Determination and prediction of the available energy and amino acids digestibility of full-fat soybean fed to growing pigs.

Two experiments were conducted to determine the digestible energy and metabolizable energy contents, as well as the apparent ileal digestibility and standardized ileal digestibility of amino acids in full-fat soybean fed to growing pigs. Ten full-fat soybean samples were collected from different areas in China and used in two experiments in this study. In Exp. 1, 66 growing pigs (initial body weight = 18.48 ± 1.2 kg) were randomly allotted to 1 of 11 diets (n = 6) including a corn basal diet and 10 experimental diets formulated by replacing the corn with 30% full-fat soybean. In Exp. 2, 11 growing pigs (initial body weight = 50.45 ± 3.2 kg) were surgically equipped with a T-cannula in the distal ileum and arranged in a 6 × 11 Youden square design with 11 diets and 6 periods. The diets included an N-free diet based on cornstarch and sucrose and 10 experimental diets formulated with full-fat soybeans as the sole source of amino acids. Chromic oxide was added into the diets as an indigestible maker to calculate the digestibility of the amino acids. Results showed that there was considerable variation in neutral detergent fiber, acid detergent fiber, and trypsin inhibitor contents in the 10 full-fat soybean samples with a coefficient of variation greater than 10%. On a dry matter basis, the averaged digestible energy and metabolizable energy values in the 10 full-fat soybean samples were 4,855 and 4,555 kcal/kg, respectively, both were positively correlated with the ether extract content. The best-fitted prediction equations for digestible energy and metabolizable energy of full-fat soybean were: digestible energy, kcal/kg = 3,472 + 94.87 × ether extract - 97.63 × ash (R2 = 0.91); metabolizable energy, kcal/kg = 3,443 + 65.11 × ether extract - 36.84 × trypsin inhibitor (R2 = 0.91). In addition, all full-fat soybean samples showed high apparent ileal digestibility and standardized ileal digestibility values in amino acids and were all within the range of previously published values. Those values significantly varied among different samples (P < 0.05) for most amino acids, except for glycine and proline. In conclusion, full-fat soybean is a high-quality protein ingredient with high ileal digestibility of amino acids when fed to growing pigs, and the metabolizable energy value of full-fat soybean could be predicted based on its ether extract and trypsin inhibitor contents.

Full-fat soybean is an excellent protein source supplied in swine diets, especially in weaned and growing stages. However, the high price limits its utilization in practice, so it is vital to accurately evaluate the available energy and digestible amino acids contents in full-fat soybean to better formulate a least-cost diet. Ten full-fat soybean samples were collected from different areas in China, and two experiments were conducted to evaluate the energy concentration and amino acids digestibility of full-fat soybean and to establish the corresponding prediction equations. The averaged digestible and metabolizable energy of FFSB were 4,855 and 4,555 kcal/kg (dry matter basis), and the best-fitted prediction equations for digestible energy and metabolizable energy of full-fat soybean were: digestible energy, kcal/kg = 3,472 + 94.87 × ether extract − 97.63 × ash; metabolizable energy, kcal/kg = 3,443 + 65.11 × ether extract − 36.84 × trypsin inhibitor. Except for glycine and proline, the digestibility of other amino acids significantly varied among 10 full-fat soybean samples but all were within the range of previously published values. In addition, all the amino acids exhibited high digestibility, indicating that full-fat soybean is a protein ingredient with high quality.

Effects of dietary conjugated linoleic acid supplementation on performance and immune function of weaned pigs.

Two experiments were conducted to evaluate the effect of dietary conjugated linoleic acid (CLA) on performance and immune responses of weaned pigs. In Exp. I, 72 crossbred pigs weaned at 19 to 23 days of age and weighing 7.20 +/- 0.11 kg were randomly allotted to four diets supplemented with CLA at 0, 1, 2 or 3%. On day 14, pigs were injected with ovalbumin (1mg per kg BW) and blood samples were collected on day 7 and 14 after injection to test the specific OVA antibody. In Exp. II, 36 crossbred pigs weaned at 26 to 30 days of age and weighing 8.12 +/- 0.14 kg were randomly divided into two diets containing either 0 or 2% CLA. On day 14 and 28, blood samples were obtained to determine the lymphocyte proliferation and PGE2 levels in both trials, and CD4+, CD8+ T cells subsets and interleukin-1beta production were tested in Exp. II. In Exp. I both average daily gain and average daily feed intake of weaned pigs were improved quadratically and feed efficiency was increased linearly by CLA supplementation. Lymphocyte proliferation response to concanavalin A was increased quadratically as dietary CLA concentration increased on day 14 and 28. Ovalbumin antibody production levels were increased linearly on day 7 after injection of ovalbumin and increased quadratically on day 14 after injection, which follows the increased CLA levels, whereas CLA reduced linearly the production of prostaglandin E2 (PGE2). The results of Exp. II indicated that CLA improved performance, lymphocyte proliferation, and increased the CD8+ lymphocyte population, while reduced the production of PGE2 and interleukin-lbeta (IL- 1beta). These results suggest that the supplementation of CLA enhanced lymphocyte proliferation function, possibly by regulating the PGE2 production, and improved growth performance of pigs. Further studies are needed to determine the mechanism of CLA-induced inhibition of IL-1beta production.

Conjugated linoleic acid can prevent tumor necrosis factor gene expression by inhibiting nuclear factor binding activity in peripheral blood mononuclear cells from weaned pigs challenged with lipopolysaccharide.

Twenty-four weanling barrows were fed corn-soybean diets supplemented with 2% conjugated linolenic acid (CLA) or soybean oil. On day 14 and 21, pigs were injected intraperitoneally with lipopolysaccharide (LPS) or sterile saline. Plasma samples were collected 2h after injection. Peripheral blood mononuclear cells (PBMC) were also collected on day 21, 2 h after injection to determine tumor necrosis factor-alpha (TNF-alpha) production and its mRNA expression. The results indicate that dietary CLA inhibited the production of TNF-alpha by pig PBMC both at the protein and mRNA expression level. In a second experiment, PBMC, collected from a healthy pig, were incubated with either c9,t11-CLA or t10,c12-CLA, or without CLA and stimulated with LPS. Both CLA isomers inhibited LPS-stimulated TNF-alpha production and expression, which may be partially due to inhibition of the binding activity of nuclear factor-kappaB. The t10,c12 isomer was more effective than the c9,t11-CLA isomer in reducing TNF-alpha levels and nuclear factor-kappaB activation.