft tissue averaged 15.4 kg. At constant carcass weight, neither carcass length nor longissimus area significantly reduced variation in fat-free soft tissue. Fat depth at the 12th rib and fourth sacral vertebra explained 24 and 39%, respectively, of the variation in fat-free soft tissue among carcasses of equal weight. At a constant carcass weight, unattributed variation in fat-free soft tissue was reduced approximately 28% through use of resistive impedance measurements. Greater reduction in residual variation was realized by simultaneously fitting carcass and resistive impedance measurements. Residual variation in fat-free soft tissue was reduced 51% by fitting values for resistive impedance and fat depth at the fourth sacral vertebra. The need for accurate and precise equations to predict fat-free soft tissue for application in industry and research is discussed. This content is only available as a PDF. Author notes 2 Roman L. Hruska U.S. Meat Anim. Res. Center, P. 0. Box 166, Clay Center, NE 68933. 3 Dept. of Anim. Sci., Kansas State Univ., Manhattan 66506. 4 ARS. Mention of a trade name, proprietary product or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply approval to the exclusion of other products that may be suitable. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Johnson, R., D.;Hunt, M., C.;Allen, D., M.;Kastner, C., L.;Danler, R., J.;Schrock, C., C.

doi: 10.2527/jas1988.6692180xpmid: N/A

Abstract This study was conducted at a commercial beef slaughter plant to determine the effects of carcass washing, intermittent spray chilling and carcass fatness on carcass weight yields and on moisture content of cutaneous trunci muscle and s.c. adipose tissue (AT) samples excised from two carcass locations. Beef steer carcasses (n = 36) initially had 12.8% moisture in AT. Immediately following washing, AT from the sirloin region had more (P < .01) moisture (24.5%) than AT from the fifth-rib region (15.6%). Fat (n = 20) and lean (n = 20) carcasses were selected, and their right and left sides were allotted alternately to either a non-spray chill cycle or to an intermittent cold water spray-chilling cycle lasting either 3 or 6 h. After 20 h of chilling, carcasses subjected to the 6-h spray had 12.9% more (P < .01) AT moisture and possessed 2.6% more moisture in the cutaneous trunci muscle than similar samples from the non-spray. chilled counterparts. In comparison, AT samples that were subjected to the 3-h spray had 3.9% more (P < .05) moisture, and the cutaneous trunci muscle had 2.0% more moisture, than their dry-chilled counterparts. After chilling, the spray-chilled AT had substantially higher (P < .01) moisture in the fifth-rib region (26.1%) than in the sirloin (14.8%). Spray-chilled sides in the 6-h cycle gained .3% of their hot carcass weight, whereas the corresponding non-spray sides shrank 1.2%. Spray-chilled sides subjected to the 3-h cycle shrank .4%, and their dry counterparts shrank 1.1%. Carcass washing and length of spray cycle had a greater influence than carcass fatness on surface tissue moisture retention. Modulation of these factors will help control post-chilling fluctuation of carcass weights in excess of USDA regulations and yet maximize carcass weight yields. This content is only available as a PDF. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Miller, P., A.;Lawrence, L., M.

doi: 10.2527/jas1988.6692185xpmid: 3170371

Abstract Six mature Quarter Horse mares were used in a crossover design to assess the effect of dietary protein level on metabolic response to exercise. After a 2-wk adaptation period to either a 12.9% (control) or an 18.5% CP (high-protein) diet, each mare performed a standard exercise test. The test consisted of a 15-min exercise period at 4.5 m/sec on a 9% grade motorized treadmill. Exercise resulted in an increase in heart rate (P < .001), but there was no difference (P > .05) between dietary treatments. In the jugular vein, lactate increased (P < .01) from 6.3 to 52.0 mg/100 ml in the control group and increased from 6.3 to 45.6 mg/100 ml in the high-protein group. There was an interaction (P < .05) between diet and exercise for lactate. Plasma NH3 increased (P < .001) during exercise, but not until the 15th min, at which time NH3 increased over fourfold in both groups. Dietary protein did not affect NH3; however, urea-N was higher (P < .001) in horses receiving the high-protein diet. Plasma alanine increased from 13.6 to 30.3 µmol/100 ml and glutamine increased from 49.3 to 62.5 µmol/100 ml in the control group. In the high-protein group, alanine increased from 10.2 to 25.8 µmol/100 ml, whereas glutamine increased from 39.3 to 49.2,µmol/100 ml. Our study detected no metabolic evidence for a detrimental effect of excess dietary protein in horses exercising on a graded treadmill at 4.5 m/sec for 15 min. This content is only available as a PDF. Author notes 1 Dept. of Anim. Sci. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Cromwell, G., L.;Kemp, J., D.;Stahly, T., S.;Dalrymple, R., H.

