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Unformatted text preview: Effects of Dietary Metabolizable Energy and Crude Protein Content on the Activities of Digestive Enzymes in Jejunal Fluid of Peking Ducks F. Zhao, 1 S. S. Hou, H. F. Zhang, and Z. Y. Zhang The State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100094, China ABSTRACT The response of digestive enzymes activi- ties in the jejunal fluid of Peking ducks to dietary ME and CP content was investigated. In experiment 1, jejunal digesta from 24 cannulated male white Peking ducks of 18 wk of age were collected for 1 h out of every 4 h beginning at 0930 h on d 16, 18, and 20 of the experiment. The activities of amylase, trypsin, and chymotrypsin in jejunal fluid were determined. In experiment 2, 72 male cannulated ducks were randomly sorted into 4 groups. Four treatments consisted of combinations of 3,050 and 2,800 kcal/kg of ME, and 17.50 and 14.40% CP content were available ad libitum. Jejunal digesta samples were Key words : jejunal fluid, digestive enzyme, duck 2007 Poultry Science 86:1690–1695 INTRODUCTION The small intestine is the main site of carbohydrate, protein, and fat digestion in birds. The digestive enzymes activities in intestinal fluid play an important role in di- etary nutrient hydrolyzation for absorption, and they could be a limiting factor in food intake, digestion, and subsequent growth in broiler chicks (Nitsan et al., 1991; Nir et al., 1993). Overfeeding and dietary nutrients level such as ME and CP content had effects on the total activi- ties of amylase, lipase, trypsin, chymotrypsin, and disac- charidase in pancreas or intestinal digesta of chicks (Im- ondi and Bird, 1967; Kokue and Hayama, 1972; Siddons, 1972; Nitsan et al., 1974; Nir et al., 1978; Maiorka et al., 2004), which meant dietary nutrients were mediating these endogenous digestive enzyme levels, but few were reported in ducks. Recent studies showed that the TME n values of naked oats, corn, and soybean in ducks were about 15% higher than that in broiler chickens (King et al., 1997; Fan, 2003), which could contribute to the higher digestive enzymes activities in intestinal fluid of ducks (Fan, 2003). Because energy and protein are the main © 2007 Poultry Science Association Inc. Received December 3, 2006. Accepted April 7, 2007. 1 Corresponding author: firstname.lastname@example.org 1690 collected for 1 h every 4 h from 0930 to 1830 h on d 31, 33, and 35 of the experiment according to the results of experiment 1. The activities of amylase, trypsin, chymo- trypsin, lipase, sucrase, and maltase in jejunal fluid were determined. In experiment 1, significant differences were found in the average activities of amylase and chymotryp- sin among days. The collection time significantly affected the 3 enzyme activities, and average enzyme activities during the day were higher and more stable than during the night. In experiment 2, the effect of dietary ME content on the 6 digestive enzymes activities was not significant.on the 6 digestive enzymes activities was not significant....
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