In most AA digestibility experiments collection bags are changed at least every 30 min and the collected ileal digesta are stored at –20 °C to prevent microbial degradation of proteins. Other attempts to reduce microbial activity in digesta include adding acids to collection bags to reduce the pH in ileal digesta. Acids may also be added to collection pitchers. However, in some experiments, no attempt to reduce pH is made because it is assumed that the rapid reduction in temperature after collection is sufficient to prevent microbial degradation of proteins.

To our knowledge, there is, however, no information about the necessity of adding acids to collected digesta and it is not known if values for apparent ileal digestibility (AID), basal endogenous losses of AA, or standardized ileal digestibility (SID) of AA are influenced by addition of acids to digesta. Therefore, the objective of this experiment was to test the null-hypothesis that values for AID, basal endogenous losses, and SID of AA are not influenced by addition of acids to ileal digesta collection bags or to collection pitchers.

Absorption of Ca and P by active transport in the small intestine is regulated by calcitriol, which is the active form of vitamin D (1,25-dihydroxycholecalciferol) and the hormones calcitonin and PTH. One-alpha-hydroxycholecalciferol (1-α-OH-D₃) is an active vitamin D₃ analog that does not require the second hydroxylation step for vitamin D₃ to be active. It is possible that supplementation of 1-α-OH-D₃ may increase absorption of Ca and P.

The requirement for Ca and P by gestating sows increases in late gestation compared with early- and mid-gestation because of increased needs by the developing fetuses. It is also possible that dietary concentrations of Ca and P affect the rate of absorption of Ca and P in sows but data to demonstrate this have not been reported. Therefore, the objective of this experiment was to test the hypothesis that the Ca and P concentrations in diets fed to gestating sows in late gestation and supplementation of 1-α-OH-D₃ affect apparent total tract digestibility (ATTD) and retention of Ca and P as well as the ATTD of GE and concentration of DE in diets. The second hypothesis was that there is an interaction between dietary Ca and P concentrations and supplementation of 1-α-OH-D₃ in diets fed to gestating sows.

Lancheros, J. P., C. D. Espinosa, H. H. Stein. 2020. Effects of particle size reduction, pelleting, and extrusion on the nutritional value of ingredients and diets fed to pigs: A review. Animal Feed Science and Technology 268 (2020) 114603. https://doi.org/10.1016/j.anifeedsci.2020.114603.

Kim, Beob G., Su A Lee, Kyu R. Park, and Hans H. Stein. 2020. At least 3 days of adaptation are required before indigestible markers (chromium, titanium, and acid insoluble ash) are stabilized in the ileal digesta of 60-kg pigs, but values for amino acid digestibility are affected by the marker. Journal of Animal Science, 2020,  Vol. 98: No.

Lee, Su A.,  L. Vanessa Lagos, Mike R. Bedford, and Hans H. Stein. 2020. Increasing calcium from deficient to adequate concentration in diets for gestating sows decreases digestibility of phosphorus and reduces serum concentration of a bone resorption biomarker. Journal of Animal Science, 2020,  Vol. 98: No. 3:1-8.

Lagos, Vanessa L., Hans H. Stein. 2020. Torula yeast has greater digestibility of amino acids and phosphorus, but not energy, compared with a commercial source of fish meal fed to weanling pigs. Journal of Animal Science, 2020, 1-9. doi:10.1093/jas/skz375. Link to full text.

Espinosa, Ch. D, R. Scott Fry, Matthew E. Kocher, Hans H. Stein. 2019. Effects of copper hydroxychloride and distillers dried grains with solubles on intestinal microbial concentration and apparent ileal and total tract digestibility of energy and nutrients by growing pigs. Journal of Animal Science, 2019, 4904–4911.

Velayudhan, Deepak Ettungapladi , Manik M. Hossain, Hans H. Stein, and C. Martin Nyachoti. 2019. Standardized ileal digestibility of amino acids in canola meal fed to gestating and lactating sows. Journal of Animal Science, 2019, 4219–4226. Link to full text.

Lee Su A., Carrie L. Walk, Hans H. Stein. 2019. PSIV-13 Basal endogenous loss, standardized total tract digestibility, and retention of Ca in sows change throughout gestation, but microbial phytase reduces basal endogenous loss of Ca by gestating sows. Journal of Animal Science, Volume 97, Issue Supplement_2, July 2019, Pages 185–186. (Abstr.). Link to abstract.