B. Obrien et al., EFFECTS OF OFFERING A CONCENTRATE OR SILAGE SUPPLEMENT TO GRAZING DAIRY-COWS IN LATE LACTATION ON ANIMAL PERFORMANCE AND ON MILK PROCESSABILITY, Irish journal of agricultural and food research, 35(2), 1996, pp. 113-125
Grass growth declines during the autumn period. The issue arises as to
when silage and/or concentrate feeding of cows at pasture should comm
ence. The present study was undertaken to compare the effects of two l
evels of silage and two levels of concentrate, offered as supplements
to pasture towards the end of the grazing season, on production and pr
ocessability characteristics of milk Seventy cows were assigned to one
of the following treatments for a 10-week period: (1) pasture only, (
2) pasture + 2 kg grass silage dry matter (DM)/day, (3) pasture + 4 kg
silage DM/day, (4) pasture + 2 kg concentrate DM/day, and (5) pasture
+ 4 kg concentrate DM/day. The cows were stocked at 2.69/ha and graze
d as one group. Pasture was grazed to a sward surface height of 6 to 7
cm. Supplementation with silage reduced (P < 0.05) the yield of milk
constituents. This effect was linear. The concentrations of protein an
d lactose in milk were also reduced (P < 0.05). Concentrate supplement
ation resulted in a significant linear increase (P < 0.001) in the yie
ld of milk and milk constituents and in lactose concentration but fat
concentration was reduced at the higher level of supplementation. Free
fatty acid concentrations in milk were significantly reduced by both
silage (P < 0.05) and concentrate (P < 0.01) supplementation in weeks
6 and 10 only. Milk casein number was similar for all treatments. Renn
et coagulation time, rate of curd aggregation and curd firmness were a
lso similar for all treatments.