Journal of Animal Science

Moran,, C.;Quirke, J., F.;Prendiville, D., J.;Bourke,, S.;Roche, J., F.

doi: 10.2527/1991.69114249xpmid: 1752801

Abstract The effect of a single implantation (on d 1) with one or two long-acting, biodegradable estradiol implants (1E or 2E) on plasma estradiol concentrations in beef heifers was determined. The growth rates of these (2E) heifers, and of heifers repeatedly implanted with trenbolone acetate (TBA) or zeranol (Z) on d 1, 84, 168, and 252 of the trial, were compared to growth rates of controls. Trenbolone acetate alone was compared to TBA+2E, and 2E was compared to 1E. At a mean age of 84 d (d 1 of experiment), 81 Hereford × Friesian heifers were allocated at random to the following treatments: Control (n = 15); TBA (n = 15); 1E (n = 12); 2E (n = 15); Z (n = 13); or TBA+2E (n = 11). Mean live weight (kg) prior to slaughter on d 368 and hot carcass weight (kg) for heifers assigned to treatment Groups 1 to 6, respectively, were 366 and 200, 391 and 212, 374 and 201, 386 and 207, 387 and 210, and 391 and 208 (residual SD = 30.3 and 20.2). Heifers assigned to both the 2E and Z treatments were heavier on d 368 (P < .05) and had longer teats on d 279 (P < .05), less pelvic fat (P < .05), and heavier kidneys (P < .005) than control heifers. Heifers assigned to the TBA treatment had shorter teats on d 279 (P < .001) but greater final live weight (P < .05) and carcass weight than control heifers. Heifers given TBA alone had more pelvic fat (P < .05) and lighter kidneys (P < .05) than those given TBA+2E. Mean estradiol concentrations in both the ipsilateral and contralateral jugular veins of heifers assigned to the 2E and TBA+2E treatments, and in the ipsilateral jugular veins of heifers given 1E, were greater (P < .05) than those in control heifers; concentrations did not decline during the experiment. This content is only available as a PDF. Author notes 3 Present address: Boehringer Ingelheim Vetmedica GmbH, D-6507 Ingelheim am Rhein, Postfach 200, Germany. 4 Dept. of Anim. Husb. and Prod. 5 Dept. of Anim. Physiol. and Nutr. Copyright © 1991 by American Society of Animal Science

Newman, M., A.;Wilson, L., L.;Cash, E., H.;Eberhart, R., J.;Drake, T., R.

doi: 10.2527/1991.69114259xpmid: 1752802

Abstract Quarter milk samples from 51 purebred (Angus, Polled Hereford, and Simmental) and 69 crossbred (Angus × Simmental × Charolais three-way cross) beef cows were collected aseptically at three times during lactation to determine the prevalence of intramammary infection, milk somatic cell counts (SCC), and effects of infection on calf weight gain. Quarter infection prevalence was 13.1, 14.9, and 27.5% in early, mid, and late lactation; corresponding cow infection prevalence was 25.8, 29.2, and 54.4%. Staphylococcus aureus was isolated from 2.9, 2.7, and 3.2% of quarters in early, mid, and late lactation, respectively. Corynebacterium bovis, generally regarded as a minor pathogen, was isolated from 4.0, 7.6, and 18.2% of quarters at the three respective times. Geometric SCC means (103 cells/ml) were 1,522, 344, and 509 for S. aureus-infected quarters; 344, 899, and 221 for Staphylococcus hyicus-infected quarters; 65, 36, and 86 for C. bovis-infected quarters; and 20, 17, and 18 for uninfected quarters in early, mid, and late lactation, respectively. Adjusted 205-d weight gain for calves with S. aureus-infected dams was 9.6 kg less (P < .05) than for calves with uninfected dams. Adjusted 205-d weight gain for calves with dams infected with any mastitis pathogen did not differ significantly from that of calves with uninfected dams. At weaning half of the infected cows and half of the uninfected cows were given an intramammary infusion product containing 300 mg of cephapirin benzathine in each quarter; the remaining cows were untreated controls. Quarter samples were collected aseptically from all cows 14 to 28 d after subsequent calving. Quarter prevalence of infection after calving was lower (P < .05) in treated (8.2%) than in control (22.4%) cows. Significantly more infections present at weaning were eliminated in treated than in control cows, but the new infection rate during the dry period and early lactation did not differ between the two groups. This content is only available as a PDF. Author notes 1 Dept. of Vet. Sci. 2 Dept. of Dairy and Anim. Sci. Copyright © 1991 by American Society of Animal Science

