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 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, 35-day-old male Jiangnan White Geese were randomly assigned to 4 groups, with 6 replicates per group and 10 birds per replicate. The 4 groups were: NPNR (normal protein 16%, normal AM/AP ratio 0.34; control group), NPHR (normal protein 16%, high AM/AP ratio 0.44), LPNR (low protein 14%, normal AM/AP ratio 0.34), and LPHR (low protein 14%, high AM/AP ratio 0.44). The results showed that: 14% protein diets increased average daily feed intake (ADFI) (P < 0.05). Increasing the AM/AP ratio uplifted the body weight (BW) of geese at 56 d, improved average daily weight gain (ADG) and decreased feed to gain ratio (F/G) (P < 0.05). The LPHR group showed the best growth performance. Increasing the AM/AP ratio led to an increase in crude protein content in the breast muscle (P < 0.05), also enriched the amino acids composition in the liver and muscles, specifically elevated the Lys content in the liver and leg muscles, and Glu, Leu, Lys and Pro content in the breast muscles (P < 0.05). Breast muscle absolute weight at 56 d and the protein deposition from 52d to 56d of geese was improved with increasing dietary AM/AP ratio (P < 0.05). Low-protein diet with high AM/AP ratio also accelerated the protein fractional synthesis rate and protein fractional growth rate in breast muscles. Dietary treatments resulted in antagonistic interactions between the AMPK and mTOR pathways. Relative to the control group, the LPHR group showed down-regulation of AMPKα1 mRNA and up-regulation of mTOR mRNA in the breast muscle (P < 0.05). High AM/AP ratio in the diets caused the leg muscle fibers to swell and thicken. In conclusion, increasing AM/AP ratio in a low-protein diet was beneficial to the growth of geese from 35 d to 56 d and promoted protein deposition in breast muscles.