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Department of Animal Science: Faculty Publications

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Full-Text Articles in Animal Sciences

Animal Model Estimation Of Genetic Parameters And Response To Selection For Litter Size And Weight, Growth, And Backfat In Closed Seedstock Populations Of Large White And Landrace Swine, Jose Bento S. Ferraz, Rodger K. Johnson Oct 1993

Animal Model Estimation Of Genetic Parameters And Response To Selection For Litter Size And Weight, Growth, And Backfat In Closed Seedstock Populations Of Large White And Landrace Swine, Jose Bento S. Ferraz, Rodger K. Johnson

Department of Animal Science: Faculty Publications

Records from 2,495 litters and 14,605 Landrace and Large White pigs from two farms, but established from the same base population and run as replicated selection lines, were analyzed. Selection within herd was on estimated breeding values weighted by economic values. Animal models and REML procedures were used to estimate genetic, phenotypic, and environmental parameters for the number of pigs born alive (NBA), litter weight at 21 d (LW), average daily gain from approximately 30 to 104 kg (AD GI, and backfat thickness adjusted to 104 kg (BF). Random animal genetic effects ( 01, permanent (NBA and LW) or litter …

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Estimation Of The Parameters Involved In A First-Order Autoregressive Process For Contemporary Groups, K. M. Wade, R. L. Quaas, L. Dale Van Vleck Jun 1993

Estimation Of The Parameters Involved In A First-Order Autoregressive Process For Contemporary Groups, K. M. Wade, R. L. Quaas, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

A methodology was developed for estimating the parameters involved in a first-order autoregressive process; these parameters comprise a variance component associated with the random effect, a correlation coefficient, p, and a residual variance. These parameters were estimated using REML with an expectation maximization algorithm. For two single trait analyses (milk and fat production being the dependent variable), the example chosen for the analyses was year-month -- treated as random and following a first-order autoregressive process within fixed herd. Initially, estimates failed to converge, possibly because of a time trend in the data, which was not accounted for by the model. …

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Correlations For Genetic Expression For Growth Of Calves Of Hereford And Angus Dams Using A Multivariate Animal Model, R. Nunez-Dominguez, L. Dale Van Vleck, K. G. Boldman, Larry V. Cundiff Apr 1993

Correlations For Genetic Expression For Growth Of Calves Of Hereford And Angus Dams Using A Multivariate Animal Model, R. Nunez-Dominguez, L. Dale Van Vleck, K. G. Boldman, Larry V. Cundiff

Department of Animal Science: Faculty Publications

The purpose of this study was to estimate the correlation between the expression of genes from sires in purebred and crossbred progeny (rPC) and in Hereford and Angus F1 calves (rHA). Performance traits were weights at birth, 200 d, and 365 d. Progeny from Hereford, Polled Hereford, and Angus bulls mated to Hereford or Angus cows were used to estimate rpc. Progeny from Charolais, Shorthorn, Simmental, Limousin, Maine-Anjou, Chianina, Gelbvieh, Tarentaise, and Salers bulls mated to Hereford or Angus cows were used to estimate rm. Performances in purebreds (P) and crosses (C) or in Hereford …

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Pregnancy Rate Is Greater When The Corpus Luteum Is Present During The Period Of Progestin Treatment To Synchronize Time Of Estrus In Cows And Heifers, T. Sanchez, M. E. Wehrman, E. G. M. Bergfeld, K. E. Peters, F. N. Kojima, Andrea S. Cupp, V. Mariscal, Roger J. Kittok, Richard J. Rasby, J. E. Kinder Mar 1993

Pregnancy Rate Is Greater When The Corpus Luteum Is Present During The Period Of Progestin Treatment To Synchronize Time Of Estrus In Cows And Heifers, T. Sanchez, M. E. Wehrman, E. G. M. Bergfeld, K. E. Peters, F. N. Kojima, Andrea S. Cupp, V. Mariscal, Roger J. Kittok, Richard J. Rasby, J. E. Kinder

Department of Animal Science: Faculty Publications

Our hypothesis was that conception in bovine females would be enhanced if the corpus luteum was present during the period of progestin treatment to synchronize estrus. In this study, 67 heifers (one replicate) and 124 cows (two replicates) were randomly assigned to one of two treatment groups. Seven days after estrus (Day 0), all animals were implanted with norgestomet and the implant remained in place for 10 days. All implants were removed on Day 17. Cows and heifers in one group received prostaglandin F2α (PGF2α) on Day 7 of the estrous cycle (PG 7; norgestomet without corpus …

