Digestion, rumen fermentation and circulating concentrations of insulin, growth hormone and IGF-1 in steers fed diets based on different proportions of maize silage and grass silage

Juniper, D. T., Browne, E. M., Bryant, M. J. and Beever, D. (2008) Digestion, rumen fermentation and circulating concentrations of insulin, growth hormone and IGF-1 in steers fed diets based on different proportions of maize silage and grass silage. Animal, 2 (6). pp. 849-858. ISSN 1751-7311 doi: 10.1017/S1751731108001857

Abstract/Summary

Replacing grass silage with maize silage results in a fundamental change in the ratio of structural to non-structural carbohydrates with commensurate changes in rumen fermentation patterns and nutrient utilisation. This study investigated the effects of feeding four forage mixtures, namely grass silage (G); 67 g/100 g grass silage133 g/100 g maize silage (GGM); 67 g/100 g maize silage133/100 g grass silage (MMG); maize silage (M) to four ruminally and duodenally canulated Holstein Friesian steers. All diets were formulated to be isonitrogenous (22.4 g N/kg DM) using a concentrate mixture. Dietary dry matter (DM) and organic matter (OM) digestibility increased with ascending maize silage inclusion (P,0.1) whereas starch and neutral detergent fibre digestibility declined (P,0.05). Ratio of non-glucogenic to glucogenic precursors in the rumen fluid increased with maize silage inclusion (P,0.01) with a commensurate reduction in rumen pH (P,0.05). Mean circulating concentrations of insulin were greatest and similar in diets MMG and GGM, lower in diet M and lowest in diet G (P,0.01). There were no effects of diet on the mean circulating concentration of growth hormone (GH), or the frequency, amplitude and duration of GH pulses, or the mean circulating concentrations of IGF-1. Increasing levels of DM, OM and starch intakes with the substitution of grass silage with maize silage affected overall digestion, nutrient partitioning and subsequent circulating concentrations of insulin.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/4455
Identification Number/DOI	10.1017/S1751731108001857
Refereed	Yes
Divisions	Life Sciences > School of Agriculture, Policy and Development > Department of Animal Sciences > Animal, Dairy and Food Chain Sciences (ADFCS)- DO NOT USE
Uncontrolled Keywords	grass; insulin; maize; silage; VFA
Publisher	Cambridge University Press
Publisher Statement	Copyright The Animal Consortium 2008
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