Journal of Animal Science

Males, James, R.;Gaskins, Charles, T.

doi: 10.2527/jas1984.5951115xpmid: N/A

Summary In an initial experiment, 229 mixed breed steer calves were allotted randomly to 18 pens. The pens of cattle were allotted to the following dietary treatments: 1) bromegrass-alfalfa hay; 2) barley silage; 3) wet NH3-treated wheat straw + formaldehyde-treated soybean meal; 4) wet NH3-treated wheat straw + soybean meal; 5) dry NH3-treated wheat straw and 6) chopped wheat straw. Roughage consisted of 50%, supplement 15% and steam rolled barley 35% of diet dry matter. Gains were .96, .78, .76, .69, .67 and .58 kg•steer−1•d−1 for the six diets, respectively. The higher (<.01) gain obtained with the hay diet was due to higher (<.01) dry matter intake (dry matter intakes were 7.3, 6.2, 6.6, 6.2, 5.5 and 5.4 kg•steer−1• d−1, respectively). All diets except for formaldehyde soybean meal were evaluated in a Latin square digestion trial. Dry matter and gross energy digestibility were 56.15, 56.39; 60.19, 60.17; 49.60, 49.27; 45.26, 44.94 and 44.85, 45.28% for the five diets, respectively. Digestibility of the barley silage diet was higher (<.01) than all other treatments. The wet NH3-treated straw diet resulted in higher but nonsignificant dry matter digestibility compared with the other straw diets. In another experiment, 131 steer calves were allotted to 14 pens. The dietary treatments were: 1) bromegrass-alfalfa hay; 2) barley silage; 3) NH3-barley silage; 4) dry NH3-wheat straw; 5) wet 3% NH3-wheat straw, 6) wet 1.5% NH3-wheat straw. Gains were 1.27, 1.14, 1.02, .59, .93 and .78 kg•steer−1•d−1, respectively. The higher (P <.01) gains with the hay diet were associated with higher (<.01) dry matter intake. Ammonia treatment of barley silage did not affect gains. The wet NH3 treatment of straw was superior to dry NH3 treatment in both experiments. In a final experiment, supplementation of the wet 1.5% NH3 straw with dehydrated alfalfa (24.2% crude protein) or soybean meal (31.31% crude protein) supplements resulted in a numerical improvement in gains compared with the unsupplemented control diet. Dry matter intake of barley silage diets limited performance compared with cattle fed hay as a roughage source. Protein supplementation of NH3-treated straw diets resulted in improved performance. This content is only available as a PDF. Author notes 2 Dept. of Anim. Sci. 3 The authors wish to acknowledge the assistance of Dan Caldwell (forage preparation), Milt Russell and Dan Coonrad (animal care) and Loyd Falen (laboratory analysis). Copyright 1984 by American Society of Animal Science American Society of Animal Science

Cromwell, G., L.;Stahly, T., S.;Speer, V., C.;O&apos;Kelly,, R.

doi: 10.2527/jas1984.5951125xpmid: 6511687

Summary A cooperative study involving 296 pigs was conducted at two experiment stations and at a commercial research farm to evaluate the efficacy of nosiheptide as a growth promotant for growing-finishing swine. At each station, five or six replicate pens of four or five pigs/pen were fed a fortified, corn-soybean meal basal diet with 0, 5.5, 11 or 22 ppm nosiheptide. Initial and final weights averaged 11 and 92 kg, respectively. Daily gain increased quadratically (623, 664, 669, 678 g/d; P<.03) and feed/gain decreased quadratically (3.35, 3.24, 3.24, 3.28; P<.02) with increasing level of nosiheptide. Breakpoint analysis indicated that gain pla-teaued at 6.8 ppm and feed/gain at 5.5 ppm of nosiheptide. Averaged across all levels of nosiheptide, gain and feed/gain during the growing phase (11 to 52 kg body weight) were improved by 13.1 and 7.6%, respectively, by feeding the antibiotic. For the entire growing-finishing period, gain was improved by 5.3% and feed/gain by 2.9% in pigs fed nosiheptide. Although there were large differences in gain and feed/gain, the responses to dietary treatments were similar among the three stations. The results indicate that nosiheptide is an effective growth-promoting agent for growing-finishing swine. This content is only available as a PDF. Copyright 1984 by American Society of Animal Science American Society of Animal Science

Hackett, A., J.;Wolynetz, M., S.

