A high amylose to amylopectin ratio in a low-protein diet promoted growth performance and protein deposition of breast muscle in geese.

This experiment was conducted to investigate the effects of different dietary protein levels and amylose to amylopectin (AM/AP) ratios on the growth performance and muscle development of geese. A total of 240 healthy male Jiangnan White geese (body weight [BW] 2124.8 ± 91.4 g, 35-d-old) were randomly assigned to 4 groups, with 6 replicates per group and 10 birds per replicate. The experimental period was 21 d. The 2 × 2 factorial design included two protein levels (16% and 14%) and two AM/AP ratios (0.34 and 0.44). The 4 groups were: control group, normal protein (16%) with normal AM/AP ratio (0.34) (NPNR); normal protein (16%) with high AM/AP ratio (0.44) (NPHR); low protein (14%) with normal AM/AP ratio (0.34) (LPNR); and low protein (14%) with high AM/AP ratio (0.44) (LPHR). The results showed that compared with normal protein diet, low protein diet increased average daily feed intake (ADFI; P = 0.008). Increasing the AM/AP ratio increased BW of geese at 56 d (P = 0.003), improved average daily weight gain (ADG; P = 0.003) and decreased feed-to-gain ratio (F/G; P = 0.009). Increasing the AM/AP ratio led to an increase in crude protein content in the breast muscle (P = 0.015), also enriched the amino acids composition in the liver and muscles, specifically elevated the Lys content in the liver (P = 0.004) and leg muscle (P = 0.031), and Glu, Leu, Lys, and Pro contents in breast muscles (P < 0.05). Both a low protein diet and a high AM/AP ratio increased short-term breast muscle protein deposition. High AM/AP ratio diets accelerated the protein fractional synthesis rate (P = 0.036) and fractional growth rate (P = 0.002) in breast muscles. Antagonistic interactions between AMPK and mTOR pathways were observed. Compared with the control group, the LPHR group showed down-regulation of AMPKα1 mRNA (P = 0.020) and up-regulation of mTOR mRNA in the breast muscle (P = 0.047). High AM/AP ratio in the diets induced hypertrophy and thickening of leg muscle fibers. In conclusion, increasing the AM/AP ratio in a low-protein diet promoted protein deposition in breast muscles and benefited geese growth.