Effect of digestible amino acids to energy ratios on performance and yield of two broiler lines housed in different grow-out environmental temperatures

Abstract

Two broiler lines, Line A and Line B, were fed experimental diets from 22 to 42 d with objectives to determine effects of digestible amino acids ( AA ) to metabolizable energy ratios on feed intake ( FI ), performance, and processing yield. Experimental diets were formulated to 3,150 kcal/kg with 5 levels of digestible lysine ( dLys )—80, 90, 100, 110, and 120% of recommended AA level giving g dLys/Mcal values of 2.53, 2.85, 3.17, 3.48, and 3.80, respectively. All other AA were formulated to a fixed ratio to dLys. A total of 4,050 chicks were utilized in each trial (9 replicate pens for each AA level and each line; 45 chicks/pen) conducted twice: one in hot environmental temperature ( HT ) (24 h mean ∼85.3 °F; 80.9% RH) and another in cool environmental temperature ( CT ) (24 h mean ∼71.6 °F; 61.7% RH). Results showed that FI was not impacted by dietary AA levels in HT for both lines. Higher FI ( P < 0.05) was observed in CT for lower dietary AA levels (<100% AA level) for both lines, with overall higher FI occurring in Line B. Higher FI for Line B was also accompanied by higher body weight in HT and CT. Treatment diets had quadratic effects on average daily gain ( ADG ), feed conversion ratio ( FCR ), and processing yields (breasts and tenders) in both HT and CT, with broilers in CT performing better ( P < 0.05). The optimal response values for ADG in HT and CT were 89.72 g and 113.44 g occurring at 120 and 109.5% AA level, respectively. The optimal response values for FCR in HT and CT were 1.79 and 1.58 occurring at 120 and 117.5% AA level, respectively. The optimal response values for breast meat yield in HT and CT were 575.9 g and 776.5 g occurring at 112.6 and 114.5% AA level, respectively. The optimal response values for tender meat yield in HT and CT were 119.8 g and 154.9 g occurring at 120 and 115% AA level, respectively. Line A had a higher breast and tender yield % (of live weight) for both environmental temperatures which correlated to body composition data with higher % protein mass and % digestible AA retention. In this study, findings indicated that effects of increased digestible AA density on FI, performance, and processing yield are specific to strain and grow-out temperature, but the optimum response was attained for both lines with diets containing 110 to 120% AA levels (3.48–3.80 g dLys/Mcal) during the 22 to 42 d finisher period.

A review of heat stress in chickens. Part II: Insights into protein and energy utilization and feeding

“…Moreover, Alhotan et al (2021) fed an AA density ranging from 80% to 110% of breeder recommendations to broilers exposed to cyclic HS. In contrast with the results reported by Maharjan et al (2020) , no interactions between environmental temperature and dietary AA density were observed on performance and processing data. However, linear effects of AA density indicated that BWG, feed efficiency, and breast muscle yield responded to increased AA density in both environments.…”

“…Altering dietary density of essential AA has been shown to have promising results in heat-stressed broilers. In broilers under hot temperatures, Maharjan et al (2020) fed five levels of digestible Lys (dLys) from 80% to 120% of the recommended level with all other AA:dLys ratios held constant and observed quadratic responses in average daily gain and FCR up to the 120% dLys level, and no influence on FI. In contrast, the optimal average daily gain and FCR were closer to the 100% recommendation of dLys under thermoneutral conditions.…”

Effects of dietary energy levels on performance and carcass yield of 2 meat-type broiler lines housed in hot and cool ambient temperatures

“…Finding the appropriate protein to energy ratio in the diet can be crucial for the optimal performance of broilers. The performance and processing yield benefits by increasing dietary amino acid density is becoming more evident ( Temim et al., 1999 ; Viera and Angel, 2012 ; Maharjan et al., 2020c ), whereas less is known regarding dietary energy density. The present study evaluated the effects of dietary ME levels ranged from 2,800 to 3,300 kcal/kg on performance parameters and processing yield characteristics.…”

Effect of L-Threonine Supplementation to Diet on Some Productive and Physiological of Traits Broiler Chickens Under Heat Stress Conditions

“…It also increases the need for nutrients and amino acids such as methionine, lysine and Threonine. So The growth rates of broiler under heat stress conditions depend on a sufficient supply of amino acids to produce proteins involved in various physiological functions, such as signal transduction, hormone signaling, cell structure, and antioxidant systems (Maharjan, 2020). Therefore, nutritional and management therapies can be introduced to minimize the heat stress due to high environmental temperatures in broiler production.…”