THE EFFECT OF CLOSING DATE OF PASTURE IN AUTUMN AND TURNOUT DATE IN SPRING ON SWARD CHARACTERISTICS, DRY-MATTER YIELD AND MILK-PRODUCTION OF SPRING-CALVING DAIRY-COWS
Jr. Roche et al., THE EFFECT OF CLOSING DATE OF PASTURE IN AUTUMN AND TURNOUT DATE IN SPRING ON SWARD CHARACTERISTICS, DRY-MATTER YIELD AND MILK-PRODUCTION OF SPRING-CALVING DAIRY-COWS, Irish journal of agricultural and food research, 35(2), 1996, pp. 127-140
Studies in Ireland and elsewhere have shown that grazed grass can make
a major contribution to the diet of lactating dairy cows and is less
expensive than silage or concentrates. Therefore, the provision of a l
arge supply of grass in spring for cows in early lactation is an impor
tant management objective. The aim of this study was to investigate th
e effect of closing date of pasture in autumn and subsequent turnout d
ate in spring on the performance of spring-calving dairy cows in early
lactation. Fifty-two spring-calving dairy cows were randomly assigned
to one of four treatments in the spring of 1994. The treatments invol
ved two closing dates in the autumn, 20 October 1993 (early closing) a
nd 2 December 1993 (late closing), and two turnout dates in spring, 4
March 1994 (early turnout) and 25 March 1994 (late turnout). The durat
ion of milk production measurement in Spring was 12 weeks (4 March to
27 May, 1994). Delaying closing date in the autumn significantly (P <
0.001) reduced the availability of herbage in the following spring. Li
kewise, early turnout in spring significantly reduced pre-grazing herb
age yields. In late May when the experiment finished the effect of clo
sing date on pre-grazing herbage yields was still present whereas the
effect of turnout date had disappeared. There was no interaction betwe
en closing date in autumn and turnout date in spring for milk yield, m
ilk composition or live-weight change. Closing date did not have a sig
nificant effect on milk yield or milk composition. Early turnout incre
ased milk yield (P < 0.05) and fat and protein concentrations (P < 0.0
1) during the 3-week period when the late-turnout group were housed. I
t is concluded that in a compact, spring-calving herd, at stocking rat
es of 2.7 to 3.0 cows/ha, in the south of Ireland, all animals should
be removed from pasture by late November to early December and turnout
to pasture in spring should be from early March.