Inheritance of multiple births in cattle

Abstract

Records on approximately one million calvings were examined for presence of a gene with major effect on the frequency of multiple births. The records were summarized by parity of the cow and registration number of the cow's sire, and an overall age-corrected frequency of multiple births computed for daughters of each sire. The distribution of 876 progeny groups with more than 100 calvings showed no sign of discontinuity, and the same was true for 120 progeny groups with more than 1000 calvings. The daughters of one particular bull had 9.95% multiple births in about 6000 calvings. This bull left more than 80 sons which were used for artificial insemination. The sons ranged from less than one to more than 10% multiple births among their daughters, but no segregation was observed. Heritability estimates (on the binomial scale) ranged from 0.006 in parity 1 to about 0.04 in parities 3–5. Genetic correlations between incidence of multiple births in first and subsequent parities were estimated at 0.52–0.64, while those among parities 2–5 were from 0.70 to 0.84.