Some factors related to the voluntary intake of silage by individual dairy cows housed as a group during two winter-feeding periods

Abstract

ABSTRACTThe consumption of grass silage by each individual cow in a group housed during two consecutive winter-feeding periods was continuously recorded. During the first winter, one of two concentrates, containing high starch or high fibre, were offered on a sliding scale and half the cows were injected with bovine somatotropin (bST). During the second winter, one of two concentrates, containing high or low rumen-undegradable protein were offered at a flat rate ivith two-thirds of the cows receiving bST. The cows injected with bST had significantly greater yields of milk but their consumption of silage was similar to that of cows not treated with bST. The type of concentrate offered had no significant effect on silage consumption. Although there were significant variations in the consumption of silage from day to day, there were highly significant variations in consumption attributable to individual cows. This individuality of intake persisted in a consistent manner throughout a feeding period and could not be explained on the basis of milk production, body weight, age or parity. In 24 of the cows which were used in both years, their individual intakes for the two periods were significantly correlated. The possibility that this individuality may be of economic importance is discussed.