The effect of supplemental l-threonine on laying performance, serum free amino acids, and immune function of laying hens under high-temperature and high-humidity environmental climates

Abstract

Many countries and cities around the world are located in humid subtropical areas, such as the south of China. Summers in these areas are very hot and humid, with daily temperature averages above 30°C and 75% RH. It has been reported that high temperatures reduce feed intake, egg production, egg weight, and egg quality [1][2][3]. The detrimental effects of high temper- SUMMARYBabcock Brown layers (n = 960), 40 wk of age, were allocated to 1 of 5 dietary treatments groups, each of which included 6 replicates of 32 hens. Each group received the same basal diet formulated with corn, peanut meal, and crystalline amino acids for 8 wk. l-Threonine was added to the basal diet at 0 (control), 0.1, 0.2, 0.3, and 0.4%, to achieve 0.47 (NRC, 1994), 0.57, 0.67, 0.77, and 0.87% threonine, respectively. Although supplementing the diet with lthreonine did not affect ADFI, FCR, egg weight, or egg quality (P > 0.05), the egg production response to supplemental l-threonine was quadratic, and it was maximized at 0.2% supplemental l-threonine. No differences were observed for uric acid, lactate dehydrogenase, alkaline phosphatase, Ca, and P concentrations among the treatments. Serum total protein concentration increased quadratically to supplemental threonine, and the response was maximized at 0.2 and 0.3% supplemental l-threonine. Serum free threonine increased quadratically as supplemental threonine increased, and the response was maximized between 0.2 and 0.3% supplemental lthreonine. The addition of l-threonine at 0.3% of the diet resulted in linearly increasing levels of IgG and total Ig (P < 0.05) as compared with those of the control group. In conclusion, current NRC (1994) recommendations for dietary threonine are insufficient for modern commercial laying hens strains reared under subtropical summer climates. We suggest that 0.2% threonine resulted in optimal egg production, whereas 0.3% l-threonine may have had a positive effect on the humoral immune response of laying hens under conditions of high temperature and humidity.

Effect of Low-Protein Diets with Crystalline Amino Acid Supplementation on Egg Production, Blood Parameters and Nitrogen Balance in Laying Japanese Quails

“…Data presented in Tables 2 and 3 indicate that productive performance (growth traits and egg production) were not significantly affected by feeding low-CP diet with crystalline amino acids supplementation. The results of the current study are in line with the findings of Sibel et al (2009) and Azzam et al (2011) who found that threonine supplementation to the basal diet for laying quails had no effects on BW, feed intake, G:F and egg production. Moreover, Parlat et al (2003) stated that laying quails when fed diets containing different threonine levels had no significant difference in feed intake among groups.…”

“…Supplemental dietary Val led to a partial improvement of albumen percentage, while supplementary Thr and low or normal CP diet produced the lowest albumen percentages compared to 16% CP diet supplemented with Trp or amino acids mixture throughout the whole trial. Azzam et al (2011) found no effect of low-CP diet with supplemented Thr on egg quality parameters; consequently no effects on albumen and yolk percentages were observed from different dietary Thr intake.…”

The effects of supplemental threonine on performance, carcass characteristics, immune response and gut health of broilers in subtropics during pre‐starter and starter period

“…The serum total protein concentration of broiler birds quadratically increased to supplemental L‐threonine in laying hens (Azzam, Dong, Xie, Wang, & Zou, ). In the process of protein anabolism and proteolysis, the serum protein level is always an indicator of the protein metabolism and immunity function situation in vivo.…”

Effects of Dietary Threonine Levels and Stocking Density on the Performance, Metabolic Status and Immunity of Broiler Chickens

“…However, Kadam et al (2008) observed that injections of 10, 20 or 30 mg threonine into yolk sac increased the humoral response to sheep red blood cells significantly in broilers at 21 days post-hatch. Recently, in laying hens, Azzam et al (2011b) found that serum total protein and IgG increased significantly at 3 g Thr kgG 1 diet. In current study, stocking density had no affect on levels of plasma immune globulins (Table 4).…”