期刊
GRASS AND FORAGE SCIENCE
卷 61, 期 4, 页码 375-384出版社
BLACKWELL PUBLISHING
DOI: 10.1111/j.1365-2494.2006.00544.x
关键词
dairy cows; spring turnout date; grass dry matter intake; milk production; sward quality
类别
The objective of this study was to investigate the effects of an early (February; F) or delayed (April; A) primary spring grazing date and two stocking rates, high (H) and medium (M), on the grazing management, dry matter (DM) intake of grass herbage and milk production of spring-calving dairy cows grazing a perennial ryegrass sward in the subsequent summer. Sixty-four Holstein-Friesian dairy cows (mean of 58 d in milk) were assigned to one of four grazing treatments (n = 16) which were imposed from 12 April to 3 July 2004. Cows on the early spring-grazing treatment were grazed at 5.5 cows ha(-1) (treatment FH) and 4.5 cows ha(-1) (treatment FM) while cows on the late-grazing treatment were grazed at 6.4 cows ha(-1) (treatment AH) and 5.5 cows ha(-1) (treatment AM). The organic matter digestibility and crude protein concentration of the grass herbage were higher on the early-grazing treatment than on the late-grazing treatment. The cows on the FM treatment had significantly (P < 0.001) higher milk (24.5 kg), solids-corrected milk (22.5 kg), fat (P < 0.01, 918 g) and protein (831 g) yields than the other three treatments. Cows on the FM treatment had a higher (P < 0.001) DM intake of grass herbage by 2.3 kg DM per cow per day than cows on the AH treatment, which had a DM intake significantly lower than all other treatments (15.2 kg DM per cow per day). The results of the present study showed that grazing in early spring has a positive effect on herbage quality in subsequent grazing rotations. The study also concluded that early spring-grazed swards stocked at a medium stocking rate (4.5 cows ha(-1); FM) resulted in the highest DM intake of grass herbage and milk production.
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