Sticker, L., S.;Bunting, L., D.;Wyatt, W., E.;Wolfrom, G., W.

doi: 10.2527/1991.69114273xpmid: 1752803

Abstract Forty-eight Angus and Brangus steers (249 kg initial BW) were used in a randomized complete block design. Steers grazed annual ryegrass (Lolium multiflorum [L.] Lam. ) for 107 d and were sampled at 35 and 70 d. Treatments consisted of a corn supplement (C) or corn supplement plus either 80 mg•steer-1•d-1 of lysocellin (L) or 60 mgsteer-1•d-1 of tetronasin (T). When compared with C, ADG of L- and T-fed steers was higher (P < .05) for the complete 107-d study (1.15 vs 1.25 kg/d). At 35 d, ruminal acetate:propionate ratio tended (P = .07) to be higher for C than for L- and T-fed steers (4.6 vs 3.8). When compared with T, steers fed L tended (P = .11) to have higher acetate:propionate ratios. Ruminal concentrations of ammonia and free amino acids were not affected (P > .05) by treatment, but ruminal proteolytic activity tended (P = .13) to be lower for L- and T-fed than for C steers at 70 d. Ionophores did not alter (P > .05) ruminal mineral concentrations, but ruminal Mg concentration tended (P = .14) to be higher for T- than for L-fed steers at 70 d. When compared with L- and T-fed steers, C steers had lower (P < .05) plasma concentrations of Mg (23.7 vs 21.9 mg/liter) and Ca (113.0 vs 104.2 mg/liter) at 35 d. Plasma mineral concentrations were similar (P > .05) for L- and T-fed steers. Data are interpreted to indicate that L and T may improve ADG, decrease ruminal acetate: propionate ratio, and alter mineral metabolism. This content is only available as a PDF. Author notes 2 Dept. of Anim. Sci., Louisiana State Univ., Baton Ronge 70803. 4 Iberia Res. Sta., Louisiana State Univ., Jeanerette 70544. 5 Pitman-Moore, Inc., Terre Haute, IN 47808. Copyright © 1991 by American Society of Animal Science

Wiley, J., S.;Petersen, M., K.;Ansotegui, R., P.;Bellows, R., A.

doi: 10.2527/1991.69114279xpmid: 1752804

Abstract Two experiments were conducted in consecutive years to determine the effects of prepartum nutrient level and postpartum ruminally undegraded protein intake on nutrient status, milk production, subsequent calf production, and reproductive performance of 126 crossbred, primiparous beef heifers. Prepartum treatments were low nutrient intake (LN) (approximately 2.5 kg of TDN, .5 kg of CP animal-1•d-1 and maintenance nutrient intake (MN) (5 kg of TDN, 1 kg of CP animal-1•d-1), which were fed for 75 d before parturition. Two postpartum protein supplements were formulated to provide 250 g/d of ruminally degradable protein (RD) and one to supply ruminally undegraded protein (UD) at 250 g/d of additional UD CP compared to the RD supplement. Cholesterol was lower (P < .01) in heifers given UD than in heifers given RD. Blood urea nitrogen was higher (P < .01) for UD-fed heifers than for RD-fed heifers and was higher in LN heifers (P < .06) than in MN heifers. Milk production did not differ (P > .11) as a result of LN, MN, UD, or RD. Postpartum cow weight gain was greatest (P < .01) for UD and LN heifers. The percentage of heifers bred during the first estrous cycle of the breeding season was greater (P < .02) for UD than for RD. Overall, prepartum nutrition did not interact with postpartum protein supplement, nor did it have any effect on postpartum interval, whereas UD increased cow weight gain postpartum and reduced postpartum interval. This content is only available as a PDF. Author notes 4 Present address: New Mexico St. Univ., Anim. and Range Sci. Dept. 3-1, Box 30003, Las Cruces 88003-0003. 5 Fort Keogh Livest. and Range Res. Lab, USDA-ARS, Miles City, MT 59301. 6 Anim. and Range Sci. Dept. Copyright © 1991 by American Society of Animal Science

