Abstract
This study aimed to investigate the effects of different low-protein (LP) levels and amino acids (AAs) patterns on production performance, egg quality and intestinal function of laying hens. A total of 384 (33-week-old) Hy-Line hens were randomly assigned to control group (CONT, crude protein (CP) 15.91 % + 4AAs), LPF group (CP 14.53 % + 4AAs), LPS group (CP 14.58 % + 8AAs) and LPH group (CP 13.05 % + 8AAs), the formal trial period was 20 weeks. The results showed that the LPF and LPH groups significantly increased feed conversation ratio (FCR) (P < 0.05), the LPS group decreased FCR (P < 0.05). The LPH group significantly decreased laying rate and egg mass (P < 0.05). The plasma reproductive-related hormones anti-Mullerian hormone (AMH), follicle stimulating hormone (FSH) levels significantly decreased in the LPH group (P < 0.05), and leptin (LEP) significantly decreased in LP diets (P < 0.01). Intestinal morphology and function analysis indicated that the LPH group significantly enhanced duodenal villus height-to-crypt depth ratio (V/C) (P < 0.05), up-regulated the expression levels of oligopeptide transporter 1 (PEPT1) and Solute Carrier Family 7 Member 1 (SLC7A1) (P < 0.05). The LPH group had lower short chain fatty acids (SCFAs) content, such as butanoic acid and isovaleric acid (P < 0.05). Additionally, different LP levels and AA patterns significantly altered the cecal microbial composition in phylum and genus levels. At the genus level, Desulfovibriowere was negatively correlated with acetic acid (r = -0.48; P < 0.01), Fournierella were positively correlated with LEP (r = 0.46; P < 0.01), while Methanocorpusculum, Desulfovibrio and Synergistes were negatively correlated with LEP (r = -0.46, -0.51, -0.45; P < 0.01), Rikenellaceae_RC9_gut_group were negatively correlated with FCR (r = -0.47; P < 0.01), and Methanocorpusculum was negatively correlated with EP (r = -0.46, P < 0.01). In conclusion, the LP diet (CP 14.58 % + 8 AAs) improved egg production performance without negatively affecting egg quality, while maintaining intestinal function in laying hens.