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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Genetics and Animal Breeding » Research » Publications at this Location » Publication #172530
Title: GENETIC RELATIONSHIPS BETWEEN MALE AND FEMALE REPRODUCTIVE TRAITS IN BEEF CATTLE

Author
item GARGANTINI, G. - UNIV. OF NEBR.-LINCOLN
item Cundiff, Larry
item Lunstra, Donald
item Van Vleck, Lloyd

Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2005
Publication Date: 6/1/2005
Citation: Gargantini, G., Cundiff, L.V., Lunstra, D.D., Van Vleck, L.D. 2005. Genetic relationships between male and female reproductive traits in beef cattle. Professional Animal Scientist 21:195-199.

Interpretive Summary: Ratios of expected responses in females show that indirect selection of males based on two measures of age at puberty based on sperm prediction (AP1 and AP3)and measures of scrotal circumference (SC3), testis length (L3) and volume (V3) at production of 500 million sperm with 50% or greater progressive motility, yearling height (YW) and 15 month weight (15W) and height (15h) may be useful for improving pregnancy rate in heifers. Selection based on these reproductive and growth traits of males would increase pregnancy rate in heifers more than direct selection of females. Although response to indirect selection using male traits was not indicated to be more effective than response to direct selection for improving age at puberty in females, estimates of genetic correlations between AP in heifers and YSC in bulls and between AP and SC3 were favorable but the small magnitude of the estimates indicate that the genetic links with AP in heifers are not strong. The estimates of genetic correlations, however, suggest favorable genetic links between AP1 and AP3 in males and AP in females. Results from the present study suggest little genetic response in female fertility traits would be expected from selecting sires on yearling and 15 mo scrotal circumference. In addition, response to indirect selection of females based on AP would not be expected to effectively improve PR of heifers. Other studies, however, with more data on males, have suggested more favorable relative genetic responses in female fertility traits from indirect selection based on scrotal circumference of males. Male reproductive traits such as scrotal circumference also are easier and less expensive to measure than female reproductive traits and can be associated with greater selection intensity.

Technical Abstract: Reproductive traits were measured in 234 bulls and 1,184 heifers from matings of three dam breeds (Angus, Hereford, MARC III) with six sire breeds (Angus, Hereford, Brahman, Boran, Tuli, Belgian Blue) from the Germ Plasm Evaluation (GPE) Program at USMARC. Male traits were: yearling scrotal circumference (YSC), height (YH), and weight (YW); age at puberty (AP1, production of 50 million sperm with > 10% progressive motility); age, scrotal circumference, average testis length and testicular volume when produced 500 million sperm with > 50% progressive motility (AP3, SC3, L3 and V3); and 15 mo weight (15W) and height (15H). Traits of females were age at puberty (AP, first estrus) and pregnancy diagnosis (PR) at 18 mo. The objective was to determine whether indirect selection would be effective for improving fertility traits. Estimates of heritabilities and genetic correlations between male and female traits were obtained using REML. Heritability estimates for YSC, YH, YW, AP1, AP3, SC3, L3, V3, 15W, 15H, AP, and PR were 0.05, 0.20, 1.00, 0.47, 0.33, 1.00, 0.52, 1.00, 1.00, 0.54, 0.52, 0.10. Estimates of genetic correlations between AP and YSC, YH, YW, AP1, AP3, SC3, L3, V3, 15W, 15H were -0.57, 0.66, 0.01, 0.16, 0.05, -0.23, -0.14, -0.20, -0.04, and 0.35. Estimates of genetic correlations between PR and YSC, YH, YW, AP1, AP3, SC3, L3, V3, 15W, 15H were 0.35, -0.48, 0.49, -0.45, -0.35, -0.97, -0.24, -0.67, 0.51, and 0.44. Selection of males on AP1, AP3, SC3, L3, V3, YH, 15W, and 15H may be useful for improving PR. Although no male trait was found to be effective for improving age at puberty in females through indirect selection, genetic correlations between AP and YSC and between AP and SC3 were favorable. Direct selection would seem to be more effective than indirect selection for AP in heifers. Male reproductive traits such as scrotal circumference, however, are easier and less expensive to measure than female reproductive traits and are associated with greater selection intensity.