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Articles 1 - 22 of 22
Full-Text Articles in Life Sciences
Estimates Of Genetic Parameters For Direct And Maternal Effects On Embryonic Survival In Swine, Luis T. Gama, Keith G. Boldman, Rodger K. Johnson
Estimates Of Genetic Parameters For Direct And Maternal Effects On Embryonic Survival In Swine, Luis T. Gama, Keith G. Boldman, Rodger K. Johnson
Department of Animal Science: Faculty Publications
Survival of 16,838 potential embryos was determined by counting corpora lutea and fetuses at 50 d of gestation for 1,081 litters by 225 sires. These data, coded as 1 or 0 depending on whether an ovulation was represented by a fetus, were used to estimate direct and maternal additive genetic variances and their covariance for embryonic survival. Data were from fist-parity gilts of a Large White-Landrace composite population subdivided into two lines, one selected for an index of ovulation rate and embryonic survival for seven generations and a contemporary control line. Variance components were obtained by ANOVA and expectations of …
Comparison Of Methods Of Estimating Variance Components In Pigs, J. W. Keele, T. E. Long, R. K. Johnson
Comparison Of Methods Of Estimating Variance Components In Pigs, J. W. Keele, T. E. Long, R. K. Johnson
Department of Animal Science: Faculty Publications
Components of variance due to average effects of genes (σ g2), environmental effects common to littermates (σ c2), and environmental effects peculiar to individual pigs (σ e2 )were estimated (ˆ) by the Pseudo Expectation Approach (PE). Data were litter size (LS), backfat (BF; centimeter) and ADG (kilograms/day) collected from the Nebraska Gene Pool swine population between 1967 and 1986. Mean square errors (MSE) for ĥ2 and ĉ2 (ôg2 and ôc2 divided by phenotypic variance) by PE and nested ANOVA and h2 estimated by offspring on parent regression (REGOP) …
Effects Of Selection Of Data On Estimates Of Breeding Values By Three Methods For Litter Size, Backfat, And Average Daily Gain In Swine, T. E. Long, R. K. Johnson, J. W. Keele
Effects Of Selection Of Data On Estimates Of Breeding Values By Three Methods For Litter Size, Backfat, And Average Daily Gain In Swine, T. E. Long, R. K. Johnson, J. W. Keele
Department of Animal Science: Faculty Publications
Estimated breeding value was calculated based on individual phenotype (SP), an index of individual phenotype and full- and half-sib family averages (SI), or Best Linear Unbiased Rediction (BLUP). Traits considered were litter size (LS), backfat (BF), and ADG. Estimated breeding values were calculated using all data and after deletion of the poorest 5, 10, 15, or 20% of the records for BF and ADG, or 4.8, 8, 13, or 21% of the records for LS. When ail data were used, expected genetic gain from BLUP was greater than for SP by 22,7, and 31% and greater than for SI by …
Estimated Breeding Values For Meat Characteristics Of Crossbred Cattle With An Animal Mode1, L. Dale Van Vleck, A. F. Hakim, Larry V. Cundiff, R. M. Koch, J. D. Crouse, K. G. Boldman
Estimated Breeding Values For Meat Characteristics Of Crossbred Cattle With An Animal Mode1, L. Dale Van Vleck, A. F. Hakim, Larry V. Cundiff, R. M. Koch, J. D. Crouse, K. G. Boldman
Department of Animal Science: Faculty Publications
Longissimus muscle area, shear force measure, and sensory panel scores for flavor, juiciness, and tenderness, and marbling score were obtained from 682 steer carcasses, resulting from crosses among five Bos taurus and Bos indicus breeds. The single-trait model used included birth year and as covariates breed fractions, weaning age, and days on feed. The numerator relationship matrix was for 1,350 animals (682 steers, 74 pure breed and 52 F1-cross sires and 542 dams). The coefficient matrix was inverted to examine standard errors of prediction. Estimated breeding value is the sum of the estimate of genetic deviation and the weighted (fractions) …
