Document Type

Article

Publication Date

1-1-1974

Abstract

Season of calving had important effects on the shape of the lactation curve, affecting peak milk yield, persistency, and lactation lengths in a Louisiana Holstein herd. Feeding regime and age at calving also had marked effects. Plane of nutrition appeared to have more important effects on components of the lactation curve than did season of calving. Most interaction effects were small. Lactation milk yield for Holstein cows in five Louisiana herds calving in the hot season of the year was consistently from 200 to 300 kg (5 to 8%) less than that for cows calving during cool and mild seasons. Yields during the first 90 days of lactation were 10 to 14% less. Interactions of sire by season of calving for part and whole lactation milk and milk fat yields accounted for less than 1% of the total variance. Interactions of cow by season of calving were of the same general magnitude. Thus, genotype-climatic interactions for milk production for Holstein cattle under Louisiana conditions are not important enough to consider in the selective breeding program. © 1974, American Dairy Science Association. All rights reserved.

Publication Source (Journal or Book title)

Journal of Dairy Science

First Page

833

Last Page

841

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