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Department of Animal Science: Faculty Publications

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Full-Text Articles in Animal Sciences

The Effects Of Sorbic Acid In High Moisture Sorghum Grain Diets On Performance Of Weanling Swine, J. D. Crenshaw, E. R. Peo, Jr., A. J. Lewis, N. R. Schneider Jan 1986

The Effects Of Sorbic Acid In High Moisture Sorghum Grain Diets On Performance Of Weanling Swine, J. D. Crenshaw, E. R. Peo, Jr., A. J. Lewis, N. R. Schneider

Department of Animal Science: Faculty Publications

Three experiments were conducted with 288 weanling pigs to determine the effects of sorbic acid (SA) added to dry (DSG), high moisture (HMSG) or reconstituted (RSG) sorghum grain diets on gains and feed conversion. Dietary treatments for Exp. 1 were: DSG with and without .1% SA; HMSG with .1% SA and RSG with .1% SA. The DSG diets were fed ad libitum. The HMSG and RSG diets were mixed fresh from oxygen-limiting storage every 3 and 7 d and were also fed ad libitum. Pigs fed RSG diets consumed more feed than those fed HMSG diets (P<.08). Performance was similar between pigs fed DSG diets without or with SA. Dietary treatments for Exp. 2 and 3 consisted of sorghum grains reconstituted to two moisture contents (MC), with additions of either 0, .05 or .I% SA. The diets were mixed fresh from oxygen-limiting storage every 7 d and fed ad libitum. In Exp. 2 and 3, pigs fed the higher MC diets were more efficient in feed conversion (P<.03) than those fed the lower MC diets. In Exp. 3, a quadratic response (P<.04) for average daily gain and average daily feed intake was observed for the main effect of SA. Feed efficiency improved (P<.05) in a linear fashion as SA levels were increased in the diets. The results of these experiments indicate that weanling pigs may be fed HMSG or RSG without adverse effects on pig performance. Inconsistencies in pig response to SA were observed. Feed temperature measurements indicated that SA prevented heat production in the RSG diets for at least 10 d after removal from oxygen-limiting storage, while diets without SA became moldy within 5 d.

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Threonine Requirement Of Pigs Weighing 5 To 15 Kgs., A. J. Lewis, E. R. Peo, Jr. Jan 1986

Threonine Requirement Of Pigs Weighing 5 To 15 Kgs., A. J. Lewis, E. R. Peo, Jr.

Department of Animal Science: Faculty Publications

Weanling crossbred pigs (avg initial wt 6.4 kg) were fed diets containing six levels of threonine to determine the threonine requirement of young pigs fed diets somewhat similar to those used in commercial swine production. The diets (16% crude protein) were composed primarily of grain sorghum, oat groats and soybean meal supplemented with minerals, vitamins, lysine, tryptophan, methionine and isoleucine, and were calculated to be adequate in all nutrients except threonine and crude protein. Threonine levels were .53, .57, .62, .68, .75 and .83% of the diet. There were two trials, each with 96 pigs. The pigs were fed the …

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Zinc-Amino Acid Complexes For Swine, D. A. Hill, E. R. Peo, Jr., A. J. Lewis, J. D. Crenshaw Jan 1986

Zinc-Amino Acid Complexes For Swine, D. A. Hill, E. R. Peo, Jr., A. J. Lewis, J. D. Crenshaw

Department of Animal Science: Faculty Publications

Two experiments were conducted to determine the effect of sources of dietary zinc on gain, feed conversion and blood and bone traits of swine. In the first experiment 96 pigs were used in a 28-day study.

