Effects of lysine and methionine in a low crude protein diet on the growth performance and gene expression of immunity genes in broilers

Abstract

Globally, the poultry industry is 1 of the most advanced livestock industries. Feed contributes to the biggest proportion (65–70%) of the production cost. Most feed ingredients in Malaysia are imported, which contributes to the high food bill annually, and alternative feed formulation may help decrease the cost of poultry feed. Feed formulation are improved to efficiently meet the dietary requirements of the broilers and 1 of the ways is by reducing the level of crude protein in the diet while supplementing essential amino acids. In this study, the effects of methionine and lysine, which are the 2 most limiting amino acids in the chicken diet, were supplemented in a low crude protein diet, and its effects on the growth and expression of immunity genes such as MUC2, SLC, GAL6, and LEAP-2 were studied. A total of 300 Cobb500 broilers were tested with 10 different dietary treatments. Experimental treatment diets consist of high, standard, and low levels of methionine and lysine in the diet with reduced crude protein. The control group consists of diet with standard levels of lysine, methionine, and crude protein as recommended for Cobb500 broilers. Ribonucleic acid was extracted from the jejunum, spleen, and liver for gene expression analysis which was performed with real-time polymerase chain reaction using SYBR Green chemistry. Results of the growth performance at 6 wk showed improved feed conversion ratio when lysine was increased by 0.2% in a low crude protein diet at 1.96 ± 0.11. Gene expression of MUC2 gene in the jejunum showed a significant increase across all experimental diets with the treatment with higher lysine in low crude protein diet with the highest increase of 3.8 times as compared with the control diet. The other genes expressed in the spleen and liver were mostly downregulated. It was concluded that supplementation of high lysine with standard methionine in a low crude protein diet performed better in terms of lowest feed conversion ratio and high upregulation of MUC2 gene.

Different amino acid supplementation patterns in low-protein diets on growth performance and nitrogen metabolism of goslings from 1 to 28 days of age

“…In the present study, serum proline and lysine were lowest in the LPR group, consistently lower than in the LPM group. The lower serum proline and lysine may explain why the growth performance was the weakest in the LPR group since lysine ( Jespersen et al, 2021 ) is vital in promoting poultry growth ( Lee et al, 2020 ). Our data demonstrated that the proline might be essential in promoting growth in goslings fed with low-protein diets.…”

Effect of dietary serine supplementation on performance, egg quality, serum indices, and ileal mucosal immunity in laying hens fed a low crude protein diet

“…In attempt to better understand the positive effects of dietary Ser addition on the performance of birds fed LCP diets, the expression of some important genes related to ileal mucosal immunity was further investigated. Mucins are the main component of the intestinal mucus layer, whose main function is to protect the intestine from the hostile external elements (chemical, physical, or bacterial) as a form of innate immunity in poultry ( Erf, 2004 ; Lee et al., 2020 ). MUC2 is a typical secreted mucin, and any dietary changes may influence its expression and function in the intestinal mucus layer ( Linden et al., 2008 ; van der Sluis et al., 2009 ).…”

The effects of dietary protein and fiber levels on growth performance, gout occurrence, intestinal microbial communities, and immunoregulation in the gut-kidney axis of goslings

“…It has been reported that no significant difference in weight gain was observed in geese with dietary protein levels ranging from 16 to 22%, which seems overly general in scope ( Summers et al, 1986 ). Conversely, the concentrations of dietary protein exert a strong effect on intestinal flora balance and disease resistance in poultry ( Lee et al, 2020 ). Visceral gout, which occurs mainly in birds, is a metabolic disease caused by impaired kidney function, followed by an accumulation of urate crystals in various organs ( Zhang et al, 2018 ).…”