Direct Responses To Selection For Increased Litter Size, Decreased Age At Puberty, Or Random Selection Following Selection For Ovulation Rate In Swine, W. R. Lamberson, R. K. Johnson, D. R. Zimmerman, T. E. Long
Direct Responses To Selection For Increased Litter Size, Decreased Age At Puberty, Or Random Selection Following Selection For Ovulation Rate In Swine, W. R. Lamberson, R. K. Johnson, D. R. Zimmerman, T. E. Long
Department of Animal Science: Faculty Publications
Nine generations of selection for high ovulation rate were followed by two generations of random selection and then eight generations of selection for increased litter size at birth, decreased age at puberty, or continued random selection in the high ovulation rate line. A control line was maintained with random selection. Line means were regressed on generation number and on cumulative selection differentials to estimate responses to selection and realized heritabilities. Genetic parameters also were estimated by mixedmodel procedures, and genetic trends were estimated with an animal model. Response to selection for ovulation rate was about 3.7 eggs. Response in litter …
Derivative-Free Restricted Maximum Likelihood Estimation In Animal Models With A Sparse Matrix Solver, K. G. Boldman, L. Dale Van Vleck
Derivative-Free Restricted Maximum Likelihood Estimation In Animal Models With A Sparse Matrix Solver, K. G. Boldman, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Estimation of (co)variance components by derivative-free REML requires repeated evaluation of the log-likelihood function of the data. Gaussian elimination of the augmented mixed model coefficient matrix is often used to evaluate the likelihood function, but it can be costly for animal models with large coefficient matrices. This study investigated the use of a direct sparse matrix solver to obtain the log-likelihood function. The sparse matrix package SPARSPAK was used to reorder the mixed model equations once and then repeatedly to solve the equations by Cholesky factorization to generate the terms required to calculate the likelihood. The animal model used for …
Prediction Of Breeding Values For Twinning Rate And Ovulation Rate With A Multiple Trait, Repeated Records Animal Model, L. Dale Van Vleck, K. E. Gregory, S. E. Echternkamp
Prediction Of Breeding Values For Twinning Rate And Ovulation Rate With A Multiple Trait, Repeated Records Animal Model, L. Dale Van Vleck, K. E. Gregory, S. E. Echternkamp
Department of Animal Science: Faculty Publications
A genetic correlation near unity between ovulation rate in heifers and later twinning frequency led to consideration of using measures of ovulation rate in heifers for each estrous cycle, beginning at puberty, to increase accuracy of selection for twinning rate. An initial evaluation with a multiple trait animal model for predicting breeding values included six genetic groups: 1) selected Scandinavian bulls, 2) transfers from other populations at the Research Center to a twinning project, 3) early-purchased Holsteins, 4) late-purchased Holsteins, 5) early purchases-other breeds. and 6) late purchases-other breeds. For ovulation and twin measures, heritabilities of .l00 and .070 and …
Amino Acid And Energy Interrelationships In Pigs Weighing 20 To 50 Kilograms: Weight And Efficiency Of Weight Gain, L. I. Chiba, A. J. Lewis, E. R. Peo, Jr.
Amino Acid And Energy Interrelationships In Pigs Weighing 20 To 50 Kilograms: Weight And Efficiency Of Weight Gain, L. I. Chiba, A. J. Lewis, E. R. Peo, Jr.
Department of Animal Science: Faculty Publications
The relationships between dietary amino acids and DE for pigs weighing 20 to 50 kg were investigated in two experiments
Feeding Value Of Grain Sorghum For The Lactating Sow, G. F. Louis, A. J. Lewis, E. R. Peo, Jr.
Feeding Value Of Grain Sorghum For The Lactating Sow, G. F. Louis, A. J. Lewis, E. R. Peo, Jr.
