Growth performance and accretion of selected amino acids in response to three levels of dietary lysine fed to fast- and slow-growing broilers

Abstract

Literature data indicate that feed intake is sensitive to the dietary Lys content particularly in fast-growing birds. From a conceptual and a practical viewpoint, an interaction between genotype (i.e., fast-growing vs. slow-growing birds) and dietary Lys content is of interest, but it needs confirmation owing to a dearth of studies addressing this issue. A study was conducted with 266 Cobb 500 birds and 266 Thai native crossbreed birds serving as models for fast-growing broilers ( FGB ) and slow-growing broilers ( SGB ), respectively. Within genotype, chicks were randomly allocated to diets containing either a high ( H-LYS = 1.36%), medium (1.17%), or low Lys (1.01%) content. Growth performance and the accretion of protein and selected amino acids were determined in birds from 1 to 21 d of age. Treatments were arranged in a factorial design with 6 replications/treatment. Low Lys vs. H-LYS caused a 42.1% lower feed intake in FGB ( P < 0.001), but not in SGB ( P = 0.596). The feed conversion ratio ( FCR (g feed/g BW gain)) was lowest in FGB ( P < 0.001) and increased with decreasing dietary Lys contents ( P < 0.001). The Lys induced increase in FCR, however, was more pronounced in SGB ( P = 0.025). The absolute protein gain (g/bird) was influenced by the Lys content of feed and decreased by ∼54% and ∼23% in FGB and SGB, respectively ( P < 0.001). The efficiency (% of intake) of protein accretion was found to be greater in FGB ( P ≤ 0.001) and decreased with decreasing dietary Lys ( P ≤ 0.001). The efficiency of Lys accretion was found to be negatively affected by the dietary Lys content in FGB ( P < 0.001) but not SGB ( P genotype × dietary Lys = 0.008). It can be concluded that a dietary Lys content of 1.01% does not safeguard both growth performance and body protein accretion efficiency in both FGB and SGB. The suboptimal growth performance in FGB, but not SGB, is partially counteracted by a Lys-induced reduction in feed intake.

Comparison of carcass traits and nutritional profile in two different broiler‐type duck lines

“…Indeed, the accretion of amino acids in fast‐growing birds is relatively different from that in slow‐growing birds. A recent study suggested that the accretions of Arg, Ile, Val, and Leu tended to be lower in slow‐growing broilers than in fast‐growing broilers (Tran et al, 2021). Likewise, our data showed that the concentrations of Leu and His in WKDs were significantly lower than in CVDs.…”

Determination of the Optimal In-Feed Amino Acid Ratio for Japanese Quail Breeders Based on Utilization Efficiency

“…Birds had lower feed intake amounts at lower concentrations of limiting amino acids (N1 and N2, Table 3 ), an effect related to the Lys content [ 18 ]. Dietary Lys deficiency renders the rate of protein synthesis unfeasible for cell cycle proliferation, leading to cell apoptosis [ 19 ].…”

Effects of a direct fed microbial (DFM) on broiler chickens exposed to acute and chronic cyclic heat stress in two consecutive experiments

“…The percentage of carcass fat and lean was used with body weight to calculate body fat and lean tissue at hatch and 36 d of age. The differences between the 2 sampling days were divided by the number of days to calculate a daily fat and lean accretion value between hatch and 36 d ( Tran et al, 2021 ).…”