Abstract This study was conducted to examine the effects of a diet formulated with industrial amino acids and a commercial vitamin-mineral mixture on the characteristics of carcass and meat cuts of slow-growing broilers slaughtered at different ages. The experiment involved 600 one-day-old male and female white Naked Neck chicks. The chicks were allotted randomly to a 2 × 3 factorial arrangement consisting of two diets and three slaughter ages, in a completely randomized experimental design with five replicates of 20 birds each. The experimental period was 84 days. Six chicks were selected and slaughtered on the first day, and then at 56, 70 and 84 days of age 10 birds unit was selected and slaughtered per experimental period. Weight and yield of carcass, abdominal fat and breast, thigh and drumstick meat were determined. Additionally, moisture, protein, fat and mineral matter contents and protein and fat deposition in the breast, drumstick and thigh muscles were determined. The diet did not influence the yields of carcass, abdominal fat, or meat cuts or the nutritional composition of meat. Slaughter age influenced the yields of breast and thigh meat and abdominal fat; the protein content of breast meat; and the moisture, crude protein, fat, and mineral matter contents of drumstick and thigh meat. There was an interaction effect between diet and slaughter age for protein deposition in breast meat. The age factor influenced fat deposition in the drumstick muscles. Protein deposition in the thigh muscles was influenced by the diet. Moreover, a difference was observed between the ages for protein and fat deposition in the thigh muscle. In conclusion, the use of a commercial mixture in the diet results in decreased protein deposition in the breast and thigh muscles, although this difference does not affect the characteristics of carcass or meat cuts. Birds slaughtered at 70 days exhibit similar carcass characteristics to those of birds slaughtered at 84 days, indicating the possibility of an earlier slaughter age.

Abstract To examine the association between phytase and xylanase in diets with nutritional adjustments on intestinal morphometry, serum biochemistry and microbiology of broilers, 250 broilers were evaluated in a completely randomized design with five treatments and five replicates. The following treatments were tested: positive control diet - without phytase or xylanase; negative control diet - with an energy reduction of 100 kcal/kg, without phytase or xylanase; and three diets containing xylanase and phytase and energy reductions of 50, 100 and 150 Kcal/kg. For all energy-reduced diets, the nutritional matrix of phytase with phosphorus (0.15%), calcium (0.165%) and sodium (0.035%) was considered. An effect of the association between enzyme inclusion and metabolizable energy reduction in the diets was observed only by contrast analysis, for villus height. Intestinal health was not changed. Only the serum phosphorus concentration was altered by the treatments at the different evaluated ages. The association of phytase (500 FTU/kg) with xylanase (16000 BXU/kg) in diets with reductions of up to 150 Kcal/kg metabolizable energy, 0.15% digestible P, 0.165% Ca and 0.035% Na does not alter the intestinal morphometry, serum biochemistry or microbiology of broilers.

Abstract In order to evaluate the effect of rosemary oil and micro mineral sources on the performance and egg quality of laying hens, 288 hens were used and distributed in a completely randomized design using a 2x3 factorial (mineral sources x rosemary oil) with six different diets and six replications. Diets were formulated containing inorganic or organic minerals, with or without added rosemary oil (100 and 200 mg kg-1). The treatments showed interaction for average egg weight, yolk color, albumen and yolk percentage, with significant results from the use of organic minerals compared to inorganic minerals. The addition of 200 mg kg-1 rosemary oil in diets improved laying rate, egg mass, specific gravity, number of pores on the shell when compared to other treatments. In conclusion, the use of 200 mg kg-1 of rosemary oil improves the performance of red laying hen eggs. The association between organic minerals and 100 mg kg-1 rosemary oil in laying hen diets increases yolk color and percentage of albumen. The use of organic minerals is superior to inorganic minerals as to improve the quality of eggs, increasing average egg weight, yolk color and percentage of albumen.