Sire Differences in Sex Ratio of Progeny

• Published in: Journal of dairy science Vol. 58; no. 11; pp. 1723 - 1726
• Main Authors: Powell, R.L., Norman, H.D., Dickinson, F.N.
• Format: Journal Article
• Language: English
• Published: Champaign Elsevier Inc 01.11.1975; Am Dairy Sci Assoc; American Dairy Science Association
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(75)84775-8

Sex ratio, the percentage of progeny that are males, was studied among sires by gross ratio, mean weighted difference, and least squares procedures. The sex ratio among over one-half million single births was 52.9%, about 1% higher than that for an extensively edited subset of 14,559 progeny by 94 bulls used to examine sire differences. The ranges of gross ratios and mean weighted differences for these bulls were from 38.7 to 64.4% and –13.8 to 18.0%. Each sire had 80 or more progeny, and sire differences from the assumed population means of 51.7% and 0 were about as large as expected by sampling. Corresponding ranges for a subset of 60 bulls used in the least squares analyses were 23 and 21%; range for least squares constants was 25%. Heritability estimates near zero indicated that additive genetic variance is small or zero. However, the possibility that such tests may be inapplicable to the detection of rare bulls with real differences in sex ratio of progeny is discussed.