Different proportions hay: concentrates in feeding bulls for slaughter at 14 months of age

Homb, T.

Zeitschrift für Tierphysiologie Tierernahrung und Futtermittelkunde 33(2): 80-87


ISSN/ISBN: 0044-3565
PMID: 4833063
Accession: 000061228

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In 4 experiments bulls aged 6 and 14 months were given barn-dried hay, mostly timothy, and a mixture of 75% barley meal, 15% soya bean meal and 10% wheat bran in different proportions. Before the experiment calves were reared on milk replacer, concentrates and hay and during it they were tied up, given hay as a group and concentrates individually. Feeding was approximately to appetite. In each trial digestibility of hay was estimated using wethers at maintenance intake, and in the third experiment digestibility of the mixed diets also was measured in this way. Digestibility of concentrate was calculated by difference, by regression and from Norwegian feed tables. Hay and concentrate together were digested better than would be predicted from digestibility of either separately. The first experiment used groups of 8 cattle given hay to concentrate ratios of 10:90, 40:60 or 70:30. All bulls were slaughtered after 223 days when mean daily gain corrected to 50% dressing percentage was 990, 984 and 731 g, and feed units (FU)/kg corrected gain were 5.0, 5.0 and 5.8. Six animals per group were used in the second test and were given only concentrates or hay to concentrates 20:80, 40:60 or 60:40. After 196 days corrected daily gains were 1011, 1169, 1050 and 1050 g requiring 4.7, 4.0, 4.7 and 4.9 FU/kg. Experiment 3 used 8 bulls per group which had hay to concentrates 20:80, 50:50 or 80:20. In 215 days corrected daily gains were 1061, 1086 and 686 g, requiring 5.1, 4.9 and 5.2 FU/kg. The same ratios were used in the last experiment in which each group was of 6 bulls. Corrected gains in 208 days were 864, 827 and 608 g, using 5.9, 5.7 and 5.8 FU/kg. Points for finish (meatiness and fatness) were highest for bulls given 60% hay or less; those getting more hay were killed too early to give good carcasses. Animals not given hay were unthrifty, and had low pH and high total volatile fatty acids and propionic acid in rumen liquor. Feed energy of rations was measured as digestible energy, metabolisable energy, net energy for fattening and Scandinavian feed units, and correlated to corrected daily gain in each case. Correlation was closest using FU. Efficiency of utilisation of feed was not related to proportion of hay in diet.