Supplementation of selenium, vitamin E, chromium and betaine above recommended levels improves lactating performance of sows over summer.

Heat stress (HS) exacerbates the body weight loss of lactating sows and reduces litter weight gain. Selenium (Se), vitamin E (VE), chromium (Cr) and betaine have been shown to ameliorate symptoms of HS, and yeast nucleotides and mannan oligosaccharides have been reported to improve lactational performance and immune response in pigs. Therefore, a combination of these nutrients may improve lactational performance of sows in summer. The effects of two nutritionally enhanced diets on lactational performance of sows in summer were investigated in two experiments. In experiment 1, we compared the effects of a nutritionally fortified diet (0.4 ppm Se, 95 IU/kg VE, 0.4 ppm Cr and 0.2% betaine; named as SVCB diet) with the NRC 2012 standard diet (0.15 ppm Se, 44 IU/kg VE) on lactational performance of sows in summer. Results showed that the SVCB diet reduced body weight loss (P = 0.039) and tended to reduce backfat loss (P = 0.075) of sows without affecting feed intake, while litter weight gain was not influenced. In experiment 2, we further enhanced the nutrients in the SVCB diet (0.8 ppm Se, 1% yeast nucleotides, and 0.1% mannan oligosaccharides; named as SNM diet). Results showed that the SNM diet did not improve feed intake of sows, farrowing performance, or litter weight gain compared with the SVCB diet, but increased body weight loss of the third parity sows (P = 0.037). Overall, a combined supplementation of Se, VE, Cr, and betaine above the NRC recommended levels can reduce mobilisation of body reserve of lactating sows in summer.

Dietary nano-chromium tripicolinate increases feed intake and decreases plasma cortisol in finisher gilts during summer.

Chromium (Cr) is an essential mineral element and has been used in pig diets to improve growth performance, insulin sensitivity, immune response and carcase traits and to reduce heat or other stress responses. The aims of thiss study were to determine the impact of nano-sized chromium tripicolinate (nCrPic) on growth performance, feed efficiency and carcase characteristics of finisher gilts during the summer period. A total of 60 finisher Large White x Landrace gilts were stratified on initial weight and then within strata randomly allocated into two treatment groups in three replicates during mid-summer for 28 days. All pigs were housed in individual pens and had ad libitum access to feed and water. Pigs were fed either a control finisher diet (wheat-based diet containing 13.8 MJ digestible energy (DE) per kilogram and 0.56 g available lysine/MJ DE) or a control diet containing 400 ppb Cr as nCrPic. Dietary nCrPic supplementation increased feed intake by 6 % over the entire study (P = 0.05). In particular, dietary nCrPic increased average daily feed intake (ADFI) by 8 % (P = 0.02) during the final 2 weeks of the study. Moreover, dietary nCrPic tended to improve average daily feed (ADFI) over the entire study (P = 0.09). However, there were no significant effects of nCrPic on feed conversion ratio (FCR), final weight, hot standard carcase weight (HCWT), P2 depth or dressing percentage. Plasma cortisol was decreased by 25 % (P = 0.06) by dietary nCrPic supplementation. However, there were no effects of nCrPic on plasma glucose, insulin and nonesterified fatty acids (NEFA), might because of the higher feed intake. In conclusion, this study demonstrates that dietary nCrPic supplementation at 400 ppb can increase feed intake in finisher gilts during mid-summer, suggesting that nCrPic can ameliorate some of the negative effects of heat stress in pigs, possibly via decreased of circulating cortisol.