Journal of Animal Science

Cisneros,, F.;Ellis,, M.;McKeith, F., K.;McCaw,, J.;Fernando, R., L.

doi: 10.2527/1996.745925xpmid: 8726722

Abstract Pigs representing two crossbred genotypes, a breeding company hybrid (BCH) and a three breed cross (Hampshire × [Yorkshire × Duroc]) (HYD) were evaluated at five slaughter weights (SLW): 100, 115, 130, 145, and 160 kg. A total of 160 pigs were grown in like-sex (barrows [B] or gilts [G]), like-genotype groups, with four pigs/group, from 60 kg live weight. A corn-soybean meal-based diet was available on an ad libitum basis (15.8% crude protein, 3,300 kcal/kg ME). One-half of the pigs from each group (80 pigs) were slaughtered for carcass and meat quality evaluation. Genotype BCH grew faster, had lower backfat depths in the loin and lumbar regions, and a smaller loin eye area than HYD, but both groups had a similar gain:feed ratio. Few consistent genotype differences in cutting and curing yields and meat quality were observed. Differences between sexes for growth and carcass traits were generally in agreement with previous research; however, the magnitude of the differences was small. There were few nonlinear regressions involving SLW and limited differences between genotypes or sexes in the slopes of the linear regressions. Increases in SLW were associated with increases in feed intake, backfat depth and loin eye area, and minimal changes in growth rate or gain:feed. Percentage of loin increased and ham, shoulder, and spare rib percentages decreased with slaughter weight. The weight of trimmed, boneless cuts increased with slaughter weight, but percentage trimmed, boneless cuts was reduced. Curing yields for belly increased with slaughter weight. Changes in meat quality with increasing slaughter weight were relatively small. Longissimus lumborum fat content increased and moisture content decreased with slaughter weight. These results suggest that modern genotypes can be slaughtered at live weights up to 160 kg with limited impact on growth performance, commercial meat yields, or meat quality characteristics. This content is only available as a PDF. Author notes 2 Financial support was provided by a scholarship from the Instituto Nacional de Investigaciones Forestales y Agropecuarias, Mexico. Copyright © 1996 by American Society of Animal Science

Leach, L., M.;Ellis,, M.;Sutton, D., S.;McKeith, F., K.;Wilson, E., R.

doi: 10.2527/1996.745934xpmid: 8726723

Abstract Growth performance, carcass characteristics, and meat quality of halothane carrier (Nn) and negative (NN) pigs grown from 40 kg live weight and slaughtered at three weights (110, 125, and 140 kg live weight) were studied. Daily gains were similar for the two genotypes (974 g for Nn and 964 g for NN), but Nn pigs had a higher gain:feed ratio than NN pigs (P < .01). Dressing percentage was higher in Nn pigs than in NN pigs (P < .001), but there were no genotype differences for carcass length, backfat thickness, or loin eye area. Percentage yield of trimmed, boneless wholesale cuts was higher for Nn pigs than for NN pigs (P < .05). This resulted from higher trimmed, boneless ham, boston, and picnic weights (P < .05) in Nn than in NN pigs (6.9, 3.2, 3.5 kg vs 6.6, 3.0, 3.4 kg, respectively). The weight of fat-free lean was higher in Nn pigs (P < .05). The longissimus thoracis muscle from carrier pigs had lower 45 min (P < .001) and 24 h (P < .01) pH. Longissimus lumborum samples from carriers had lower (P < .001) subjective meat quality scores and a higher drip loss (P < .001); however, cooking loss, eating quality, and shear force values were similar for the two genotypes. There were no important slaughter weight × genotype interactions for the traits reported. Overall, the data from this study suggest Nn pigs had an advantage over NN pigs in terms of feed efficiency, carcass yield fat-free lean content, and commercial lean cut yields but had a higher incidence of PSE. This content is only available as a PDF. Author notes 2 Pig Improvement Company, Inc., Franklin, KY. Copyright © 1996 by American Society of Animal Science

Kemp,, B.;Soede, N., M.

doi: 10.2527/1996.745944xpmid: 8726724

Abstract Data from two experiments were used to study the relationship between weaning-to-estrus interval (WEI, varying from 3 to 6 d) and the duration of estrus, the interval from onset of estrus to ovulation and fertilization results at 120 h after ovulation, in 201 multiparous sows. An increase in WEI resulted in a decrease in the duration of estrus (Duration of estrus (h) = [81 (exp1) or 88 (exp2)]−.33 × WEI, R2 = .25, P < .001) and a decrease in the interval from onset of estrus to ovulation (onset estrus to ovulation (h) = [54 (exp 1) or 59 (exp 2)]−.20 × WEI, R2 = .23, P < .001). Sows that were inseminated between 0 and 24 h before ovulation showed consistent high fertilization results (91% normal embryos), irrespective of WEI. Sows that were inseminated outside this range showed an increased proportion of unfertilized eggs (P < .001). This increase occurred similarly in all weaning to estrus intervals. These results suggest that negative effects of a longer WEI on subsequent litter sizes and farrowing rates as described in literature might be a result of suboptimal timing of insemination relative to ovulation and not of poor fertility in these sows. This content is only available as a PDF. Copyright © 1996 by American Society of Animal Science