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Growth, Carcass And Palatability Traits Of Intact Males And Steers Implanted With Zeranol Or Estradiol Early And Throughout Life, Chris R. Calkins, D. C. Clanton, T. J. Berg, J. E. Kinder Jan 1986

Growth, Carcass And Palatability Traits Of Intact Males And Steers Implanted With Zeranol Or Estradiol Early And Throughout Life, Chris R. Calkins, D. C. Clanton, T. J. Berg, J. E. Kinder

Department of Animal Science: Faculty Publications

This study was conducted to assess the impact of implanting intact beef males with protein anabolic agents at varying intervals throughout life. Ninety-six intact males were assigned to three implant treatments: 1) not implanted, 2) implanted at 9 wk of age, weaning and at 56-d intervals thereafter with a 36-mg zeranol implant or 3) estradiol implant at 9 wk of age and 68 d post-weaning. During the 118-d, post-weaning growing period, eight animals per treatment (one replication) were castrated. After a 114-d finishing period, cattle were slaughtered (average age of 13 to 14 mo). Feedlot performance, carcass and palatability data …

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Effect Of Dietary Flourine On Growth, Blood And Bone Characteristics Of Growing-Finishing Pigs, T. W. Burnell, E. R. Peo, Jr., A. J. Lewis, J. D. Crenshaw Jan 1986

Effect Of Dietary Flourine On Growth, Blood And Bone Characteristics Of Growing-Finishing Pigs, T. W. Burnell, E. R. Peo, Jr., A. J. Lewis, J. D. Crenshaw

Department of Animal Science: Faculty Publications

Three hundred eighty-four growing-finishing pigs were used in two experiments to determine the effect of dietary fluorine (F) on growth, blood and bone physical characteristics. Fourteen dietary treatments were formulated by supplementing F (as NaF) to a milo-soybean meal basal diet (7 ppm F) to provide levels of 7, 132, 257, 382, 507 and 632 ppm F for Exp. 1, and 7, 25, 43, 61, 79, 97, 115 and 133 ppm F for Exp. 2. Average daily gain (ADG) and average daily feed intake (ADFI) were not affected (P>.09) when F was fed at levels between 7 and approximately …

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Effect Of Dry, High-Moisture And Reconstituted Normal And High-Lysine Corn Diets And Particle Size On Energy And Nitrogen Metabolism In Growing Swine, G. L. Asche, J. D. Crenshaw, A. J. Lewis, E. R. Peo, Jr. Jan 1986

Effect Of Dry, High-Moisture And Reconstituted Normal And High-Lysine Corn Diets And Particle Size On Energy And Nitrogen Metabolism In Growing Swine, G. L. Asche, J. D. Crenshaw, A. J. Lewis, E. R. Peo, Jr.

Department of Animal Science: Faculty Publications

Two metabolism studies were conducted with 24 (Exp. 1) and 36 (Exp. 2) crossbred barrows (initial weight 35 kg) to determine the effect of corn type - normal corn (NC) and high-lysine corn (HLC) - and storage method - dry (D), high-moisture (HM) and reconstituted (RC) - on energy and N digestibility. Diets fed in Exp. 1 were: 1, NC-soybean meal formulated at .78% lysine (dry matter basis); 2, HLC-soybean meal containing the same amount of corn as diet 1 (.87% lysine); 3, HLC-soybean meal with the same lysine level as diet 1. In Exp. 1, dry matter, energy and …

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Selection Practices And Genetic And Phenotypic Trends Estimated From Nebraska Spf Swine Field Records, P. J. David, R. K. Johnson, T. E. Socha Nov 1985

Selection Practices And Genetic And Phenotypic Trends Estimated From Nebraska Spf Swine Field Records, P. J. David, R. K. Johnson, T. E. Socha

Department of Animal Science: Faculty Publications

Records collected during 1971 through 1979 from 101,606 pigs raised in 18 herds that were members of the Nebraska SPF Swine Accrediting Association were evaluated for phenotypic trends and predicted and observed genetic trends. Traits considered were backfat at 100 kg (BF) and weight at 140 d of age (WT). Phenotypic change on average was beneficial for BF (-.05 mm/yr) but undesirable for WT (-.2 kg/yr). However, the average observed genetic trend was nil for BF and .6 kg/yr for WT. An average, predicted response based on observed selection differentials and estimates of within herd-sex genetic parameters was in good …

