The feed intake of milk cows II. The effect of roughage quality during late pregnancy and lactation

Abstract

SUMMARY1. An experiment is described in which the individual feed intakes of 16 cows under winter housing conditions in yards, during the transition to spring grazing and on. summer grazing, were determined by faecal indexdigestibility methods. The influence of quality of feed before calving on intake and subsequent performance and the influence of pasture quality and availability on feed intake were included in the study.2. The provision of a diet of 67% organic matter digestibility, either as high quality hay or as low quality hay with concentrates, increased feed intake before calving when compared with a diet of low quality hay (digestibility 62%) alone. Compared with previous lactation yields the better diets were associated with the maintenance of milk yield, while the low quality hay diet before calving was associated with a 10%, but non-significant, reduction in milk yield.3. There was a marked rise in faecal output and digestible organic matter (DOM) intake after calving. During lactation, and especially on pasture, faecal output and DOM intake were both correlated with milk yield and metabolic live-weight. Total DOM intake was lower when the availability of feed was restricted and increased when feed was readily available; this increase was associated with a high maintenance requirement.4. When herbage with OM digestibility of 74–82% was consumed, faecal output rose with decreasing digestibility, but DOM intakes were relatively constant. Provided that efficient utilisation can be achieved, total utilisation per acre might be increased if herbage were grazed at the lower end of this range of digestibility.