The effect of supplementation of grass silage with rapeseed meal or Gasol-treated barley on the performance of growing cattle

Authors

• Pekka Huhtanen Department of Animal Husbandry, University of Helsinki, 00710 Helsinki
• Esko Poutiainen Department of Animal Husbandry, University of Helsinki, 00710 Helsinki
• Timo Mikkola Department of Animal Husbandry, University of Helsinki, SF-00710 Helsinki

DOI: https://doi.org/10.23986/afsci.72188

Abstract

Grass silage was offered ad libitum to 16 Ayrshire cattle in a 2 x 2 factorial experiment lasting 196 days. The silage was supplemented with barley preserved with 0.85 % of propionic acid (PAB) or 1.28 % Gasol solution (GB) 45 g DM/kg W0.75. Four of the animals in PAB and GB groups received no protein supplement(NPS) and four of the animals in both groups received extracted rapeseed meal as protein supplement(RSM). RSM was fed according to UDP (undegradable feed protein) requirements. The average age of the animals at the beginning of the experiment was 86 days and the average liveweight 106 kg. The average daily gains were 1066 and 1070 g/d for PAB and GB groups and 1012 and 1124 g/d (P < 0.01) for NPS and RSM groups. In feed intake and feed conversion there were no significant differences between the groups. Supplementation of silage barley diet with RSM increased the digestibility of organic matter from 71.1 to 73.5 % (P < 0.05), of crude protein from 62.8 to 67.4 % (P < 0.05) and of crude fibre from 57.2 to 60.2 % (P < 0.05). Both barleys were well preserved and there was no deterioration during the storage. The degradation rates of DM, crude protein and starch determined by nylon bag method were lower in GB than in PAB. Crude protein disappearances in 9 hours were 46.6 % for GB and 76.4 % for PAB. The utilization of absorbed protein calculated by factorial method averaged 0.566 ± 0.01 in the four different groups. Plasma urea N level was higher (P < 0.05) in the RSM than in the NPS group. The proportion of acetic acid in the rumen VFA was lower (P < 0.05) and that of propionic acid higher (P < 0.01) in the RSM than in the NPS group. PAB resulted in a higher (P < 0.05) proportion of propionic acid in rumen VFA than did GB.