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Covariances Among First-Lactation Milk Records Of Cousins, L. Dale Van Vleck, C. L. Hart Aug 1985

Covariances Among First-Lactation Milk Records Of Cousins, L. Dale Van Vleck, C. L. Hart

Department of Animal Science: Faculty Publications

Covariances among first-lactation milk records expressed as deviations from herdmate averages of Holstein cows related as cousins of varying degree, as daughterdan1, as full and maternal sibs, and as aunt-niece of varying degree were examined to determine whether genetic maternal effects are important. The multiple regression of the expected coefficients of additive direct, additive maternal, dominance direct, and dominance maternal genetic variance components; and additive direct by additive maternal and dominance direct by dominance maternal genetic covariances on the 24 estimated covariances between pairs of relatives gave a multiple correlation coefficient of .95. The regression of actual covariance on the …

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Including Records Of Daughters Of Selected Bulls In Estimation Of Sire Component Of Variance, L. Dale Van Vleck Jul 1985

Including Records Of Daughters Of Selected Bulls In Estimation Of Sire Component Of Variance, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Methods to account for selection in estimation of variance components are computationally difficult and require inclusion of records on which selection was based. The last criterion often cannot be met. Within a time records of daughters in the small sample set for a bull should be relatively free of effects of selection. If only such records are used, many herd-year- season subclasses, however, contain only one record, so that those records are eliminated when herd-year-season effects are absorbed. Including records of daughters of few but heavily used and selected bulls would provide more comparisons within herd-year-seasons, but treating effects of …

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Reduced Nocturnal Temperatures For Early Weaned Pigs, M. C. Brumm, D. P. Shelton, R. K. Johnson Mar 1985

Reduced Nocturnal Temperatures For Early Weaned Pigs, M. C. Brumm, D. P. Shelton, R. K. Johnson

Department of Animal Science: Faculty Publications

Three experiments of 5 wk duration were conducted to evaluate the effect of reduced nocturnal temperatures (RNT) on weaned pig performance. Treatments were 1) a control regimen (CR) of 30 C constant air temperature lowered 2 C/wk and 2) a regimen where the temperature from 1900 to 0700 h was lowered to 25 C for three nights followed by 20 C for four nights during the first week and then lowered 1 C/wk thereafter (RNT). Weaned pigs averaging 23 ± 2 d of age at the start of the experiments gained faster (P<.01) in the RNT treatment vs the CR treatment in Exp. 1, 2 and 3, respectively (.32 vs .28; .39 vs .37; .35 vs .34 kg/d). The improvement in gain was accompanied by an increase (P<.005) in feed intake for the same period (.48 vs .44; .61 vs .55;.58 vs .54 kg/d). There was no difference in feed conversion. Weaned pigs that were 1.9 to 2.3 kg lighter initially gained slower (P<.0005) compared with their heavier contemporaries (.27 vs .33; .33 vs .43 and .31 vs .33 kg/d) in Exp. 1, 2 and 3, respectively, This reduced gain was accompanied by a reduced (P<.0005) feed intake (.40 vs .51; .50 vs .66; .50 vs .62 kg/d). There was no interaction of initial weight and temperature regimen.

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Heritability Estimates Of Milk Production From Daughter On Dam Regression By Year And Management Level, L. Dale Van Vleck, L. R. Cox, S. L. Mirande Feb 1985

Heritability Estimates Of Milk Production From Daughter On Dam Regression By Year And Management Level, L. Dale Van Vleck, L. R. Cox, S. L. Mirande

Department of Animal Science: Faculty Publications

Heritability estimated by year of freshening for first-lactation milk records of artificially sired Holstein cows in the northeastern United States from daughter on dam regression averaged about .34 on the linear scale and .31 on the logarithmic scale. Little change could be detected from 1965 to 1982. Number of daughter-dam pairs was 197,338. Heritability estimates on the .5 and .4 power scales always were bounded by estimates on the linear and log scales. Heritability estimates were smallest in low management levels. Residual standard deviations for measurements to the .4 power were similar for all levels of management for a particular …

