Effects of dietary citric acid on performance, digestibility of calcium and phosphorus, milk composition and immunoglobulin in sows during late gestation and lactation

An experiment was conducted to determine the effects of dietary citric acid (CA) on the performance, coefficient of total tract apparent digestibility (CTTAD) of crude protein (CP), calcium (Ca) and phosphorus (P), plasma biochemistry parameters, colostrum and milk composition and immunoglobulin of sows during late gestation and lactation. Forty-eight sows (landrace × large white, mean parity 3.82 ± 1.00) were randomly allotted to four dietary treatments (n = 12 sows/treatment) supplemented with 0 (control), 5, 10 or 15 g/kg CA. The experiment started at day 90 of gestation and ran until day 24 of lactation for 48 days. Blood samples were collected on day 107 of gestation, day 0 (farrowing) and day 24 (weaning) of lactation. The colostrum and milk samples were obtained on day 0 (farrowing) and day 14 of lactation, respectively. Faecal samples were collected from the sows on days 20 and 21 of lactation. The results from the present study indicated that supplementation of 15 g/kg CA in the basal diet could significantly increase the CTTAD of CP and P (P < 0.05). Additionally, the CTTAD of Ca was significantly increased with 10 and 15 g/kg CA supplemented diets (P < 0.05). There were no significant differences in sow and litter performance among treatments (P > 0.05), such as sow average daily feed intake (ADFI), sow body weight (BW) change, litter size, litter weight at birth and weaning and weight gain of the piglets. Throughout the experiment, the Ca concentration of plasma was significantly enhanced by adding 10 g/kg CA (P < 0.05). Supplementing CA increased the P concentration of plasma on day 107 of gestation (P < 0.05). The total protein (TP) of plasma on the days of farrowing and weaning and the TP of colostrum and milk were improved by adding 15 g/kg CA (P < 0.05). Supplementation of 10 and 15 g/kg CA enhanced the IgG and IgA levels in the plasma of sows. Immunoglobulin levels in colostrum and milk were significantly enhanced with 15 g/kg CA supplemented diets compared with the control (P < 0.05), with the exception of IgG of milk (P > 0.05). In conclusion, dietary supplementation of CA during late gestation and lactation had no significant effects on sow and litter performance. Additions of 10 and 15 g/kg CA enhanced the absorption of dietary Ca, P and protein, improved humoral immune function in sows and could be beneficial to piglets via colostrum and milk.