Journal of Animal Science

Troxel, T., R.;Cruz, L., C.;Ott, R., S.;Kesler, D., J.

doi: 10.2527/1993.71102579xpmid: 8226355

Abstract In Exp. 1, 101 suckled beef cows were administered two injections of prostaglandin F2α (PGF2α) 11 d apart. Cows in Group 1 received no additional treatment. Cows in Groups 2 and 3 received 250 μ g of GnRH plus 47-h calf removal. Cows in Group 3 also received a norgestomet ear implant that was inserted 4 d after the first PGF2α injection and left in situ for 8 d. The second PGF2α injection was administered approximately 28 h before the time of norgestomet implant removal. The GnRH was administered approximately 30 h after the time of norgestomet implant removal (or 58 h after the second PGF2α injection). Calf removal was the period from the time of implant removal to AI. All cows were artificially inseminated once 75 h after the second PGF2α injection (47 h after implant removal). Reproductive status before the time of GnRH treatment (presynchronization) was determined by multiple sampling (2, 13, and 23 d before GnRH treatment) for blood progesterone concentrations (62% anestrous and 38% cyclic). The GnRH treatment increased (P < .01) the ovulation response and norgestomet reduced (P < .01) the incidence of short luteal phases in the presynchronization anestrous cows. Norgestomet treatment increased (P < .05) the timed breeding pregnancy rates for both presynchronization anestrous and cyclic cows. In Exp. 2, 174 suckled beef cows were administered Syncro-Mate B (which includes norgestomet). Cows in Group 1 received no additional treatment, whereas cows in Group 2 received 250 μ g of GnRH (30 h after norgestomet implant removal). (ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Author notes 4 Present address: Univ. of Arkansas Cooperative Extension Service, P.O. Box 391, Little Rock 72203. 5 Present address: Central Luzon State Univ., Nueva Ecija, Philippines 3120. 6 College of Vet. Med. Copyright © 1993 by American Society of Animal Science

Dhuyvetter, D., V.;Petersen, M., K.;Ansotegui, R., P.;Bellows, R., A.;Nisley,, B.;Brownson,, R.;Tess, M., W.

doi: 10.2527/1993.71102586xpmid: 8226356

Abstract Two studies, using 128 crossbred, multiparous beef cows grazing native winter and spring rangeland, were conducted to determine effects of protein supplementation on nutrient status and subsequent calf and reproductive performance. Post-parturient cows (body condition score [BC] = 3.9) were fed 1.82 kg of one of two supplements (54% CP at 490 g of CP/d) per cow on alternate days. Supplements were formulated to contain 50% (245/490 g of CP) ruminally undegradable (UD) CP (RU50) or 25% (119/490 g of CP) UD CP (RU25) and were fed until breeding (BC =4.2). Late-calving cows (Study 1) were individually fed supplement while grazing native range. Early-calving cows (Study 2) were group-fed supplement on alternate days while grazing native range and were daily fed approximately 5.4 kg of medium-quality grass hay (10.5% CP). Latecalving cows had similar (P > .22) BW losses postpartum, whereas early-calving cows fed RU50 lost 39 kg less (P < .01) BW than did cows fed RU25. Cows that received RU25 returned to estrus sooner (P < .02), in the late-calving study, than cows fed RU50 (47 vs 56 d, respectively). The percentage of cows serviced in the first 21 d of breeding (96 and 100% for late- and early-calving studies, respectively) and pregnancy rates (88 and 86% for late- and early-calving studies, respectively) did not differ regardless of postpartum protein supplement. When adequate CP was provided in the diet for optimum function of the rumen, addition of ruminally undegraded CP decreased weight loss of mature, postpartum beef cows grazing native range. (ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Author notes 1 The authors gratefully acknowledge the Montana Beef Council for partial support of this research project. 2 The authors gratefully acknowledge C. K. Clark, N. Roth, K. Bryan, Z. Brady, P. Olind, M. Guthrie, and D. M. Hallford for their technical assistance. 3 Present address: New Mexico State Univ., Dept. of Anim. and Range Sci., Dept. 3-1, Box 30003, Las Cruces 88003-0003. Reprint requests: M. K. Petersen. 4 Fort Keogh Livest. and Range Res. Lab., ARS, USDA, Miles City, MT 59301. Copyright © 1993 by American Society of Animal Science

