Influence of milking and restricted suckling regimes on milk production and calf growth in temperate and tropical environments

Abstract Two experiments were carried out to investigate the effect of restricted suckling and milking regimes on milk yield, milk composition and calf growth. Experiment 1 was carried out in temperate conditions in the United Kingdom and experiment 2 under tropical conditions in Mexico. In experiment 1 a Latin rectangle (change-over) design with 3-week periods was used with eight Holstein Friesian cows suckling their Simmental-sired calves. Saleable milk yield (SMY), sucked milk (CSM), milk composition and calf performance were studied. The treatments were: once a day milking (a.m.) with suckling immediately after (1χAM); once a day milking (a.m.) with suckling p.m. (1χPM); twice daily milking with suckling after a.m. milking (2χAM); twice daily milking with suckling after each milking (2χ2χ). The cows were offered maize silage ad libitum and 4·3 kg dry matter (DM) per day of rapeseed meal plus minerals and vitamins. The calves had ad libitum access to concentrates (165 g crude protein (CP) per kg DM) and wheat straw. In experiment 2, 11 B. indicus χ B. taurus cows, suckling their Brahman-sired calves were used in an experiment with the same treatments and experimental design. Cows were offered star grass (Cynodon nlemfuensis) hay ad libitum and 4.0 kg DM per day of concentrate (117 g CP per kg DM). The calves had ad libitum access to concentrate (151 g CP/kg DM), star grass hay and Ramon leaves. For 1χAM, 1χPM, 2χAM and 2χ2χ respectively in experiment 1, the total milk yields (TMY = SMY + CSM) were 17.9, 18.0, 16.7 and 19.5 kg/day (s.e.d. 1.11) and SMY represented 0.70, 0.45, 0.77 and 0.53 of TMY. Corresponding results for experiment 2 were 6.0, 6.2, 7.0 and 7.1 kg/day (s.e.d. 0.32) and 0.69, 0.45, 0.78 and 0.61. Effects of treatment on milk yield and composition were consistent with the feedback inhibitor of lactation theory. It was concluded that different milking and restricted suckling patterns can be used to manipulate saleable milk production and calf growth. Holstein Friesian dairy cattle in a restricted suckling system without the calf presence at milking, behaved similarly to zebu-crossbred cows by reducing milk let down at milking.