Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/19/2010
Publication Date: 12/1/2010
Citation: Schieck, S.J., Shurson, G.C., Kerr, B.J., Johnston, L.J. 2010. Evaluation of glycerol, a biodiesel co-product, in grow-finish pig diets to support growth and pork quality. Journal of Animal Science. 88:3927-3935. Interpretive Summary: Production of bio-diesel results in increased availability of crude glycerin (the principal co-product of biodiesel production) which can be used as a feedstuff in diet formulations fed to growing pigs. Previous research has shown that long-term feeding crude glycerin to growing pigs has little to no impact on pig performance, but may have an affect on pork quality. Consequently the current study was conducted to determine if the duration of feeding dietary crude glycerol (short- or long-term) would influence growth performance, carcass characteristics, and muscle and fat quality of growing-finishing pigs. The current experiment demonstrated that growing-finishing pigs fed diets containing 8% crude glycerol achieved growth performance similar to pigs fed a typical corn-soybean meal diet and that the effects of crude glycerol on carcass traits appear to be limited to improvements in belly firmness with short-term feeding of glycerol. This information is important for nutritionists at universities, feed companies, and swine production facilities showing them the ability to use crude glycerol as a viable feed ingredient in diets fed to growing pigs.
Technical Abstract: Two-hundred sixteen crossbred pigs (BW = 31.3 + 1.76 kg) were used to determine the effects of long-term and short-term feeding of crude glycerol on growth performance, carcass traits, and pork quality of grow-finish pigs. Pigs were blocked by initial BW, and pens within blocks were assigned randomly to 1 of 3 dietary treatments in a 4-phase feeding program (24 pens; 9 pigs/pen). Dietary treatments were: Control – a corn-soybean meal based diet (CON); Long-term – CON + 8% glycerol fed throughout the entire experiment (LT); and Short-term – pigs fed CON for the first 6 weeks followed by CON + 8% glycerol fed during the last 8 weeks of the experiment (ST). Pigs fed LT had higher (P < 0.05) ADG while pigs fed ST tended (P = 0.07) to grow faster than CON (CON = 0.962 kg/d, LT = 0.996 kg/d, ST = 0.992 kg/d, SE = 0.01). Average daily feed intake was greater (P < 0.05) for pigs assigned to LT compared to CON, while ST-fed pigs had similar ADFI to CON (CON = 2.78 kg/d, LT = 2.93 kg/d, ST = 2.86 kg/d, SE = 0.03). Gain:feed ratio was greater (P < 0.05) for pigs fed ST compared to LT, but both were similar to CON fed pigs (CON = 0.346, LT = 0.339, ST = 0.346, SE = 0.002). Hot carcass weight (HCW) was greater (P < 0.05) for LT-fed pigs compared to CON, while ST-fed pigs had HCW similar to both LT and CON-fed pigs (CON = 94.7 kg, LT = 97.4 kg, ST = 96.6 kg, SE = 1.17). Dressing percentage of CON-fed pigs was similar to both LT and ST-fed pigs, but LT-fed pigs had a higher (P < 0.05) dressing percentage than ST-fed pigs (CON = 74.5%, LT = 74.9%, ST = 74.4%, SE = 0.22). Tenth rib BF and loin eye area were not affected by dietary treatment. There was a trend (P = 0.08) for LT-fed pigs to have lower fat-free lean percentage than CON fed pigs (CON = 53.32 %, LT = 52.25 %, ST = 52.55 %, SE = 0.48). Short-term glycerol feeding increased (P < 0.05) belly firmness compared to CON, and tended (P = 0.09) to increase belly firmness compared to LT-fed pigs (CON = 30.27°, LT = 35.30°, ST = 42.26°, SE = 3.91). Dietary treatment had no effect on pork quality of loins based on taste panel assessments. Grow-finish pigs fed diets containing 8% crude glycerol achieved growth performance similar to pigs fed a typical corn-soybean meal diet. Effects of crude glycerol on carcass traits appear to be limited to improvements in belly firmness with short-term feeding of glycerol.