Abstract

Effects of different levels of protein-to-energy ratios (PER) on nutrient utilization, digestive organs index and digestive enzymes activities in Leiothrix luteal were investigated in this research. It was found that different PER feedstuff had no significant effects on the utilization of dry matter (DM), calcium (Ca) and total phosphorus (TP). With the improvement of the PER, average daily feed intake (ADFI)gradually increased, the apparent utilization rate of energy and fat gradually improved, while the apparent utilization rate of crude protein increased at first and then decreased. Development of digestive organs of L. luteal was affected by the level of dietary PER, with the increase in PER, the digestive organ indices of muscular stomach, duodenum, jejunoileum and rectum exhibited a downward trend, the main influencing factors were the level of metabolizable energy in diets. With the intestinal tract moving backward, the relative activity of proteases gradually reduced, manifesting as pancreas > duodenum > jejunoileum. The relative activity of carbohydrate digestion enzymes gradually increased as the intestinal tract moved backward. With the improvement of PER, the relative activity of lipase gradually decreased in pancreas, duodenum, and jejunoileum. L. luteal possessed a strong ability to digest crude fiber and total phosphorus; the reason might be closely related to the types and quantities of intestinal flora, which was affected by the feeding habits of this bird. By comprehensively considering the nutrient utilization, digestive organ indices and digestive enzymes activities, the formula of PER II was more appropriate for nutritional needs of L. luteal in captivity.

Key words: Leiothrix luteal, protein-to-energy ratios, nutrients, digestion and utilization, enzyme activities.