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Effect Of Dietary Energy Intake During Lactation On Performance Of Primiparous Sows And Their Litters, J. L. Nelssen, A. J. Lewis, E. R. Peo, J. D. Crenshaw Jan 1985

Effect Of Dietary Energy Intake During Lactation On Performance Of Primiparous Sows And Their Litters, J. L. Nelssen, A. J. Lewis, E. R. Peo, J. D. Crenshaw

Department of Animal Science: Faculty Publications

A total of 146 primiparous sows was used in four replications of an experiment to investigate the effect of energy intake during a 28-d lactation on sow and litter performance. Dietary treatments consisted of three energy intakes; 10, 12 or 14 Mcal of metabolizable energy (ME)·sow– 1 ·d–1. All sows were fed equal amounts of crude protein, vitamins and minerals daily, which met or exceeded standard recommendations. The experiment was initiated at parturition. Sow weight and backfat loss during lactation decreased linearly (P

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Comparison Of Iterative Procedures For Solving Equations For Sire Evaluation, L. Dale Van Vleck, D. J. Dwyer Jan 1985

Comparison Of Iterative Procedures For Solving Equations For Sire Evaluation, L. Dale Van Vleck, D. J. Dwyer

Department of Animal Science: Faculty Publications

Gauss-Seidel, successive over-relaxation, end-of-round relaxation, and block iteration methods of obtaining solutions for sire effects from equations rising from progeny with records in mixed model procedures were compared. Equations transformed to provide direct solutions for genetic group plus sire effects as well as constrained and unconstrained equations were compared also. Equations for milk yield for the Northeast Artificial Insemination Sire Comparison numbered 301 for Ayrshires, 325 for Brown Swiss, 6,010 for Holsteins, and 926 for Jerseys after absorption of herd-year-season effects. Numbers of coefficients were 15 to 20% less for transformed equations, which decreased computing time per round of interation …

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Extension Factors For Trimester Yields Of Milk And Fat, K. Agyemang, E. C. Clapp, L. Dale Van Vleck Jan 1985

Extension Factors For Trimester Yields Of Milk And Fat, K. Agyemang, E. C. Clapp, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Evidence of problems with sire proofs of extended incomplete records suggests the desirability of another method of evaluating dairy bulls for milk that minimizes the need for extending records by instead considering yields of three parts of a lactation (days 1 to 90, 91 to 180, and 181 to 270) as distinct and separate traits. Records of less than 90 days (or 180 or 270 days) require extension to 90-day (or 180- or 270-day) equivalents. Last sample day production of 17,826, 15,282, and 12,115 first-lactation records of Holstein cows was used to calculate extension factors to predict remaining yields to …

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Trends In Genetic And Phenotypic Variances For Milk Production, S. L. Mirande, L. Dale Van Vleck Jan 1985

Trends In Genetic And Phenotypic Variances For Milk Production, S. L. Mirande, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Residual standard deviations estimated separately for each year of first freshening from first lactation milk records of artificially sired Holstein cows increased from 1960 to 1982, especially after 1976. The pattern on the square root scale was similar. On the logarithmic scale, residual standard deviations were smallest in the middle of the time period. Heritabilities estimated from paternal half-sib correlations were greater than .30 on all scales until about 1976 when estimates began to go below .20. Estimates were similar for untransformed and transformed records. When records were divided into four herd production groups within each year, the same patterns …

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The Nutritional Value Of Normal And High Lysine Corns For Weanling And Growing-Finishing Swine When Fed At Four Lysine Levels, G. L. Asche, A. J. Lewis, E. R. Peo, Jr., J. D. Crenshaw Jan 1985