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Estimation Of Nonadditive Genetic Variances For A Total-Merit Model Including Maternal Effects, L. Dale Van Vleck Mar 1993

Estimation Of Nonadditive Genetic Variances For A Total-Merit Model Including Maternal Effects, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Henderson described a method to reduce the number of mixed-model equations when estimating additive and nonadditive genetic variances or predicting additive and nonadditive genetic merits. The extension to a maternal effects model is straightforward. When maternal genetic effects are strictly additive, an algebraic identity was found that reduces by a factor of two the order of a matrix that must be inverted each round to account for the genetic covariances among direct and maternal genetic effects. An algorithm for derivative-free restricted maximum likelihood was developed based on Henderson's total-merit model that is the basis for a reduced number of equations. …

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Breed Comparisons For Growth Traits Adjusted For Within-Breed Genetic Trend Using Expected Progeny Differences, R. Nunez-Dominguez, L. Dale Van Vleck, Larry V. Cundiff Jan 1993

Breed Comparisons For Growth Traits Adjusted For Within-Breed Genetic Trend Using Expected Progeny Differences, R. Nunez-Dominguez, L. Dale Van Vleck, Larry V. Cundiff

Department of Animal Science: Faculty Publications

Records (2,910) of birth (BWT), weaning (WW), and yearling weight (YW) of F1 calves produced in a top-cross experiment involving Angus, Hereford, Pooled Hereford, Charolais, Limousin, Simmental, Gelbvieh, Maine-Anjou, Chianina, Tarentaise, Shorthorn, and Salers bulls mated to Hereford and Angus cows and records (4,592) of WW on three-breed-cross calves out of 986 F1 females of the same breed crosses were used in this study. The purposes were to estimate how much of the EPD of the sires was realized in crossbred calves and to estimate sire breed effects for the traits adjusted for genetic trend and sire sampling. …

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Bioavailability Of Calcium In Sun-Cured Alfalfa Meal And Effect Of Dietary Calcium Concentration On Bone And Plasma Characteristics During Two Phases Of Gestation In Gilt, G. L. Walker, D. M. Danielson, E. R. Peo, Jr., R. F. Mumm Jan 1993

Bioavailability Of Calcium In Sun-Cured Alfalfa Meal And Effect Of Dietary Calcium Concentration On Bone And Plasma Characteristics During Two Phases Of Gestation In Gilt, G. L. Walker, D. M. Danielson, E. R. Peo, Jr., R. F. Mumm

Department of Animal Science: Faculty Publications

A study was conducted with gravid gilts to determine the bioavailability of Ca in sun-cured alfalfa meal (AM) and the effect of dietary Ca concentration on bone and blood characteristics during two phases of gestation.

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Sequential Transformation For Multiple Traits For Estimation Of (Co)Variance Components With A Derivative-Free Algorithm For Restricted Maximum Likelihood, L. Dale Van Vleck, K. G. Boldman Jan 1993

Sequential Transformation For Multiple Traits For Estimation Of (Co)Variance Components With A Derivative-Free Algorithm For Restricted Maximum Likelihood, L. Dale Van Vleck, K. G. Boldman

Department of Animal Science: Faculty Publications

Transformation of multiple-trait records that undergo sequential selection can be used with derivative-free algorithms to maximize the restricted likelihood in estimation of covariance matrices as with derivative methods. Data transformation with appropriate parts of the Choleski decomposition of the current estimate of the residual covariance matrix results in mixed-model equations that are easily modified from round to round for calculation of the logarithm of the likelihood. The residual sum of squares is the same for transformed and untransformed analyses. Most importantly, the logarithm of the determinant of the untransformed coefficient matrix is an easily determined function of the Choleski decomposition …

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Environmental Effects On Neonatal Mortality Of Beef Calves, S. M. Azzam, J. E. Kinder, Merlyn K. Nielsen, L. A. Werth, K. E. Gregory, Larry V. Cundiff, R. M. Koch Jan 1993

Environmental Effects On Neonatal Mortality Of Beef Calves, S. M. Azzam, J. E. Kinder, Merlyn K. Nielsen, L. A. Werth, K. E. Gregory, Larry V. Cundiff, R. M. Koch