Adams, T., E.;Daley, C., A.;Adams, B., M.;Sakurai,, H.

doi: 10.2527/1996.745950xpmid: 8726725

Abstract Testes function, feedlot performance, and carcass traits were evaluated in bulls actively immunized against gonadotropin-releasing hormone (GnRH) at different ages. Bull calves were randomly assigned to one of seven treatment groups (n = 15 calves/group). Calves were unimmunized (Group 1), immunized at 1.5, 4, 7, or 12 mo of age with a GnRH-keyhole limpet hemocyanin (KLH) conjugate (Groups 2 to 5, respectively), or castrated at 4 mo of age (Groups 6 and 7). Immunized bulls did not receive a secondary, or booster, immunization. Calves in group 6 received Synovex-C at castration and Synovex-S at weaning and feedlot entry. Anti-GnRH titer was evident at slaughter in all immunized bulls. However, the final immune response of bulls immunized at 1.5 mo was significantly lower than the response of bulls immunized at later stages of development. Final scrotal circumference and testis weight in bulls immunized at 4, 7, or 12 mo of age were significantly reduced relative to unimmunized bulls. The final live weight, feedlot gain, and carcass weight of immunized and unimmunized bulls did not differ (P > .05) from the same parameters in steers implanted with Synovex. Longissimus muscle area, marbling score, and backfat thickness did not differ between immunized and unimmunized bulls. The sex class score of the carcasses of immunized bulls did not differ from the score of steer carcasses. In contrast, a significantly higher proportion of carcasses from unimmunized bulls graded as bullock carcasses. Taken together, these data indicate that a single immunization against GnRH at 4 to 12 mo of age results in significant attenuation of testicular growth in bulls. These data also demonstrate that immunization against GnRH reduces the masculinity of carcasses from bulls, but does not affect feedlot performance, longissimus muscle area, marbling score, or backfat thickness. These results suggest that single immunization with the GnRH-KLH conjugate may have practical utility as a noninvasive alternative to surgical castration in management of beef cattle. This content is only available as a PDF. Copyright © 1996 by American Society of Animal Science

Herring, A., D.;Sanders, J., O.;Knutson, R., E.;Lunt, D., K.

doi: 10.2527/1996.745955xpmid: 8726726

Abstract Birth (n = 308), weaning (n = 291), feedlot and carcass (n = 142), and yearling heifer traits (n = 139) were evaluated in F1 calves sired by Brahman (BR), Boran (BO), and Tuli (TU) bulls and born to multiparous Hereford and Angus cows. Calves sired by BR were heaviest (P < .05) at birth and largest (P < .05) for cannon bone length. Tuli crosses were smaller (P < .05) for birth weight and cannon bone length than BR and BO crosses. No significant differences were observed for gestation length among sire breeds. Brahman crosses had larger (P < .05) weaning weight, hip height, and preweaning ADG than calves sired by BO and TU. Similar trends were observed for feedlot traits. Carcasses of BR crosses were heavier (P < .05) and had less (P < .05) internal fat than those of BO and TU crosses. Tuli crosses averaged greater (P < .05) skeletal maturity than BO crosses. Tuli crosses averaged greater marbling (P < .05) than BR crosses and less (P < .05) Warner-Bratzler shear force than BO crosses. No differences were observed in longissimus muscle area, fat thickness, or yield grade among sire breeds. Heifers sired by BR were heaviest (P < .05) and tallest (P < .05) at yearling measurement. Brahman F1 heifers had larger (P < .05) pelvic height and pelvic area, due to larger skeletal frame size, than BO and TU F1 heifers. These results indicate large differences in growth and skeletal size exist among calves sired by these three breeds. Several important differences also exist for carcass quality traits, but not for carcass yield traits, among these three breeds. This content is only available as a PDF. Author notes 1 Present address: Dept. of Anim. Sci. … Food Technol., Texas Tech Univ., Lubbock 79409. Copyright © 1996 by American Society of Animal Science

Distel, R., A.;Villalba, J., J.;Laborde, H., E.;Burgos, M., A.