The Nutritional Value Of Normal And High Lysine Corns For Weanling And Growing-Finishing Swine When Fed At Four Lysine Levels, G. L. Asche, A. J. Lewis, E. R. Peo, Jr., J. D. Crenshaw

Department of Animal Science: Faculty Publications

One-hundred-ninety-two weanling pigs from two separate trials, (initial weight 6.0 and 5.6 kg) and 400 growing-finishing pigs (initial weight 17 kg) were fed normal and high lysine corn diets containing four levels of lysine in a 2 • 4 factorial arrangement. Crossbred (Large White • Landrace x Duroc) pigs were used in all experiments. The objectives of the experiments were to (1) compare normal and high lysine corn when fed at different lysine levels, (2) determine the lysine requirements for the three stages of growth and (3) evaluate the effect of protein level on the lysine requirement. All diets were …

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Weaining Weight Response Of Pigs To Simple And Complex Diets, L. V. Himmelberg, E. R. Peo, Jr., A. J. Lewis, J. D. Crenshaw Jan 1985

Weaining Weight Response Of Pigs To Simple And Complex Diets, L. V. Himmelberg, E. R. Peo, Jr., A. J. Lewis, J. D. Crenshaw

Department of Animal Science: Faculty Publications

Five experiments were conducted to determine (1) the value of simple vs complex diets on gains and feed conversion of pigs weaned at a constant age but varying in weight, (2) the optimum post-weaning time to change from a complex to a simple diet and (3) the effect of previous treatment on subsequent performance.

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Metabolic Clearance And Production Rates Of Oestradiol And Progesterone During Pubertal And Postpubertal Development In Gilts, R. K. Christenson, J. J. Ford, D. A. Redmer Jan 1985

Metabolic Clearance And Production Rates Of Oestradiol And Progesterone During Pubertal And Postpubertal Development In Gilts, R. K. Christenson, J. J. Ford, D. A. Redmer

Department of Animal Science: Faculty Publications

The crossbred gilts studied were aged 80 days (prepubertal), 180 days (prepubertal or postpubertal) and 260 days (postpubertal or pregnant). Estimates of metabolic clearance rate (MCR) of oestradiol and progesterone were consistently less (21 and 27%) in plasma than in blood, and these differences were not influenced by age of gilt. The MCR (1/day per kg body weight) for oestradiol and progesterone in plasma was greater (P < 0·05)for 80-day-old prepubertal gilts than for older gilts. The MCR values of oestradiol and progesterone were similar in 180-day-old and 260-day-old gilts independent of reproductive state. Production rate (PR) of oestradiol and progesterone increased with age (80-180days), and age and reproductive state differences were much more pronounced for PR of progesterone than of oestradiol. These results support the hypothesis that a reduction in the MCR and an increase in PR of oestradiol and progesterone in the gilt are associated with the process of pubertal development, and changes in gonadal steroid concentrations appear not to alter the MCR of oestradiol and progesterone.

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Effect Of Dietary Fat On Pig Performance And Dust Levels In Modified-Open-Front And Environmentally Regulated Confinement Buildings, L. I. Chiba, E. R. Peo, Jr., A. J. Lewis, M. C. Brumm, R. D. Fritschen, J. D. Crenshaw Jan 1985

Effect Of Dietary Fat On Pig Performance And Dust Levels In Modified-Open-Front And Environmentally Regulated Confinement Buildings, L. I. Chiba, E. R. Peo, Jr., A. J. Lewis, M. C. Brumm, R. D. Fritschen, J. D. Crenshaw

Department of Animal Science: Faculty Publications

Four trials were conducted with 1,480 pigs (initial wt: 23 kg in trial 1, 29 kg in trial 2 and 49 kg in trial 3 and 4) to determine the effect of dietary fat on pig performance, nutrient separation in an automated feed distribution system, dust levels in swine buildings and integrity of the respiratory system of swine. Two modified-open-front (B-1 and B-2) and two environmentally regulated (E-1 and E-2) growing-finishing buildings, of identical design, were used in each trial. In trial 1,250 pigs (25 pens of 10 pigs/pen) in B-1 were fed a ground, mixed, corn-soybean meal diet (15% …

