Energy and amino acid requirements of broiler chickens: keeping pace with the genetic progress

Aftab, Usama

doi:10.1017/s0043933919000564

Cited by 25 publications

(21 citation statements)

References 24 publications

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“…Accordingly, our results show the strains with the higher breast yield (M, and partially R1 and R2) spent a lot of time close to the feeder. Many authors [28][29][30] have shown that an increase in breast yield requires high protein and amino acid levels in feed.…”

Section: Discussionmentioning

confidence: 99%

Performance, Behavior, and Welfare Status of Six Different Organically Reared Poultry Genotypes

Mancinelli

Mattioli

Bosco

et al. 2020

Animals

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In alterative rearing systems, the use of outdoor space has a crucial role. It is well known that only some commercial poultry genotypes are suitable to be reared in these systems. It is necessary to find a balance between productive performance and adaptability. The aim of this study was to evaluate the productive performance, behavior, and welfare status of six poultry genotypes reared in an organic system. One hundred males/genotype (Hubbard RedJA (A), CY5XJA87 (CY), M22XJA87 (M), Ranger Classic (R1), Ranger Gold (R2), and Rowan Ranger (R3)) were reared from 1 to 81 days of age. The number of culled birds was recorded daily, whereas live weight and feed consumption were recorded weekly. Behavior evaluation was undertaken through a computerized system one week before slaughtering; the breast yield and muscle/bone ratio of the drumstick was also evaluated in refrigerated carcasses. The results showed that A and R3 had good adaptability, showing active behaviors and satisfactory productive performance 3083.6 g and 3022.1 g, respectively. Although CY and M achieved the best productive performance, they did not appear adapted to the organic system due to a higher frequency of static behaviors (rest and roost), mortality, footpad dermatitis, breast blisters, and poor feather condition.

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Section: Discussionmentioning

confidence: 99%

Performance, Behavior, and Welfare Status of Six Different Organically Reared Poultry Genotypes

Mancinelli

Mattioli

Bosco

et al. 2020

Animals

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“… Cerrate and Corzo (2019) has reported the dLys requirement in meat broilers increased by 0.009% per year. The update in requirement of digestible AA/Mcal in primary breeder has been suggested ( Applegate and Angel, 2014 ; Aftab, 2019 ) because of the increased need for nutrients for the modern high yielding broiler. An increased requirement of digestible AA for the modern broiler is because primary breeders have genetically selected for increased breast meat yield ( Dozier et al., 2008 ).…”

Section: Discussionmentioning

confidence: 99%

“…Productive traits of meat broilers such as rate of gain and breast meat yield have been exponentially improving because of genetic progress ( Fancher, 2014 ; Aftab, 2019 ). The selection for increased gain rate has sustained the improved efficiency seen with broilers ( Carre et al., 2014 ).…”

Section: Introductionmentioning

confidence: 99%

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

Maharjan¹,

Mullenix²,

Hilton³

et al. 2020

Poultry Science

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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.

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“…Perhaps, the greater Lys accretion in FGB is related to the intensive genetic selection of modern genotype broilers. The process of genetic selection led to greater proportions of breast meat (i.e., 12% of BW in 1957 compared with 23% in 2014 [ Aftab, 2019 ]) and beast meat has the highest Lys contents within the broiler's carcass, that is, ∼8% ( Kerr et al., 1999 ). Unfortunately, the current data do not provide further clues to substantiate this notion.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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Literature data indicate that feed intake is sensitive to the dietary Lys content particularly in fast-growing birds. From a conceptual and a practical viewpoint, an interaction between genotype (i.e., fast-growing vs. slow-growing birds) and dietary Lys content is of interest, but it needs confirmation owing to a dearth of studies addressing this issue. A study was conducted with 266 Cobb 500 birds and 266 Thai native crossbreed birds serving as models for fast-growing broilers ( FGB ) and slow-growing broilers ( SGB ), respectively. Within genotype, chicks were randomly allocated to diets containing either a high ( H-LYS = 1.36%), medium (1.17%), or low Lys (1.01%) content. Growth performance and the accretion of protein and selected amino acids were determined in birds from 1 to 21 d of age. Treatments were arranged in a factorial design with 6 replications/treatment. Low Lys vs. H-LYS caused a 42.1% lower feed intake in FGB ( P < 0.001), but not in SGB ( P = 0.596). The feed conversion ratio ( FCR (g feed/g BW gain)) was lowest in FGB ( P < 0.001) and increased with decreasing dietary Lys contents ( P < 0.001). The Lys induced increase in FCR, however, was more pronounced in SGB ( P = 0.025). The absolute protein gain (g/bird) was influenced by the Lys content of feed and decreased by ∼54% and ∼23% in FGB and SGB, respectively ( P < 0.001). The efficiency (% of intake) of protein accretion was found to be greater in FGB ( P ≤ 0.001) and decreased with decreasing dietary Lys ( P ≤ 0.001). The efficiency of Lys accretion was found to be negatively affected by the dietary Lys content in FGB ( P < 0.001) but not SGB ( P genotype × dietary Lys = 0.008). It can be concluded that a dietary Lys content of 1.01% does not safeguard both growth performance and body protein accretion efficiency in both FGB and SGB. The suboptimal growth performance in FGB, but not SGB, is partially counteracted by a Lys-induced reduction in feed intake.

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Energy and amino acid requirements of broiler chickens: keeping pace with the genetic progress

Cited by 25 publications

References 24 publications

Performance, Behavior, and Welfare Status of Six Different Organically Reared Poultry Genotypes

Performance, Behavior, and Welfare Status of Six Different Organically Reared Poultry Genotypes

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

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

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