Broiler Responses to Reduced Protein and Energy Diets Supplemented With Lysine, Methionine and Threonine

Abstract

This study was performed to evaluate the effect of supplementation of low crude protein (CP) corn-soybean meal diets which contained low ME levels with lysine (Lys), methionine (Met) and threonine (Thr) above that recommended by the National Research Council (NRC, 1994) on broiler performance, carcass characteristics and serum constituents from 12 to 33 d of age. A total of 100 Ross chicks were randomly distributed in a randomized complete block design among 20 cages with 5 replicate cages / treatment with four dietary treatments: T1＝Control diet (21% CP and 3150 kcal/kg ME); T2, T3 and T4 contained 19.5% CP and 115% of Lys, Met and 108% of Thr compared to the NRC requirements; T2, T3 and T4 contained 3150, 3100 and 3050 kcal of metabolizable energy (ME)/kg, respectively. Cumulative feed intake, body weight gain and feed conversion ratio from 12 to 33 d of age was not affected by treatment. Birds which had received T2 and T3 had a higher dressing percentage compared to those which had received T1. Breast muscle yield followed the same trend; heavier breasts were obtained from birds which had received T2 and T3. Serum uric acid concentration was influenced by treatment; it was significantly higher for birds which had received the control diet compared to all other treatments. Based on presented evidences, it can be concluded, that by fortifying crystalline amino acids to broilers diet at this stage of production, dietary CP and ME could be reduced to 19.5% and 3050 kcal/kg, respectively.

The effect of synthetic essential amino acids supplementation to low crude protein diets on growth performance and serum metabolites in broiler chickens

“…The same findings have been recorded in broiler chickens fed on control diet (22.2% CP) and low CP (16.2%) supplemented with EAAs under tropical climate [15]. However, serum total protein was significantly decreased in chickens fed on control diet according to NRC compared with those fed low CP and supplemented with lysine, methionine and threonine above the recommended level of NRC [29] Uric acid is the product of protein catabolism and turnover in the body. In diets with low CP with supplementation of EAAs, glycine deficiency may explain the decreased serum uric acid level [5,14].…”

“…In diets with low CP with supplementation of EAAs, glycine deficiency may explain the decreased serum uric acid level [5,14]. Uric acid has been found higher in serum of broiler fed control diet (21% CP) than those fed low CP (19.5%) and supplemented with 115% lysine, methionine and 108% threonine above NRC requirement [29] . Moreover, the higher uric acid with high dietary protein level maybe duet to the high consumption of AA and the low level of serum uric acid maybe due to the poor AA ingestion particularly glycine [5,14].…”

“…Mans Vet Med J 23 (2019) [24][25][26][27][28][29] or both EAAs and non-essential amino acids (NEAAs) [4]. CP levels in broiler diets can be reduced by 3 to 4 percentage points without sacrificing performance provided that free amino acids are supplemented in the diet to equal the amino acid levels in a standard diet [8].…”

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

“…Next to the protein content of the carcass, the fat content of the carcass also, points to a decreased net protein synthesis. Indeed, it is generally accepted that the consumption of a diet containing a low Lys-to-energy ratio enhances the accretion of body fat owing to relative excess of dietary energy ( Leenstra, 1986 ; Leeson et al., 1996 ; Rosa et al., 2007 ; Abudabos and Aljumaah, 2012 ).…”

Digestible threonine for slow-growing broilers: performance, carcass characteristics, intestinal mucin, and duodenal morphometry

“…This suggests that more detailed observations of the specificities of slowgrowing lines with respect to the effect of this amino acid on meat cuts should be made. The interactions among threonine, lysine, and methionine can also optimize the accumulation of meat (Abudabos and Aljumaah, 2012).…”