Department of Animal Science: Faculty Publications
Two experiments were conducted to investigate the effects of a corn-soybean meal (CSBM) and a sorghum-soybean meal (S-SBM) diet on reproductive performance and nutrient utilization by sows. In Exp. 1,75 sows (39 gilts; 36 primiparous) were fed either a C-SBM or a S-SBM gestation diet from breeding to d 109, On d 110, sows were assigned to lactation diets; half of the sows from each dietary treatment were assigned to a lactation diet based on the opposite grain. Sow weight change from d 54 to farrowing was greater (P < .06) for sows fed S-SBM than for sows fed C-SBM. There was no difference (P > SO) in weight change of sows during lactation. Feed consumption during …
Gonadotrophin Concentrations And Ovulation Rates In Suffolk Ewes Actively Or Passively Immunized Against Inhibin Alpha, B. D. Schanbacher, S. R. Schemm, S. M. Rhind
Gonadotrophin Concentrations And Ovulation Rates In Suffolk Ewes Actively Or Passively Immunized Against Inhibin Alpha, B. D. Schanbacher, S. R. Schemm, S. M. Rhind
Department of Animal Science: Faculty Publications
Mature Suffolk ewes were either actively or passively immunized against the synthetic fragment of porcine inhibin alpha, pIα(1-30),to determine the effects on gonadotrophin secretion and ovulation rate. Thirteen control ewes were immunized against human serum albumin, 12 ewes were actively immunized against pIα(1-30)and 36 ewes were passively immunized with pIα(1-30)antiserum. Blood samples were collected at 4-h intervals for 72 h from oestrus-synchronized ewes following the withdrawal of the progestagen pessaries. Mean gonadotrophin concentrations measured during the oestrous cycle of control ewes, ewes actively immunized against pIα(1-30) and ewes passively immunized against pIα(1-30)were similar, but their secretory profiles differed. Serum concentrations …
Effects Of Breeding Season Length And Calving Season On Range Beef Cow Productivity, Gene H. Deutscher, J. A. Stotts, Merlyn K. Nielsen
Effects Of Breeding Season Length And Calving Season On Range Beef Cow Productivity, Gene H. Deutscher, J. A. Stotts, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
A 5-yr study was conducted beginning in 1983 with 460 cows to evaluate the effects of three breeding seasons (30,45, and 70 d in length) and two times of spring calving, March (early) and April (late), on cattle production under Nebraska Sandhills range conditions. Criteria evaluated included pregnancy and weaning percentages, calving date and distribution, cow weights and body condition at four intervals, calf birth and weaning weights, and cow productivity. The 30-d breeding season included a 10-d estrus synchronization and AI period; in the other breeding seasons only natural breeding was used. The same sires were used over the …
Distribution Of Time To First Postpartum Estrus In Beef Cattle, S. M. Azzam, L. A. Werth, J. E. Kinder, Merlyn K. Nielsen
Distribution Of Time To First Postpartum Estrus In Beef Cattle, S. M. Azzam, L. A. Werth, J. E. Kinder, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
The function of a distribution that describes postpartum interval (PPI) under any experimental treatment is useful for simulation modeling, understanding the effects of stimuli on the endocrine system, and estimating the average PPI in experiments terminated before all animals have expressed estrus. This study was undertaken to compare the fit of three statistical distributions, the Weibull, the log-normal, and the linear hazard rate (LHR), to the empirical distribution of PPI for five treatment regimens: no bull exposure postpartum, bull exposure from 53 d postpartum, bull exposure from 3 d postpartum, and bull exposure from an average of 63 d postpartum …
Use Of A Simulation Model To Evaluate The Influence Of Reproductive Performance And Management Decisions On Net Income In Beef Production, L. A. Werth, S. M. Azzam, Merlyn K. Nielsen, J. E. Kinder
Use Of A Simulation Model To Evaluate The Influence Of Reproductive Performance And Management Decisions On Net Income In Beef Production, L. A. Werth, S. M. Azzam, Merlyn K. Nielsen, J. E. Kinder
Department of Animal Science: Faculty Publications
A stochastic dynamic model of reproduction and a deterministic cow-herd economic simulation model were used to evaluate how management decisions and reproductive performance interact to influence net income in a cow-calf operation (1,000 cows) for 1 yr of production. The stochastic model was used to determine herd performance when length of breeding season (45, 70, or 120 d) interacted with three postpartum intervals of an estrus (48, 65, or 90 d) and three conception rates at first service (60, 70, or 80%). Short, moderate, and long postpartum intervals were used to reflect differences in reproductive performance. In addition, replacement heifers …
C. R. Henderson: Farm Boy, Athlete, And Scientist, L. Dale Van Vleck
C. R. Henderson: Farm Boy, Athlete, And Scientist, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Charles R. Henderson was proud to be a product of a farm in Page County, Iowa. He was a one man track team in Coin, Iowa, and a brilliant student. He became a world class competitor in track at Iowa State College and, at the same time, compiled a top academic record. His early experiences set the stage for the exceptional contributions of his animal breeding career, which did not begin until he was nearly 40 yr of age, but which spanned 40 yr when he was the acknowledged leader in development of statistical methodology applied to animal breeding. His …
