The Relationship of Production of Heifers Milked Prepartum to the Composition of Colostrum

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Abstract
16 first-lactation Ayrshire heifers were divided into 2 equal groups on the basis of expected dates of parturition, every other animal being assigned to each group. Group 1 was handled in the usual way. Heifers in group 2 were milked for 3 to 18 days with an avg. of 10 days before parturition. Total production before calving for prepartum-milked heifers varied from 2 to 142 lb. Production on the day before calving varied from 0.1 to 24.3 lb. Total N and the non-casein N of the milk produced on the day of parturition for the heifers not milked prepartum averaged 2.34 and 1.34 g. per 100 ml., respectively, whereas the milk from heifers milked prepartum averaged 1.13 and 0.5 g. per 100 ml., respectively. The non-casein N amounted to 57.3% of the total N for the heifers not milked prepartum, but only 39.1% the heifers milked prepartum. The total N and the non-casein N in the milk of heifers milked prepartum on the day of parturition were dependent on the level of production and the total amt. produced before parturition.