Terlouw, S., L.;Rieke, A., R.;Cantley, T., C.;Miller, L., F.;Day, B., N.

doi: 10.2527/1991.69114294xpmid: 1752805

Abstract The objective of this study was to determine the effects of recombinant porcine somatotropin (rpST) treatment during the finishing phase on subsequent reproductive function in crossbred gilts. Forty gilts weighing 50 kg and housed in a swine finishing facility were randomly assigned to control or rpST treatment. Four control and four rpST-treated gilts were allotted per pen. Twenty rpST-treated gilts received 6 mg of rpST•gilt-1•d-1 in 1 ml of buffered carrier and 20 control gilts received 1 ml of buffered carriergilt-1•d-1. Injections were administered daily at 1400 in the extensor muscle of the neck. All gilts received an 18% CP diet containing 1.2% lysine. Treatment was terminated when the average weight in each pen reached 110 kg. Gilts treated with rpST gained more weight (P < .05) than control gilts (59.8 ± 1.0 vs 53.5 ± 1.0 kg). Age at puberty was not different (rpST, 182.2 ± 3.3; control 181.4 ± 3.1 d). Prior treatment with rpST did not significantly affect length of estrus (rpST, 1.9 ± .1; control, 1.8 ± .1 d) or estrous cycle length (rpST, 20.6 ± .4; control, 20.4 ± .4 d). Ovulation rates at second estrus were similar for rpST gilts (15.1 ± .5) and control gilts (14.4 ± .5). More embryos (P = .10) were recovered on d 9 to 12 of gestation from rpST-treated gilts than from control gilts (13.1 ± .9 vs 10.7 ± .9).(ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Author notes 3 Anim. Sci. Res., IMC, Inc., P.O. Box 207, 1331 S. First Street, Terre Haute, IN 47808. 4 Dept. of Anim. Sci. Copyright © 1991 by American Society of Animal Science

Lubritz, D., L.;Eisen, E., J.;Robison, O., W.

doi: 10.2527/1991.69114299xpmid: 1752806

Abstract Genetic differences in natural vs hormone-induced ovulation rates were compared in immature female mice from five lines that had undergone long-term single-trait and antagonistic index selection for litter size and(or) 6-wk BW. Lines used were control (K); high litter size (L+); high BW (W+); low litter size and high BW (L−W+); and high litter size and low BW (L+W−). Natural ovulation rate at a mean age of 34.3 d and hormone-induced (5 IU of pregnant mare's serum gonadotropin followed 2 d later by 5 IU of human chorionic gonadotropin) superovulation rate at a fixed age of 31 d were obtained. Total number of eggs ovulated was affected by line (P < .001), treatment (P < .001), and line × treatment interaction (P < .001). Line differences were subsequently tested within treatment because of the significant line × treatment interaction. Line differences were important (P < .001) for natural ovulation, hormone-induced ovulation, and response to hormones. Mean natural ovulation rates for K, L+, W+, L−W+, and L+W− were 14.1, 19.8, 15.1, 13.6, and 16.4, respectively. Selection changed ovulation rate by 40, 16, 7, and −4% in the L+, L+W−, W+ and L−W+ lines, respectively (P < .01). Hormone-induced ovulation rates in K, L+, W+, L−W+, and L+W− were 32.3, 24.6, 19.6, 20.9, and 22.1, respectively. Exogenous hormones increased ovulation by 18.2, 4.8, 4.6, 7.3, and 5.7 ova for K, L+, W+, L−W+, and L+W−, respectively (P < .001). Lines with lower natural ovulation rates had higher responses to superovulation. Increased ovulation rate due to treatment ranged from 24.3% in L+ to 129% in K. These results indicate significant differences among lines in ovarian response to exogenous hormones. This content is only available as a PDF. Author notes 2 The authors acknowledge the comments of Daniel Pomp and two anonymous reviewers and the technical assistance of Beth Johnson. 4 Dept. of Anim. Sci. Copyright © 1991 by American Society of Animal Science

