Foram realizados dois experimentos para avaliar os efeitos da granulometria do milho das rações, expressa pelo diâmetro geométrico médio (DGM), 0,337; 0,574; 0,680; 0,778; 0,868 e 0,936mm, sobre o desempenho, o metabolismo energético e a morfologia intestinal (número e altura de vilosidades do duodeno) de frangos de corte machos, de 21 aos 42 dias de idade. No 1° experimento, partículas de 0,868 mm proporcionaram às aves maior consumo de ração, maior ganho de peso e melhor conversão alimentar. A altura das vilosidades intestinais não foi influenciada pelo DGM das dietas, mas aumentou com a idade das aves (21, 35 e 42 dias de idade). Não foi observado efeito da granulometria sobre a deposição de gordura abdominal ou sobre as proporções das partes da carcaça. O peso da moela esteve positivamente relacionado com o aumento da granulometria das dietas. No 2° experimento, as aves alimentadas com milho de 0,337 mm apresentaram menor consumo de energia metabolizável e maior excreção de energia bruta. A granulometria não influenciou na retenção de nitrogênio.

The experiment was conducted to evaluate the effect of dietary fiber on the performance and energy balance of broiler chickens of a fast-growing strain (Cobb500) and a slow-growing strain (Label Rokens during the period of 1 one to 42 days of used In total, 360 male broilers (240 fast-grorain and 120 slow-grtrain)were, housed in collective cages. A completely randomized experimental dewith in a 3x2 factorial arrangement was applied, consisting of three groups of birds (slow-growing-SG; fast-growing fed ad libitum-FGAL; and fast-growing pair-fed with SG broilers-FGPF) and two iso-protein dis (a 3100 kcal ME/kg low-fiber diet and a 2800 kcal ME/kg high-fiber diet-Hwith containing 14% wheat bran and 4% oat hulls). Dietary fiber level did not affect feed intake (FI); however, it resulted in lower weight gain (WG) and worse feed conversion ratio (FCR) (p ≤ 0.001) in birds fed the HFD diet due to its lower energy content. The FGPF group presented higher WG than SG and better FCR (p ≤ 0.001), indicating that fast-growing birds present better performance than SG broilers, even under restricted feed intake. The SG group retained more energy relative to body weight (p ≤ 0.001), which is associated to higher body fat retention in this strain (p ≤ 0.001). The slow-growing strain did not present better use of high-fiber diet than fast-growing strain as expected.

In this study, 360 male broilers, out of which 240 of a fast-growing strain (Cobb500), and 120 of a slow-growing strain (Label Rouge), were used to evaluate the effect of dietary fiber on digesta transit time and digestive metabolism during the period of 1 to 42 days of age. A completely randomized experimental design with a 3x2 factorial arrangement was applied, consisting of three groups of birds (slow-growing -SG; fast-growing fed ad libitum -FGAL; and fast-growing pair-fed with SG broilers -FGPF) and two iso-protein diets (a 3100 kcal ME/kg low-fiber diet -LFD-and a 2800 kcal ME/ kg high-fiber diet -HFD-with 14% wheat bran and 4% oat hulls). HFD-fed birds presented lower ME retention (p < 0.001) and lower dry matter metabolizability (DMM) (p < 0.001), which is possibly related to the shorter digesta transit time observed in these birds (p < 0.001). DMM was reduced with age, whereas metabolizable energy remained almost constant (p < 0.001) independently of strain. This may be related to the increase in feed intake as birds age. The slowgrowing strain did not present better utilization of the high-fiber diet as compared to the fast-growing strain in none of the analyzed ages, even though showing a significant better use of fiber and dietary energy from 31 days of age.

