By Olsson, G., , 1996
Description
The aim of this 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 3 weeks prepartum and increased gradually to the designed allowance 3 days prepartum. The increase continued until the early lactation rations were reached, approximately 3 weeks post partum. All cows in each experiment were fed the same energy level from 12 to 16 weeks post partum, except for in 1 trial, where restricted versus 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 metabolizable energy (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 prepartum, starting 2 days prepartum. The decrease was significantly greater at high levels of feeding. Multiparous cows fed a lower level of feed prepartum had a significantly lower milk yield during the 1st month post partum, but the level had no effect on the remainder of 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 efficiency. The concentrate:forage ratio prepartum had no significant effect on feed intake, milk yield or animal health. However, when a high concentrate ratio was additionally maintained post partum, significantly higher yields of milk, protein and lactose and a lower milk fat percentage were observed as well as impaired animal health. A high dietary fat level resulted in healthier cows around calving, increased milk yield, decreased milk fat content and greater body weight loss during the 1st month post partum. 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 pre- or post partum had no effect on the severity of sole haemorrhages in primiparous cows
The aim of this 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 3 weeks prepartum and increased gradually to the designed allowance 3 days prepartum. The increase continued until the early lactation rations were reached, approximately 3 weeks post partum. All cows in each experiment were fed the same energy level from 12 to 16 weeks post partum, except for in 1 trial, where restricted versus 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 metabolizable energy (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 prepartum, starting 2 days prepartum. The decrease was significantly greater at high levels of feeding. Multiparous cows fed a lower level of feed prepartum had a significantly lower milk yield during the 1st month post partum, but the level had no effect on the remainder of 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 efficiency. The concentrate:forage ratio prepartum had no significant effect on feed intake, milk yield or animal health. However, when a high concentrate ratio was additionally maintained post partum, significantly higher yields of milk, protein and lactose and a lower milk fat percentage were observed as well as impaired animal health. A high dietary fat level resulted in healthier cows around calving, increased milk yield, decreased milk fat content and greater body weight loss during the 1st month post partum. 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 pre- or post partum had no effect on the severity of sole haemorrhages in primiparous cows
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