Feed conversion efficiency and marginal milk production responses of pasture-fed dairy cows offered supplementary grain during an extended lactation

Abstract

A study was conducted to quantify the feed conversion efficiency (FCE) and marginal milk responses of pasture-fed cows offered supplementary grain during an extended lactation of 670 days. The experiment used three groups of 10 Holstein cows in four experimental periods of 4 weeks, beginning when cows were ∼60, 240, 420 and 530 days in milk (DIM). In each experimental period, cows were individually fed diets of either freshly cut perennial ryegrass pasture supplemented with triticale (60 and 420 DIM), or pasture silage and lucerne hay supplemented with wheat (240 and 530 DIM). On each occasion, one of the three groups was offered additional grain at 0.0, 2.5 or 5.0 kg DM/cow.day. Milk produc..