Animal Science Abstract
The effects of an Aspergillus oryzae extract containing alpha-amylase activity on ruminal fermentation and milk production in lactating Holstein cows
J. M. Tricarico1,A, J. D. Johnston2, K. A. Dawson1, K. C. Hanson3, K. R. McLeod3 and D. L. Harmon3
AE-mail: jtricarico@alltech.com
1Alltech Biotechnology Inc., Nicholasville, KY 40356, USA2Ritchie Feed & Seed Inc., Ottawa, ON K1B 4V5, Canada
3Department of Animal Science, University of Kentucky, Lexington, KY 40546, USA
Abstract
The effects of an Aspergillus oryzae extract containing alpha-amylase activity (AmaizeTM, Alltech Inc., Nicholasville, KY) were examined in vivo and in vitro. A lactating cow study employed 20 intact and four ruminally fistulated Holstein cows in a replicated 4 × 4 Latin-square design to examine the effects of four concentrations of dietary AmaizeTM extract on milk production and composition, ruminal fermentation and serum metabolite concentrations. The treatment diets contained 0, 240, 480 or 720 alpha-amylase dextrinizing units (DU) per kg of total mixed ration ( TMR) (dry-matter basis). The supplemental alpha-amylase increased the yields of milk ( P = 0·02), fat ( P = 0·02) and protein ( P = 0·06) quadratically. The maximum milk yield was obtained when 240 DU per kg of TMR were offered. Ruminal in situ starch disappearance was not affected by alpha-amylase supplementation in lactating cows or ruminally cannulated steers. Supplemental alpha-amylase extract reduced the molar proportion of propionate in the rumen of steers ( P = 0·08) and lactating cows ( P = 0·04), and in rumen-simulating cultures ( P = 0·04). The supplement also increased the molar proportions of acetate ( P = 0·06) and butyrate ( P = 0·05), and the serum beta-hydroxybutyrate ( P = 0·01) and non-esterified fatty acid ( P = 0·03) concentrations in lactating cows. The improvements in milk production appear to be a consequence of the effects of alpha-amylase on ruminal fermentation and the potential changes in nutrient metabolism that result from them. We conclude that supplemental alpha-amylase may be given to modify ruminal fermentation and improve milk and component yield in lactating Holstein cattle.
Keywords: Aspergillus oryzae, dairy cows, milk production, starch.
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