The Holstein first-calf heifers imported from Canada in 2007 served as the target of our research, as well as their female offspring obtained in Kazakhstan and local white-and-black cattle herd mates.
This paper presents the material to study lactation performance, reproductive capacity, and natural resistance of purebred Holstein first-calf heifers as compared to white-and-black first-calf heifers with 5/8 blood of the Holstein breed.
Milk-producing records for completed lactation were performed based on the data of everyday milk-yield control in 405 first-calf heifers.
Lactation performance in the Holstein first-calf heifers turned out to be higher than in local herd mates by 32-35% (Table 1).
First-calf heifer lactation curves are rather flat; average monthly drop in milk yields throughout lactation was about 5%, but they are double-peaked in Holsteins.
The effects of inadequate nutrition during pregnancy are more severe in first-calf heifers than in older cows.
First-calf heifers will be lower in dominance and will probably not receive any of a hand-fed supplement if they are not fed separately from the cows.
To improve the chances for dropping a live healthy calf, bred first-calf heifers should be fed adequate nutrition during the gestation period to support the gain necessary to achieve 85 percent of mature weight by calving.