young bulls
Proven and Young Holstein Bulls Compared for Daughter Yields, Productive Life, Somatic Cell Score, and Inbreeding
Tue, 2013-02-19 09:25 — Jihad Mustafa AbdallahThe objective of this study was to compare daughters of proven (progeny-tested) and young sampling bulls available for use at the same time for yield traits, productive life, somatic cell score, and inbreeding. Data were from USDA sire evaluations of July 1989 through July 1994. Proven bulls used between 1989 and 1994 were identified based on the change in number of daughters. Young bulls were identified based on age and date a bull first entered artificial insemination. Young bulls were classified into two categories: one included all young bulls available in one year and the other included the top 50% on parent average for milk. Daughter deviations for yields, productive life and somatic cell scores, and average inbreeding were obtained from May 2000 evaluation. Daughter deviation milk was not different between proven and top 50% young bulls but was lower for all young bulls. Young bulls (all and top 50%) exceeded proven bulls in daughter deviation fat and protein. Progeny of proven bulls had favorably higher productive life in most years but unfavorably higher somatic cell score than progeny of young bulls. Inbreeding was consistently higher for daughters of young bulls than for those of proven bulls. Results indicate that young bulls were competitive with proven bulls. Use of young bulls from among the top 50% should result in equal or higher genetic progress in yields compared to contemporaries by proven bulls.
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TwitterGenetic Change in Milk, Fat, Days Open, and Body Weight After Calving Based on Three Methods of Sire Selection
Tue, 2013-02-19 09:13 — Jihad Mustafa AbdallahThree Holstein lines, were compared, based on different methods of sire selection, for genetic change in 3.7% FCM, fat yield, days open, and predicted body weight after calving. The three lines were 1) evaluated sires selected only for 3.7% FCM (milk line), 2) evaluated sires selected on an index that included 3.7% FCM and type traits (index line), and 3) young bulls selected on pedigree for 3.7% FCM (young line). Cows from these lines were born in 1971 through 1993 in five experimental herds owned by the State Farm Division of North Carolina Department of Agriculture. Breeding values of cows in each line computed with a repeatability model were averaged by and regressed on birth year to estimate genetic change. Genetic gains in 3.7% FCM were 81 kg/yr for the milk line, 61 kg/yr for the line selected on index, and 68 kg/yr for the young sire line. Estimates of genetic gain in fat yield were 2.99, 2.16, and 2.54 kg/yr in the three lines, respectively. Genetic gains in 3.7% FCM and fat yield in the milk line were significantly different from the index and young sire lines, but the index and young sire lines were not significantly different. Estimates of genetic change in days open were 0.71, 0.57, and 0.63 d/yr in the milk, index, and young sire lines, respectively. These estimates were not significantly different. Average breeding values for body weight decreased for births from 1971 to 1981 then rapidly increased for later births in all lines.
