Changes in milk yield and milk composition as a consequence of the omission of one milking weekly in dairy cows

Five Holstein cows (21.0 L/d, 227 DIM) previously adapted to the omission of one milking weekly (Sunday pm) were used to study the effects of Sunday omission on milk yield, milk composition and udder health for 10 wk. Cows were milked twice a day at 8 am and 6 pm but on Sunday one milking only was performed at 12 am. Throughout the experiment, milk yield was recorded and milk samples were taken at each milking. Milk yield and milk composition were approximately constant but SCC increased with lactation stage (P < 0.05). The omission of one milking caused an important decrease (P < 0.05) in milk yield (29%), fat content (21%) and log SCC (27%), on the omission day and a compensatory increase over the following two days (P < 0.05), but milk protein and lactose did not vary. All variables reached the average weekly value three days after the milking omission (6 milkings). In conclusion, omitting one milking weekly slightly reduced milk yield and milk composition and did not affect udder health. Milk recording should be conducted in the middle of the week to avoid alterations caused by the milking omission in dairy cows.