Effects of replacing different proportions of barley grain by barley fibre on performance of dairy bulls

Summary in the original language of the document

The objective of the present experiment was to study the effects of partial replacement of barley grain with barley fibre (BF) on animal performance, carcass traits and diet digestibility of growing dairy bulls. The feeding experiment comprised 20 Finnish Ayrshire bulls and 12 Holstein-Friesian bulls, and four treatments (8 bulls per treatment). There were four diets with two offered at stage 1 (from the initiation of the study to 450 kg live weight) and four at stage 2 (from 450 kg live weight to slaughter). The control diet (BF0) included grass silage (460 g kg–1 dry matter) and barley grain (540), BF25 diet included grass silage (460), barley grain (405) and BF (135), BF50 diet included grass silage (460), barley grain (270) and BF (270), and BF75 diet included grass silage (460), barley grain (135) and BF (405). At stage 1 there were only two treatments (BF0 and BF50) and at stage 2, all four treatments were included. All bulls were fed total mixed ration ad libitum. The mean initial live weight of the bulls was 261 kg and the mean final live weight 650 kg. At stage 1 there were no significant treatment differences in dry matter, energy or protein intakes or in live weight gain. At stage 2, replacing barley grain with BF led to a linear decrease of daily live weight gain (P < 0.05) and a linearly reduced feed conversion (kg dry matter kg–1 live weight gain) (P < 0.05). The apparent digestibility of the organic matter and neutral detergent fibre decreased linearly with increasing BF supplementation (P < 0.001). The dressing proportion and the carcass fat score decreased linearly (P < 0.05) with partial replacement of barley grain with BF. On carcass conformation, treatment had a significant (P < 0.05) quadratic effect: the BF25 and BF50 diets were classified highest. The results indicate that 50% of barley starch can be replaced with BF without affecting growth, but feed efficiency factors may decrease when barley starch is replaced with BF. At 75% replacement, feed intake was reduced, which resulted in a lower energy intake and reduced level of performance.