The use of return interval pattern to indicate dairy herd
infertility problems
O.M. Castle
New Zealand Dairy Production and Marketing Board, Wellington
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Proceedings of the New Zealand Society of Animal Production.
1963, 23: 88-99
In this paper the causes of variation in the non-return rates of
herds using Artificial Breeding in New Zealand are examined. The herds
have been divided into four non-return rate groups according to their
deviation from the average of all herds in the same A.B. technician
group, and the percentage of short, normal, and long return intervals in
the four groups has been used to estimate the incidence of such factors
as failure to conceive and embryonic mortality. Some assumptions have
had to be made, but the estimates provide background information for
field studies on these aspects. They. enable an assessment to be made of
the relative importance of factors causing variation in herd non-return
rates, failure to conceive and embryonic mortality appearing to be
equally important. The problem of locating "true" problem herds for
survey work has been examined and it has been found that the field can
be narrowed by taking the return interval pattern as well as the
non-return rate into account.
Keywords: NZSAPAB;
Last Updated 24-08-2000
