Production and composition of colostrum and milk of Gir cows and their calves' responses to tactile stimulation and feeding plan.

Two complementary experiments were conducted to (1) describe the production and composition of colostrum, transition milk and whole milk in pasture-managed dairy Gir cows and (2) evaluate the effects of tactile stimulation and feeding plan on circulating hormone concentrations in dairy Gir calves. In Experiment 1, we followed Gir cows (n = 38) from calving to 120 days of lactation, and in Experiment 2, we evaluated their calves (n = 37) from birth to 30 days post-weaning. In Experiment 1, milk yield and composition were recorded. In Experiment 2, calves were assigned to four treatments: Conv-NS (conventional feeding, no tactile stimulation), Conv-TS (conventional feeding, tactile stimulation), Opt-NS (optimised feeding, no tactile stimulation) and Opt-TS (optimised feeding, tactile stimulation). Tactile stimulation (TS; gentle hand stroking performed by the handler) was applied twice daily from birth to 60 days old. Both optimised and conventional feeding calves had access to natural suckling during each milking; however, calves in the optimised treatment also received additional milk via a teat bottle after suckling. Calves' circulating hormone concentrations (cortisol and oxytocin) were evaluated during pre-weaning, weaning and post-weaning periods. Cows whose calves were assigned to the Opt-NS produced more residual milk (P ≤ 0.01) but had lower total milk yield compared with cows in the Conv-NS, Conv-TS and Opt-TS. During the post-weaning period, calves in the Conv-TS, Opt-NS and Opt-TS exhibited lower cortisol concentrations (P ≤ 0.05) than those in the Conv-NS (control). Additionally, calves in the Opt-TS showed higher oxytocin concentrations (P = 0.02) during the post-weaning period compared with Conv-NS at pre-weaning. Solid feed intake increased similarly across all treatments throughout the experimental period. In summary, the combination of tactile stimulation and optimised feeding did not impair milk yield in cows, even under systems where calves have access to their dams during milking.