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, 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 (PL3m and GL3m diets, respectively) or 6% lactose (PL6m and GL6m diets, respectively). Compositions of pelleted diets (PL3p and GL3p) were those of PL3m and GL3m diets, respectively. All diets contained .5% polyethylene glycol 4000 (PEG) except the PL3m0 diet. The latter diet differed from PL3m 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 less than .05). Feed:gain ratios for guar gum diets were 7% higher (P less than or equal to .002) than those of pectin diets. The AMEn 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 less than .05) with guar gum than with pectin. Increasing lactose level from 3 to 6% did not affect (P greater than .05) AMEn 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 less than .05). The AMEn values of pelleted diets (PL3p and GL3p) were, on average, 2.5% lower (P = .005) than their mash counterparts (PL3m and GL3m). Water losses related to feed intake were greater with guar gum than with pectin (P less than .001) and with 6% lactose than with 3% (P = .001), but were not affected (P greater than .05) by pelleting. Lactic acid losses related to feed intake were increased by guar gum compared with pectin (P less than .001), with more pronounced effects induced by high lactose level (P less than .05) and pelleting (P less than .05). In many respects, the effects of guar gum seemed similar to those observed in an acid liquid diarrhea.