Favero, R., J.;Faulkner, D., B.;Kesler, D., J.

doi: 10.2527/1993.71102594xpmid: 8226357

Abstract Three trials involving 128 heifers were conducted to determine whether norgestomet implants administered during the mid- and late luteal phases after breeding could be used to synchronize a second estrus in nonpregnant, inseminated heifers without adversely affecting pregnancy in pregnant heifers. All heifers were initially synchronized with Syncro-Mate B and artificially inseminated 47 h after implant removal. On d 9 (Trial 1) or d 12 (Trial 2) after the timed AI, the heifers were randomly assigned to treated or control groups. Treated heifers received two silicone implants containing 10.0 mg of norgestomet each (Trial 1) or one silicone implant containing 3.6 mg of norgestomet (Trial 2). Silicone implants were removed on d 21 after the initial AI. In Trial 1, the calving rate to the initial AI of the control heifers was 35 vs 55% for the norgestomet-implanted heifers (P > .05). In Trial 2 the calving rate to the initial AI of the control heifers was 9 vs 45% in the treated heifers (P < .01). At the return estrus 52% of the control heifers returned to estrus within a 3-d period, whereas 93% of the norgestomet-treated heifers returned to estrus within a 3-d period ( P < .01). Norgestomet treatment had no effect on serum progesterone concentrations of the pregnant heifers on d 21 after the initial AI. In Trial 3, both control and treated heifers were administered silicone implants containing 3.6 mg of norgestomet on d 12; additionally, the treated heifers received an injection containing 3.0 mg of norgestomet and 5.0 mg of estradiol valerate. Norgestomet implants were removed on d 21. (ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Copyright © 1993 by American Society of Animal Science

Kattnig, R., M.;Winder, J., A.;Wallace, J., D.;Bailey, C., C.

doi: 10.2527/1993.71102601xpmid: 8226358

Abstract Effects of cow BW, hip height, and estimated genetic potentials (EBV) for weaning weight direct and milk on cow productivity, fecal OM output, OM intake, and efficiency (kilograms of calf BW/kilogram of OM intake by the cow) were evaluated with 44 free-grazing crossbred cows under semidesert conditions. Calf BW were measured during early, mid-, and late lactation. Data were collected in four periods: Period 1 = late spring (early lactation), Period 2 = late summer (mid-lactation), Period 3 = mid-autumn (late lactation), and Period 4 = mid-winter (nonlactation). Calf BW increased linearly with cow BW (P < .01) in Periods 1, 2, and 3. Fecal OM output and OM intake increased with cow BW in Periods 2 (P < .01) and 4 (P < .01), and on average (P < .02). Overall efficiency decreased with increasing cow BW (P < .04). Taller cows excreted more fecal OM and had greater OM intake throughout the study (P < .02 to P < .11). Overall efficiency decreased with increasing cow hip height (P < .05). Weaning weight direct EBV of cows was related linearly to cow BW (P < .01 to P < .07) and to calf BW (P < .01 to P < .07). Calf weight in all periods increased linearly with milk EBV (P < .001). Overall, fecal OM output, OM intake, and efficiency were not affected by milk EBV. This content is only available as a PDF. Author notes 2 Present address: Dept. of Anim. Sci., Univ. of Arizona, Tucson. Copyright © 1993 by American Society of Animal Science

Anderson, V., L.;Slanger, W., D.;Boyles, S., L.;Berg, P., T.

