Interactions between calving season and cattle breed in a seasonal Alpine organic and low-input dairy system

Seasonal low-input milk production receives increasing interest in Alpine regions. In contrast to typical pasture-based, seasonal milk production regions such as Ireland or New Zealand, the harsher climatic conditions in the Alps require a 5–6 months barn feeding period. In addition, the dairy cow types commonly used in Alpine regions have not been selected under low-input conditions. Among others, this raises the question of the optimum calving season for different Alpine dairy cow types in low-input systems. The aim of this paper was therefore to investigate the effect of calving season on diet composition and productivity of two different cow types in an Alpine low-input and pasture-based production system. Thirty four lactations of Brown Swiss (BS) and 39 lactations of a special strain of Holstein Friesian (HFL) were compared in a seasonal, low-input system. The BS cows represented the average Austrian BS population and were primarily selected for high milk yield. HFL is a local strain of Holstein Friesian and was primarily bred for lifetime performance under low-input conditions. The dataset comprised cows which calved during the barn feeding period (late October/early November until late March/early April); the grazing period lasted from April until October. The date of calving was expressed relatively to the date of turn out to pasture and was included as a continuous covariable in a mixed model. As expected, moving calving dates towards spring increased the proportion of pasture in the diet and decreased concentrate consumption for both breeds. A significant interaction between breed and calving date was found for milk and milk solid yield per lactation, which decreased for BS when comparing autumn and spring calving, while it remained relatively stable for HFL. However, the larger quantities of concentrates fed to cows calving in autumn, did not reduce body weight loss of BS. The results indicate that for HFL spring calving is likely to be more suitable in order to yield the full economic benefit, while moving calving dates towards autumn might support BS to exploit its greater genetic merit for milk production.