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Effect of level of intake on digestion in cows: influence of animal genotype and nature of hay

2003; Elsevier BV; Volume: 81; Issue: 1 Linguagem: Inglês

10.1016/s0301-6226(02)00227-0

1872-6070

Michel M. Doreau, Amadou Diawara,

Reproductive Physiology in Livestock

The effect of level of intake on cow digestion was studied in six dry Holstein cows fitted with ruminal cannulas and six dry Charolaise cows without cannula. Three levels of intake were compared, corresponding to 80, 50 and 20 g DM/kg BW0.75. Animals received either a good quality hay or a medium quality hay (three cows per breed for each hay, according to Latin square designs). Digestibility of organic matter and fibre was not modified by intake and breed. Particle retention time in the rumen and in the total tract were higher at low intake than at medium and high intake, whatever the hay. Ruminal total and dry contents of Holstein cows, as well as DM proportion, decreased with intake, whatever the hay. In situ degradation was not modified by level of intake. Median ruminal particle size and mean rectal particle size were lower at low intake than at medium and high intakes. This experiment showed that the relations between digestive events and level of intake did not depend on hay quality. The increase in particle retention time in the rumen at low intake did not result in an increase in digestibility. Charolaise and Holstein cows did not differ by hay digestibility, retention time of particles in the digestive tract or rectal particle size.