doi: 10.2527/jas1984.5951129xpmid: 6511688

Summary Data from records of 330 crossbred ewe lambs mated to 142 rams over 11 breeding periods were analyzed for lambing percentage to one service. These ewe lambs in two separate flocks were reared and maintained indoors year-round and were derived from the three synthetic crossbred strains being developed at the Animal Research Centre in Ottawa, Ontario, Canada. At first exposure to rams, the ewes were 6 to 7 mo of age and had no hormonal treatments to induce or synchronize estrus. The two flocks were bred alternately in January, May or September to establish an 8 mo breeding cycle. The rams were at least 10 mo old and were maintained in one of two lighting regimens. Fifteen percent of the ewes lambed and the average prolificacy was 1.6. It appears that ewe lambs mated to rams maintained in a constant day length (10 h light: 14 h dark/24 h) environment had lower fertility than those ewe lambs mated to rams maintained in an environment such that the day length was altered between 4 mo of 10 h light: 14 h dark/24 h and 4 mo of 18 h light: 6 h dark/24 h. Although the fertility level was low, the data suggest that the breeding of ewes 6 to 7 mo of age is feasible. This content is only available as a PDF. Author notes 3 Statistical Research Section, Engineering and Statistical Research Institute, Agriculture Canada, Ottawa, Ontario, Canada K1A 0C6. Copyright 1984 by American Society of Animal Science American Society of Animal Science

Zalesky, D., D.;Day, M., L.;Garcia-Winder,, M.;Imakawa,, K.;Kittok, R., J.;D&apos;Occhio, M., J.;Kinder, J., E.

doi: 10.2527/jas1984.5951135xpmid: 6511689

Summary The effect of bull exposure on the resumption of estrous activity following parturition was studied in an experiment using mature Hereford and Hereford × Angus beef cows. In the spring of 1981 and 1982, cows were assigned by breed and calving date to one of two treatment groups. Cows were exposed to bulls either from 3 to 85 d postpartum (BE; n=45, 1981; n=35, 1982) or from 53 to 85 d postpartum (NE; n=39, 1981, n=36, 1982). Blood samples were collected from all cows once weekly from calving until 85 d postpartum to determine progesterone concentrations. The first increase in progesterone, which indicated onset of estrous cycles occurred at 43 ± 2 vs 63 ± 2 d (<.01) in 1981 and at 39 ± 2 vs 61 ± 3 d (<.01) postpartum in 1982 in BE cows and NE cows, respectively. Early postpartum exposure of cows to bulls reduced the postpartum anestrous interval. This content is only available as a PDF. Author notes 1 Published as Paper No. 7186, Journal Ser. Nebraska Agr. Exp. Sta. Anim. Sci. Dept. Acknowledgement is made to Jane A. Ossenkop and Lois V. Botts for assistance in preparation of this manuscript. Address requests for reprints to: J. E. Kinder, 218 Marvel Baker Hall, Univ. of Nebraska, Lincoln, NE 68583. 2 Dept. of Anim. Sci. Copyright 1984 by American Society of Animal Science American Society of Animal Science

Jungst, Steve, B.;Kuhlers, Daryl, L.

doi: 10.2527/jas1984.5951140xpmid: 6542564

Summary Data from 1,234 purebred and crossbred litters were analyzed with a multiple regression procedure to obtain estimates of breed additive, breed maternal, specific combining ability (SCA) and average maternal heterosis effects for the Duroc (D), Hampshire (H), Landrace (L), Spot (S) and Yorkshire (Y) breeds. The traits studied were: number farrowed (NB), litter birth weight (LBWT), average pig birth weight (BWT), litter size at 21 d (N21), litter weight at 21 d (L21WT) and average pig weight at 21 d (WT21). The three traits measured at birth included stillborn pigs. The data were analyzed with a statistical model that included effects of research farm, sow group within year and farm and the regressions of the dependent variables on the D, H, S and Y breed additive genetic and breed maternal effects, deviated from the L breed. The model also included the regressions of the dependent variables on all possible two-breed heterotic combinations (SCA) and on average maternal heterosis. The breed additive and maternal regression coefficients indicated phenotypic effects of substituting D, H, S and Y genes for L genes. The SCA regression coefficients were the phenotypic effects of individual heterosis increasing from 0 to 100% for each two-breed combination. For the breed additive genetic component of the phenotype, the breeds ranked (from largest to smallest effect) H, Y, L, D, S for NB; Y, L, H, S, D for LBWT and Y, H, L, S, D for BWT. At 21 d, the breeds ranked Y, D, L, S, H for N21; Y, L, H, D, S for L21WT and Y, H, L, S, D for WT21. When the breeds were ranked based on the breed maternal component that influenced the phenotype, the breeds ranked D, L, Y, S, H for NB; D, L, H, S, Y for LBWT; D, S, L, H, Y for BWT; H, L, D, S, Y for N21; H, D, L, S, Y for L21WT and D, S, H, L, Y for WT21. This content is only available as a PDF. Author notes 2 Dept. of Anim. and Dairy Sci. Copyright 1984 by American Society of Animal Science American Society of Animal Science