No abstract

The effects of lutein and conjugated linoleic acid (CLA) on growth performance and immune response of broiler chickens were evaluated in the presence and absence of Salmonella lipopolysaccharide (LPS) immune challenge. Cobb chicks (360; 1 to 22 d of age) were used in a 3 × 2 factorial arrangement of CLA (0, 1, and 2%) and lutein (0 and 50 mg/kg) dietary levels. At d 8 and 15, birds were injected with BSA to assess IgY production. At d 20, birds were injected with LPS. Samples of liver, spleen, and duodenum were collected at 3 and 16 h post-LPS challenge for RT-qPCR analysis of RXRα, RXRγ, PPARα, PPARγ, TLR-4, IL-1β, IL-2, IL-10, and IL-12 gene expression. CLA decreased BW, BW gain (BWG), and G:F from d 1 to 20, but these effects were reversed when lutein was included in the 1% CLA diet (P < 0.001). The production of IgY anti-BSA increased following a 2% CLA supplementation (P < 0.01). LPS increased the liver:BW ratio at 3 h post-injection (P < 0.001) and decreased BWG at 3, 16, and 40 h (P < 0.001). Lutein decreased plasmatic nitric oxide levels (P < 0.01). LPS downregulated PPARα mRNA in the duodenum (P = 0.02) and liver (P = 0.04), and PPARγ (P = 0.01) and RXRα (P = 0.08) in the spleen; these effects were not reversed by CLA or lutein as initially hypothesized. Although LPS upregulated IL-1β (P = 0.02) and IL-12 (P = 0.07) expression, lutein downregulated these pro-inflammatory cytokines in the liver (P = 0.03 and P = 0.07, respectively). Lutein decreased splenic (P = 0.09) but increased hepatic (P = 0.06) TLR-4 mRNA. A dietary CLA supplementation of 2% increased hepatic RXRα (P = 0.10). In conclusion, CLA decreased broiler chicken growth performance, but lutein could prevent this negative effect (depending on CLA dose). Lutein had an anti-inflammatory effect, and a 2% CLA supplementation improved the humoral immune response.

Four Nutritional Programs (NP) used in the Brazilian poultry industry were tested in two broiler strains (Cobb 500 and Ross 308). NP varied in the concentrations of their main essential amino acids (AA) and were classified as Low, Regular, High and Mixed (high AA concentrations up to 21 days and regular concentrations after that). Minimum digestible Met+Cys/Lys, Thr/Lys, Arg/Lys, Ile/Lys, and Val/Lys ratios were 0.74, 0.64, 1.05, 0.65 and 0.75, respectively, in all NP, and no minimum amount of CP was fixed. There were no interactions between strain and NP for any of the evaluated responses. From 1 to 47 days of age, birds fed the Low NP presented lower average body weight and body weight gain (BWG). The high NP allowed for better feed conversion ratio (FCR), followed by the Regular and the Mixed NP. Ross 308 broilers were heavier, presenting worse FCR due to higher FI. Birds fed the High NP had lower carcass yield than those fed the Low NP. The Low and Regular NP had lower costs per WG when compared with the High NP. Low and Regular NP presented higher gross margin returns compared with the High NP. The Regular and Mixed NP are the most recommended, presenting intermediate performance and higher economic returns.

No abstract

Although most industries use a specific diet for the pre-starter phase, ingredients are used in the later phases, primarily corn and soybean meal, which at this stage do not have high digestibility. Three experiments : Exp : were carried out to evaluate the substitution of corn by white or parboiled rice : WR, PR : and the inclusion of 6% soy protein isolate : SPI : in pre-starter diets (1 to 7 d). In Exp 1 (1 to 21 d), WR, PR, and SPI were added to the diets until the birds were 21-day-old, whereas in Exps 2 and 3 (1 to 33 d), only until birds were 7-day-old. Birds were fed a basal diet based on corn and soybean meal until the end of the experimental period. In Exp 1, the coefficients of total tract apparent retention : CTTAR : of the pre-starter and the starter diets, ileal and jejunal digestibility of starch in the starter diets, and broiler performance were measured. Subsequently, the same pre-starter diets Exp 1 were evaluated in pellet (Exp 2) or mash (Exp 3) form and different oil percentage (Exp 2) or not (Exp 3). We hypothesized that the ingredients particle size (Exp 2) and fat content (Exp 3) could influence feed intake. There was no interaction among the evaluated factors (P > 0.05). Rice (WR or PR) promoted better results than corn in terms of CTTAR of dietary components, jejunal and ileal starch digestibility, and broiler performance (P < 0.01). In Exp 1, diets with 6% SPI presented better CTTAR, except Nitrogen ( N: ), but lower feed intake, which negatively affected broiler performance (P < 0.01). In Exps 1, 2, and 3, the inclusion of SPI did not improve broiler performance (P > 0.05), so that SPI may not be the best choice for pre-starter diets. The study also suggests that better growth performance and nutrient digestibility can be obtained in broiler chickens if corn is replaced by rice in pre-starter diets.