Department of Animal Science: Faculty Publications

Calving records from 1969 to 1989 from the Roman L. Hruska U.S. Meat Animal Research Center were used to investigate how climatic conditions, in addition to dystocia, age of dam, size of calf, and sex affect calf survival from birth to 1 wk of age. Data were analyzed separately for cows calving with (n = 11,094) or without (n = 72,187) dystocia. Neonatal mortality was described by a logit model and parameters were estimated by maximum-likelihood procedures. Calves born to cows with dystocia were five times as likely to die neonatally than calves born without assistance. Of all calves that …

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Effects Over Lambs On Muscle Time Of Feeding A Β-Adrenergic Agonist To Wether Animal Performance, Muscle Growth, Endogenous Proteinase Activities, And Meat Tenderness, T. D. Pringle, Chris R. Calkins, Mohammad Koohmaraie, Steven J. Jones Jan 1993

Effects Over Lambs On Muscle Time Of Feeding A Β-Adrenergic Agonist To Wether Animal Performance, Muscle Growth, Endogenous Proteinase Activities, And Meat Tenderness, T. D. Pringle, Chris R. Calkins, Mohammad Koohmaraie, Steven J. Jones

Department of Animal Science: Faculty Publications

Forty wether lambs were used in a 2 x 4 factorial arrangement to determine the response of animal performance, muscle growth, proteinase activity, and meat tenderness to 0-adrenergic agonist (BAA) supplementation. Lambs were fed a finishing diet with or without 4 ppm of L644,969 and slaughtered after 0, 2, 4, and 6 wk of treatment. The ADG was higher (P < .05) in the treated than in the control lambs after 2 wk and returned to control levels thereafter. Semitendinosus weight and calpastatin activity were higher and μ-calpain activity was lower in the treated than in the control lambs after 2, 4, and 6 wk. Cathepsin B activity was higher ( P < .0 1) and cystatin-like activity was lower ( P < .05) after 2 wk in treated than in control lambs but returned to control levels thereafter. Longissimus protein:DNA was higher after 4 ( P < .05) and 6 ( P < .01) wk in the treated lambs than in the controls. The concentration of RNA and RNA:DNA ratio were higher ( P < .0 1) in the longissimus and semitendinosus muscles in the treated lambs after 2 wk and remained higher throughout the study. Semitendinosus protein and RNA content were higher after 2, 4, and 6 wk and DNA content was higher after 2 and 6 wk in the treated than in the control lambs. Longissimus shearforce values were higher ( P < .001) in the treated than in the control lambs at all slaughter end points. These data indicate a rapid alteration of muscle growth, activity of the calpain-calpastatin system, and meat tenderness during BAA treatment. It also seems that the BAA-stimulated muscle growth is closely related to the activity of the calpain-calpastatin system.

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Effect Of Calcium Source, Dietary Calcium Concentration, And Gestation Phase On Various Bone Characteristics In Gestating Gilts, G. L. Walker, D. M. Danielson, E. R. Peo, Jr., R. F. Mumm Jan 1993

Effect Of Calcium Source, Dietary Calcium Concentration, And Gestation Phase On Various Bone Characteristics In Gestating Gilts, G. L. Walker, D. M. Danielson, E. R. Peo, Jr., R. F. Mumm

Department of Animal Science: Faculty Publications

Sixty gravid crossbred gilts were allotted to a 2 x 3 x 2 factorial arrangement of treatments: two Ca sources (sun-cured alfalfa meal and CaC03), three dietary concentrations of Ca (50, 75, and 100% of NRC requirements), and two phases of gestation (55 and 105 d). The objectives were to determine the effect of Ca source, dietary Ca concentration, and gestation phase on bone characteristics (bone breaking strength, bone ash percentage, bone density, and bone ash density in the rib, thoracic, and coccygeal bones), to correlate bone responses to determine relative bone activity, and to determine reliability of …

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Effect Of Immunization Against Lhrh On Isoforms Of Lh In The Ovine Pituitary, D. D. Zalesky, B. D. Schanbacher, H. E. Grotjan Jan 1993

Effect Of Immunization Against Lhrh On Isoforms Of Lh In The Ovine Pituitary, D. D. Zalesky, B. D. Schanbacher, H. E. Grotjan