doi: 10.2527/jas1988.6692193xpmid: N/A

Abstract Hampshire-Yorkshire pigs were used to evaluate the efficacy of the beta-adrenergic agonist cimaterol on performance and carcass characteristics and to determine whether the length of withdrawal period influenced the response to cimaterol. The basal diet was an unmedicated corn-soybean meal diet (14% CP) fortified with minerals and vitamins. Treatments were the basal diet, the basal plus .25 ppm cimaterol with a 1-, 3- or 5-d withdrawal period and the basal plus .5 ppm cimaterol with a 1-d withdrawal period prior to slaughter. Each diet was fed to eight pen-replicates of five pigs/pen from 62 to 107 kg. Growth rate and efficiency of feed utilization were improved (P < .03) by cimaterol. Pigs fed .5 ppm cimaterol tended to be less sound on their feet and legs (P < .10) and to have more hoof cracks and pad abrasions than controls. Carcass yield, backfat, longissimus area and calculated muscle percentage were improved (P < .05) by cimaterol, with the decrease in 10th rib fat depth (P < .10) and increase in percentage of muscle (P < .05) being greater for the .5 vs .25 ppm level of cimaterol. In pigs fed cimaterol, the proportion of fat in the longissimus was decreased (P < .05), whereas protein was increased (P < .10). Cimaterol is an effective repartitioning agent for pigs with the .5 ppm level being more effective than the .25 ppm level in improving carcass leanness and muscling, but resulting in more feet and leg unsoundness. A 3-or 5-d withdrawal of the .25 ppm level of cimaterol did not reduce its effectiveness. This content is only available as a PDF. Author notes 2 Dept. of Anim. Sci., Univ. of Kentucky. 3 American Cyanamid Co. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Holcombe, D., W.;Smith, G., S.;Khan, M., F.;Hallford, D., M.;Rozman,, K.

doi: 10.2527/jas1988.6692200xpmid: 3170372

Abstract Elimination of [14 C] heptachlor from body burdens of sheep was measured using mature ewes nursing single offspring, and the influence of exogenous ovine growth hormone (oGH) on elimination was studied. Six ewes (62 ± 2.5 kg BW) were dosed (i.p.) once with [14C] heptachlor (2.04 mg/kg BW; .88 µCi/mg heptachlor) and three were treated additionally with oGH (oGH; 5 mg/d) for 21 d. Three additional ewes served as controls. Excreta were collected each day for 21 d. Milk and blood were collected every 3rd d until ewes were euthanized at d 21. 14C activity was measured in excreta, milk, blood and tissues. Total cumulative activity of [14C] heptachlor and (or) metabolites in excreta (21 d) did not differ (P > .20) in ewes given oGH (25 ± 2%) vs none (23 ± 2%). Milk yield and protein content were unaffected (P > .10) by oGH. Ewes given oGH eliminated 2.2 ±.2% of total 14C dosage into milk during 21 d, whereas ewes untreated with oGH eliminated 1.3 ±.2% (P < .10); total 14C activity eliminated into milk plus excreta was similar for ewes given oGH or none (P > .10). For all six ewes, half-times (T1/2) for distribution and elimination of 14C activity (heptachlor and metabolites) were 1.5 d and 11.7 d, respectively. Blood concentrations of 14C activity during 21 d yielded elimination half-time as 23 d. Unlike bovines, which eliminate heptachlor slowly (T1/2 ≈70 to 80 d) and mainly into milk fat, lactating ovines eliminated heptachlor and (or) metabolites mainly into excreta and about sixfold faster than bovines. This content is only available as a PDF. Author notes 2 Present address: Dept. of Anim. Sci., Univ. of Nevada, Reno 89557. 3 Dept. of Anim. and Range Sci. Appreciation is expressed to the National Hormone and Pituitary Program for supplying the oGH (NIDDK-oGH-12, AFP4015A) and assay materials [anti-oGH (NIDDKanti-oGH2, AFP-C012308); iodination grade oGH (NIDDK-oGH-I-3, AFP-52856)] used in this experiment. We also thank D. Rankins, W. Hoefler, C. Roberts, M. Alikhani, R. Reynolds, D. Kious and M. Hoefler for their assistance. Direct reprint requests to G. S. Smith. 4 Kansas Univ. Medical Center, Kansas City. 5 Institut fur Toxikologie, GSF-Munchen, Fed. Rep. Germany. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Traywick, G., B.;Esbenshade, K., L.

