Lactation Studies. I. Effect of Gestation

Abstract

Inhibition of lactation due to advancing gestation starts sometime after the fifth month Ragsdale et al. (1), using Guernsey Advanced Registry records, observed a reduction of 480 to 800 lb. of milk in the lactation record as pregnancy during lactation exceeded 5 too. Gowen (5), also using Guernsey Advanced Registry records, estimated the decline in the lactation record attributable to pregnancy at 400 to 600 lb. of milk. There was no influence on butterfat percentage. Gaines and Davidson (2), using the same source for data, estimated the decrease to be 2.5 lb. of 4 per cent fat-corrected-milk (hereafter referred to as F.C.M.) for the first 5 too. of pregnancy and 256 lb. of F.C.1VI for the gestation period (9.2 too.). Gooch (3), using Jersey monthly test records, noted only a slight decline in lactation, starting the seventh month of pregnancy. Sikka (6) found monthly variations accounted for 9.57 per cent of the total variation in persistency of Ayrshire cows. Gaines and Davidson (2) reported that younger cows were more persistent milkers than older cows.