doi: 10.2527/1993.71102608xpmid: 8226359

Abstract Growth, feed efficiency, and carcass characteristics of 70 crossbred steers fed one of four diets were compared. The four diets differed in source of protein supplementation: 100% soybean meal (SB), 67% SB and 33% crambe meal (CM), 33% SB and 67% CM, and 100% CM. All supplements were fed in isonitrogenous amounts. Steers were fed backgrounding diets (12.9% CP) for 84 d and finishing diets (11.2% CP) for 96 d. Average initial weight was 303.4 kg. Backgrounding gains ranged from 1.38 to 1.41 kg/d ( P = .92). Finishing gains ranged from 1.43 to 1.47 kg/d ( P = .86). Range in entire-experiment gains was 1.41 to 1.46 kg/d ( P = .85). Feed efficiencies were equal; entire-experiment efficiencies averaged . 144 (P = .96). Growth and efficiency patterns were the same for all four treatments. No overall treatment differences were detected for the seven carcass variables ( P = .26 to .96). Average fat depth, longissimus muscle area, yield grade, and dressing percentage were .95 cm, 84.0 cm2, 2.45, and 61%, respectively. At the protein percentage levels of these diets, CM substituted equally for SB for growth rate, feed efficiency, and carcass characteristics. This content is only available as a PDF. Author notes 3 Anim. and Range Sci., North Dakota State Univ., Fargo 58105. 4 Anim. Sci. Dept., Ohio State Univ., Columbus 43210. Copyright © 1993 by American Society of Animal Science

Meyer,, K.;Carrick, M., J.;Donnelly,, B.J.P.

doi: 10.2527/1993.71102614xpmid: 8226360

Abstract Estimates of covariance components and genetic parameters were obtained for birth, weaning, 200-d, and 400-d weight for a herd of Polled Herefords and a herd of a multibreed synthetics, the so-called Wokalups. Data originated from an experiment in Western Australia selecting for preweaning growth rate. Analyses were carried out by REML fitting an animal model including genetic and permanent environmental maternal effects. Wokalups showed consistently more phenotypic variation, partly due to a scale effect, and higher direct and lower maternal heritabilities than Herefords. Maternal environmental effects were more than twice as important in Herefords than in Wokalups. Estimates of both genetic and environmental correlations among weaning and subsequent weights were essentially unity, identifying maternal effects found for postweaning weights as a “carry over” of those on weaning weight. This content is only available as a PDF. Author notes 2 Current address: Queensland Dept. of Primary Industries, G.P.O. Box 46, Brisbane, Queensland 4001, Australia. 3 W.A. Dept. of Agric., Baron Hay Court, South Perth, Western Australia 6151, Australia. Copyright © 1993 by American Society of Animal Science

Johnson, M., Z.;Schalles, R., R.;Dikeman, M., E.;Golden, B., L.

doi: 10.2527/1993.71102623xpmid: 8226361

Abstract Data from 2,101 Brangus calves born from 1986 to 1990 were analyzed with a REML procedure using a derivative-free algorithm in a mixed linear animal model to obtain variance component estimates of ultrasound-measured longissimus muscle area and fat thickness. Direct additive heritabilities ( h2a) of .39 and .40 were obtained for age-constant weaning and yearling longissimus muscle area (WLMA and YLMA, respectively), with a genetic correlation (rg) of .66 between them. The rg of YLMA with birth weight (BWT), weaning weight (WWT), postweaning gain (PWG), yearling weight (YWT), frame score (FS), and scrotal circumference (SC) were .17, .29, .43, .38, .01, and .19, respectively. The h2a of age-constant yearling 12th rib fat thickness (FAT) was .14, and cattle averaged .44 cm (SD = .19). Positive rg were obtained between FAT and WLMA (.19) and YLMA (.12). Negative rg of FAT with WWT, YWT, and SC were -.17, -.53, and -.33, respectively. Positive rg were obtained between FAT and BWT (.52), PWG (.44), and FS (.14). Maternal heritabilities (h2m) of WLMA, YLMA, and FAT were .01, .01, and .10, respectively. Weight-constant WLMA, YLMA, and FAT h2a were .36, .39, and .11, respectively. Selection based on either age-constant YLMA or FAT could potentially result in 1.06 cm2 or .005 cm change per year, respectively, which would be slightly greater than change from selection based on weight-constant YLMA or FAT. Selection based on WLMA or YLMA should be effective, and changes in these traits, growth, and SC should be possible in tandem. (ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Author notes 2 Present address: Dept. of Anim. Sci., Oklahoma State Univ., Stillwater 74078-0425. Copyright © 1993 by American Society of Animal Science

