Auteur: Atkins N.A., Bleach E.C.L. and Sinclair L.A.
Jaar van uitgifte: 2015
Out-wintering replacement dairy heifers is commonly practised among low input pasture-based dairy systems, and is potentially an option to facilitate expansion for high output dairy farms. The effects on performance of Holstein dairy heifers out-wintered on perennial ryegrass, fodder beet, or housed during the winter of 2013/2014 in the UK were examined. Forty eight, 23-(±2.8) month-old, in-calf heifers were randomly assigned to one of three treatments: out-wintered on perennial ryegrass and grass silage (G); out-wintered on fodder beet and grass silage (F); or housed and fed grass silage and concentrate (H). The study commenced in November 2013, with heifers continuing on their respective treatments for 13 weeks, before being housed for six weeks before parturition. Post-partum all animals received the same diet with performance measured for 12 weeks. Mean live weight (Lwt) and body condition score (BCS) during the winter was unaffected by treatment, but BCS of heifers that received G tended to be lower (P=0.090) at housing. Post-partum, mean Lwt was unaffected by treatment; however, mean BCS was lower (P=0.022) in animals that received G. Milk yield was not affected by treatment, but milk fat (g kg‑1) was lowest (P=0.027) and milk protein (g kg‑1) highest (P=0.026), in F. The results indicate that Holstein heifers can be successfully out-wintered without impacting on first lactation performance in a high output dairy system.