Effect of suckler cow genotype and nutrition level during the winter on voluntary intake and performance and on the growth and slaughter characteristics of their progeny

A 4-year study comparing Hereford x Friesian (HF) and Limousin x Friesian (LF) spring-calving cows and two grass silages on the performance of suckler cows and their progeny was undertaken using 163 cows. Cows were offered, to appetite, grass silage of either low (L) or moderate (M) digestibility in late pregnancy and early lactation. Cows and their calves spent from April until weaning in October at pasture. Bulls were slaughtered at 16 months of age and heifers at 20 months of age. There was no significant effect of cow genotype on dry matter (DM) intake, annual live-weight change or reproductive performance but annual body condition score gain was higher (P < 0.05) for HF than for LF cows. Cows offered the M silage had higher (P < 0.001) DM intake, lower winter live-weight loss (P < 0.001) and lower (P < 0.01) live-weight gain at pasture than cows offered the L silage. Calf birth, weaning and slaughter weights were not significantly different (P > 0.05) between genotypes. The male progeny of LF cows had a higher kill-out proportion (P < 0.001) and carcass weight (P < 0.05) and lower (P < 0.05) carcass fat score than HF cows. Compared to the M silage, the male progeny from cows offered the L silage had a greater daily gain from birth to slaughter (P < 0.05), slaughter weight (P < 0.05) and carcass weight (P < 0.05). The corresponding differences for female progeny were in the same direction but were not statistically significant.