Estimates Of Genetic Selection Differentials And Generation Intervals For Four Paths Of Selection, C. P. Van Tassell, L. Dale Van Vleck
Estimates Of Genetic Selection Differentials And Generation Intervals For Four Paths Of Selection, C. P. Van Tassell, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Estimated genetic values from an animal model based on first lactation milk records for 6OOO AI Holstein sires and 1,074,971 Holstein cows born in 1981 or before were used to estimate average genetic selection differentials and generation intervals for the four paths of selection for each year of birth. Selection differentials for paths of sires of bulls, dams of bulls, sires of cows, and dams of cows averaged over all years were 405, 395, 239, and 42 kg and for the most recent 5 yr 884, 598, 235, and 28 kg. Generation intervals averaged for all years were by path …
Heritability Estimates Of Transformations Of Normally Distributed Records, A. L. Destefano, L. Dale Van Vleck
Heritability Estimates Of Transformations Of Normally Distributed Records, A. L. Destefano, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Milk yields were simulated for identical twin and parent-progeny pairs to determine effect of transformations on genetic variance. Use of identical twin pairs excludes variability due to Mendelian sampling and contribution by the other parent present in parent-progeny records. Phenotypic variances of 616,800; 1,439,200, and 2,261,600 and means from 2267 to 13,603 by increments of 2267 were used for linear scale records. Phenotypic variances of .0100O, .01875, and .02750 and means equal to the natural logarithm of the means for linear scale were used for log scale records. Heritability varied from .05 to .95 by increments of .lo. For each …
The Effect Of Cimaterol And Its Withdrawal On Carcass Composition And Meat Tenderness Of Broiler Chickens, B. L. Gwartney, Chris R. Calkins, Steven J. Jones
The Effect Of Cimaterol And Its Withdrawal On Carcass Composition And Meat Tenderness Of Broiler Chickens, B. L. Gwartney, Chris R. Calkins, Steven J. Jones
Department of Animal Science: Faculty Publications
To examine the effects of cimaterol (CIM) and its withdrawal on meat tenderness and carcass composition, 214-old broiler chickens (n = 288) were randomly assigned to one of nine treatments. For Treatments 1 through 6, bids were fed a control diet or a diet containing 1 ppm CIM until slaughter at 35, 42, or 49 d of age. Treatments 7 and 8 consisted of birds fed the CIM diet for 14 d and then withdrawn from CIM for either 7 or 14 d before slaughter (42 or 49 d of age). In Treatment 9, birds were fed the CIM diet …
Effects Of Trenbolone Acetate On Carcass Characteristics And Serum Testosterone And Cortisol Concentrations In Bulls And Steers On Different Management And Implant Schemes, Steven J. Jones, R. D. Johnson, Chris R. Calkins, M. Dikeman
Effects Of Trenbolone Acetate On Carcass Characteristics And Serum Testosterone And Cortisol Concentrations In Bulls And Steers On Different Management And Implant Schemes, Steven J. Jones, R. D. Johnson, Chris R. Calkins, M. Dikeman
Department of Animal Science: Faculty Publications
The objective of this study was to determine the effects of different implanting schemes on serum testosterone and cortisol concentrations, and carcass traits of bulls and steers implanted with trenbolone acetate (TBA) and zeranol (Z). Twenty Polled Hereford bulls were randomly assigned to one of three treatments after birth. Five calves served as nonimplanted control bulls (NIB). Nine bulls were implanted (IB) with 140 mg of TBA and 36 mg of Z at about 1 mo of age and reimplanted with both compounds 10 wk later. When IB calves were about 21 wk of age, the TBA implant was removed …
Ovulation Rate And Twinning Rate In Cattle: Heritabilities And Genetic Correlation, L. Dale Van Vleck, K. E. Gregory, S. E. Echternkamp
Ovulation Rate And Twinning Rate In Cattle: Heritabilities And Genetic Correlation, L. Dale Van Vleck, K. E. Gregory, S. E. Echternkamp
Department of Animal Science: Faculty Publications
Repeated measures of ovulation rate on puberal heifers should be an effective way to select for increased twinning rate. A reliable estimate of the genetic correlation between ovulation and twinning rates is needed to implement such selection and to predict its efficiency. Restricted maximum likelihood was used to estimate genetic correlations from subsets of data collected from the twinning project at the Roman L. Hruska U.S. Meat Animal Research Center. The animal model included numerator relationships among the animals and 6x4 effects of year-season of measurement, age at measurement, and birth group. Genetic correlations between averages of ovulation rates for …
Amino Acid And Energy Interrelationships In Pigs Weighing From 20 To 50 Kilograms: Rate And Efficiency Of Protein And Fat Deposition, L. I. Chiba, A. J. Lewis, E. R. Peo, Jr.
