Rumen-protected rice bran to induce the adaptation of calcium metabolism in dairy cows
2010
Martín-Tereso López, J.
Dairy cows suffer from hypocalcaemia in the days around calving, which may result in a condition generally known as milk fever. Calcium metabolism sharply shifts at the start of lactation, because Ca needs suddenly become much greater than at the end of gestation. Calcium metabolism is able to adapt to different physiological situations, but adaptation requires several days to be effective, resulting in this transient hypocalcaemia. A way to prevent milk fever is to induce adaptation of Ca metabolism weeks before calving by reducing dietary availability of Ca, to prepare Ca metabolism for calving. Rice bran contains a very low level of Ca and a high level of phytic acid, which is a well-know dietary antagonist of Ca in monogastric species. Preventing the ruminal degradation of phytic acid, rice bran can reduce the nutritional availability of dietary Ca in cows. In this thesis, fat coating and formaldehyde treatment proved effective to protect phytic acid in rice bran from ruminal degradation. Formaldehyde treatment was chosen as the preferred method, because it had no detrimental effects on voluntary feed intake. Feeding rumen-protected rice bran reduced dietary Ca availability, thereby inducing the adaptation of Ca metabolism. Furthermore, the product, fed before calving to multiparous cows, improved calcaemia for the first three days after calving. Rumen-protected rice bran, fed in the last weeks of gestation, could represent a practical dietary strategy to prevent milk fever.
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