doi: 10.2527/1996.745965xpmid: 8726727

Abstract The aim of this study was to determine the effects of experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-quality roughage) or fresh oats (Avena sativa) (high-quality roughage) on voluntary intake and nitrogen retention when sheep ate a low-quality roughage 9 mo after initial exposure. From 1 to 5 mo of age, experienced wethers (EW) grazed cured weeping lovegrass, whereas inexperienced wethers (IW) grazed fresh oats (initial exposure). Then both EW and IW were fed sorghum (Sorghum bicolor) hay for 45 d, fresh weeping lovegrass for 105 d, and finally alfalfa hay for 120 d. Nine months after completion of the initial exposure EW and IW were offered sorghum hay (low-quality roughage), and, in addition, both groups were offered sorghum with ad libitum access simultaneously to alfalfa hay at six levels of availability. Experienced wethers ingested 15% more (P < .02) sorghum than IW. When given sorghum simultaneously with alfalfa at different levels of availability, EW ingested more (P < .10) sorghum than IW when only sorghum was freely available. Nitrogen retention was negative in both groups, but it was less negative in EW than in IW per unit of metabolic weight (P < .09) and per wether (P < .04). The results show that early dietary experience can have profound and persistent effects on consumption of foods low in nutritional quality, apparently through changes in critical physiological mechanisms. This content is only available as a PDF. Author notes 3 Present address: Dept. of Rangeland Resources, Utah State Univ., Logan 84322-5230. Copyright © 1996 by American Society of Animal Science

, de Passillé, Anna Maria;Rushen,, Jeffrey;Ladewig,, Jan;Petherick,, Carol

doi: 10.2527/1996.745969xpmid: 8726728

Abstract To determine whether calves can distinguish between different people, we examined their contact with familiar and unfamiliar people and with people who handled them positively or aversively. When a familiar or unfamiliar person entered the calves' pens, latency to contact and duration of contact were the same, but bouts of contact were shorter and more frequent if the person was unfamiliar. In Exp. 2, calves were treated repeatedly in their home pens, by three handlers: one treated them positively, one aversively, and a third (neutral) did not interact with them. After seven treatments, calves tended to avoid all three handlers. After 12 treatments, calves contacted the positive handler significantly more than the aversive handler in their home pens. However, when retested outside their home pens, the calves did not discriminate. In Exp. 3, calves were treated positively and aversively in a novel treatment pen rather than in their home pens. The calves made more contact with the positive handler than the aversive handler after seven treatments. When retested in their home pens, most of the calves continued to avoid the aversive handler, but some made contact with the aversive handler. Calves can readily discriminate between different people based on their previous experience. They can develop a general fear of people as a result of aversive handling, and positive handling is required to overcome this. However, some calves do not generalize their fear of an aversive handler to places other than those in which they were handled. This content is only available as a PDF. Author notes 3 Present address: Dept. of Anim. Sci., The Royal Veterinary and Agricultural Univ., Copenhagen, Denmark. Copyright © 1996 by American Society of Animal Science

Smith, Dana, R.;Knabe, Darrell, A.;Smith, Stephen, B.

doi: 10.2527/1996.745975xpmid: 8726729

Abstract The objective of this study was to document the influence of specific dietary fatty acids on rates of lipid synthesis and sensitivity to insulin in porcine adipose tissue. Weanling pigs were assigned to one of six groups, and each group was fed diets containing 10 g/100 g of added cornstarch or 10 g/100 g of added fatty acid. The fatty acid-enriched diets contained either a combination of 14:1 plus 16:1 (14:1/16:1 diet), 16:0, 18:0, 18:1, or 18:2 (n-6). With the exception of the cornstarch diet, all diets contained approximately 35% 14:0. Subcutaneous adipose tissue samples were collected at slaughter from the area overlying the first cranial vertebra. Fresh samples were incubated for 2 h in 20 mM glucose and 0, 10, 100 or 1,000 µU/mL of porcine insulin. The smallest adipocytes were observed in adipose tissue from pigs fed the 16:0 or 18:2 diets. Glucose incorporation into lipids was greater (P < .05) in adipose tissue from cornstarch-fed pigs than in adipose tissue from the other treatment groups. Lipogenesis was 67, 53, 35, 32, and 20% lower (P < .05) in adipose tissue from 16:0-, 14:1/16:1-, 18:0-, 18:2-, and 18:1-fed pigs, respectively, than in adipose tissue from the cornstarch-fed pigs. Insulin increased lipogenesis by 19% (P < .05) in adipose tissue from the cornstarch-fed pigs and by 15 to 40% (P < .05) in adipose tissue from the 14:1/16:1-fed pigs. Insulin did not stimulate lipogenesis (P > .4) in adipose tissue from pigs fed the 16:0, 18:0, or 18:1 diets. The data suggest that fatty acid chain length and unsaturation are determinants in the effects of dietary fat and insulin on de novo lipogenesis. This content is only available as a PDF. Copyright © 1996 by American Society of Animal Science

