Effect of Dietary Calcium Inclusion Rate in Diets for Lactating Sows

Ninety-three sows (Camborough PIC) were used to evaluate the effects of dietary calcium (Ca) inclusion rate in lactating sows. Sows were allotted at the end of gestation into a RCBD (Block = Parity ≤ P2 or ≥ P3) with the following feed treatments: 0.63 vs. 0.79 vs. 0.95% total Ca with total phosphorus (P) constant at 0.63% and available P constant at 0.43%. All diets were formulated to meet or exceed NRC requirements (NRC, 2012) for major nutrient specifications. Feed was provided ad-libitum to sows throughout the study and all diets were fed in meal form. Sows were weighed upon entry into the farrowing rooms and an equation was used to estimate their weight 48 h post-farrow. Feed treatments were fed to sows immediately after entering the farrowing room. Daily feed intake, litter starting weight, litter wean weight, sow wean weight, wean to estrus interval and subsequent reproductive performance were recorded. Data were analyzed as a randomized complete block using the PROC MIXED procedure of SAS with sow as the experimental unit, treatment as a fixed effect, and parity as a random effect. Data were reported as LS Means and contrasts and treatment comparisons were performed. Results were considered significant at P ≤ 0.05 and considered a trend at P > 0.05 and P ≤ 0.10. There were no significant differences in sow body weight loss, sow average daily feed intake or piglet average daily gain as a result of increasing total Ca. Wean to estrus interval was significantly reduced (4.22, 3.98, and 4.75 days, P=0.03) as the Ca level increased to 0.79% from 0.63%. Percentage of pigs removed was least for sows fed with 0.95% dietary Ca (12.88, 13.19, 6.89, P=0.05) during the study. Overall, there were no significant differences or tendencies in the other measured variables. Based on the present study, there were no major sow or litter performance criteria changes for a total Ca to total P ratio from 1 to 1.5. Further studies evaluating the effects of Ca to P ratio on piglet removal rate is warranted, but in this study a higher amount of dietary calcium did not improve sow lactation or piglet growth performance significantly.