Maize silage as a supplement for pasture-fed dairy cows in early and late lactation

Abstract

Eight experiments were conducted over 2 years with 92 lactating dairy cows individually fed various combinations of irrigated perennial pasture and maize silage in an indoor feeding facility. Responses to different amounts of maize silage and pasture in early and late lactation were measured. Daily pasture intake ranged from 6.2 to 12.4 kg dry matter (DM)/cow, while maize silage intake ranged from 0 to 12.4 kg DM/cow. The marginal return to feeding maize silage at up to 5 kg DM/cow.day to cows in early lactation eating about 7 kg DM/day of pasture as their basal ration was 0.89 kg extra milk for each kg DM maize silage eaten. In late lactation, this was reduced to 0.63 kg milk/kg DM. Milk yield responses to maize silage at both stages of lactation were lower at higher levels of pasture feeding. Although milk fat content was maintained over a wide range of maize silage, feeding large quantities of maize silage in early lactation was detrimental to milk production. The likely explanation for poor animal performance at the high levels of maize silage was dietary protein insufficiency.