Efeito dos níveis de energia da ração sobre o desempenho e teor de gordura na carcaça de frangos de corte

It was studied the effect of energy levels in the diet, obtained from vegetal oil inclusion, on the performance, diet cost per kilogram of broiler and fat content of the carcass, There were used 4,800 broiler chicks, 2,400 males and 2,400 females, and they were distributed in six treatment (energy levels in kcal ME/kg of diet) in three different phases: start diet from one to 20 days of age: A - 2930, B - 2980, C - 3030, D - 3080, E - 3130, F - 3180, growth diet from 21 to 40 days: A - 2980, B - 3030, C - 3050, D - 3130, E - 3150, F - 3230, finishing diet from 41 to 45 days of age: A - 3030, B - 3080, C - 3130,, D - 3180, E - 3230, F - 3280. The protein content was 22, 20 and 18% in each phase, respectively, There were evaluated the feed intake, energy intake, protein intake, weight gain, feed conversion mortality, diet cost per kg/bw. Sixty broilers were slaughtered, five males and five females per treatment, randomly chosen to determine the carcass composition considering the dry matter content, lipids content and protein content, total fat in carcass and fat per kilogram of broiler. The data were submitted to variance analysis and the means were compared using SNK. The broilers fed with medium and low levels of dietary energy showed the highest weight gain. At energy levels of the treatment D in the three phases, the lowest cost per kilogram of broiler was obtained. The females presented the highest fat content per kilogram of broiler produced.

Use of cecal microflora cultured under aerobic or anaerobic conditions in the control of experimental infection of chicks with Salmonella Enteritidis

One-day-old broiler chicks received cecal microflora (CM) cultured under aerobic, anaerobic conditions, or both (mixed) and were then infected with Salmonella Enteritidis, in order to compare the efficacy of these different types of culture in terms of the number of chicks infected, cecal colonization and faecal excretion of the challenging bacteria. Regardless of culture type, CM always led to a smaller number of S. Enteritidis for any of the parameters studied compared to untreated chicks. Aerobic CM demonstrated better efficacy in reducing the number of infected chicks and cecal colonization by S. Enteritidis, followed by mixed CM. No difference was observed in faecal excretion of S. Enteritidis between the chicks that received different types of CM culture. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Posthatching water and feed deprivation affect the gastrointestinal tract and intestinal mucosa development of broiler chicks

We studied the effect of feed and water deprivation on gastrointestinal tract and intestinal mucosa development of chicks at 24, 48, and 72 h posthatching. The treatments were water and feed ad libitum, water ad libitum and no feed, no water but feed ad libitum, and no water and no feed. The relative weight of the yolk sac was not influenced by the treatments. However, at 48 and 72 h posthatching, the relative weight of the liver increased, and the gizzard + proventriculus weight decreased in birds receiving feed ad libitum. An increase in jejunum and ileum relative weights and lengths was observed when the birds were supplied with feed and water. The lack of water produced the same effect as the lack of feed, both causing a higher number of villi per area with reduction in villus size, when compared with feed and water ad libitum treatments. The results of this study revealed that feed and water are able to affect intestinal villus development after hatching, indicating that both feed and water must be supplied to the chicks immediately after hatching.

Influence of early qualitative feed restriction and environmental temperature on long bone development of broiler chickens

This investigation was carried out to study the influence of early qualitative feed restriction and environmental rearing temperature on long bone development in broiler. Energy and protein restriction reduced femur width and humerus weight, but did not affect tibia parameters. Broilers kept at cold environmental temperature showed reduced femur, tibia and humerus length and tibia weight, but the calculated density was not affected by rearing temperature. These findings suggest that qualitative feed restriction and environmental temperature influenced the normal long bone growth; however, bone weight/bone length index (calculated density) was not affected by rearing temperature. (c) 2007 Elsevier Ltd. All rights reserved.

Maternal antibody transfer to broiler progeny varies among strains and is affected by grain source and cage density

Two experiments were conducted to examine the effects of broiler breeder dietary grain source and cage density on maternal antibody (MatAb) transfer to progeny in 2 genetic strains (A and B). Broiler breeders were assigned to 16 litter floor pens and fed either corn- or wheat-based diets. Breeders were administered 4 live vaccines against Newcastle disease virus (NDV). At 23 wk of age, pullets and cocks, which reflected the full BW distribution from each treatment, were moved to a cage breeder house and placed at 1 or 2 hens/cage. Breeders were artificially inseminated at 44 wk (experiment 1) and 52 wk of age (experiment 2). Eggs were collected for 8 d, incubated, and placed in individual pedigree bags at d 19 of incubation. Blood samples from 5 chicks per treatment combination were collected at hatch in both experiments. Spleen and bursa were collected from the same chicks for histomorphometry analyses in experiment 2. In the second experiment, 12 chicks per treatment were placed in cages. Progeny were provided diets based on the same grain (corn or wheat) as their parents. Serum samples were collected at 5, 9, and 13 d of age and analyzed for anti-NDV MatAb. Data were analyzed as a 2 x 2 x 2 factorial design considering strain, dietary grain source, and cage density as main factors. Interaction effects were observed in breeders and progeny. Experiment 1 showed that strain A chicks had lower levels of MatAb when hens were housed at 2 hens/cage rather than 1 hen/cage. The MatAb levels of strain B chickens were not affected by cage density in either experiment. Experiment 2 demonstrated similar effects of cage density on MatAb levels and the area of bursa follicles for both strains. Progeny of breeders fed corn-based diets had smaller spleen white pulp only when hens were housed at 2 hens/cage compared with 1 hen/cage. The results of these experiments suggest that breeder strain and cage-density conditions affected MatAb transfer to progeny and embryo development of spleen and bursa.

