Effect of flaxseed oil, animal fat, and vitamin E supplementation on growth performance, serum metabolites, and carcass characteristics of finisher pigs, and physical characteristics of pork

Dietary lipid supplementation can reduce de novo lipogenesis and increase intramuscular fat content of pork simultaneously, and vitamin E supplementation can increase the oxidative stability of pork. A total of 96 pigs (Yorkshire) were used to investigate the effect of dietary lipid (0 or 1% flaxseed oil + 1, 3, or 5% poultry fat for diets supplemented with lipids) and vitamin E (11 or 220 IU/kg) supplementation in a 4 × 2 factorial arrangement of treatments on growth performance, serum metabolites, and carcass traits of finisher pigs, and physical characteristics of pork. Forty-eight pens containing 2 gilts or 2 castrated males per pen were randomly assigned to 8 diets with 3 gilt pens and 3 castrated male pens per treatment. Pigs were switched from finisher-1 [initial body weight (BW): 54.3 ± 3.4 kg] to finisher-2 diets when the average pen BW reached 84.1 ± 4.0 kg. Standardized ileal digestible Lys and Ca and P were adjusted with the DE content accordingly to maintain constant Lys, Ca, and P to DE ratios. Pigs were harvested when they reached the target BW of 110.0 ± 3.0 kg. There were no lipid x vitamin E interactions in growth performance. As dietary lipids increased from 0 to 6%, average daily feed intake decreased linearly (P < 0.018) and gain to feed ratio improved linearly (P < 0.001) during the finisher-1, finisher-2, and overall phases. Supplementation with 220 IU vitamin E/kg reduced the efficiency of feed, Lys, and DE utilization for BW gain (P < 0.036) during the finisher-1 and overall phases. As dietary lipids increased, serum cholesterol and triglyceride concentrations increased linearly (P < 0.003). Supplementation of the diet with 1% flaxseed oil + 1, 3, or 5% poultry fat resulted in greater serum total protein, albumin, cholesterol, and triglyceride concentrations (P < 0.037) compared with no lipid supplementation. Pigs fed the diets containing 0, 2, and 4% lipids and supplemented with 220 IU vitamin E/kg had greater 10th rib BF and lower fat-free lean than those fed the dies contained 11 IU vitamin E/kg, whereas 10th rib BF was lower and fat-free lean was greater in pigs those fed the diet containing 6% lipids and supplemented with 200 IU vitamin E/kg than those fed the diet contained 11 IU vitamin E/kg (lipid x vitamin E, P < 0.020). Dietary lipids had no effect on subjective marbling score and ether extract content of loin muscle or most other pork and loin muscle characteristics, but belly thickness and width increased (linear, P < 0.040) as dietary lipids increased. Vitamin E supplementation increased marbling score (P = 0.042), but it had no clear effect on loin muscle color (subjective, and L* a* and b*), ham and loin muscle pH, loin muscle characteristics, or belly firmness. As expected, feed intake decreased and feed efficiency improved progressively with increasing dietary lipid supplementation from 0 to 6%. Although there were interactions, dietary lipids seemed to have no clear effects on the carcass BF or fat-free lean. Similarly, dietary supplementation with 1% flaxseed oil + 1, 3, or 5% poultry fat had no effect on subjective marbling score or ether extract content of loin muscle. Supplementation with 220 IU vitamin E/kg increased carcass leanness with 6% dietary lipids, but increased carcass BF with 0 to 4% dietary lipids. Vitamin E supplementation increased subjective marbling score, but seemed to have no clear effects on loin muscle color, ham and loin muscle pH, loin muscle characteristics, or pork belly firmness.