Abstract in English:The intensification of the production system in the poultry industry and the vertical integration of the poultry agribusiness have brought profound changes in the physical and social environment of domestic fowls in comparison to their ancestors and have modified the expression of aggression and submission. The present review has covered the studies focusing on the different aspects linked to aggressiveness in the genus Gallus. The evaluated studies have shown that aggressiveness and subordination are complex behavioral expressions that involve genetic differences between breeds, strains and individuals, and differences in the cerebral development during growth, in the hormonal metabolism, in the rearing conditions of individuals, including feed restriction, density, housing type (litter or cage), influence of the opposite sex during the growth period, existence of hostile stimuli (pain and frustration), ability to recognize individuals and social learning. The utilization of fighting birds as experimental material in the study of mechanisms that have influence on the manifestation of aggressiveness in the genus Gallus might comparatively help to elucidate important biological aspects of such behavior.
Abstract in English:This study evaluated the effects of strain, stocking density and dietary energy level on the feathering of broiler chickens. Four trials were carried out between September 2000 and April 2002. There were 10,685 broiler chicks from the strains Ross 308, Cobb 500, Hybro PG, Hubbard, MPK, and Isa Vedette. The bids were reared at stocking densities varying between 10 and 16 birds/m² and were given diets containing different metabolizable energy levels. Broiler feathering was evaluated either by atrributing scores from 1 to 10 to feather covering along the thigh and back (visual inspection), or by determining the percentage weight of the feathers at 28 and 42 days of age. Increasing rearing densities resulted in poorer feathering, mainly if 12 or 13 birds/m² were compared with 16 birds/m². The strains showed different feathering; it was better in Cobb 500 and MPK birds, whereas Hubbard birds showed poorer feathering, mostly along the back. The energy level in the diet has also affected feathering scores. Medium energy level resulted in better feathering along the back at 28 days, and the low level, in better feathering along the thigh at 35 days of age. Finally, feather scores were better in females than in males.
Abstract in English:The production system using cages is a highly polemical issue in Europe, because of the space restriction imposed to laying hens. It is considered that the cage system might compromise important comfort movements, welfare and egg quality. This study evaluated egg quality and welfare of two strains of hens housed in a conventional system (battery laying cages) or litter system with nest and perches, and submitted to heat stress or comfort conditions. Two groups of 20 birds (10 Hy-line W36 and 10 Hy-line Brown) were submitted to two environmental conditions (26°C and 60% RH or 35°C and 70% RH) and two housing systems (cages or litter) in the early production phase. Egg quality was analyzed based on egg weight, eggshell thickness, specific gravity, and Haugh units. Yolk and shell contamination by Salmonella sp was also assessed. A significant (p<0.05) reduction in quality parameters was observed in eggs produced by laying hens under heat stress, mainly in the birds housed in cages.
Abstract in English:The Brazilian Swine and Poultry Research Center (Embrapa Suínos e Aves) maintains a chicken breeding program for meat production since 1985. Two control lines (LLc and PPc) are maintained, whereas two male lines (TT and ZZ) and three female lines (PP, VV and KK) have been selected. This paper reports the genetic gain after 15 generations of combined selection (mass and independent culling levels) in order to develop the commercial broiler stocks Embrapa 021 and Embrapa 022. Selection pressure has been exerted on weight gain, carcass traits and fertility. In addition, female lines have also been selected for egg production, whereas males have been selected for feed efficiency since 1992. All lines have been selected for breast area instead of carcass traits since 1999. The genetic gain was estimated as the deviation between selected lines and the respective unselected lines at 42 days of age. In female lines, body weight improved 504, 548 and 587 g; average breast area increased 27.60; 16.99 and 26.43 cm²; adjusted feed conversion (42-49 d) improved -1.46; -0.97 and 1.76 units, and egg production varied 6.99; 7.12 and -3.43% units for PP, VV and KK, respectively. In male lines, body weight improved 758 and 408 g; average breast area increased 31.95 and 19.38 cm², and adjusted feed conversion improved (42-49 d) -0.99 and 1.26 for TT and ZZ, respectively. This breeding program has been effective to generate genetic gain and to develop two commercial products, Embrapa 021 (standard) and Embrapa 022 (high yield). Nevertheless, feed efficiency is still not satisfactory.
