RECORDS OF CALVING

Timaru Herald, Volume CXLV, Issue 21180, 29 October 1938, Page 15

RECORDS OF CALVING

AVERAGE PERIOD FOUND DIFFERENCES IN SEXES An investigation into the calving records of the tuberculin-tested herd of dairy cows at the Lord Wandsworth Agricultural College (England) was prompted by the suggestion that bull calves always tend to go long over time.

Apparently this impression is more apparent than real. A period of 41 years between July, 1933, and February, 1938, is covered by this investigation, and during this time 150 calves were born, no account being taken of abortions.

• The Milk Recording Society’s period for gestation of 281 days has always been used on this farm for calculating probable calving dates, but it appears that this period is too short, the average of 150 calves being 2841 days. The average gestation period for bull calves, which accounted for 54 per cent of the total births, was 285 days, one day longer than the average for heifer calves.

Although, therefore, the difference between the sexes is small, nevertheless it should be mentioned that whereas in 14 instances bull calves were born ten days or more beyond the expected time, in only a single instance did this occur with a heifer calf. The five winter months, OctoberFebruary inclusive, yielded 60 per cent of the total births, with January the most prolific month in the year. This would, apparently, suggest that matings made in the months February to June inclusive are the most likely to succeed for such an uneven incidence of calvings is not intentionally planned. Fewest births occurred in March and April. Although births were most numerous during the winter months, it was also found that the pregnancy period was prolonged, as the average gestation periods show: — November 285.7 days December 287.2 days January 285.4 days February 284.8 days In the autumn of 1934 the adult dairy stock was very severely affected with husk. During this period 13 births were recorded, of which five took place on the average—three days earlier than expected indicating the adverse effect of continual coughing in the heavily pregnant cow. The record of individual cows were examined to see whether any animals showed a tendency to produce only bull calves or vice versa, but there was no definite evidence of this. There was also no evidence that the animals which "goes over time” does so with regularity at every calving.