ABSTRACT The present study was conducted to evaluate the performance, carcass yield, and histomorphometry of the small intestine of broilers fed yeast sugarcane supplemented with enzymatic blend from 22 to 42 days of age. Seven hundred broiler chicks were distributed in a completely randomized design in a factorial design (2x3+1), two levels of the enzyme blend (0 and 200 g/ton), three protein levels (0%, 6% and 12%) and a control diet. The level of 6% yeast showed higher feed intake and weight gain after 33 days. From 22 to 42 days there was no significant effect (p<0.05) to the use of yeast in animal performance, carcass yield and cuts. At 42 days an interaction between the factors for width and crypt depth in the duodenum and jejunum, respectively, was observed. The inclusion of yeast in the diets for broilers from 22 to 42 days did not affect the performance and yield of the carcass. Yeast increased the muscle wall of the jejunum. The use of the enzymatic blend did not influence performance but affected the integrity of the intestinal mucosa.

Two experiments were carried out to compare two techniques (amino acid supplementation and dilution) for formulating experimental diets for pre-starter (1 to 8 days) and starter (8 to 22 days) broiler chicks and to estimate digestible lysine requirements using the dose-response method. In each experiment, 1,200 male Cobb 500 chickens were randomly distributed according to a 5x2 factorial arrangement (lysine level x formulation technique) with six replicates of 20 birds each. For the supplemented diet, a basal diet was formulated to meet the nutritional requirements, then L-lysine HCl was added to achieve digestible lysine levels of 0.975, 1.082, 1.189, 1.296 and 1.403% in the pre-starter diets and 0.840, 0.932, 1.024, 1.116 and 1.208% in the starter diets. For the diluted diet, a diet high in crude protein (CP) and relatively low in lysine was formulated and to which was added a protein-free diet until lysine levels were similar to those described above for the supplemented diet. The results suggest that the dilution technique favored the performance potential and better met lysine requirements compared with the supplementation technique. Lysine levels required for optimal feed conversion ratio of broilers during the pre-starter and starter phases were estimated at 1.361 and 1.187%, which are equivalent to lysine intake of 0.340 and 0.797 g/day, respectively.

The aim of this work was to compare the efficiency of total (TC) or partial (PC) collection excreta methods to determine metabolizable energy in poultry feeds. A number of 180 12- to 21-day-old broilers were distributed into two treatments of six replicates of 10 birds each. A reference-diet was formulated to supply broiler requirements, and the test-diets consisted of 60% of reference diets and 40% of corn or soybean meal. Celite was added at 1% to the diets as a marker. Excreta and diet samples were analyzed for dry matter, energy, nitrogen, and acid-insoluble ash (AIA). AME of corn determined by partial collection (PC) was higher (3544 kcal/kg) as compared to total collection (TC) (3133 kcal/kg). However, no difference were observed for soybean meal (1797 vs. 1821 kcal/kg) between both methods. Marker recovery rates in the excreta were 101, 111, and 96% for the basal-diet, and the test-diets with corn or soybean meal, respectively. This result indicates the importance of marker recovery rate in the excreta to evaluate feed AME and digestibility.