Amino Acid And Energy Interrelationships In Pigs Weighing From 20 To 50 Kilograms: Rate And Efficiency Of Protein And Fat Deposition, L. I. Chiba, A. J. Lewis, E. R. Peo, Jr.
Department of Animal Science: Faculty Publications
Two experiments were conducted to investigate the relationships between amino acids and DE for pigs weighing 20 to 50 kg. In Exp. 1, there were three dietary lysine levels that were either adjusted (1.50, 2.35 and 3.20 g/Mcal DE) for five DE levels (3.00 to 4.00 Mcal/kg) or unadjusted (.45, .71 and .%% of the diet) for three DE levels (3.50 to 4.00 Mcal/kg). In Exp. 2, diets containing six 1ysine:DE ratios (1.90 to 3.90 g/Mcal) at two DE levels (3.25 and 3.75 Mcal/kg) were fed. Pigs were housed individuiiy, and could eat and drink ad libitum. When pigs weighed …
Genotype By Environment Interaction For Holstein Milk Yield In Colombia, Mexico, And Puerto Rico, T. L. Stanton, R. W. Blake, R. L. Quaas, L. Dale Van Vleck, M. J. Carabano
Genotype By Environment Interaction For Holstein Milk Yield In Colombia, Mexico, And Puerto Rico, T. L. Stanton, R. W. Blake, R. L. Quaas, L. Dale Van Vleck, M. J. Carabano
Department of Animal Science: Faculty Publications
Components of (co)variance and genetic parameters were estimated by REML procedures from first lactation mature equivalent Holstein milk records from 54,604 Colombian, Mexican, and Puerto Rican cows and 198,079 US cows. The objective was to determine the cause of heterogeneous daughter response to sire selection for milk yield between the regions. Data from Latin America were partitioned by country and by herd-year SD class for milk to obtain five joint analyses between the US and Latin America, low herd-year SD, high herd year SD, Colombia, and Mexico. Sire and residual variances for milk were 41 and 29% smaller in Latin …
Influence Of Growth Rate And Exposure To Bulls On Age At Puberty In Beef Heifers, M. S. Roberson, M. W. Wolfe, T. T. Stumpf, L. A. Werth, Andrea S. Cupp, N. Kojima, P. L. Wolfe, Roger J. Kittok, J. E. Kinder
Influence Of Growth Rate And Exposure To Bulls On Age At Puberty In Beef Heifers, M. S. Roberson, M. W. Wolfe, T. T. Stumpf, L. A. Werth, Andrea S. Cupp, N. Kojima, P. L. Wolfe, Roger J. Kittok, J. E. Kinder
Department of Animal Science: Faculty Publications
Two experiments were conducted to test the following hypotheses: 1) exposure of beef heifers to sterile bulls increases the proportion of heifers attaining puberty by 14 mo of age and 2) rate of growth interacts with bull exposure to influence age at puberty in beef heifers. In Exp. I, heifers were assigned to one of two treatments: 1) heifers were exposed to bulls (BE approximately 70-d period of exposure) or 2) heifers were isolated from bulls (NE) and served as controls. In Exp. 11, heifers were assigned to either BE or NE treatments (175-d period of exposure to bulls) and …