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Reproductive And Testicular Characteristics Of Purebred And Crossbred Boars, E. R. Wilson, R. K. Johnson, R. P. Wettemann
Reproductive And Testicular Characteristics Of Purebred And Crossbred Boars, E. R. Wilson, R. K. Johnson, R. P. Wettemann
Department of Animal Science: Faculty Publications
One-hundred-ninety-five Duroc (D), Hampshire (H), Duroc x Hampshire (D x H) and Hampshire x Duroc (H x D) boars were evaluated for reproductive performance. One-hundred- sixteen boars were castrated at approximately 225 days of age to evaluate testicular and epididymidal weights and sperm numbers. Testes from crossbred boars were 95.33 ± 22.81 g heavier (P<.01) and contained 14.41 ± 3.92 billion more sperm (P<.01) than those from purebred boars. Testes from Hampshire boars were 50.40 ± 31.75 g heavier with 6.27 ± 5.45 billion more sperm than those from Durocs. There were no significant differences between breeds for caput-corpus epididymidal measurements. Durocs had 24.55 ± 12.16 billion more sperm (P<.05) in the cauda epididymis than Hampshire boars. Testes weight and testes sperm numbers were significantly correlated with caput-corpus epididymidal and cauda epididymidal sperm numbers. Correlations of testicular and epididymidal characteristics with growth rate and backfat to 100 kg were small and nonsignificant. Twenty 7.5-month to 9-month-old D1 D x H and H x D boars and 19 H boars were each mated to two Yorkshire gilts to evaluate reproductive efficiency. Conception rates were: D, 63.2%; D x H, 67.5%; H x D, 60.0%; and H, 48.6%. Number of embryos 30-days postbreeding was 10.66 ± .49 and 11.25 ± .43 (P>.10) for gilts mated to purebred and crossbred sires, respectively. Twenty-eight of 36 crossbred boars mated each time they were exposed to an estrus gilt but only 11 of 36 of the purebred boars mated each time. None of the crossbred boars failed to mate …
Age-Season Adjustment Factors Considering Herd Feeding Practices, G. R. Wiggans, L. Dale Van Vleck
Age-Season Adjustment Factors Considering Herd Feeding Practices, G. R. Wiggans, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
The influence of percent of net energy in the herd's ration derived from concentrates on age-season effects was studied in New York Holstein Dairy Herd Improvement records. Ten feeding groups were defined by herd-feeding information. There was some increase in milk yield with an increasing proportion of concentrates in the ration. For six of these groups, the two highest, two middle, and two lowest in percent net energy from concentrates, age-season effects were calculated. The trends in age effects and seasonal effects were similar for all groups with the groups having a higher fraction of net energy from concentrates showing …
Interpolation For Extension Factors, G. R. Wiggans, L. Dale Van Vleck
Interpolation For Extension Factors, G. R. Wiggans, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
A complete table of extension factors for all lengths of part records can be approximated closely from a much smaller table of reciprocals of the factors. The procedure is to use linear interpolation on the reciprocals from the small table. The required extension factor is the reciprocal of the result of interpolation. This procedure is more accurate than interpolation on the factors themselves since the reciprocals are more nearly linearly related to length of part record than are the extension factors themselves.
Memorial: Marvel L. Baker
Department of Animal Science: Faculty Publications
Marvel L. Baker, Professor Emeritus of Animal Science and Dean Emeritus of the College of Agriculture, University of Nebraska-Lincoln died April 20, 1977 after being in poor health for several months.
An Analysis Of The Dependency Structure Between A Gilt's Prebreeding And Reproductive Traits. Ii. Principal Component Analysis, L. D. Young, R. K. Johnson, I. T. Omtvedt
An Analysis Of The Dependency Structure Between A Gilt's Prebreeding And Reproductive Traits. Ii. Principal Component Analysis, L. D. Young, R. K. Johnson, I. T. Omtvedt
Department of Animal Science: Faculty Publications
Seventeen variables measured before breeding and three measures of reproduction were taken on 339 purebred Duroc, Hampshire and Yorkshire gilts and 192 two-breed cross gilts resulting from matings among these breeds. Eight principal components accounted for 90% of the dependency structure existing among the 17 traits measured before breeding. Two principal components accounted for 97% of the dependency structure existing among the three reproductive traits. The first principal component (PCll) from the prebreeding traits was a general measure of growth ability and accounted for 28% of the variation in the 17 measurements. The second principal component (PC12) contrasted slow growing …
An Analysis Of The Dependency Structure Between A Gilt's Prebreeding And Reproductive Traits. I. Phenotypic And Genetic Correlations, L. D. Young, R. K. Johnson, I. T. Omtvedt
An Analysis Of The Dependency Structure Between A Gilt's Prebreeding And Reproductive Traits. I. Phenotypic And Genetic Correlations, L. D. Young, R. K. Johnson, I. T. Omtvedt
Department of Animal Science: Faculty Publications
This study involved the records of 339 purebred Duroc, Hampshire and Yorkshire gilts and 192 two-breed cross gilts resulting from matings among the three breeds. The primary purpose of this paper was to investigate the relationship of prebreeding traits, including the growth of the gilt and her littermates, with subsequent measures of reproduction. Heritabilities were estimated for several traits and in general the estimates were somewhat higher than most estimates in the literature. Genetically, all measures of growth were favorably and moderately to highly correlated to ovulation rate, with the relationship being stronger for traits measured late in growth as …
Expected Phenotypic Response In Weaning Weight Of Beef Calves From Selection For Direct And Maternal Genetic Effects, L. Dale Van Vleck, David St. Louis, J. I. Miller
Expected Phenotypic Response In Weaning Weight Of Beef Calves From Selection For Direct And Maternal Genetic Effects, L. Dale Van Vleck, David St. Louis, J. I. Miller
Department of Animal Science: Faculty Publications
An equation is derived to predict expected phenotypic response to selection when the trait under selection is influenced by both direct and maternal genetic effects. The expected phenotypic response after the i+lth generation of selection is Pi+1 = (i+l){Delta}D + i{Delta}M + {Delta}MC where {Delta}D and {Delta}M are the averages of the genetic selection differentials of the parents for the direct and maternal effects and {Delta}MC is the maternal genetic selection differential for selected females. An example, corresponding to published reports of genetic variances and covariance for direct and maternal effects on weaning weight, illustrates the importance of the covariance …