The extent of release of encapsulated methionine in the intestine of cattle

Effects of ethanol, heat, and lipid treatment of soybean meal on nitrogen utilization by ruminants

Ruminant nitrogen utilization of soybean meal treated with 1) 70% ethanol at 23 or 78 degrees C, 2) 10% coconut oil or tallow, or 3) a combination of 70% ethanol at 78 degrees C and coconut oil or tallow was evaluated. Nitrogen solubility was lowest for soybean meal treated with ethanol at 78 degrees C, ethanol plus coconut oil and ethanol plus tallow. In situ nitrogen disappearance was lowest for soybean meal treated with ethanol at 78 degrees C, ethanol plus coconut oil, and ethanol plus tallow. Rates of nitrogen disappearance between 3 and 12 h were lowest for soybean meal treated with ethanol at 78 degrees C, ethanol plus coconut oil, and ethanol plus tallow. Nitrogen retained by lambs was greater for lambs fed soybean meal treated with ethanol at 78 degrees C than for those fed untreated soybean meal. Ruminal ammonia 4 h postfeeding was lowest for lambs fed soybean meal treated with ethanol at 78 degrees C, ethanol plus coconut oil, and coconut oil. These data indicate that the 78 degrees C ethanol treatment improved nitrogen utilization.

Protein digestion in the intestine of sheep

1. The rate of flow of digesta along the intestinal tract, and particularly the changes occurring in proteins during their passage through the intestine were determined in six rams; each animal was fistulated with three cannulas which involved six different sites of the intestine. Cr2O3 was used as a marker substance to measure the rate of flow of the digesta.

2. In the sections of the intestine from 1 to 15 m posterior to the pylorus the amounts of water, dry matter and total nitrogen decreased gradually as a result of their absorption through the intestinal wall. The region of the intestine situated at a distance of 7–15 m from the pylorus was more active with respect to the absorption of N, whereas water and dry matter were adsorbed to a greater extent in the region from 1 to 7 m from the pylorus.

3. The only part of the intestine in which substantial increases of water, dry matter and total N were found was the section immediately distal to the pylorus, and these increases were caused by the inflow of bile, and pancreatic and duodenal juices. The net increase found beyond the entry of the common bile duct was 2.7 g protein N and 2.0 g non-protein N (NPN)/24 h.

4. The activities of trypsin, chymotrypsin and carboxypeptidase A and the ratio α-NH2 NPN: protein N increased from the pylorus up to a distance of 7 m and decreased again from this point to a distance of 15 m from the pylorus.

5. In the sections of the intestine between 1 and 3 and between 3 and 7 m distant from the pylorus the extent of proteolysis exceeded considerably that of absorption of amino acids through the intestinal wall. This was concluded from the decrease in the rate of flow of protein amino acids (by 31% between 1 and 3 m distant from the pylorus and by 34% between 3 and 7 m) and the simultaneous increase in non-protein amino acids (by 20% in the region between 1 and 3 m) or no change in non-protein amino acids (between 3 and 7 m).

6. The relatively greater decrease in non-protein amino acids (by 57%) compared with that of protein amino acids (by 41%) occurring in the section 7 to 15 m distant from the pylorus showed that this is an area of most intensive absorption of amino acids.

7. In the lower section of the intestine, from 15 to 25 m distant from the pylorus, the total amount of amino acids showed almost no change; probably a net effect of loss and gain of amino acids mainly due to microbial activities. Increases in the dehydrogenase activity suggested enhancement of bacterial activity in this lower region of the intestine.

8. The supply of essential amino acids to the tissues of sheep is improved, compared with the amino acid composition of the diet, as the result of ruminal biosynthesis of essential amino acids and ruminal degradation of non-essential amino acids and preferential absorption of essential amino acids through the intestinal wall, particularly in the section of most intensive absorption, 7–15 m distant from the pylorus.