Bereskin,, B.

doi: 10.2527/jas1984.5951149xpmid: 6542565

Summary Genetic and phenotypic parameters for sow productivity traits were derived from analyses of records for 999 purebred Duroc and Yorkshire litters at the Beltsville Agricultural Research Center. Included were 682 spring-farrowed litters and 317 fall-farrowed litters. Primary traits examined were number of pigs born alive in the litter (NA), litter size at 21 d of age (N21), litter weight at 21 d (W21) and an index (I21) combining the three traits. Also analyzed were total number of pigs farrowed alive or stillborn, litter weight of pigs born alive and litter size and litter weight at 42 d of age (weaning). Selection was based mainly on the sow productivity index among litters in the spring season and mainly on performance traits among fall-farrowed pigs. Select and control lines were maintained in both breeds in both seasons. Yorkshires started at higher levels of productivity than Durocs in spring 1975, showed more fluctuation and ended in spring 1982 at about their starting levels. Durocs started at lower productivity levels and recorded generally significant increases by 1982, with comparable selection differentials for the two breeds. Heritabilities, estimated from daughter-biparental (mid-dam, paternal granddam) regressions using records expressed as deviations from contemporary breed-line means, varied widely among the breed-line groups. Suggested composite heritability estimates were 5,10 and 20% for NA, N21 and W21, respectively. Genetic correlations, computed from daughter-biparen-tal covariances, were high and positive (.7 or above) among all traits. Based on estimated genetic gains, it was proposed that W21, alone or in combination with N21 and(or) NA in an index, be used as the primary selection criterion to bring about genetic improvement in sow productivity traits. This content is only available as a PDF. Author notes 1 USDA, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Science Institute, Nonruminant Animal Nutrition Laboratory, Beltsville, MD 20705. 2 The author acknowledges with appreciation the contributions of R. L. Figulski and D. L. Parsons, Animal Caretaker Leaders, for managing the swine herd and for collecting and recording the necessary data; the cooperation of W. H. Peters, Supervisory Animal Husbandman; and the contributions of Bonnie Morgan, Statistical Assistant. 3 Mention of the trade name, proprietary product or vendor does not constitute a guarantee or warranty of the product by the USDA and does not imply its approval to the exclusion of other products or vendors that may also be suitable. Copyright 1984 by American Society of Animal Science American Society of Animal Science

Hudson,, G.F.S.

doi: 10.2527/jas1984.5951164xpmid: N/A

Summary Predicted breeding values (PBV) are usually required only for potential parents, i.e., live animals. However, data from all animals (dead or alive) should be used in calculating the PBV of live animals to avoid certain types of selection bias and to improve accuracy of evaluation. Over time, a substantial data base may be collected, necessitating extensive computing effort. A method of combining a reduced animal model with recursive prediction is described that reduces the number of equations to be solved simultaneously. A numerical example is given and applications to within herd evaluation systems are discussed. This content is only available as a PDF. Author notes 1 Partial financial support for this project was provided by Ontario Ministry of Agriculture and Food and by the Canadian Assoc. of Animal Breeders. The author thanks Gail M. Belonsky, two anonymous reviewers and the Section Editor for comments that improved the clarity of this paper. 2 Dept. of Anim. and Poul. Sci. Copyright 1984 by American Society of Animal Science American Society of Animal Science

Butts, W., T.;Onks, D., O.;Neel, J., B.;Corrick, J., A.;Holloway, J., W.

