Abstract An experiment was conducted to test the hypothesis that increasing dietary Ca and P and without or with 25-hydroxycholecalciferol (25-OH-D3) improves the apparent total tract digestibility (ATTD) and the standardized total tract digestibility (STTD) by gestating sows of Ca and P as well as bone ash of newborn pigs. A total of 64 multiparous sows were allotted to eight dietary treatments in a randomized complete block design with eight dietary treatments. Diets were arranged in a 4 × 2 factorial with four Ca and P concentrations and two levels of 25-OH-D3 (0 or 50 µg/kg). Experimental diets were based on corn, soybean meal, and sugar beet pulp and the Ca:P ratio was constant among diets. Sows were fed experimental diets from day 45 of gestation until farrowing and were placed in metabolism crates from day 92 to 104 of gestation. Feces were collected from the feed fed from day 98 to day 104 and analyzed for Ca and P. Metatarsals from the right leg of one newborn pig per litter were collected on the day of birth and analyzed for bone ash. Data were analyzed using the Proc Mixed of SAS (SAS Stat Inc., Cary, NC, USA) and the model included main effects of dietary Ca and P and 25-OH-D3 and interactions between the main effects. Contrast statements were used to determine linear and quadratic effects of levels of Ca and P. Results indicated that increasing dietary Ca and P resulted in increased (P 0.05) concentrations of Ca and P in feces, but the increase was greater for sows fed diets without 25-OH-D3 than for sows fed diets with 25-OH-D3 (interaction, P 0.01; Table 1). However, sows fed diets containing 25-OH-D3 had greater (P 0.05) ATTD and STTD of Ca and P regardless of dietary Ca and P because of reduced (P 0.05) fecal Ca and P compared with sows fed diets without 25-OH-D3. Bone ash of newborn pigs was reduced (P 0.05) as dietary Ca and P increased, but 25-OH-D3 did not affect bone ash of newborn pigs. No effects of 25-OH-D3 or dietary Ca and P were observed for sow body weight, farrowing duration, litter size, or newborn pig weight (data not shown). In conclusion, supplementation with 25-OH-D3 improved Ca and P digestibility in gestating sows, likely due to greater concentrations of the active vitamin D metabolite in the small intestine. However, neither 25-OH-D3 nor extra Ca and P in the diet impacted bone ash of newborn pigs indicating that even if sows are provided Ca and P below requirements, they will prioritize bone tissue synthesis of the offspring, likely by reducing body stores of Ca and P.
Huerta et al. (Wed,) studied this question.