| dc.description.abstract | Nutrient digestibilities in three high-protein feedstuffs used for swine feeding were determined. An effort was made to obtain meals that were representative of those available to pork producers and feed manufacturers in Texas. The three meals were: 44% CP solvent-processed soybean meal (SBM), 41% CP direct solvent-processed cottonseed meal (CSM) and 50% CP meat and bone meal (M&B).
Six crossbred barrows (22.7 kg initial body weight) were surgically fitted with simple T-cannulas at the end of the small intestine and used in a replicated 3x3 Latin Square design to determine the digestibility of dry matter, ash, energy, nitrogen and amino acids at the end of the small intestine and over the total digesttive tract for the three high-protein meals. Nitrogen and amino acid content of the meals were determined prior to beginning the test and the values were used in formulating diets. Cornstarch-based diets were formulated to contain .60% dietary lysine; .25% chromic oxide was included as an indigestible marker.
Nitrogen and amino acid digestibilities determined at the end of the small intestine and over the total tract tended to be highest for SBM, lowest for M&B, with CSM intermediate but closer to SBM. At the end of the small intestine, digestibilities for nitrogen and the average of the ten essential amino acids were 79.3 and 82.8% for SBM, 79.0 and 79.6% for CSM and 66.0 and 67.1% for M&B. Digestibilities for lysine and tryptophan (the two most limiting amino acids in grain-soybean meal diets) in SBM, CSM and M&B, respectively, were: 85.6, 80.9%; 69.8, 77.6%; 67.4, 49.7%. Digestibility coefficients determined over the total digestive tract followed the same pattern but values for nitrogen and the average of the essential amino acids tended to be higher and more uniform than ileal values (86.7 and 86.9%, SBM; 81.8 and 80.9%, CSM, 76.7 and 74.2%, M&B.
CSM had a lower (P<.05) energy digestibility (81.7%) than SBM (90.8%) and M&B (89.4%) which probably resulted from its higher fiber content (10.3%) compared to SBM (3.2%) and M&B (3.3%). Metabolizable energy values (kcal/g) were highest for SBM (3.83) followed by M&B (3.68) and CSM (3.50). In contrast to nitrogen and energy digestibilities which ranged from 66.0 to 83.5% at the terminal ileum among the three meals, ash digestibilities were much lower (25.4 to 33.1%). A much larger percentage of the ash disappeared in the lower gut (36.3 to 50.5%) than for nitrogen (2.8 to 10.8%) and energy (3.8 to 6.5%). These data suggest that the apparent availability of amino acids determined at the end of the small intestine give a better measure of the amount actually available to the pig than those determined over the total digestive tract. | en |