Department of Animal Science: Faculty Publications

The role of LHRH in modulating intrapituitary LH content as well as the distribution of LH among its isoforms was examined in sheep. Rams (n = 3) and wethers (n = 6) were actively immunized against an LHRH-humanserum globulin conjugate. Pituitaries collected from these animals plus pituitaries from corresponding numbers of nonimmunized rams and wethers were extracted with a buffered saline solution containing protease inhibitors. Immunization markedly reduced total amounts of immunoreactive LH in the pituitary. An aliquot of each pituitary extract was desalted by flow dialysis against water and chromatofocused on a pH 10.5-7.0 gradient. Concentrations of LH in …

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Increasing Exogenous Progesterone During Synchronization Of Estrus Decreases Endogenous 17Β-Estradiol And Increases Conception In Cows, M. E. Wehrman, M. S. Roberson, Andrea S. Cupp, F. N. Kojima, T. T. Stumpf, L. A. Werth, M. W. Wolfe, Roger J. Kittok, J. E. Kinder Jan 1993

Increasing Exogenous Progesterone During Synchronization Of Estrus Decreases Endogenous 17Β-Estradiol And Increases Conception In Cows, M. E. Wehrman, M. S. Roberson, Andrea S. Cupp, F. N. Kojima, T. T. Stumpf, L. A. Werth, M. W. Wolfe, Roger J. Kittok, J. E. Kinder

Department of Animal Science: Faculty Publications

The objectives of this study were to determine the effects of dose of exogenous progesterone (P4) prior to artificial insemination on concentrations of 17β-estradiol (E2) and on conception rates in bovine females. Heifers (n = 100) and cows (n = 100) received P4-releasing intravaginal devices (PRIDs) to produce two different circulating concentrations of P4. All animals received a single PRID 10 days before (Day -10) the start of the breeding season (Day 0). In animals that received the low dose of P4 (1 PRID, target concentration of 2-3 ng/ml of plasma), …

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Effect Of Genetic Groups On Estimates Of Additive Genetic Variance, C. Pieramati, L. Dale Van Vleck Jan 1993

Effect Of Genetic Groups On Estimates Of Additive Genetic Variance, C. Pieramati, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

This study examined the effect of genetic grouping on REML estimates of additive genetic variance with an animal model with selected base populations. A simulated population of 40 animals (20 males and 20 females) was followed under selection or random mating conditions for 10 generations. Each population was replicated 20 or 50 times. Genetic grouping reduced estimates of additive genetic variance in populations with selected base animals, whereas grouping had little effect on the estimate in unselected populations. The effect of genetic grouping varied according to the quantity and kind of information that was missing (percentage of deleted data and …

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Estimates Of Variances Due To Direct And Maternal Effects For Growth Traits Of Romanov Sheep, G. A. Maria, K. G. Boldman, L. Dale Van Vleck Jan 1993

Estimates Of Variances Due To Direct And Maternal Effects For Growth Traits Of Romanov Sheep, G. A. Maria, K. G. Boldman, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Records of growth traits of 2,086 Romanov lambs were used to estimate variance components for an animal model and genetic correlations between growth traits. Traits analyzed were birth weight (BWT), weaning weight (WW), 90-d weight (W90), and daily gain for the periods birth to weaning (DG1) and weaning to 90 d (DG2). Weaning was at approximately 40 d. Variance components were estimated using restricted maximum likelihood with an animal model including fixed effects for year x season, sex, rearing type, and litter size and random effects for the direct genetic effect of the animal (with relative variance h2), …

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Economical And Biological Efficiencies Of Beef Cattle Differing In Level Of Milk Production, M. Van Oijen, M. Montano-Bermudez, Merlyn K. Nielsen Jan 1993

Economical And Biological Efficiencies Of Beef Cattle Differing In Level Of Milk Production, M. Van Oijen, M. Montano-Bermudez, Merlyn K. Nielsen

Department of Animal Science: Faculty Publications

Economical and biological efficiencies of beef production to weaning and to slaughter were estimated in three groups, different in milk available (low, medium, and high) to the calves but with the same potential for growth. Data from different breed groups of cows (low [L] = Hereford x Angus, medium [M] = Red Poll x Angus, and high [H] = Milking Shorthorn x Angus) were used. Economical efficiency was the ratio of income to expenses and biological efficiency was the ratio of calf weight to total feed energy required. Income was derived from cull cows and calves at weaning or carcasses …

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Alternative Methods Of Selection For Litter Size In Mice: Iii. Response To 21 Generations Of Selection, Yvonne Kochera Kirby, Merlyn K. Nielsen Jan 1993

