Threonine Requirements in Dietary Low Crude Protein for Laying Hens under High-Temperature Environmental Climate

Abstract

Simple SummaryThe threonine (Thr) requirement of laying hens in a high-temperature climate is scarcely referred in the review of literature. Therefore, our aim was to estimate the dietary Thr requirement in low CP diets in a high-temperature environmental climate. Based on our findings, the optimal dietary Thr requirements to optimize egg production, serum uric acid, and serum CuZn-SOD were 0.58%, 0.59%, and 0.56%, respectively, by regression analysis.AbstractLohmann Brown hens (n = 420), at 28 weeks of age, were divided into five dietary treatments, and each treatment included six replicates of 14 laying hens. Dietary crude protein (14%) was presented as the control diet. Dietary L-Thr was added to the control diet for 12 weeks. Dietary Thr levels are 0.43%, 0.49%, 0.57%, 0.66%, and 0.74%, based on digestible base. From 28 to 40 weeks, hen-day egg production presented a quadratic trend to supplementing dietary Thr (R2 = 0.96, p = 0.02), and reached a maximum level at 0.58%. Serum uric acid demonstrated a quadratic trend (R2 = 0.62, p = 0.02) at 0.59%. Both serum total cholesterol and 3-hydroxy-3-methylglutaryl (HMG-CoA) reductase showed lower levels (p < 0.05) at 0.66% Thr. Serum CuZn-SOD elevated (p < 0.05) at 0.49%, 0.57%, and 0.66% Thr, as compared to the control group, and showed a quadratic trend (R2 = 0.87, p = 0.003) at 0.56%. Supplemental L-Thr decreased (p < 0.05) the expression of ileal HSP70 at 0.66% Thr. In summary, the optimal dietary Thr requirements to optimize egg production, serum uric acid, and serum CuZn-SOD were 0.58%, 0.59%, and 0.56%, respectively, by regression analysis.

Effects of dietary stinging nettle (Urtica dioica) on hormone stress and selected serum biochemical parameters of broilers subjected to chronic heat stress

“…In agreement with the obtained findings from this study, Zhang et al (2020) In the present study, the serum level of UA was significantly higher in the HS group compared to the control group (Table 3; p < 0.05). UA is the end-metabolic product of protein metabolism in avian species and has been suggested as a potent scavenger of free radicals in broiler chickens (Azzam et al, 2019). Xie et al (2015) reported that the circulating level of UA increased in HS broilers and it could be utilized as a detectable indicator of oxidative stress.…”

“…In the present study, the serum level of UA was significantly higher in the HS group compared to the control group (Table 3 ; p < 0.05). UA is the end‐metabolic product of protein metabolism in avian species and has been suggested as a potent scavenger of free radicals in broiler chickens (Azzam et al., 2019 ). Xie et al.…”

Amino acid requirements for laying hens: a comprehensive review

“…(2013b) 24-40 Hy-Line W36 4.8 vs. 6.6 12.14 NS Cardoso et al. (2014a) 60 -76 DeKalb White Leghorn 5.2 vs. 6.2 11.72 108.2 vs. 110.1 Azzam et al. (2019) 28-40 Lohman brown 4.3 vs. 7.4 11.93 NS Abbreviation: NS, nonsignificant.…”

“…(2010) 54-58 Lohman brown LRP 131 50 508 505 Rocha et al. (2013b) 24-40 Hy-Line W36 Polynomial 142 523 523 606 Azzam et al. (2019) 28-40 Lohman brown Polynomial 140 708 Mean 41.9 133 500 469 Simple mean of total threonine recommendations based on FCR (SD = ±7.8) and egg mass (SD = ±6.3) is 457 ± 6.9 mg/g/bird.…”

Production performance, egg quality and some blood parameters of heat‐stressed laying hens as affected by dietary supplemental Vit B6, Mg and Zn

“…There are several environmental factors that affect layer chickens in production, but the most debilitating is heat stress, which affects production parameters, especially for birds that are sensitive to heat waves because of their feather covering and lack of sweat glands, heat stress results in a higher incidence rate of oxidative stress in birds (Azzam et al, 2019;Khan et al, 2014). Heat stress may also increase mortality rate which leads to economic losses (Khan et al, 2011).…”