In vitro Estimation of the Solubility of Dry Matter and Crude Protein of Wet Feed and Dry


Abstract: Two experiments were conducted to determine the in vitro solubility of dry matter and crude protein of wet feed and dry feed of a commercial broiler diet. In the first experiment, to two g of feed samples of a commercial broiler pelleted diet was added 0-dry (80 g/kg water content) and 1.5 g water per g of feed (640 g/kg water content), and they were then incubated at one of two different levels of pepsin-HCl solutions, low (48 mg pepsin in 2 ml 0.1M HCl), or high (64 mg pepsin in 3 ml 0.1M HCl) for 0, 15, 30, 60, 120, 180, and 240 minutes at 42ºC. In the second experiment, to 2 g of a commercial broiler feed was added 0-dry (80 g/kg water content), 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 1.8, and 2.0 g water per g of dry feed (240, 340, 430, 480, 540, 580, 630, and 700 g/kg water content, respectively). To each feed sample was also added 64 mg pepsin with 3 ml-HCl (the high level from experiment 1), and then incubated for 10, 20, 30, 60, 180 and 240 minutes at 42ºC. After filtration and drying processes, dry matter and crude protein analyses were done for each sample. In experiment 1, wetting the feed with 1.5 g water per g feed followed by incubation in pepsin-HCl solution increased both dry matter solubility and crude protein solubility. There were also higher solubilities of feed nutrient with a high concentration of pepsin-HCL with a than low concentration of pepsin-HCL. In experiment 2, dry feed samples (80 g/kg water content) and feed samples with 240 and 340 g/kg water content had similar nutrient solubility, but their solubility values were significantly (P<0.05) lower than those of wet feed samples with 540, 580, 630 and 700 g/kg water content. Feed samples with 630 and 700 g/kg water content had high solubility values throughout the incubation periods. The results revealed that increased nutrient solubility might just as easily have been achieved by the addition of a larger volume of liquid to dry feed because additional water in wet feed samples was the only difference between these and the dry feed samples.

Keywords: wet feed, dry matter, crude protein, in vitro solubilization, pepsin, HCl

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