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Effect On Receiving Diets Containing Alfalfa And Certain Feed Additives On Performance Of Feeder Pigs Transported Long Distances, M. C. Brumm, E. R. Peo, Jr. Jan 1985

Effect On Receiving Diets Containing Alfalfa And Certain Feed Additives On Performance Of Feeder Pigs Transported Long Distances, M. C. Brumm, E. R. Peo, Jr.

Department of Animal Science: Faculty Publications

Three experiments were conducted to determine the effect of receiving diets containing alfalfa meal and certain feed additives on performance of comingled feeder pigs transported 900 to 1,100 kin. In Exp. 1, the inclusion of 9.4% dehydrated alfalfa meal in receiving diets for 2 wk resulted in no difference (P>.I) in gain or feed conversion from purchase to market compared with pigs fed a basal corn-soybean meal (CS) diet or a diet containing 20% ground whole oats (O). In Exp. 2, pigs fed receiving diets containing 10% dehydrated alfalfa meal had no improvement (P>. 1) in gain (.60 …

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Effect Of Source Of Dietary Energy And Energy Restriction During Lactation On Sow And Litter Performance, J. L. Nelsson, A. J. Lewis, E. R. Peo, Jr., B. D. Moser Jan 1985

Effect Of Source Of Dietary Energy And Energy Restriction During Lactation On Sow And Litter Performance, J. L. Nelsson, A. J. Lewis, E. R. Peo, Jr., B. D. Moser

Department of Animal Science: Faculty Publications

The effects of source of energy and energy restriction during lactation on sow and litter performance were investigated in an experiment with 90 primiparous sows. At parturition, the sows were randomly assigned to diets containing either tallow or cornstarch as a major energy source.

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An Evaluation Of Threonine And Isoleucine As The Third And Fourth Limiting Amino Acids In Corn For Growing Swine, D. A. Grosbach, A. J. Lewis, E. R. Peo, Jr. Jan 1985

An Evaluation Of Threonine And Isoleucine As The Third And Fourth Limiting Amino Acids In Corn For Growing Swine, D. A. Grosbach, A. J. Lewis, E. R. Peo, Jr.

Department of Animal Science: Faculty Publications

A metabolism experiment and two growth experiments were conducted to determine if threonine and isoleucine are the third and fourth limiting amino acids in corn for growing swine. In each experiment there were four dietary treatments. The basal diet contained corn fortified with minerals, vitamins, lysine and tryptophan. Threonine additions of 0 or .17% and isoleucine additions of 0 or .22% of the diet were evaluated in a 2 • 2 factorial arrangement of treatments. The addition of threonine reduced (P<.001) the daily urinary excretion of urea N and total N. There was a tendency for urea N excretion to be reduced further when isoleucine was added in combination with threonine.

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Prediction Of Heifer Transmitting Ability From Genetic Evaluations Of Sire, Dam, And Maternal Grandsire, R. A. Westell, L. Dale Van Vleck Jan 1985

Prediction Of Heifer Transmitting Ability From Genetic Evaluations Of Sire, Dam, And Maternal Grandsire, R. A. Westell, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Estimated transmitting abilities for milk of 258,201 Holstein heifers from first lactations were regressed on sire's milk proof, maternal grandsire's milk proof, and either dam's estimated transmitting ability from milk in first lactation or dams' estimated transmitting ability from milk of all lactations. Effects of year of birth of dam, dam's estimated transmitting ability for milk from first lactation, for milk from all lactations, estimated transmitting ability for fat from first lactation or for fat from all lactations were determined by sorting data into deciles by each of these criteria and calculating partial regression coefficients within each decile. For data …

