Authors : G. D. Plascencia, C. Mendoza , C. V?squez and R. A. Zinn
Abstract: Three Jersey x Holstein steers (215 " 4.8 kg ) with cannulas in the rumen and proximal duodenum were used in a 3 x 3 Latin squares design experiment to evaluate the level of fat supplementation (0, 4, and, 8% yellow grease) on characteristics of duodenal chyme, bile production, and digestion of fatty acids. Dry matter intake was restricted to 2.15% of BW. Characteristics of bile obtained during evisceration of 18 beef carcasses were as follows: pH = 7.48 ? 0.29; total solids = 8.32% ? 0.66; density, 1.012 ? 0.02 g/mL and total lipids, 1468 ? 82 mg/dL. Increasing level of fat supplementation decreased (linear effect, P = 0.07) postruminal fatty acid digestion, due primarily to decreased absorption of saturated fatty acids. The estimated NEm (Mcal/kg) of yellow grease averaged 5.87 and 5.46 for the 4, and 8% of level supplementation, respectively. There were no treatment effects (P>0.20) on pH and density of duodenal chyme. Although, pH was lower (2.34 vs 3.81, P<0.01), and density was greater (1.3% P<0.01) for proximal duodenum than for distal duodenum chyme. Bile production averaged 31.9 ? 0.35 mL/kg BW. Increasing level of fat intake increased (linear effect, P = 0.07) bile production. Increasing the level of supplemental fat from 4 to 8% increased bile production and duodenal lipid flow by 10.3 and 35.7%, respectively. Thus, with increasing level of fat supplementation, the bile:lipid ratio (mL of bile/g of lipid in duodenum) of distal duodenal chyme decreased (linear effect, P<0.01) from 23.4 to 16.7. The bile:lipid ratio of distal duodenal chyme explained 69% of the variation in intestinal fatty acid digestion. We conclude that the decrease in NE value of supplemental fat with increasing level of fat intake is largely due to disproportionate increases in bile production, and hence, decreased bile:lipid ratios.
Plascencia, G. D. , C. Mendoza , C. V?squez and R. A. Zinn , 2004. Influence of Levels of Fat Supplementation on Bile Flow and Fatty Acid Digestion in Cattle . Journal of Animal and Veterinary Advances, 3: 763-768.