Genetic Studies of Dairy Production Early in Lactation
نویسندگان
چکیده
منابع مشابه
Genetic parameters of a biological lactation model: early lactation and secretion rate traits of dairy heifers.
Early lactation parameters are difficult to estimate from commercial dairy records due to the small number of records available before the peak of production. A biological model of lactation was used with weekly milk records from a single Holstein herd to estimate these early lactation parameters and the secretion rate of milk from the average cell throughout lactation. A genetic analysis of th...
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The objectives were to estimate (co)variance components and genetic parameters for lactation curve traits in Holstein dairy cows in Iran. The used data were records on Holstein cows collected during January 2003 to December 2012 by the Animal Breeding Center of Iran (Karaj, Iran). In order to describe the lactation curve, an incomplete gamma function was fitted to 691200 test-day records on 962...
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The aim of the present study was to estimate genetic and phenotypic parameters of milk production traits in the first and second lactations of Romanian Simmental dairy cattle. For the estimation of variance, heritability, genetic and phenotypic correlations among milk yield, fat yield, protein yield, and percentages of fat and protein, 3400 first and second lactation records over a period of fi...
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Long-chain fatty acids mobilized during early lactation of dairy cows are increasingly used as energy substrate at the expense of acetate. As the synthesis of acetate in the rumen is closely linked to methane (CH4) production, we hypothesized that decreased acetate utilization would result in lower ruminal acetate levels and thus CH4 production. Twenty heifers were sampled for blood, rumen flui...
متن کاملEffect of Restricted Grazing in Early Lactation on Milk Production from Dairy Heifers
Dairy heifers had an estimated grazed pasture intake of either 11.8 (H) or 6.0 (L) kg DM/heifer/day for four weeks in early lactation and a common pasture allowance thereafter. Group L produced less milk (2202 vs. 2433 R) and milk protein (75.0 vs. 81.6 kg) than Group H in 31 weeks but milk fat yield (104.9 vs. 109.8 kg) and milk composition were not significantly affected. All heifers lost bod...
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ژورنال
عنوان ژورنال: Journal of Dairy Science
سال: 1963
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(63)89257-7