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The importance of implementing a by-product withdraw strategy prior to slaughter in finishing pigs: A review of strategies that mitigate the negative impact on carcass yield
Ingredients such as dried distillers grains with solubles (DDGS) and wheat middlings (midds) contain higher amounts of fiber and are lower in energy than their originating grain sources. Previous research has shown that feeding high-fiber diets to pigs throughout the finishing period has negative effects on carcass yield and hot carcass weight. Also, dietary therapies, such as ractopamine HCl, pelleting the diet, or increasing energy through fat addition prior to marketing, has not been successful to negate fiber’s effect on carcass yield. Limited research suggests that removal of high-fiber ingredients approximately 20 to 30 d prior to slaughter can restore carcass yield. However, the optimal time period for withdrawing high-fiber ingredients prior to marketing has only recently been more closely researched. Two trials were conducted to determine the number of days prior to slaughter that high-fiber ingredients (30% DDGS and 19% midds; 19% NDF) should be removed from finishing pig diets to optimize growth performance, carcass characteristics and digestive tract weights. First a university setting trial demonstrated that withdrawal strategy did not significantly influence growth performance, but carcass yield decreased (P<0.01) in pigs fed the high-fiber diet compared with those fed the corn-soybean meal control (9.3% NDF) and increased (quadratic; P<0.03) as days of withdrawal increased from 0 to 15 d. Pigs continuously fed the high-fiber diet had heavier (P<0.01) full large intestine weight than pigs fed the control. A second study in a commercial setting demonstrated that pigs fed the high-fiber diet throughout had decreased (P<0.01) HCW compared with those fed the control diet. Percentage yield was not significantly influenced by high-fiber diet withdrawal period; however, HCW increased linearly (P<0.05) as withdrawal period increased up to 19 d. In summary, pigs fed high-fiber diets have decreased carcass yield but yield can be restored by switching pigs to a corn-soybean meal diet 15 to 19 d prior to marketing.
Keywords: finishing pigs, fiber, yield