Production region does not influence digestibility of calcium or phosphorus in sunflower co-products fed to growing pigs, but microbial phytase increases digestibility of both calcium and phosphorus

An experiment was conducted to test the hypothesis that the geographical location of production of sunflower co-products does not affect the apparent total tract digestibility (ATTD) of P and Ca and the standardized total tract digestibility (STTD) of P. Six sources of sunflower meal (SFM) were obtained from the U.S. (two sources), Ukraine (two sources), Hungary, and Italy. A source of sunflower expellers (SFE) from the U.S. was also used. Seven diets were formulated by mixing each source of sunflower co-product with cornstarch; therefore, the sunflower co-product was the only source of P in these diets. Seven additional diets that were identical to the previous seven diets, with the exception that 300 units per kg of microbial phytase were added to each diet, were also formulated. A total of 112 barrows (initial body weight: 18.0 ± 1.4 kg) were allotted to the 14 diets using four blocks of 28 pigs, two pigs per diet in each block, and a total of eight replicate pigs per diet. Pigs were housed individually in metabolism crates to allow for the total collection of fecal materials for four days after seven days of adaptation to the diets. Diets and dried fecal samples were analyzed for dry matter, Ca, and P, and the ATTD of Ca and P, and STTD of P were calculated. Results indicated that diets containing phytase had greater (P < 0.001) ATTD of Ca and P and greater (P < 0.001) STTD of P than diets without phytase. Pigs fed the diet containing the SFE had reduced (P < 0.05) ATTD and STTD of P compared with pigs fed diets containing SFM, but no differences in STTD of P among the six sources of SFM were observed. Pigs fed the diet containing one of the sources of SFM from the U.S. had greater (P < 0.05) ATTD of Ca compared with pigs fed diets containing the Ukraine sources of SFM, but the ATTD of Ca was not different between SFM and SFE. In conclusion, there was no difference in the ATTD and STTD of P among SFM sources, but ATTD and STTD of P in SFE were less than in SFM. Small differences in the ATTD of Ca among SFM sources were calculated, but no difference between SFM and SFE was observed for ATTD of Ca. The ATTD and STTD of P and ATTD of Ca increased if microbial phytase was added to the diets containing SFM or SFE.