Effect of grazing cycle on milk production of cows on kikuyu pasture

Author: W.P. Henning, H.H. Barnard and J.J. Venter
Year: 1995
Issue: 1
Volume: 25
Page: 7 - 12

Kikuyu pasture (Pennisetum clandestinum) was evaluated as forage for milk production during the 1985/86 and 1986/87 grazing seasons at the Bathurst Research Station in the seaboard area of the Eastern Cape. The effect of different rotational grazing cycle lengths on milk production, body weight, herbage intake, digestibility and grazing time was investigated. Pastures were stocked at two Friesian cows per ha and grazed for 1, 2 or 4-day periods of 15, 30 or 60 days rotation cycles, respectively. Data were recorded during the grazing season which lasted from December to May each year. Milk (10.9 kg) and fat-corrected milk (FCM; 10.1 kg) yields were highest (P ≤ 0.01) with the 30-day cycle. Neither butterfat (3.55 ± 0.035%), nor protein (3.19 ± 0.022%) content of the milk was affected by rotation cycle. Milk yield patterns showed a marked autumn slump with the 15-day cycle while the other two cycles reflected a steady decline in milk production from 13.5 kg in December to 8.4 kg in May. Mean live body weight (550.7 ± 2.92 kg) did not differ between cycles but followed different patterns during the growing season. Neither organic matter (OM) intake (14.2 ± 0.188 kg), nor OM in vitro digestibility (56.3 ±1.07%) differed between cycles. OM digestibility decreased (P ≤ 0.01) in all treatments from 67.6% in December to 44.7% in May. Cows in the 15-day cycle grazed longer (8.1 hours; P ≤ 0.01) per day to compensate for the lack of DM availability. Overall, the 30-day cycle proved to be the best grazing strategy for kikuyu pasture in this investigation.

Keywords: Canopy height, dairy cows, kikuyu pasture, milk yield, rotation cycle
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