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Fertility indices for beef bulls *
Author(s) -
PERRY VEA,
CHENOWETH PJ,
POST TB,
MUNRO RK
Publication year - 1990
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1990.tb07383.x
Subject(s) - fertility , zoology , beef cattle , biology , microbiology and biotechnology , medicine , environmental health , population
SUMMARY Young (16‐ to 30‐month‐old) beef bulls of 6 different genotypes were assessed for production and reproduction traits at different ages and intervals from single‐sire mating. Fertility indices, in the form of multiple regression equations using pregnancy rate as the dependent variable, were derived from these assessments using non‐orthogonal analyses of variance and covariance. “Among” and “within” genotype fertility indices showed significant correlations with pregnancy rate. “Within” genotype fertility indices showing significant multiple correlations (p<0.01) at 11 (r = 0.75), 8 (r = 0.89), 6 (r = 0.86) and 2 (r = 0.80) months prior to mating. It was found that the most important traits to include in the fertility indices were peripheral LH levels following GnRH stimulation, testicular volume, libido and body weight. In general, the fertility indices showed good correlations with bull reproductive performance and were not significantly affected by bull genotype.