Passive Immunity of Progeny from Broiler Breeders Vaccinated with Oil-Emulsion Bacterin Against Salmonella Enteritidis

Young poultry are very susceptible to Salmonella Enteritidis (SE) infections because of the absence of complete intestinal flora colonization and an immature immune system. This study evaluated the role of passive immunity on the resistance of young birds against early infections caused by SE. The progeny of broiler breeders vaccinated with an oil-emulsion bacterin was compared to the progeny of unvaccinated birds. Efficacy was determined by challenging birds at 1 and 14 days of age with SE Nal Spc strain, phage type 4. After challenge at 1 day of age, the progeny of vaccinated birds presented a significantly lower number (log(10)) of SE Nal Spc reisolation (P < 0.05) in liver (2.21), spleen (2.31), and cecal contents (2.85) compared with control groups (2.76, 3.02, and 6.03, respectively). The examination of the internal organs, 3 days after infection, revealed that 28% of the birds (7/25) from vaccinated breeders were positive, whereas 100% (25/25) of the chicks derived from unvaccinated birds were positive. Birds challenged at 14 days of age presented a lower number of positive samples compared with those challenged at 1 day of age, and the progeny of vaccinated birds presented statistically lower numbers (log(10)) of colony-forming units/ml of SE Nal Spc only in the cecal contents compared with nonvaccinated breeder progeny (2.11 vs. 2.94). Age seems to influence the susceptibility of birds to SE infections: in control groups, the number of positive birds at 14 days of age (9/25) was lower when compared with the group infected at 1 day of age (25/25). The number of positive fecal samples of the progeny of vaccinated birds was significantly lower (36) than those of the control group (108) after challenge at 1 day of age. Unchallenged progeny of vaccinated birds presented passive antibodies detectable by enzyme-linked immunosorbent assay (ELISA) up to 21 days of age. on the other hand, antibodies of the control group were detected by ELISA 14 days after challenge. These results show a significant contribution of breeder vaccination by increasing the resistance of the progeny against early SE infections. However, the bacteria were not completely eliminated, suggesting that additional procedures are needed to effectively control SE infections.

Estimating the thermoneutral zone for broiler breeders using behavioral analysis

Knowledge about bird's heat stress is extensively discussed in the literature. From behavior data collected during the summer of 2000/2001 in an open-sided reduced scale model of a poultry barn, this study estimated the thermoneutral zone for female broiler breeders. The birds were electronically identified and the frequency of use of passage, indicating movement, and drinker, indicating thirst, where the antennas were placed, was recorded. Environmental data such as dry and wet bulb temperature were collected in the geometric center of the model and continuously registered by a datalogger. From the statistical analysis, it was possible to predict a real-time-based zone where the birds showed coherent behavior towards the use of the drinker and movement in the passage. (c) 2007 Elsevier B.V. All rights reserved.

Evaluation of Salmonella-Lytic Properties of Bacteriophages Isolated from Commercial Broiler Houses

Because of recent interest in bacteriophage therapy in poultry, information regarding the interaction of bacteriophages and potential host bacteria in the environment should be collected. The present studies were initiated with a rather typical commercial broiler integrator within the south-central United States to examine environmental Salmonella levels in two broiler complexes, attempt to isolate Salmonella-lytic bacteriophages, and elucidate a possible reason for differing apparent Salmonella prevalence. Significantly ( P<0.05) less Salmonella was isolated from houses in complex 1 ( 15/44 [ 34%] Salmonella-positive drag swabs) as compared to houses in complex 2 ( 22/24 [ 92%]). A total of seven Salmonella-lytic bacteriophages were isolated from Salmonella-positive environments, and two bacteriophages were isolated from a single Salmonella-negative house. During the initial bacteriophage isolation, individual bacteriophages did not replicate in the Salmonella host isolated from the same environment, and lysis of additional Salmonella hosts relied on high numbers of bacteriophage to be present. This suggests that the presence of these bacteriophages in the environment of a commercial broiler house had little to no effect on the presence of Salmonella. This study highlights the need to find additional bacteriophage sources, more effective isolation methods, and more innovative approaches to using bacteriophages to treat enteric disease.

Effect of Phytase Supplementation in Diets on Nutrient Digestibility and Performance in Broiler Chicks

A performance trial was conducted with broiler chicks to Study the effect of phytase (PHY) supplementation in diets formulated With reduced AME, Ca, and P. The nutrient digestibility was determined during the 14- to 21-d and 28- to 35-d periods. The treatments consisted of 3 diets (NC1, NC2. NC3) differing ill nutrient content and each diet with Or without supplemental PHY (NC1, 0 oi 500; NC2, 0 or 750; NC3, 0 or 1,000 U of PHY/kg feed) and I positive control diet (PC). Compared with the PC diet. negative control diets (NC) resulted in lower AME and apparent ileal amino acid digestibility for some amino acids. Phytase Supplementation of the NC diets increased AME. apparent ileal amino acid digestibility, and apparent ileal crude protein digestibility. Phytase addition also increased mineral absorption in 2 1 - and 35-d-old broilers fed NC diets. Reduced nutrient digestibility appears to be I factor in the weight gain and feed intake results. Reducing Ca and P content reduced feed intake in a stepwise fashion in the NC diets. Phytase increased feed intake and generally improved nutrient digestibility, which resulted in an increase in digestible nutrient intake. Averaged across NC diets. PHY improved body weight. Bone-breaking strength was the most consistent predictor of Ca and P reduction. All NC diets had significantly lower bone-breaking strength than the PC. Phytase supplementation of the NC diets gave bone-breaking strengths that were comparable to the PC. Diets with PHY had the highest bioeconomic index.