Novel feed additives to improve lipid profiles in pigs
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Opportunities to export high quality pork products to trade partners like Japan are economically favorable outlets for US pork producers. Domestic consumers also rely heavily on fresh pork appearance, especially color and marbling, to make initial and repeat purchasing decisions. Two studies were performed to elucidate novel ways to improve pork quality, specifically by altering the lipid profile and increasing intramuscular fat (i.m.). In experiment 1, forty individually reared barrows (100 kg ± 3 kg, PIC C23 x 337) were randomly assigned to 1 of 5 treatments containing dried distillers grains with solubles and 3 percent added fat to determine the resulting carcass characteristics and fresh pork quality. The treatments included 1) a positive control containing a corn and soybean meal base with 3 percent choice white grease (PCON), 2) 30 percent high protein dried distillers grain and 3 percent choice white grease (HPDDG), or 30 percent DDGS with 3) no added fat (DDGS), 4) 3 percent choice white grease (DDGS + CWG), or 5) 3 percent butter oil (DDGS + BO). Postmortem carcasses characteristics and quality attributes were not different between diets (P greater than 0.08) except the semimembranosus muscle from pigs fed HPDDGS had the most basic ultimate pH (P = 0.01) suggesting pigs fed HPDDGS had less glycolytic potential at the time of slaughter. Including DDGS in the diet decreased (P less than 0.01) MUFA and increased (P less than 0.01) PUFA. Butter oil increased (P less than 0.01) CLA content in fat, but did not increase SFA or iodine value. Although added fat in the diet altered fatty acid composition in multiple fat depots, adding additional saturated fat to the diet in the form of butter oil did not mitigate the unsaturation of DDGS. Skycis® (narasin, NAR) is a swine performance ionophore labeled to increase rate of gain in the last 4 weeks of the finishing phase. The objective of experiment 2 was to evaluate inclusion of NAR in pig diets and determine the source of carcass yield, specifically dressing percentage, improvements observed in previous studies. Barrows (n=50) and gilts (n=50) of PIC C22 x 337 genetics were randomly assigned to a diet containing 0 or 15 ppm NAR initiated at 39.5 kg of body weight and continued until slaughter. Barrows tended (P = 0.09) to have heavier viscera, significantly (P less than 0.01) more fat at the 10th rib, and a greater (P = 0.01) percentage of i.m. fat compared to gilts. Gilts were heavier muscled than barrows as evidenced by many gender differences (P less than 0.05) observed in the cutability phase of the study, specifically larger LM (P less than 0.01). Heavy muscled, lean animals such as gilts may have increased organ mass from up regulated metabolic activity, but pigs with greater intake will also have heavier intestinal tract compensating for the increased consumption suggesting barrows in this study ate more, especially late in the growth curve. Pigs fed NAR had heavier (P less than 0.01) hearts, but few treatment differences were observed in carcass quality and cutability. In general, fat content increased and made up a larger percentage of total carcass weight in pigs fed NAR. The current results do not confirm the source of previously observed differences in DP in pigs fed NAR, but could be attributed to the tendency of NAR to increase carcass fatness.