Rumen-protected rice bran to induce the adaptation of calcium metabolism in dairy cows

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

Tolerance and safety evaluation of L-glutamic acid, N,N-diacetic acid as a feed additive in broiler diets

The novel chelator, L-glutamic acid, N,N-diacetic acid (GLDA) can be used as a dietary ingredient to safely reduce Zn supplementation in complete feed, without compromising the Zn status of farm animals. The objective of this study was to study dietary tolerance, bioaccumulation, and evaluate the safety of GLDA when supplemented in broiler diets at 0, 100, 300, 1000, 3,000, and 10,000 mg/kg. A total of 480 one-day-old Ross 308 male broilers were randomly allocated to 48 pens and fed one of the 6 experimental diets. Production performance was used to assess tolerance to the additive. At trial end, toxicity was evaluated using hematology, plasma biochemistry (n = 144) and gross necropsy (n = 48). Residue levels of GLDA were assessed in liver, kidney and breast tissue of birds used for necropsy. Performance showed an increase (P < 0.05) in body weight for GLDA inclusion at 300 mg/kg. A decrease on the measured performance parameters was found for the 10,000 mg/kg GLDA inclusion level (P < 0.05). The additive was added as a tetra-sodium salt, leading to sodium levels being 2.5 times higher in the latter treatment compared to the control diet which may have led to impaired intestinal barrier function. Mortality was not different between treatments. Residue levels for GLDA at the highest inclusion indicate that 0.0005% of total GLDA consumption is accumulated in breast tissue. Higher values of GLDA were found in kidney and liver at the highest inclusion level, potentially confirming that the small fraction of GLDA absorbed was readily excreted by the animal. At 100 and 300 mg/kg GLDA inclusion there were negligible amounts of GLDA present in all tissues measured. The present experiment demonstrated a high dietary tolerance to GLDA in broilers and indicated that GLDA does not pose a significant risk to food safety when supplemented below 3,000 mg/kg