Production responses of tropical crossbred cattle to supplementary feeding and to different milking and restricted suckling regimes

The relationships between cow nutrition, restricted suckling and milking patterns and their effect on milk yield, milk composition and calf growth were examined under tropical conditions in south east Mexico. Eleven Bos indicus 3 Bos taurus cows, 14 days postpartum, with calves weighing on average 37 kg were used in a change-over experimental design. All cows were fed Cynodon nlemfuensis hay ad libitum, and either 4.0 kg Leucaena leucocephala, 2.0 kg sorghum grain and 0.25 kg sugar-cane molasses on a fresh weight basis (L1), or twice this amount of the same supplement (L2). The calves were offered the same hay ad libitum in addition to suckling milk. The milking / restricted suckling treatments were: twice-daily milking with suckling after morning milking (2 3 AM), and once-daily milking in the morning with afternoon suckling (1 3 PM). The two regimes were examined at L1 and L2 feeding levels. A suckling time of 30 min was allowed at each suckling occasion. For 2 3 AML1, 2 3 AML2, 1 3 PML1 and 1 3 PML2, respectively saleable milk yields (SMYs) (kg/day) were 5.43, 5.99, 3.47, 4.09 (S.E.M. 0.174); calf suckled milk (CSM) (kg/day) 1.36, 1.46, 3.14, 3.43 (S.E.M. 0.160); and total milk yield (kg/day) 6.79, 7.46, 6.62, 7.53 (S.E.M. 0.226). For SMYs, fat contents (g /kg) were 30.0, 29.4, 29.0, 28.7 (S.E.M. 1.11), respectively, and for CSM 59.6, 63.4, 38.8, 42.4 (S.E.M. 2.46). Protein contents (g /kg) for SMYs were 27.5, 29.1, 29.3, 30.4 (S.E.M. 0.67) and for CSM 27.9, 28.4, 29.1, 30.3 (S.E.M. 0.81). Total food intakes of cows were 10.84, 12.12, 10.99, 12.16 (S.E.M. 0.331) kg DM/day. Calf growth rates were, respectively, 0.17, 0.20, 0.41, 0.52 (S.E.M. 0.029) kg/day, and hay DM intake 0.58, 0.49, 0.41, 0.34 (S.E.M. 0.040) kg/day. It was concluded that level of supplementation and restricted suckling and milking regimes could both be used to manipulate TMY, SMY and calf performance.  2000 Elsevier Science B.V. All rights reserved.