Effect of maturity of corn [Zea mays] on carbohydrate and protein utilization by dairy cows receiving corn silage
2008
Tanigawa, T.(Hokkaido. Animal Research Center, Shintoku (Japan)) | Oosaka, I. | Kawamoto, S. | Hara, S.
The objective of this study was to evaluate the effect of maturity of corn on carbohydrate and protein utilization by dairy cows fed corn silage (CS). Three different CS were prepared by harvesting corn at milk ripe, yellow ripe and full ripe stages with a cut length of 9.0 mm. Each silage was given to three ruminally and duodenally canulated cows with soybean meal to equalize crude protein supply. As corn grew from milk to yellow ripe stage, starch content of CS was increased, while neutral detergent fiber (NDF) content was decreased. Maturity of corn did not affect DM intake of CS. Cows fed CS at milk ripe stage showed significantly lower (P0.05) starch intake and higher NDF intake than those fed CS at yellow and full ripe stages. Starch digestibility in the rumen decreased (P0.05) with maturity of corn, though that in total tract did not show any changes. Ruminal and total tract digestibilities of NDF of CS at milk ripe stage were significantly higher (P0.05) than those at yellow and mature ripe stages. Duodenal microbial protein flow decreased (P0.05) with maturity of corn. Efficiency of microbial protein synthesis in feeding of CS at full ripe stage tended to be lower than those at milk and yellow ripe stages. TDN value decreased (P0.05) with maturity of corn. The results suggest that utilization of starch and NDF should be improved in CS at yellow and mature ripe stages.
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