Sire × Nutrition Interactions and Genetic Parameters for Energy Intake, Production and Efficiency of Nutrient Utilization in Young Bulls, Heifers and Lactating Cows

Abstract

Abstract Sons of 19 Red Danish, 19 Danish Friesian, 2 Danish Red and White and 16 Danish Jersey bulls were reared from 6 weeks to 11 months of age on a high concentrate (C) or high roughage (R) diet. Daughters of the same sires were reared on diets formulated to promote low (L), medium (M) or high (H) daily gain from 6 weeks of age to puberty. Heifers then were managed similarly through 250 days of their first lactation. Sire × diet interactions were significant for traits measured in bulls; genetic correlations between the same traits expressed in C-versus R-feeding systems were -0.10 for daily energy intake (DEI), 0.16 for average daily gain (ADG), and 0.18 for efficiency of nutrient utilization (EFF). Heritabilities of these traits were higher when expressed in the R-feeding system than in the C-feeding system (1.09 versus 0.29 for DEI, 0.58 versus 0.28 for ADG, and 0.82 versus 0.34 for EFF), whereas phenotypic variances of the traits were larger under C-feeding. Sire × rearing intensity interactions were not significant for most traits of growing or lactating females. Heritability estimates of DEI, ADG and EFF in females ranged between 0.22 and 0.27; and heritabilities of weight at calving, energy corrected milk yield (ECM), and DEI and EFF during lactation were 0.35, 0.50, 0.16 and 0.69, respectively. Weight change patterns related to post-partum energy balance were lowly heritable (0.14 to 0.23). Genetic correlations of ECM were -0.67 with post-partum weight loss, 0.60 with number of days of lactation when minimum body weight was reached, 0.50 with DEI during lactation, and 0.91 with lactation EFF.