Effect of dietary supplementation of n-3 fatty acids and elevated concentrations of dietary protein on the performance of sows.

A study was conducted to determine the effect of dietary supplementation of n-3 fatty acids (O3FA) with or without elevated concentrations of protein on the performance of sows during the first and the subsequent parity. Sixty-four pregnant gilts with BW of 195.0 +/- 2.1 kg and backfat (BF) thickness of 12.9 +/- 0.2 mm were assigned to 4 dietary treatments from d 60 of gestation (late gestation) to d 21 of lactation. Dietary treatments were 1) a control diet; 2) a high-protein diet (HP); 3) the control diet + 0.2% O3FA (O3); and 4) the HP diet + 0.2% O3FA (HPO3). For the control and O3 treatments, CP contents were 12.3% for late gestation and 17.9% for lactation, and for the HP and HPO3 treatments, CP contents were 18.4% for late gestation and 19.5% for lactation. On d 60 and 110 of gestation and after farrowing (within 12 h postfarrowing), on d 10 and 21 of lactation, BW, BF thickness, and blood samples were obtained. The total number of piglets and the number of piglets born alive and their birth weights were measured within 12 h postfarrowing. Colostrum and milk samples were obtained on d 2 and 21 of lactation, respectively. All piglets were weaned at 21 d. The wean-to-estrus interval and ADFI were recorded. The same measurements were obtained from the control and O3 groups during the subsequent parity. Dietary treatment did not affect BW, BF thickness, ADFI, and the wean-to-estrus interval of sows during their first reproductive cycle. Supplementation of O3FA increased both eicosapentaenoic acid and docosahexaenoic acid contents (P < 0.05) in colostrum and mature milk. First-parity litter size and piglet birth weight did not differ among treatment groups. Piglet BW was greater (P < 0.05) for the O3 group compared with both the control and HPO3 groups at d 10 and 21 of lactation. The same pattern was also noted for overall piglet BW gain. Both piglet and litter characteristics of the HP group did not differ from those of other groups throughout lactation. During the subsequent parity, both total and live piglet birth weights tended (P < 0.07) to be greater for the O3 group than for the control group. Compared with the control group, piglet BW and BW gain in the O3 group showed a pattern similar to the previous parity. Results indicated that O3FA alone during lactation improved the growth of nursing piglets, regardless of parity. However, the O3FA diet, with or without elevated protein, did not affect first-parity gestation performance, although O3FA alone may have improved piglet birth weight in the subsequent litter.