Prepartum Milking. IV. The Effect of Prepartum Milking on Milk Production and Length of Time Required to Reach Peak of Lactation

Summary Twenty-two cows were milked prepartum and their production records were compared with a similar group of 22 postpartum-milked cows. In the prepartum-milked group, 21 of the cows had a subsequent or previous lactation and these yields were compared with their prepartum yields. In the postpartum-milked group there were 16 cows with a subsequent or previous lactation, the yields of which were compared with the yields during the experimental lactation. In the three comparisons made, there was no significant difference in yields of F.C.M. The prepartum and the postpartum groups were compared to determine if there was any difference in the length of time required to reach the peak of lactation. The prepartum cows reached their peak in 35.9 ± 2.53 days and the postpartum cows reached theirs in 44.8 ± 4.51 days. This difference was not statistically significant. Within the prepartum-milked group, a comparison was made to determine whether the 21 cows which had two records reached their peak any earlier in their prepartum lactation than in their subsequent or previous lactation. The length of time required to reach peak of lactation during the prepartum lactation was 36.7 ± 2.54 days, as opposed to 44.6 ± 3.69 during their subsequent or previous lactation. This difference was significant at the 5 per cent level of probability. A similar comparison was made within the postpartum group of 16 cows with two records. There was no significant difference in the length of time required to reach peak of lactation in this case.