Alternative Methods Of Selection For Litter Size In Mice: Iii. Response To 21 Generations Of Selection, Yvonne Kochera Kirby, Merlyn K. Nielsen

Department of Animal Science: Faculty Publications

Alternative methods of selection to increase litter size in mice have been practiced for 21 generations followed by six generations of relaxed selection. Three replicates were used with four selection criteria: index of components (IX: I = 1.21 x total ovulation rate + 9.05 x ova success), uterine capacity (UT), litter size (LS), and an unselected control (LC). In IX, ovulation rate and ova success were measured by number of corpora lutea and number of pups born/number of corpora lutea, respectively. In UT, uterine capacity was measured and defined as number of pups born to unilaterally ovariectomized (right ovary excised) …

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Yearling Bulls Shorten The Duration Of Postpartum Anestrus In Beef Cows To The Same Extent As Do Mature Bulls, Andrea S. Cupp, M. S. Roberson, T. T. Stumpf, M. W. Wolfe, L. A. Werth, N. Kojima, Roger J. Kittok, J. E. Kinder Jan 1993

Yearling Bulls Shorten The Duration Of Postpartum Anestrus In Beef Cows To The Same Extent As Do Mature Bulls, Andrea S. Cupp, M. S. Roberson, T. T. Stumpf, M. W. Wolfe, L. A. Werth, N. Kojima, Roger J. Kittok, J. E. Kinder

Department of Animal Science: Faculty Publications

The objective of this study was to determine whether yearling bulls, when pastured with cows, reduced the duration of postpartum anestrus to the same extent as did mature bulls. This experiment was conducted over a 3-yr period. Cows were stratified by parity group to achieve 37% 2-yr-old and 63% mature (> 2-yr-old) cows within each treatment group (approximately 50 cows per treatment per year). Cows were assigned in the order in which they calved to one of three treatment groups: 1) isolated from bulls (NBE; n = 158); 2) exposed to mature bulls that were z 3 yr of age …

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Differences In Heritability Estimates From Multiple-Trait And Repeated-Records Models, L. Dale Van Vleck, K. E. Gregory May 1992

Differences In Heritability Estimates From Multiple-Trait And Repeated-Records Models, L. Dale Van Vleck, K. E. Gregory

Department of Animal Science: Faculty Publications

Analyses of ovulation rates in consecutive estrous cycles with multiple-trait and repeated-records animal models resulted in different estimates of heritability. The estimate from the repeated-records model was seen to be approximately the product of the average genetic correlation and the average heritability from the multiple-trait procedure. A simple model is used to show algebraically that such a result is expected particularly if the environmental correlations are small among records of the same animal. Comparison of results of the two types of analyses of 10 replications of 10 combinations of underlying heritabilities and genetic correlations confirms this explanation.

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Similar Distribution Of Gonadotropin Isohormones Is Maintained In The Pituitary Throughout Sexual Maturation In The Heifer, T. T. Stumpf, M. S. Roberson, M. W. Wolfe, D. D. Zalesky, Andrea S. Cupp, L. A. Werth, N. Kojima, K. Hejl, Roger J. Kittok, H. E. Grotjan, J. E. Kinder Jan 1992

Similar Distribution Of Gonadotropin Isohormones Is Maintained In The Pituitary Throughout Sexual Maturation In The Heifer, T. T. Stumpf, M. S. Roberson, M. W. Wolfe, D. D. Zalesky, Andrea S. Cupp, L. A. Werth, N. Kojima, K. Hejl, Roger J. Kittok, H. E. Grotjan, J. E. Kinder

Department of Animal Science: Faculty Publications

Our working hypotheses for this study were that 1) the profile of intrapituitary LH and FSH isoforms would be shifted toward acidic forms as sexual maturation progresses in the bovine female; and 2) concentration of 17β-estradiol (E2) in circulation during sexual maturation would be a major factor modulating the percentage of the more acidic isoforms. In addition, the biological: immunoreactive (B:l) ratios of each isoform of LH were evaluated at selected stages of sexual maturation. Heifers (7 mo of age) were assigned to one of three treatment groups: 1) ovariectomized (OVX; n = 16); 2) OVX and administered …

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Genetic Variation Liver Mass, Body Mass, And Liver:Body Mass In Mice, L. D. Jones, Merlyn K. Nielsen, R. Britton Jan 1992

