Effects of feeding strategy before calving on dairy cow performance

The aim of the thesis was to study the effects on animal performance of different feeding levels or concentrate/forage ratios to high yielding dairy cows during the transition period. The rations were introduced three weeks before calving and increased gradually to the designed allowance three days before calving. After calving the escalation continued until the early lactation rations were reached, about three weeks after calving. All cows in each experiment were fed the same energy level from 12 to 16 weeks after calving, except for in one trial, where restricted vs. ad libitum feeding was studied. Two levels of vegetable fat (3% or 6% crude fat in the total diet) were also compared. Daily intake of ME during the days prior to calving was, on average, 110, 160 and 190 MJ at low, medium and high feeding levels, respectively. Cows experienced a marked decline in intake of ME before calving starting 2 days prepartum. The decrease was significantly greater at high feeding levels. Multiparous cows fed a low feeding level prepartum had a significantly lower milk production during the first month after calving, but the level had no effect on the rest of the lactation. This effect was not observed in primiparous cows. Ad libitum feeding did not result in higher milk yield but in higher milk protein content and production and poorer feed conversion. The concentrate/forage ratio before calving had no significant effect on feed intake, milk yield or animal health. However, when a high concentrate ratio was maintained also after calving significantly higher yields of milk, protein and lactose and lowered milk fat-% were observed as well as an imparied animal health. A high dietary milk fat level resulted in healthier cows around calving, increased milk yield, decreased milk fat content and greater body weight loss during the first month after calving. Parturient paresis was the most common health disorder, but the incidence was not significantly influenced by any of the treatments. A large variation in basal serum insulin level was apparent prepartum among cows with the highest ME intake. The concentrate/forage ratio before or after calving had no effect on the severity of sole haemorrhages in primiparous cows.