Mersmann, Harry, J.

doi: 10.2527/1996.745984xpmid: 8726730

Abstract Adipocytes from several mammalian species have predominant β3-adrenergic receptors (β3-AR). Attempts to classify porcine adipocyte β-adrenergic receptors (β-AR) into subtypes have not been successful. Selectivity of agonists and antagonists for stimulation of lipolysis and for ligand binding is considerably more restrictive than for the classic rat and guinea pig β-AR subtypes. The unique pattern for activity of agonists and antagonists in porcine β-AR precludes analogy to classic receptors and consequently there is no conclusive evidence regarding porcine β-AR subtypes. Porcine adipocyte membranes were used in ligand binding experiments designed specifically to demonstrate β3-AR. Equilibrium saturation curves with dihydroalprenolol, CGP 12,177, or iodocyanopindolol indicated saturation at low concentrations with a single binding site. Equilibrium competitive ligand binding with iodocyanopindolol as radioligand and isoproterenol or propranolol as competitive ligands indicated both ligands totally inhibited radioligand binding; propranolol was more potent than isoproterenol. Nonradioactive CGP 12,177 also competed with iodocyanopindolol. Ligand binding experiments provided no evidence of a low-affinity β-AR (binding at high concentrations of ligand), the β3-AR. Positive evidences of a β3-AR were that CGP 12,177, a β1- and β2-adrenergic receptor antagonist but a β3-AR agonist, partially stimulated porcine adipocyte lipolysis. Furthermore, transcripts for a β3-AR, as well as a β1- and β2-AR, have been demonstrated in RNA from porcine adipocytes in other studies. The β-AR subtypes expressed and functional in porcine adipocytes remain unknown. The multiple ligand binding sites cannot be attributed to classic β-AR subtypes. The porcine β-AR may be a single unique receptor to impart atypical binding properties, or more likely, multiple subtypes, each different enough from classic subtypes to impart the unique properties observed. This content is only available as a PDF. Author notes 2 I thank Aisha Siddiqui for execution of these experiments, Ron McNeel for consultation and coordination of the experiments, Jim Cunningham, Horace Asberry, and Frankie Biggs for care of animals, Sharon S. Miller for secretarial assistance, Adam Gillum for graphical presentations, and Leslie Loddeke for editorial guidance. 3 This work is a publication of the USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX. This project has been funded in part with federal funds from the USDA, ARS under Cooperative Agreement no. 58-6250-1-003. The contents of this publication do not necessarily reflect the views or policies of the USDA, nor does mention of trade names, commercial products, or organizations imply endorsement from the U.S. Government. Copyright © 1996 by American Society of Animal Science

Huff-Lonergan,, Elisabeth;Mitsuhashi,, Tomiko;Beekman, Dirk, D.;Parrish, F., C.;Olson, Dennis, G.;Robson, Richard, M.

doi: 10.2527/1996.745993xpmid: 8726731

Abstract Postmortem (PM) and µ-calpain-induced degradation of specific skeletal muscle proteins was monitored by SDS-PAGE and Western blotting. Samples were removed from bovine longissimus thoracis (LT) at approximately 45 min PM for the preparation of at-death (0-d) myofibrils (MF). The LT was excised at 1 d PM, vacuum-packaged, and stored at 2ºC. Samples were removed for Warner-Bratzler shear force analysis and biochemical analysis at 1, 3, 7, 14, 28, and 56 d PM. The protease µ-calpain was purified from bovine skeletal muscle and used to digest at-death MF at pH 5.6, 4ºC, 100 µM CaCl2. Degradation of the proteins titin, nebulin, filamin, desmin, and troponin-T was monitored in the PM and µ-calpain-digested samples by using SDS-PAGE and Western blotting. The PM samples that had significantly lower shear force (LSF) values (P < .05) at 1 d PM exhibited faster degradation of these five proteins than the higher shear force (HSF) samples. In LSF samples, the intact titin band (T1) was absent by 7 d PM and nebulin was absent by 3 d PM. In LSF samples, some filamin was degraded by 3 d PM, but in HSF samples degradation was not apparent until 14 d PM. In LSF samples, desmin was degraded more rapidly PM than in HSF samples. Troponin-T was broken down PM to yield two major polypeptides of approximately 28 and 30 kDa; these polypeptides appeared earlier PM in LSF samples. Degradation products, similar to those observed PM, for all five proteins also were detected in Western blots of µ-calpain-digested MF, suggesting the calpain system plays a key role in PM protein degradation. This content is only available as a PDF. Author notes 3 Currently affiliated with the Dept. of Anim. and Dairy Sci. at Auburn Univ., Auburn, AL 36849. Copyright © 1996 by American Society of Animal Science