Performance and carcass yield of broilers supplemented with plant extract during the finisher phase

In this study, 600 one-day-old male Cobb 500 broilers were distributed according a completely randomized experimental design into the different dietary treatments. Broilers were fed the following dietary treatments: positive control diet (PC), containing 54 ppm zinc bacitracin; negative control diet (NC), with no inclusion of performance enhancers and 3% reduction in metabolizable energy, crude protein, and amino acid levels; PC up to 33 days and then NC, with the dietary addition of 75, 150, or 225 ppm plant extracts, until day 42 days of age. Broiler performance and carcass yield were evaluated. Data were analyzed using the Statistical Analysis System package (SAS Institute Inc., 2008), and submitted to polynomial regression analysis using the GLM procedure at 5% significance level. There was no influence of treatments on feed intake or weight gain, but feed conversion ratio of the broiler fed the plant extract was significantly higher (p 0.05) compared with those fed the antibiotic. There was no significant effect (p>0.05) of the applied treatments on carcass yield. We concluded that the replacement of performance-enhancing additives by plant extracts, at the evaluated inclusion levels, does not promote positive performance results.

Evaluation of different digestible lysine levels for male broilers during the period of 18 to 40 days of age

A total of 1.500 male Cobb 500 broilers were used to determine the optimal digestible lysine level for 18 to 40-day-old broilers. The experimental period started when broilers were 18 days old and had an initial average weight of 737 ± 20 g. A completely randomized experimental design was applied, with five lysine levels, totaling five treatments with 10 replicates of 30 birds each. The experimental diets contained equal energy and protein levels, and 0.86, 0.95, 1.04, 1.13, and 1.22% digestible lysine. The following parameters were evaluated: average body weight at 40 days of age, daily weight gain, daily feed intake, feed conversion ratio, carcass yield and parts yield, and abdominal fat percentage. There was a quadratic effect (p 0.05) of digestible lysine levels on average body weight at 40 days of age, daily weight gain, and breast yield, and a cubic effect on feed conversion ratio and abdominal fat. There was no influence of lysine levels of daily feed intake, carcass yield, leg, or wing yields. It was concluded that digestible lysine requirements for male broilers during the evaluated period was 1.22% for performance and 1.04% for carcass yield.

Evaluation of different digestible lysine levels for male broilers during the period of 18 to 40 days of age

A total of 1.500 male Cobb 500 broilers were used to determine the optimal digestible lysine level for 18 to 40-day-old broilers. The experimental period started when broilers were 18 days old and had an initial average weight of 737 ± 20 g. A completely randomized experimental design was applied, with five lysine levels, totaling five treatments with 10 replicates of 30 birds each. The experimental diets contained equal energy and protein levels, and 0.86, 0.95, 1.04, 1.13, and 1.22% digestible lysine. The following parameters were evaluated: average body weight at 40 days of age, daily weight gain, daily feed intake, feed conversion ratio, carcass yield and parts yield, and abdominal fat percentage. There was a quadratic effect (p 0.05) of digestible lysine levels on average body weight at 40 days of age, daily weight gain, and breast yield, and a cubic effect on feed conversion ratio and abdominal fat. There was no influence of lysine levels of daily feed intake, carcass yield, leg, or wing yields. It was concluded that digestible lysine requirements for male broilers during the evaluated period was 1.22% for performance and 1.04% for carcass yield.

Energy and lysine for broilers from 44 to 55 days of age

An experiment was conducted to evaluate the performance and carcass yield of broilers at 55 days of age fed diets with different levels of metabolizable energy and lysine. Evaluated data of performance were weight gain, feed intake, energy intake, lysine intake, caloric conversion and feed conversion. Carcass assessment was performed based on data from carcass yield, breast weight, whole wings, whole legs, back, head + neck, feet and abdominal fat. A 3 x 3 factorial arrangement was used, with 3 levels of metabolizable energy (3,200; 3,400 and 3,600 kcal ME/kg) and 3 lysine levels (0.95%; 1.05% and 1.15%). There was no interaction between the two factors. Nevertheless, increasing levels of metabolizable energy improved weight gain (745 g; 841 g and 910 g, respectively) and feed intake was higher in broilers receiving the diets with 3,200 and 3,600 kcal ME/kg. Overall performance was not affected by lysine levels. Feed conversion values were 2.69, 2.42 and 2.14 for birds fed diets with 3,200; 3,400 and 3,600 kcal ME/kg, respectively. Carcass yield and breast weight increased with higher levels of energy and lysine in the diets.

Energy and lysine for broilers from 44 to 55 days of age

An experiment was conducted to evaluate the performance and carcass yield of broilers at 55 days of age fed diets with different levels of metabolizable energy and lysine. Evaluated data of performance were weight gain, feed intake, energy intake, lysine intake, caloric conversion and feed conversion. Carcass assessment was performed based on data from carcass yield, breast weight, whole wings, whole legs, back, head + neck, feet and abdominal fat. A 3 x 3 factorial arrangement was used, with 3 levels of metabolizable energy (3,200; 3,400 and 3,600 kcal ME/kg) and 3 lysine levels (0.95%; 1.05% and 1.15%). There was no interaction between the two factors. Nevertheless, increasing levels of metabolizable energy improved weight gain (745 g; 841 g and 910 g, respectively) and feed intake was higher in broilers receiving the diets with 3,200 and 3,600 kcal ME/kg. Overall performance was not affected by lysine levels. Feed conversion values were 2.69, 2.42 and 2.14 for birds fed diets with 3,200; 3,400 and 3,600 kcal ME/kg, respectively. Carcass yield and breast weight increased with higher levels of energy and lysine in the diets.