Reducing milking frequency in early lactation improved the energy status but reduced milk yield during the whole lactation of primiparous Holstein cows consuming a total mixed ration and pasture

To investigate the immediate and long-term performance effects of milking frequency during early lactation of primiparous dairy cows consuming a total mixed ration and pasture, 20 Holstein cows were assigned in a randomized block design to either once-daily (1x) or twice-daily (2x) milking during the first 8 wk of lactation (treatment period). After the treatment period, all cows were milked 2x until wk 43 of lactation. Cows were fed a total mixed ration (approximately 15 kg of DM/cow per day) and allowed to graze an oat pasture (Avena sativa). Dry matter intake was 19.1 kg of DM/cow per day on average and was not affected by treatments. Milk yield was 40% lower in cows milked 1x during the treatment period, and a carryover effect existed until wk 21 of lactation, resulting in a final reduction of 15% of milk yield in the whole lactation. Milk lactose concentration decreased, whereas fat and protein concentrations increased for cows milked 1x. Mobilization of energy reserves during the treatment period occurred in both groups, but cows milked 1x showed greater body condition score and greater backfat thickness. In conclusion, milking 1x during the first 8 wk of lactation resulted in immediate and carryover negative effects on milk and milk solid yield without affecting feed intake, resulting in the improved energy status of primiparous dairy cows.