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Prediction Of Transmitting Ability Of Heifers From Genetic Evaluations Of Dams When Dams And Herdmates Are Required To Have A First Record, R. A. Westell, L. Dale Van Vleck Jan 1985

Prediction Of Transmitting Ability Of Heifers From Genetic Evaluations Of Dams When Dams And Herdmates Are Required To Have A First Record, R. A. Westell, L. Dale Van Vleck

Department of Animal Science: Faculty Publications

Estimated transmitting ability for milk production calculated from only first lactation records was regressed on milk proofs of the sire and maternal grandsire and either estimated transmitting ability of the dam calculated from only first lactations or estimated transmitting ability of the dam calculated from all lactations of a data set in which all cows were required to have milk records of first lactation. Records of 222,576 Holstein heifers in the northeastern United States were analyzed. Partial regression coefficients were similar to those from reports in which all records in the data file were used to estimate transmitting abilities. The …

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Successive Overrelaxation, Block Iteration, And Method Of Conjugate Gradients For Solving Equations For Multiple Trait Evaluation Of Sires, L. Dale Van Vleck, D. J. Dwyer Jan 1985

Successive Overrelaxation, Block Iteration, And Method Of Conjugate Gradients For Solving Equations For Multiple Trait Evaluation Of Sires, L. Dale Van Vleck, D. J. Dwyer

Department of Animal Science: Faculty Publications

A potential difficulty with mixed model equations for multiple trait evaluation of sires is solving the equations as the number of equations increases proportionally to the number of traits. Time required to obtain inverse solutions increases by the number cubed. Thus, iterative procedures often are used. Three iterative procedures, successive over-relaxation, block iteration with relaxation, and the method of conjugate gradients, were compared for four sets of multiple trait equations for sire evaluation. Equations were solved after absorption of equations for random herd-year-season effects. Equations for two and four traits each with test and complete data sets made up the …

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Effect Of Castration On Plasma Luteinizing Hormone Concentrations In Prepubertal Boars, R. J. Kittock, J. E. Kinder, R. K. Johnson Oct 1984

Effect Of Castration On Plasma Luteinizing Hormone Concentrations In Prepubertal Boars, R. J. Kittock, J. E. Kinder, R. K. Johnson

Department of Animal Science: Faculty Publications

Mean concentrations and the occurrence of pulsatile release of luteinizing hormone (LH) were determined in 14-wk-old crossbred boars (50.5 ± 1.5 kg) after bilateral or unilateral castration at 10 wk of age. Blood was collected at 10-min intervals for 5 h. Then gonadotropin releasing hormone (GnRH; 40 / μg) was given and sampling was continued at 5-min intervals for 1 h. Compared with intact boars, bilateral castration increased (P<.001) mean LH (982 ± 56 vs 389 ± 56 pg/ml), pulsatile releases of LH (7.0 ± .6 vs 2.0 ± .6 pulses/5 h) and LH pulse amplitude (617 ± 29 vs 360 ± 58 pg/ml). Unilaterally castrated boars did not differ from intact boars in any of the above measures of LH secretion. Testis weight increased more between 10 and 14 wk of age in the unilateral castrates than in the intact boars (432 ± 42 vs 245 ± 34%; P<.05). Thus, compensatory hypertrophy occurred within 4 wk of castration. Plasma testosterone was lower for bilateral castrates than for intact animals (.1 ± .8 vs 3.6 ± .9 ng/ml; P<.05) while unilateral castrates (3.8 -+ 1.0 ng/ml) and intact boars did not differ. Plasma estradiol concentrations in bilateral and unilateral castrates were not different from levels found in intact boars (1.8 ± 1.8, 8.8 ± 2.1 and 6.0 ± 1.8 pg/ml, respectively). While mean LH after GnRH was higher in bilateral and unilateral castrates than in intact boars (2,588 ± 147 and 2,693 ± 164 vs 1,928 ± 147 pg/ml; P<.01), castration did not affect the highest LH level after GnRH, time of highest level, magnitude of LH change or rate of LH response during the first 15 rain after GnRH. The rate of change of LH from 0 min to time of maximum LH of the bilateral castrates tended to be greater than that in intact boars (b=202 vs 94; P<.10). These data indicate that the negative feedback of gonadal steroids affects LH secretion.