Bishop, M., D.;Tavakkol,, A.;Threadgill, D., W.;Simmen, F., A.;Simmen,, R.C.M.;Davis, M., E.;Womack, J., E.

doi: 10.2527/1991.69114306xpmid: 1684360

Abstract The DNA isolated from cow-hamster hybrid somatic cells segregating bovine chromosomes was analyzed by Southern blotting and hybridization with a heterologous [32P]-labeled porcine cDNA probe encoding insulin-like growth factor I (IGF-I). Thirteen of 25 cow-hamster hybrid cell lines exhibited the bovine-specific IGF-I fragment. Analysis for the retention or loss of bovine IGF-I with markers previously screened against the same panel of hybrid cells revealed a 100% concordance with lactate dehydrogenase B of bovine syntenic group U3 located on bovine chromosome 5. Restriction fragment length analyses of genomic DNA from animals representing five breeds (Angus, Polled Hereford, Simmental, Gelbvieh, and Belgian Blue) and from seven half-sib Angus calves indicated that polymorphisms for the genomic composition of the bovine IGF-I gene may exist in cattle populations. This content is only available as a PDF. Author notes 4 Present address: USDA, ARS, Roman L. Hruska U.S. Meat Anim. Res. Center, P. O. Box 166, Clay Center, NE 68933-0166. 5 Univ. of Michigan, Dept. of Derm., Ann Arbor. 6 Case Western Reserve Univ., Dept. of Genetics, Cleveland, OH. 7 Univ. of Florida, Dept of Dairy Sci., Gainesville. 8 The Ohio State Univ., Dept. of Anim. Sci., Columbus. 9 Texas A&M Univ., Dept. of Vet. Path., College Station. Copyright © 1991 by American Society of Animal Science

Wang, C., T.;Dickerson, G., E.

doi: 10.2527/1991.69114312xpmid: 1752807

Abstract A deterministic mathematical computer model was developed to simulate effects on life-cycle efficiency of lamb and wool production from genetic improvement of performance traits under alternative management systems. Genetic input parameters can be varied for age at puberty, length of anestrus, fertility, precocity of fertility, number born, milk yield, mortality, growth rate, body fat, and wool growth. Management options include mating systems, lambing intervals, feeding levels, creep feeding, weaning age, marketing age or weight, and culling policy. Simulated growth of animals is linear from birth to inflection point, then slows asymptotically to specified mature empty BW and fat content when nutrition is not limiting. The ME intake requirement to maintain normal condition is calculated daily or weekly for maintenance, protein and fat deposition, wool growth, gestation, and lactation. Simulated feed intake is the minimum of availability, DM physical limit, or ME physiological limit. Tissue catabolism occurs when intake is below the requirement for essential functions. Mortality increases when BW is depressed. Equations developed for calculations of biological functions were validated with published and unpublished experimental data. Lifetime totals are accumulated for TDN, DM, and protein intake and for market lamb equivalent output values of empty body or carcass lean and wool from both lambs and ewes. These measures of efficiency for combinations of genetic, management, and marketing variables can provide the relative economic weighting of traits needed to derive optimal criteria for genetic selection among and within breeds under defined industry production systems. This content is only available as a PDF. Author notes 2 The authors gratefully acknowledge the assistance of Harvey Blackburn in adapting the TAMU Sheep Model to the present purpose. 3 A218 Anim. Sci. Dept., Univ. of Nebraska, Lincoln 68583-0908. 4 Agric. Res. Serv., Roman L. Hruska U.S. Meat Anim. Res. Center, A218 Anim. Sci., Univ. of Nebraska, Lincoln. Copyright © 1991 by American Society of Animal Science

