II. Interactions between conception rate and submission rate on the proportion of the herd reported in calf to A.B.

Abstract

Abstract Ninety-seven herds in the Wellington-Hawke's Bay Herd Improvement Association in which at least 90% of the cows were artificially inseminated, and which used A.B. exclusively for at least 7 weeks, were divided into three submission rate (S.R.) categories: LOW S.R. — less than 80% of the cows inseminated during (he first 4 weeks of mating (28 herds); AVERAGE S.R. — at least 80% but less than 90% inseminated (46 herds); and HIGH S.R. — at least 90% inseminated (23 herds). Within each category herds were reclassified into three conception rate (C.R.) groups: LOW C.R. with a 49-day non-return rate for all first inseminations of less than 57%; AVERAGE C.R. with a non-return rate of at least 57% but less than 63%; and HIGH C.R. with a non-return rate of at least 63%. The proportions of each herd recorded as in calf to A.B. at the end of the seventh week of mating (7-wcek H.I.R.) in the three LOW S.R. groups were: LOW C.R. 66.4%; AVERAGE C.R. 66.6%; and HIGH C.R. 78.2%. In the AVERAGE S.R. groups the co...