Genetic Variation Liver Mass, Body Mass, And Liver:Body Mass In Mice, L. D. Jones, Merlyn K. Nielsen, R. Britton

Department of Animal Science: Faculty Publications

Genetic variation for liver mass (LM), body mass (BM), and 1iver:body mass (LM/ BM) was examined for outbred populations of laboratory mice. Liver mass and body mass data were collected on 170 pureline sires at 12 wk of age, representing four outbred stocks of laboratory mice; 523 of their male and female two-way cross progeny at 9 or 12 wk; and 214 four-way-cross' offspring at 12, 14, or 16 wk. Genetic differences for LM, BM, and LM/BM were found among the base sire lines and between two-way crosses. Heritabilities and genetic correlations for LM, BM, LM/BM, and LM/MBM (MBM = …

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Response Time Of Broiler Chickens To Cimaterol: Meat Tenderness, Muscle Composition, Fiber Size, And Carcass Characteristic, B. L. Gwartney, Steven J. Jones, Chris R. Calkins Jan 1992

Response Time Of Broiler Chickens To Cimaterol: Meat Tenderness, Muscle Composition, Fiber Size, And Carcass Characteristic, B. L. Gwartney, Steven J. Jones, Chris R. Calkins

Department of Animal Science: Faculty Publications

The response time to cimaterol (CIM), a P-adrenergic agonist, by broiler chickens for carcass characteristics, muscle composition, muscle fiber size, catheptic enzyme activity, and tenderness was determined. Two trials were conducted in which chickens were fed a control diet (CON) containing 0 ppm of CIM or a diet containing 1 ppm of CIM. Trial 1 consisted of 55, 31-d-old broiler chickens individually fed for up to 48 h. At 0, 6, 12, 18, 24, and 48 h, five CON and five CIM-fed chickens were killed. Trial 2 consisted of 160, 33-d-old broiler chickens group-fed for up to 14 d. At …

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Circulating Gonadotrophins During A Period Of Restricted Energy Intake In Relation To Body Condition In Heifers, M. S. Roberson, T. T. Stumpf, M. W. Wolfe, Andrea S. Cupp, N. Kojima, L. A. Werth, Roger J. Kittok, J. E. Kinder Jan 1992

Circulating Gonadotrophins During A Period Of Restricted Energy Intake In Relation To Body Condition In Heifers, M. S. Roberson, T. T. Stumpf, M. W. Wolfe, Andrea S. Cupp, N. Kojima, L. A. Werth, Roger J. Kittok, J. E. Kinder

Department of Animal Science: Faculty Publications

Beef heifers, 13 months old, were fed to achieve high (7·6 + 0·2 units) or low (3·9 ± 0·1 units) body condition by feeding them one of two diets for 20 weeks. During week 17 of the growth phase, all heifers were ovariectomized. From week 20 to week 27 (restriction phase), all heifers were fed a daily diet containing 0·071 MJ metabolizable energy kg-1 body weight. At weekly intervals throughout the restriction phase, blood samples were collected at 10-min intervals for 11 h to determine the pattern of secretion of luteinizing hormone (LH), the amount of LH released in …

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Modulation Of Luteinizing Hormone And Follicle-Stimulating Hormone In Circulation By Interactions Between Endogenous Opioids And Oestradiol During The Peripubertal Period Of Heifers, M. W. Wolfe, M. S. Roberson, T. T. Stumpf, Roger J. Kittok, J. E. Kinder Jan 1992

Modulation Of Luteinizing Hormone And Follicle-Stimulating Hormone In Circulation By Interactions Between Endogenous Opioids And Oestradiol During The Peripubertal Period Of Heifers, M. W. Wolfe, M. S. Roberson, T. T. Stumpf, Roger J. Kittok, J. E. Kinder

Department of Animal Science: Faculty Publications

The aim of this study was to determine whether the decline in oestradiol inhibition of circulating luteinizing hormone (LH) and follicle-stimulating hormone (FSH) during the peripubertal period of heifers is associated with a change in opioid modulation of LH and FSH secretion. Opioid inhibition of LH secretion was determined by response to administration of the opioid antagonist naloxone. Prepubertal heifers (403 days old) were left as intact controls, ovariectomized or ovariectomized and chronically administered oestradiol. Control heifers were used to determine time of puberty. Three weeks after ovariectomy, four doses of naloxone (0·13-0·75 mg kg-1 body weight) or saline …

