Effects of milking three times in 2 days for 3 weeks in early lactation or in the declining phase on milk production in primiparous and multiparous dairy cows

Fifty-two Holstein cows (26 primiparous) were assigned at calving to two milking frequencies: either twice daily (6 h and 17 h; control) or three times/2 days (6 h, 20 h and 14 h of the following day) during the first 3 weeks of lactation and then twice daily for at least 5 weeks. Nine weeks after the last calving (at the end of the 3rd month of lactation, on average) each of the four groups (primiparous or multiparous cows x twice daily milking/day or three times milking/2 days in early lactation) that were being milked twice daily, was divided into two sub-groups: one continued to be milked twice daily whereas the other was milked three times/2 days for 3 weeks and then twice daily. All cows were fed ad libitum the same complete diet based on grass silage. In early lactation, milking three times/2 days decreased the milk yield (3.4 kg/day; 16%), increased the fat (5.0 g/kg) and protein (2.2 g/kg) contents and decreased the lactose content (1.5 g/kg) in primiparous cows. In multiparous cows, the milk changes (-0.7 kg, + 0.9 g fat/kg, + 0.6 g proteins/kg) were not significant The energy balance was not changed. During the declining phase of lactation, milking three times/2 days reduced secretion of milk, fat, proteins and lactose by about 10% in both categories of cows. The milk composition remained unchanged. Food intake was not affected but the energy balance was improved.