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Sow Productivity Comparisons For Four Breeds Of Swine: Purebred And Crossbred Litters, H. R. Gaugler, D. S. Buchanan, R. L. Hintz, R. K. Johnson Jul 1984

Sow Productivity Comparisons For Four Breeds Of Swine: Purebred And Crossbred Litters, H. R. Gaugler, D. S. Buchanan, R. L. Hintz, R. K. Johnson

Department of Animal Science: Faculty Publications

Data were collected from 366 litters produced in a four-breed (Duroc, Yorkshire, Spotted and Landrace) diallel mating system. Purebred and crossbred litters were farrowed during five consecutive (fall and spring) farrowing seasons (fall 1976 through fall 1978). Litters were produced by randomly mating boars of each breed to at least one female of each breed. Litter size and weight at birth, litter size and weight at 42 d and pig survival to 42 d were analyzed. There were significant parity effects for all traits except survival rate, and significant year and season effects for litter size at birth and 42 …

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Relationships Among Measures Of Testicular Development And Endocrine Function In Boars, A. P. Schinckel, R. K. Johnson, R. J. Kittock May 1984

Relationships Among Measures Of Testicular Development And Endocrine Function In Boars, A. P. Schinckel, R. K. Johnson, R. J. Kittock

Department of Animal Science: Faculty Publications

Nine blood samples were taken at 30-min intervals from 36 Landrace x Large White boars at each of eight ages (42, 56, 70, 84, 98, 112, 126 and 140 d). Serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T) and estradiol- 17β (E-2) were quantified by radioimmunoassay procedures. The maximum concentration of LH and the age at maximum concentration were predicted for each boar. Variability of LH samples was described for each boar by the pooled within age variance among LH samples and by the number of LH peaks. Measurements of testicular development taken at 140 …

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Testicular Development And Endocrine Characteristics Of Boars Selected For Either High Or Low Testis Size , A. P. Schinckel, R. K. Johnson, R. J. Kittock May 1984

Testicular Development And Endocrine Characteristics Of Boars Selected For Either High Or Low Testis Size , A. P. Schinckel, R. K. Johnson, R. J. Kittock

Department of Animal Science: Faculty Publications

Thirty-six Landrace x Large White cross boars were selected from litters with either high or low estimated breeding values for 150-d paired testis weight. Blood samples were taken via jugular venipuncture at eight ages (42, 56, 70, 84, 98, 112, 126 and 140 d). At each sampling age, nine blood samples were taken at 30-min intervals. Luteinizing hormone (LH) was determined on the individual serum samples. Serum samples from each boar at each age were pooled and concentrations of follicle-stimulating hormone (FSH), estradiol-17β (E2) and testosterone (T) were determined. Paired testis width, testis length and body weight were …

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Reproductive Performance For Four Breeds Of Swine: Crossbred Females And Purebred And Crossbred Boars, D. S. Buchanan, R. K. Johnson Apr 1984

Reproductive Performance For Four Breeds Of Swine: Crossbred Females And Purebred And Crossbred Boars, D. S. Buchanan, R. K. Johnson

Department of Animal Science: Faculty Publications

Matings and litters were studied involving all three-breed crosses (sired by purebred boars) and four-breed crosses (sired by crossbred boars) from the Duroc, Yorkshire, Landrace and Spotted breeds. There were 764 female mating records and 161 boars used over five sequential breeding seasons. A sample of pregnant gilts was slaughtered each season and the remainder were allowed to carry their litters to term so that 493 litters resulted. Crossbred and purebred boars and crossbred females were evaluated for their contributions to conception rate (first service and over an 8-wk breeding season), number of services/ conception, litter size and weight at …

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