The role of pasture and silage in supporting milk production in dairy goats in New Zealand – a case study approach

Milk production on dairy goat farms in New Zealand is highly variable: the average is around 75 kg total solids/doe/year with a range of 39-135 kg total solids/doe/year. The source of variability in production is unclear but is potentially due in part to the diversity in forage-supply systems used by dairy goat farmers. The majority of milking herds that supply the Dairy Goat Cooperative are housed indoors for health and production reasons and are fed a mix of freshly-cut pasture and silage in a cut-and-carry system with the addition of concentrates and other supplemental feeds when required. To determine how pasture and silage were used in dairy goat feeding systems, four farms were enrolled in a case study approach. Estimates of the quantity of pasture and silage fed were made and samples were taken and analysed for quality periodically over a one-year period. Results showed that pasture quality generally followed the expected seasonal curve for the Waikato. Pasture quality declined from about 12.5 MJ ME/kg DM in early spring to 11 MJ ME/kg DM or less in December and was largely unavailable from March. At this time, silage becomes a much more important component of the feed-supply system. The quality of the silage was, however, variable with dry matter content, metabolisable energy and crude protein (CP) levels sometimes outside recommended limits. Total diets were deficient in nutrients at some times on some farms, especially with respect to protein. A comparison of calculated feed requirements with what was actually fed showed that protein was deficient in six of the twelve sample periods, by up to 211g of CP/doe/day. These deficits were associated with lower milk production. This study highlighted the potential for higher milk production from maintaining both pasture and silage quality.