More Summer Milk - a further investigation into improving summer milk production

Abstract

An on-farm demonstration designed to increase summer/autumn milksolids (MS) production was continued during the 1997/98 dairying season. The study investigated the combination of an earlysummer application of nitrogen (N) fertiliser and a 40-day grazing rotation (the treatment), compared with each trial farm's normal farming practice (the control). The study began on 1 November 1997 with the equal split of herds and farms into farmlets. On the treatment farmlets, 60 kg N fertiliser/ha was applied in November. All treatment herds were on a 40-day rotation from 15 December until drying off. The average rotation for the control herds was 25 days, varying between 18 and 30 days. The season was warmer and drier than average, with four of the five farms experiencing a drought from January to early March. The treatment grew an additional 3.3 tonnes DM/ha to the beginning of June, 49% of the response occurring within the first 42 days of applying N fertiliser. The extra pasture grown on the treatment farmlet had little effect on daily MS production, and overall there was a net loss of $86/ha to the treatment. Possible reasons for this lack of response include overestimation of pasture growth, poor pasture utilisation, and low protein levels. Despite the additional pasture available in mid lactation, the advantage to MS production occurred only at the end of the season, allowing the treatment cows to milk for 8 extra days. Keywords: milksolids production, pasture production, grazing management, rotation length