doi: 10.2527/jas1988.6692209xpmid: 3139608

Abstract Sexually mature gilts (n = 20) were actively immunized against GnRH. Primary and booster immunizations of GnRH conjugated to bovine serum albumin induced production of antibodies in all gilts. Nineteen of the gilts became acyclic with suppressed concentrations of gonadotropins and estradiol. Intravenous challenges with 100 µg GnRH and 5 µg D-(A1a6, des-Gly-NH210) ethylamide GnRH (a GnRH agonist that did not cross-react with antibodies produced by the gilts) caused release of LH and FSH, indicating maintenance of secretory capacity of pituitary gonadotropes in the immunized animals. Gilts were given 100 ng GnRH agonist at 2-h intervals for 72 h (n = 4) or 144 h (n = 10) or did not receive agonist (n = 5). Blood samples were taken every 6 h, and detectable concentrations of LH were observed in 42% and 52% of samples taken from gilts treated with or without agonist. In contrast, serum concentrations of FSH and estradiol were undetectable. Reproductive tracts and anterior pituitaries were taken from gilts at the conclusion of pulsatile administration of GnRH agonist or at 144 h for controls. Pituitary concentration of LH and FSH, uterine wet and dry weight, and size of the uterus were similar among groups. Paired ovarian weights for treated gilts pulsed with GnRH agonist for 72 h were heavier (P < .05); however, ovaries from all immunized gilts were atrophied without follicular structures. These results indicate that the regimen of GnRH agonist used did not overcome the effects of active immunization of the gilt against GnRH. This content is only available as a PDF. Author notes 3 Dept. of Anim. Sci. Copyright 1988 by American Society of Animal Science. American Society of Animal Science

Armstrong, J., D.;Kraeling, R., R.;Britt, J., H.

doi: 10.2527/jas1988.6692216xpmid: 3170373

Abstract Lactating sows were used to evaluate effects of morphine and suckling on secretion of LH and prolactin (PRL) and occurrence of estrus after weaning. In the first experiment, crossbred multiparous sows nursing 7.9 ± .4 pigs per litter at 25.2 ± .3 d of lactation were subjected to one of three treatments during the middle 8-h segment of a 24-h experimental period. Treatments were infusion (i.v.) of morphine (200 mg/h) with the litter present (n = 4) or transiently weaned (n = 4), or transient weaning of litters without morphine (n = 4). Transient weaning decreased (P < .05) prolactin and increased (P < .05) the frequency of LH pulses and average concentration of LH. Infusion of morphine caused transient hyperthermia and suppressed (P < .05) LH release in two of four sows nursing litters and in four sows whose litters were absent. Infusion of morphine, in the presence or absence of litters, suppressed PRL during the middle and last 8-h segments. A second experiment was conducted to test the hypothesis that chronic administration of morphine delays onset of estrus after weaning. Primiparous Duroc sows were assigned at weaning (53 to 63 d postpartum) to receive morphine (n = 10) or saline (n = 11). Saline (1.5 ml) or morphine (75 mg) was administered s.c. three times a day for 5 d after weaning. Onset of estrus after weaning was delayed in sows given morphine compared with those given saline (9.7 ± .4 vs 5.2 ± .3 d, respectively; P < .05). Days from withdrawal of morphine to estrus (5.7 ± .3) were similar to days from weaning to estrus (5.2 ± .3). These results demonstrate that acute administration of morphine prevented the increase in LH secretion associated with transient weaning and that chronic administration of morphine delayed onset of estrus after weaning, presumably through suppression of LH secretion. This content is only available as a PDF. Author notes 2 Dept. of Anim. Sci., Physiol. Program. 3 Richard B. Russell ARS, USDA, Athens, GA 30613. Copyright 1988 by American Society of Animal Science. American Society of Animal Science