RESUMO Avaliou-se o efeito dos níveis de energia metabolizável incrementados com glicerina ou óleo de soja sobre o desempenho de frangos de corte em quatro fases (1 a 7; 8 a 21; 22 a 33 e 34 a 42 dias), e o rendimento de carcaça e cortes. Foram utilizadas 2400 aves com delineamento inteiramente casualizado, em esquema fatorial (duas fontes x quatro níveis de energia), com cinco repetições. Os tratamentos foram estabelecidos por meio da inclusão da glicerina ou do óleo de soja, em intervalos de 75 kcal/kg de energia metabolizável da dieta, o primeiro nível com 75 kcal abaixo da exigência, o segundo corresponde à exigência de cada fase (2925, 2980, 3050 e 3100 Kcal) o terceiro e o quarto nível com 75 kcal e 150 kcal, acima do valor da exigência para a fase avaliada. A exigência de energia metabolizável para frangos de corte, independente da fonte de incremento energético (glicerina ou óleo de soja), foi estimada em 3.075; 3.130; 3.200 e 3.250 kcal de EM/kg de ração, para as fases de 1 a 7; 8 a 21; 22 a 33; 34 a 42 dias, respectivamente. Entretanto, a utilização de glicerina como fonte de incremento energético, promoveu melhor eficiência no desempenho nas duas primeiras fases (1 a 7 e 8 a 21 dias de idades).

ABSTRACT The effect of increased levels of metabolisable energy with glycerine or soybean oil was evaluated in the performance of broilers at four growth stages (1 to 7, 8 to 21, 22 to 33 and 34 to 42 days), in addition to the carcass and cut yield. A total of 2,400 birds were used in a completely randomised design in a 2 x 4 factorial scheme (two sources x four energy levels), with five replications. The treatments were determined by including glycerine or soybean oil at intervals of 75 kcal/kg of metabolisable energy in the diet: the first level with 75 kcal less than the requirement, the second corresponding to the requirement for each stage (2925, 2980, 3050 and 3100 Kcal), and the third and fourth levels with 75 kcal and 150 kcal more than the required value for the stage under evaluation. The metabolisable energy requirement for broilers, irrespective of the energy source (glycerine or soybean oil), was estimated at 3,075, 3.130, 3,200 and 3,250 kcal ME/kg feed, for stages 1 to 7, 8 to 21, 22 to 33 and 34 to 42 days respectively. However, the use of glycerine as a source of increased energy promoted better performance efficiency during the first two stages (1 to 7 and 8 to 21 days of age).

RESUMO Objetivou-se avaliar o uso de enzimas exógenas em dietas com Saccharomyces cerevisiae sobre o desempenho zootécnico, rendimento de carcaça e histomorfometria intestinal de frangos de corte na fase inicial. Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 2×3+1, sendo dois níveis de complexo enzimático (CE), (0 e 200g/ton), três níveis de levedura (0, 6 e 12%) e uma dieta controle, perfazendo sete tratamentos, cinco repetições de 20 aves por unidade experimental. Foram avaliados o desempenho (consumo de ração, ganho de peso e conversão alimentar), rendimento de carcaça e cortes e a histomorfometria do intestino delgado (altura, perímetro e largura de vilo, altura e largura de cripta, espessura da parede muscular intestinal e relação vilo/cripta). Na fase de 1 a 7 e de 1 a 21 dias, a inclusão de levedura na dieta promoveu redução no desempenho dos frangos. Aos 21 dias a adição de CE resultou em aumento (p<0,05) da espessura da parede muscular do duodeno, e reduziu a largura da cripta no íleo. O nível de 12% de levedura sem o CE proporcionou parede muscular intestinal do jejuno mais espessa quando comparada ao controle positivo. Não houve efeito significativo para rendimento de carcaça e cortes entre os tratamentos. Conclui-se que, a inclusão de levedura reduz o desempenho de 1 a 21 dias. A adição de complexo enzimático e levedura em dietas para frangos de corte não melhora o desempenho e rendimento de carcaça, todavia, beneficia à mucosa intestinal.

SUMMARY This study aimed at evaluating the use of exogenous enzymes in diets with Saccharomyces cerevisiae and their impact on zootechnical performance, carcass yield, intestinal histomorphometry and of broiler diets in the initial phase. A completely randomized design was used in a 2×3 + 1 factorial arrangement, with two levels of enzyme complex (EC), (0 and 200g / ton), three yeast levels (0, 6 and 12%) and a control diet, making up seven treatments, with five replicates of 20 broilers per experimental unit. We evaluated the performance (feed intake, weight gain and feed conversion ratio), carcass yield and cuts, histomorphometry of the small intestine (height, circumference and width of villi, height and width of the crypt, thickness of the intestinal muscle wall and villi/crypt relationship). From 1 to 7 and 1 to 21 days, the inclusion of yeast led to reduced broiler performance. At 21 days, the addition of EC resulted in an increase of (p <0.05) in the thickness of the muscular wall of the duodenum and decreased the width of the crypt in the ileum. The 12% level of yeast without the EC provided a thicker jejunum intestinal muscle wall when compared to the positive control. There was no significant effect on carcass yield and cuts between treatments. In conclusion, the inclusion of yeast reduces performance from 1-21 days. The enzyme complex and yeast does not change the performance or carcass yield, however, it does bring benefits to the intestinal mucosa.

ABSTRACT The objective of this study was to evaluate the effect of three levels of crude cottonseed oil on performance, organ weights, and blood parameters of growing broilers. Carcass and cut yields after 33 and 42 days of age and the economic viability of the diets were also evaluated. Male broilers of the Ross line were distributed in a completely randomized design, in a 4 × 2 factorial arrangement (0, 2, 4, and 6% inclusion of cottonseed oil, with and without ferrous sulfate) with five replicates. In the period from 22 to 33 days, quadratic and increasing linear effects were observed on feed intake and weight gain, respectively. Feed conversion during the same period was better with the addition of ferrous sulfate. The addition of ferrous sulfate caused a reduction in heart weight. From 22 to 42 days, carcass and cuts yield, organ weight, and intestine length were not influenced by the levels of oil or by the addition of ferrous sulfate. Supplementation with iron salts provided a lower red blood cell count and increased mean cell volume. Balanced diets formulated with up to 6% of crude cottonseed oil for broilers from 22-33 and 22-42 days of age do not affect their performance or the weight of their organs. Supplementation with ferrous sulfate improved feed conversion up to 33 days. Diets formulated with 4% cottonseed oil supplemented with ferrous sulfate are economically viable in the period from 22 to 42 days.