Smith,, Charles;Quinton,, Margaret

doi: 10.2527/1993.71102631xpmid: 8226362

Abstract More intense selection in a line gives greater genetic change but also gives a higher rate of inbreeding. Here, continuous selection in one line vs continuous selection in two or more sublines (for the same breeding objective and with the same total number of individuals tested) and crossing the sublines to reduce inbreeding, is studied by stochastic simulation using an infinitesimal model. On crossing, the inbreeding level in the cross, though zero, becomes equivalent to 1/n times that in the sublines, where n is the number of lines in the cross. In general, selecting in sublines and crossing gave less genetic response at the same level of inbreeding than selection in a single line. Use of the best subline generally gave less response than the whole line. It is concluded that selection response at the same level of inbreeding is greatest when all the test facilities and selection are concentrated in a single selection line. This content is only available as a PDF. Copyright © 1993 by American Society of Animal Science

Oscar, T., P.

doi: 10.2527/1993.71102639xpmid: 8226363

Abstract Broiler adipocytes in culture were used to determine whether prolonged preincubation with an antilipolytic hormone, pancreatic polypeptide, enhances lipolysis by inducing desensitization of lipolysis inhibition. Preincubation of broiler adipocytes with pancreatic polypeptide resulted in a dose-response and time-dependent enhancement (P < .05) of basal and glucagon-stimulated lipolysis. Lipolysis was enhanced at 4 and 24 h but not at .5 h of pretreatment. Acute inhibition of basal lipolysis was unaffected by long-term (24 h) exposure of adipocytes to a maximally effective dose (12 n M ) of pancreatic polypeptide. Thus, desensitization of lipolysis inhibition cannot explain the enhanced lipolysis from pancreatic polypeptide-treated adipocytes. However, preincubation with 12 n M pancreatic polypeptide for 24 h reduced (P < .05) pancreatic polypeptide and somatostatin inhibition of lipolysis stimulated by glucagon. Moreover, basal lipolysis and submaximal lipolysis were enhanced to a similar extent (27 vs 29 nmol/h) but to a greater (P < .05) extent (27 vs 13 nmol/h) than maximal lipolysis when adipocytes were exposed to 12 n M pancreatic polypeptide for 24 h. These results suggest that the enhanced lipolysis induced by prolonged exposure of adipocytes to pancreatic polypeptide resulted from increased activity of hormone-sensitive lipase and activators of this enzyme and not from attenuation of lipolysis inhibition. This content is only available as a PDF. Author notes 3 The author would like to thank J. Richardi for his excellent technical assistance on this project. Copyright © 1993 by American Society of Animal Science

Herpin,, Patrick;Le Dividich,, Jean;Amaral,, Nuno

doi: 10.2527/1993.71102645xpmid: 8226364

Abstract The effects of selection for lean tissue growth on the metabolic and physiological state (i.e., level of maturity) of the pig at birth have been examined on newborns from three breeds that markedly differ with respect to birth weight and postnatal muscle growth potential: a primitive Chinese breed (Meishan, MS), a European breed (Large White, LW), and a composite line (CL) highly selected for high rate of gain. Within each breed, 40 pigs from eight litters were used for whole carcass and tissue sampling, blood sampling, and for a fat tolerance test at 2 h of age. The CL pigs were heavier (P < .001) than the LW and MS pigs at birth but exhibited lower percentages of carcass protein, fat, mobilizable fat, and ash than the MS pigs (P < .05). In addition, MS pigs had larger adipose tissue adipocytes than pigs from the two other breeds (P < .001). Despite their 31% higher RNA capacity in longissimus muscle (higher RNA:protein ratio, P < .05), CL pigs exhibited a lower percentage of muscle protein (P < .05) than did MS pigs. Relative liver weight was higher for LW than for CL pigs ( P < .05), which had the lowest percentage of liver phospholipids (P < .01). The CL pigs exhibited lower hematocrit (P < .01), glucose ( P < .01), albumin (P < .01), Cortisol (P < .01), and thyroxine (P < .05) levels than the MS pigs. (ABSTRACT TRUNCATED AT 250 WORDS) This content is only available as a PDF. Author notes 1 The authors gratefully acknowledge the technical assistance of M. Angers, J. C. Hulin, M. Fillaut, A. Pasquier, A. M. Mounier, and F. Giovanni. Copyright © 1993 by American Society of Animal Science