doi: 10.2527/jas1984.5951176xpmid: 6511690

Summary Angus cow-calf pairs (N=114) were individually fed grass silage diets under conditions chosen to approximate nutrient intake under a free grazing, noncreep situation. Postfactum comparison with a subsequently conducted study on pasture indicated that the procedures used produced animal responses similar to those provided by a tall fescue pasture averaging 58% dry matter digestibility. Cow-calf pair efficiency was expressed as the ratio of estimated total digestible nutrient (ETDN) intake of the pair to calf weight at weaning. Initial cow weight per se was unrelated to pair efficiency. When considered jointly with calf weight at weaning, initial cow weight was unfavorably and calf weight was favorably related to pair efficiency. Calf age at weaning and milk production were favorably related to pair efficiency through their relationship with calf weight at weaning. Initial cow fat thickness, estimated ultrasonically, was not related to this measure of efficiency, indicating compensations between the year just completed and the next year in the relationship between cow fat thickness at weaning and pair efficiency. Mating schemes resulting in selection of relatively smaller females and larger males, within the variation available in a straightbred population, would be expected to alter the cow weight-calf weight ratio in a direction favorable to the component of efficiency defined in this study. This content is only available as a PDF. Author notes 1 Present address: P.O. Box 246, Brooksville, FL 34298. 2 Present address: Rt. 1, Lancaster, TN 38569. 3 Present address: Agr. Extension Service, P.O. Box 11019, Nashville, TN 37211. 4 Anim. Sci. Dept., Univ. of Tennessee, Knoxville 37916. Copyright 1984 by American Society of Animal Science American Society of Animal Science

Gunsett, F., C.

doi: 10.2527/jas1984.5951185xpmid: N/A

Summary Theoretical selection response is considered for a trait defined as a ratio of two component traits. A method is presented that estimates the genetic change in the components of a ratio when selection is practiced directly on the ratio. Theoretical responses for direct selection on the ratio are compared with linear selection index responses. The proposed linear index maximizes the correlation between the index and the genotype for the ratio of interest. Use of the linear index increases selection responses as compared with direct selection on the ratio. Monte Carlo simulation results are presented for a single generation selection experiment which indicate that the use of a linear index is more efficient for changing traits defined as a ratio of two components traits than direct selection on the ratio. Direct selection on the ratio is complicated by the disproportionate fashion by which selection pressure is exerted on the component traits. Linear selection indices place a predetermined amount of selection pressure on the traits of interest and therefore a predictable amount of genetic change should result. This content is only available as a PDF. Author notes 1 Approved for publication by Director of Agricultural Research, North Carolina Agricultural and Technical State University, Greensboro. 2 Research supported by the College of Agriculture, North Carolina A&T State University, CSRS/ USDA, Grant No. NC.X.-011-5-79-120-1. 3 Research was initiated while the author was employed by Farmers Hybrid Inc., Des Moines, IA. 4 Dept. of Anim. Sci. Copyright 1984 by American Society of Animal Science American Society of Animal Science

McCurley, J., R.;Butts, W., T.;Bovard, K., P.

doi: 10.2527/jas1984.5951194xpmid: 6511691

Summary Mature weight (A) and rate of maturing (K) were estimated for 283 Angus, 140 Hereford and 280 Shorthorn cows utilizing the asymptotic regression equation Yt=A(l-Be−Kt). The Yt was weight of the individual at age t; and B was an estimate related to early life weight changes and provided for a Y-intercept (A-B). Each breed consisted of four inbred and two noninbred lines. Regression of estimated growth curve parameters on levels of inbreeding of the individuals and of their dams and effects of early reproductive performance (EREPRO) were studied as sources of variation in addition to line differences and trends in line values over years. Considered jointly with inbreeding of the dam and with EREPRO, inbreeding of the individual was negatively related (<.01) to estimates of A in the three breeds and unrelated (>.10) to estimates of K. Each 1% increase in inbreeding of the individual was associated with about 2 kg decrease in estimated mature weight. An increase in inbreeding of the dam of an individual was negatively related to estimates of K in Angus (<.01) and Shorthorns (<.05). Inbreeding of dams was positively related to estimates of A in the three breeds, but only in Shorthorns could the relationship be declared significant. Estimates of A were about 46 kg heavier and estimates of K about .010 less for each year an individual failed to produce a calf during her first three opportunities. In general, A values declined in all three breeds during the study. Significant changes were observed in all Hereford analyses and after inbreeding was included in the Angus analysis, while inclusion of inbreeding in the Shorthorn analysis caused the change to become unimportant. The K values increased in all three breeds during the study; however, the change could be declared significant only in Herefords. This content is only available as a PDF. Author notes 2 Dept. of Anim. Sci., Univ. of Tennessee, Knoxville. 3 ARS, USD A, The Univ. of Tennessee, Knoxville. 4 Dept. of Anim. Sci., Virginia Polytechnic Institute and State Univ., Blacksburg. Copyright 1984 by American Society of Animal Science American Society of Animal Science