EFFECT OF INCREASING DIGESTIBLE UNDEGRADED PROTEIN SUPPLY TO DAIRY-COWS IN LATE-GESTATION ON THE YIELD AND COMPOSITION OF MILK DURING THE SUBSEQUENT LACTATION
Jm. Moorby et al., EFFECT OF INCREASING DIGESTIBLE UNDEGRADED PROTEIN SUPPLY TO DAIRY-COWS IN LATE-GESTATION ON THE YIELD AND COMPOSITION OF MILK DURING THE SUBSEQUENT LACTATION, Animal Science, 63, 1996, pp. 201-213
Effects of feeding a protein supplement to dairy cows during the dry p
eriod on performance during the following lactation were investigated
in two experiments. Holstein-Friesian cows were paired towards the end
of lactation, and, after drying off one of each pair received a typic
al dry cow management regime of ad libitum grass silage (experiment I)
, or a mix of grass silage and distillers' grains or pressed beet pulp
(experiment 2). The other cows were offered restricted access to the
same basal diet, together with ad libitum access to barley straw and 0
.5 kg/day high protein maize gluten meal. During the following lactati
on, animals from both groups were treated without reference to dry per
iod treatment, and were offered equal access to the same lactation die
t. Data were analysed by analysis of variance of experiment means and
by parallel curve analysis using sample means. In experiment 1, milk y
ields were similar (27.2 v. 27.9 (s.e.d. 2.12) kg/day for control and
supplemented animals respectively) but milk protein yields, and hence
concentrations, were significantly higher (P < 0.001) from supplemente
d animals (28.9 v. 31.8 (s.e.d. 0.58) g/kg). In experiment 2, milk yie
lds were significantly higher (P < 0.001) from supplemented animals (m
ean 33.3 v. 35.4 (s.e.d. 1.66) kg/day; however, milk protein yields we
re also significantly increased (P < 0.011) and the change in milk pro
tein concentration was small. No difference in dry-matter intake teas
recorded in a subset of animals during early lactation in experiment 2
. It is hypothesized that the maternal labile body protein pool was ma
intained or replenished during the dry period by the provision of the
protein supplement, and that this had a significant effect on subseque
nt lactation performance.