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Steady-State Amounts Of Α- And Luteinizing Hormone (Lh) Β-Subunit Messenger Ribonucleic Acids Are Uncoupled From Pulsatility Of Lh Secretion During Sexual Maturation Of The Heifer, M. S. Roberson, M. W. Wolfe, T. T. Stumpf, D. L. Hamernik, Andrea S. Cupp, L. A. Werth, N. Kojima, Roger J. Kittok, H. E. Grotjan, J. E. Kinder [email protected] Jan 1992

Steady-State Amounts Of Α- And Luteinizing Hormone (Lh) Β-Subunit Messenger Ribonucleic Acids Are Uncoupled From Pulsatility Of Lh Secretion During Sexual Maturation Of The Heifer, M. S. Roberson, M. W. Wolfe, T. T. Stumpf, D. L. Hamernik, Andrea S. Cupp, L. A. Werth, N. Kojima, Roger J. Kittok, H. E. Grotjan, J. E. Kinder [email protected]

Department of Animal Science: Faculty Publications

Our primary objective for this study was to determine whether steady-state amounts of α - and LH β-subunit mRNAs in the anterior pituitary are altered during sexual maturation in the bovine female. A secondary objective was to determine whether 17β-estradiol (E2) alters amounts of LH subunit mRNAs before onset of puberty. Heifers (7 mo old) were assigned to one of three treatments: 1) ovariectomized (OVX, n = 16); 2) OVX and administered E2 (OVXE, n = 16); or 3) ovary-intact (INTACT, n = 20). Pituitaries were collected at an estimated 120 days before onset of puberty (prepuberty) …

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Exogenous Progesterone And Progestins As Used In Estrous Synchrony Regimens Do Not Mimic The Corpus Luteum In Regulation Of Luteinizing Hormone And 17Β-Estradiol In Circulation Of Cows, N. Kojima, T. T. Stumpf, Andrea S. Cupp, L. A. Werth, M. S. Roberson, M. W. Wolfe, Roger J. Kittok, James E. Kinder Jan 1992

Exogenous Progesterone And Progestins As Used In Estrous Synchrony Regimens Do Not Mimic The Corpus Luteum In Regulation Of Luteinizing Hormone And 17Β-Estradiol In Circulation Of Cows, N. Kojima, T. T. Stumpf, Andrea S. Cupp, L. A. Werth, M. S. Roberson, M. W. Wolfe, Roger J. Kittok, James E. Kinder

Department of Animal Science: Faculty Publications

Our working hypothesis was that the low concentrations of progesterone (P4) and synthetic progestins administered in hormonal regimens to control estrous cycles of cows would have similar effects on secretion of LH and 17β-estradiol (E2). In addition, we hypothesized that concentrations of exogenous P4 typical of the midluteal phase of the estrous cycle and the corpus luteum (CL) would have similar effects on LH and E2, and the effects would be different from those of synthetic progestins and low concentrations of P4. Cows (n = 29) were randomly assigned to one …

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Multiple-Trait Restricted Maximum Likelihood For Simulated Measures Of Ovulation Rate With Underlying Multivariate Normal Distributions, L. Dale Van Vleck, K. E. Gregory Jan 1992

Multiple-Trait Restricted Maximum Likelihood For Simulated Measures Of Ovulation Rate With Underlying Multivariate Normal Distributions, L. Dale Van Vleck, K. E. Gregory

Department of Animal Science: Faculty Publications

A data set that was used to estimate covariance components with REML for an animal model with eight measures of ovulation rate treated as separate traits was used as a template to simulate data sets of eight multivariate normal traits that were then truncated to binomial traits. The model for simulation included eight measures on 610 animals with 1,071 animals in the numerator relationship matrix. Heritabilities were equal for the eight measures, and both genetic and phenotypic correlations among the measures were equal. Ten replications for each combination of heritability (.15, .25, and .35) and genetic correlation (.50, .66 and …

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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 Oct 1991

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 …

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Comparison Of Methods Of Estimating Variance Components In Pigs, J. W. Keele, T. E. Long, R. K. Johnson Oct 1991

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) …

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Estimates Of Genetic Parameters For Direct And Maternal Effects On Embryonic Survival In Swine, Luis T. Gama, Keith G. Boldman, Rodger K. Johnson Oct 1991

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 …

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