Influence of level of concentrate feeding on milk production and pasture utilization by Friesian cows grazing tropical grass-legume pasture

Abstract

Four groups of four Friesian cows grazed green panic (Panicum maximum var. trichog1ume)- glycine (Glycine wightii cv. Tinaroo) pastures at 4 cows ha-1 for 36 weeks from January to October 1975. Cows were individually fed 0, 2, 4 and 6 kg cow-1 day-1 respectively of a maize-soybean meal concentrate. Fat corrected milk (FCM) response to concentrate was linear and was related to the total concentrate intake (X) by the equation, FCM = 1992 + 1.03 X (R.S.D. ¦ 23; P < 0.001) Persistency of lactation decreased with decreasing levels of concentrate feeding (P < 0.01) and lactation length was reduced for cows receiving low levels of concentrates (P < 0.05). Milk fat content was reduced (P < 0.05) and solids-not-fat and casein contents increased by concentrate feeding (P < 0.05). Cows fed 6 kg concentrate cow-1 day-1 were 50 kg cow-1 heavier at drying off than cows fed no concentrate (P < 0.05). Pasture yield on offer to cows was increased linearly with increased concentrate feeding (P < 0.05) and pasture intake by cows was estimated to decrease by 0.9 kg for each kg of concentrate fed (P < 0.05). FCM response to concentrate appeared to increase markedly when pasture on offer fell below 2500 kg DM ha-1. We conclude that FCM response to concentrate will usually be linear for cows grazing tropical pastures, and the size of this response will be strongly influenced by the period of feeding and the yield of pasture on offer to cows.