Dietary Amylose/Amylopectin Ratio Modulated Growth Performance, Intestinal Health, and Lipid Metabolism in Goslings Fed Low-Protein Diets

This study investigated the effects of amylose/amylopectin (AM/AP) ratios in low-protein (LP) diets on the growth performance, fat deposition, and nutrient utilization in goslings. A total of 288 healthy, 35-day-old male Jiangnan White Geese were randomly divided into four treatment groups: one group fed a normal protein diet (16%) with an AM/AP ratio of 0.34 (NPR0.34), and three groups fed low protein diets (14%) with different AM/AP ratios (LPR0.26, LPR0.34, LPR0.44). Each group consisted of six replicates, with 12 geese per replicate, and they were fed for 28 days. The results showed that the body weight at 63 days and average daily gain (ADG) of the LPR0.44 group geese were significantly higher than those of the other groups (p < 0.01), while the feed-to-gain ratio (F/G) was lower (p < 0.05). The abdominal and mesenteric fat contents were lower in the LPR0.44 group than in the LPR0.26 group (p < 0.05), whereas the breast and leg muscle yields were higher (p < 0.05). The breast muscle redness (a*) of the LPR0.34 and LPR0.44 groups was higher than in the NPR0.34 group at 45 min (p < 0.05). The levels of C6:0, C8:0, C11:0, C12:0, and C13:0 in breast muscle saturated fatty acids (SFAs) of the LPR0.44 group were higher, while that of C18:0 was lower compared with the LPR0.26 group (p < 0.05). The serum total cholesterol (TC) and triglycerides (TGs) in the LPR0.44 group were lower than in the LPR0.26 group (p < 0.05). Hepatic lipase (HL) activity was significantly lower in the LPR0.44 group (p < 0.01). Regarding hepatic fatty acids, the levels of butyric acid (C4:0), lauric acid (C12:0), and nervonic acid (C24:1) were lower in the LPR0.44 group than in the LPR0.26 group (p < 0.05). No significant differences were observed in intestinal morphology, digestive enzyme activities, or nutrient utilization among the groups. (p > 0.05). In conclusion, adjusting the AM/AP ratio to 0.44 in a low-protein diet improved growth performance, regulated lipid metabolism, and maintained intestinal function in goslings.