Effects of winter feeding during the rearing period on performance and longevity in dairy cattle

Abstract

Black and White dairy heifers born in autumn and programmed for a calving at 2 years of age were given HIGH (H) or LOW (L) feeding levels during each wintering period of the rearing stage : from birth to 6 months (H1 or L1) and between 12-18 months (H2 or L2). H1 and H2 treatments increased energetic supplies by 22 (100 UFL) and 49 (400 UFL) per cent. HIGH feeding treatments resulted in higher winter gains (H1 : 826 g/d, L1 : 696 g/d, H2 : 885 g/d and L2 : 639 g/d). During summer grazings, compensatory growth was moderate (50 to 55 %). Feeding treatments had no effects on milk yield for each lactation. However H1 treatment contributed to a longer productive life (+ 333 days) along with higher milk (+ 4,089 kg), fat (+ 205 kg) and protein (+ 150 kg) yields. H1 cows produced more calves (+ 0.9) and heavier carcasses at culling (+ 20 kg). H2 heifers needed less veterinary assistance at first calving. Mortality was lower and mastitis troubles were less frequent in H1 and H2. Hence, the live-weight of 6 month-old heifers should amount to 30 % of adult cow weight. The ideal weight is judged to be 60 % and 90 % of mature cow weight at AI (at age 15 months) and before the first calving (at 24 months).