Phase feeding high protein TMRs to fresh cows; concurrent and carryover effects on milk and milk component yields of multiparous Holstein Friesian cows

The aim of the study was to investigate whether feeding a high protein TMR during first 7 d in milk or first 28 d in milk would result in increased concurrent and carryover milk yields thereby improving N utilization.Forty-eight multiparous Holstein Friesian cows were used in a randomized block design where cows continuously entered the treatments according to a predefined randomized order.Cows were blocked by parity and treatments of another trial carried out during far-off dry period.Three treatments started 3 2 h after calving: 1) a standard lactation TMR having a normal protein content (Con-TMR; 16.3 % CP; n = 16), 2) TMR with a high protein content during first 28 d (i.e., 28.3 1 d) after calving (28d-TMR; 21.3 % CP; n = 16), and 3) a very high protein TMR during first 7 d after calving (7d-TMR; 27 % CP; n = 16), followed by feeding all three groups with Con-TMR until 150 d in milk.The protein content of high protein TMRs was achieved by replacing sugar beet pulp with SoyPass and maize gluten meal.The statistical model included treatments, parity, day or week in milk as fixed effects, and cow, block and season as random effects.Preliminary results showed that DMI during the first 28 d in milk was affected by the treatments (P = 0.02) where the 28d-TMR group had a higher DMI compared to Con-TMR and 7d-TMR groups during the first 2 weeks in milk.The DMI did not differ among the treatments during the follow up period.Milk yield tended to show an interaction between treatment and day on 5 d to 14 d in milk (P = 0.08) and a significant effect from 14 d to 35 d in milk (P < 0.01).The average daily milk yield of 28d-TMR (44.4 2.4 kg/d; P = 0.1) tended to be higher than the Con-TMR and 7d-TMR (40.6 2.4 kg/d) in week 3 in milk.After week 4 in milk, milk yield did not differ among the treatments (follow-up period; P = 0.74).Milk protein yield was affected by the treatments during the first four weeks in milk (P = 0.025) where 28-d TMR and 7d-TMR had higher protein yields than Con-TMR.However, it was not affected during the follow-up period (P = 0.73).Milk fat and lactose yields were not affected by the high protein fresh cow TMR treatments.The increased CP content in fresh cow rations using SoyPass and maize gluten as rumen bypass protein sources led to increased milk and component yields during the feeding period, but these effects appeared not to persist in the follow up period.