EFFECTS OF PELLETING, LACTOSE LEVEL, POLYETHYLENE-GLYCOL-4000, AND GUAR GUM COMPARED TO PECTIN ON GROWTH PERFORMANCES, ENERGY VALUES, AND LOSSES OF LACTOSE, LACTIC-ACID, AND WATER IN CHICKENS

Five mash and two pelleted diets were tested in broiler chickens (7 to 19 d). Mash diets consisted of a basal fraction diluted with either .5% pectin or .5% guar gum. Mash pectin and guar gum diets contained either 3% lactose (PL(3)m and GL(3)m diets, respectively) or 6% lactose (PL(6)m and GL(6)m diets, respectively). Compositions of pelleted diets (PL(3)p and GL(3)p) were those of PL(3)m and GL(3)m diets, respectively. All diets contained .5% polyethylene glycol 4000 (PEG) except the PL(3)m(0) diet. The latter diet differed from PL(3)m diet by the PEG content, only. The real applied viscosities of pectin and guar gum diets were 1.48 and 4.94 mL/g, respectively. No effect of PEG was detected on growth performances, and excreta losses of lactose, lactic acid, and water. No negative effect of guar gum compared to pectin was observed on body weight (19 d), except with pelleted diets (P < .05). Feed:gain ratios for guar gum diets were 7% higher (P less than or equal to .002) than those of pectin diets. The AME(n), values of guar gum diets were 4% lower (P less than or equal to .001) than those of pectin diets. For mash diets, lactose digestibilities were lower (P < .05) with guar gum than with pectin. Increasing lactose level from 3 to 6% did not affect (P > .05) AME(n) values, feed: gain ratios, and body weights (19 d) but reduced (P = .001) lactose digestibilities from 78 to 64%. The positive effects of pelleting on body weights (19 d) were much less pronounced with guar gum than with pectin (P < .05). The AME, values of pelleted diets (PL(3)p and GL(3)p) were, on average, 2.5% lower (P = .005) than their mash counterparts (PL(3)m and GL(3)m). Water losses related to feed intake were greater with guar gum than with pectin (P < .001) and with 6% lactose than with 3% (P = .001), but were not affected (P > .05) by pelleting. Lactic acid losses related to feed intake were increased by guar gum compared with pectin (P < .001), with more pronounced effects induced by high lactose level (P < .05) and pelleting (P < .05). In many respects, the effects of guar gum seemed similar to those observed in an acid liquid diarrhea.