Wang, C., T.;Dickerson, G., E.

doi: 10.2527/1991.69114324xpmid: 1752808

Abstract A deterministic computer model was used to predict effects of genetic improvements in performance and of management options on life-cycle flock TDN input per unit of empty body weight (EBW) or carcass lean (CLN) equivalent value of market lamb, cull ewe, and wool output from a pure breeding system of sheep production for sheep fed to maintain normal weight. Relative values per kilogram for market lambs, cull ewes, and clean wool were 1 to .33 to 2.04 in lamb empty body equivalent, but 1 to .33 to 1 in lamb carcass lean equivalent. A 10% increase in lamb viability improved TDN/EBW or CLN by −15 to −20% for high to low lambing rates. Corresponding smaller gains were −7 to −11% for fertility, −3 to −13% for lambing rate, −1 to −3% for wool growth rate, −1 to −5% for milk production without creep feeding, −2 to −1% for mature size to about 70 kg, and −.6 to −.9% for precocity of fertility. Increasing leanness 10% improved TDN/CLN by −3 to −1% but increased TDN/EBW 3% because of higher maintenance requirements of leaner sheep. Higher protein requirements for increased lambing rate, milk production or leanness, or greater increases in non-feed than in feed costs, would mean only slightly less reduction of TDN/output than shown. Creep feeding was beneficial only for prolific, low-milking stock. Flushing reduced adverse effects of restricted feeding. Different values for wool vs meat or for costs of feed vs non-feed inputs would change results. These estimates for relative economic importance of traits apply to derivation of optimum criteria for selection among breeds or crosses, or within-breeds used in rotation crossbreeding, but would differ for specialized terminal-sire or maternal breed roles. This content is only available as a PDF. Author notes 2 A218 Anim. Sci. Dept, Univ. of Nebraska. 3 Agric. Res. Serv., Roman L. Hruska U.S. Meat Anim. Res. Center, A218 Anim. Sci., Univ. of Nebraska, Lincoln. Copyright © 1991 by American Society of Animal Science

Wang, C., T.;Dickerson, G., E.

doi: 10.2527/1991.69114338xpmid: 1752809

Abstract A deterministic computer model of a purebreeding sheep production system was used to simulate effects on life-cycle efficiency from genetic changes in lambing rate (LB), fertility (PERT), precocity of fertility (PREC), and estrus season length (ES) under annual (Y), 4-mo (A), and 73-d (S) breeding intervals. Ewes and lambs of a 1,000-ewe flock were fed to requirement through five yr, beginning with ewe lambs at the optimal breeding season and accumulating feed input (TDN) and market lamb equivalent weight of output (EBW), including cull ewes and wool. For annual lambing, improvement in cost (TDN/EBW equivalence) per 10% increase in genetic potential was −9.8, −8.2, −1.3, and −.8% for LB, PERT, PREC, and ES, respectively. For the A and S lambing intervals, corresponding gains in TON efficiency were −19 for PERT and −9% for LB when ES was 72 d, but only −6 and −5% when ES was 192 d. Increasing PREC by 10% improved cost −3% under accelerated systems when ES was 72 d, but < −1% when ES was 192 d. Cost reduction from 10% longer ES under A and S breeding intervals was greater when other reproductive performance was low (−11 and −17%) rather than high (−2 and −3%). Reduction in costs for A and S vs Y lambing intervals was greatest with long ES and was greater with low (−43 and −53%) than with high reproductive performance (−20 and −24%). When ES was 72 d, A and S intervals would reduce costs for high (−9 and −11%) but increase costs for low reproductive traits. Corresponding increases in CP/TDN required in diet would reduce gains in TDN/EBW only slightly. These results should aid in development of optimum selection criteria for stocks used for pure or rotation crossbreeding or as maternal parents of terminal crosses. This content is only available as a PDF. Author notes 2 A218 Anim. Sci. Dept., Univ. of Nebraska. 3 Agric. Res. Serv., Roman L. Hrnska U.S. Meat Anim. Res. Center, ARS, USDA, Clay Center. Copyright © 1991 by American Society of Animal Science