Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2004
Publication Date: November 4, 2004
Citation: Casas, E., Lunstra, D.D., Stone, R.T. 2004. Quantitative trait loci for male reproductive traits in beef cattle. Animal Genetics 35:451-453. Interpretive Summary: The objective of the present study was to identify the location of genes affecting male reproductive traits in cattle. Locations of genes affecting these traits were detected on chromosomes 5 and 29. Chromosome 29 influenced more than one trait. Chromosome 5 influenced the expression of follicle stimulating hormone (FSH). Location on chromosome 5 supports evidence indicating that the mechanism behind ovulation rate in females is regulated by follicle stimulating hormone with a similar effect of follicle stimulating hormone in males. Locations of genes reported here are suitable to be investigated in other populations.
Technical Abstract: The objective of the present study was to detect quantitative trait loci (QTL) for economically important male reproductive traits in a half-sib family from a Bos indicus (Brahman) x Bos taurus (Hereford) sire. The sire was mated to MARC III (1/4 Hereford, 1/4 Angus, 1/4 Red Poll, and 1/4 Pinzgauer) cows. One hundred twenty six male offspring born in 1996 were castrated at 8.5 months of age and testicular traits were measured. Traits analyzed were concentration of follicle stimulating hormone in peripheral blood at castration (FSH), paired testicular weight (PTW) and paired testicular volume (PTV) adjusted for age of dam, calculated age at puberty (AGE), and body weight at castration (BYW). A putative QTL (expected number of false-positives < 1) was observed for FSH concentration on chromosome 5. The support interval for this QTL spans cM 47 to 82, where the maximum F-statistic was detected at 70 cM from the beginning of the linkage group. Animals inheriting the Hereford allele had a 2.47 ng/ml higher concentration of follicle stimulating hormone in peripheral blood at castration than those inheriting the Brahman allele. Evidence also suggests the existence of a putative QTL on chromosome 29 for PTW, PTV, AGE, and BYW. The maximum F-statistic was detected at cM 44 from the beginning of the linkage group for PTW, PTV, and AGE, and at cM 52 for BYW. The support intervals for PTW, PTV, AGE and BYW spanned from cM 38 to cM 46, from cM 37 to cM 46, from cM 34 to cM 57, and from cM 37 to cM 59, respectively. Those animals that inherited the Brahman allele at this chromosomal region had a 45 g heavier PTW, a 42 cm3 greater PTV, a 39 day younger AGE, and a 22.8 kg heavier BYW, compared to those inheriting the Hereford allele. This is the first report of QTL for male reproductive traits in cattle.