Abstract in English:This study was carried out at Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista, Botucatu, SP, Brazil, and evaluated bone quality in broiler breeders. Twenty-three families of Ross broiler breeders were housed in 5.0-m² pens. The families were comprised of 13 females and one male at the onset of the experimental period. The mean number of females per family was 9.34 at the end of the trial. The feeding program and management followed strain guidelines (Agroceres Ross, 2003). Bone analyses were performed in the right tibia and femur using optical radiographic densitometry at 4, 8, 12, 15, 20, 24, 30, 35, 42, 47 and 52 weeks of rearing. Trap nests were used to collect eggs from the breeders two weeks before and after the evaluation weeks. At each evaluation day, five birds were sacrificed after radiographs were taken and the tibias and femurs were collected to perform the following analyses: fatfree dry matter, ash percentage, bone resistance and Seedor index. Therefore, it was possible to establish correlations between bone quality and eggshell quality. Characteristics of bone quality were highly correlated to each other; on the other hand, there were no correlations between bone quality and external egg quality. In conclusion, there was no effect of egg production on egg quality, possibly because there was no reabsorption of bone minerals.
Abstract in English:The occurrence of Salmonella in a samples of 40 imported day-old duckling flocks was assessed from 1998 to 2003 according to the guidelines of the Brazilian National Poultry Health Program (Programa Nacional de Sanidade Avícola-PNSA). The pathogen was recovered from 26 flocks (65.0%). The most common serovars were S. Saintpaul and S. Kottbus. Up to four serovars were isolated from a single flock. Transportation box swabs (82.6%) and yolk sac pool (47.1%) showed the highest and the lowest frequency of Salmonella isolation, respectively. The high percentage of Salmonella isolation from imported day-old ducklings causes concern because of the zoonotic potential of this agent and its economical importance to commercial poultry breeding.
Abstract in English:False positive serologic reactions and difficulties in the diagnosis of Mycoplasma gallisepticum (MG) in chickens have increased lately as a result of infection by low virulent MG strains and the use of live MG vaccines in poultry. The objective of this study was to evaluate the serologic responses of SPF chickens exposed to the three commercially available live MG vaccines, and one low virulent MG strain (MG-70), contributing to the diagnosis and monitoring of MG infection in birds. Six groups of SPF chickens were used. The control group was not infected nor challenged; one group was infected with the low virulent strain MG-70 (MG-70); three groups were immunized and named after the MG vaccine used, i.e., MG-6/85, MG-ts11, and MG-F; and finally one group was infected with the virulent MG standard strain, MGR. Random Amplification of Polymorphic DNA (RAPDPCR) was used to compare the strains to each other, to the standard MG-A5969, and to MGR. All strains were found to be genetically distinguishable from each other. Birds in the control group showed negative results throughout the experiment and showed no cross-reaction with M. synoviae in any serologic test. ELISA tests at 21 days post first exposure (P1E) and seven days after the second exposure (P2E), evidenced that 25% of the MG70 birds were positive, whereas vaccine groups yielded higher positivity rate, i.e., 57%, 43% and 29% for MG-6/85, MG-ts11 and MG-F, respectively. Serum plate agglutination (SPA) evidenced the first positive results at 35 days P1E on birds in the MG-F group at the rate of 100%; followed by 40% of birds in the MG-70 group at 63 days P1E. Chickens in MG-ts11 and MG 6/85 groups had identical behavior and yielded 100% positive SPA at 77 days P1E. In regard to hemagglutination inhibition (HI), 14 % of the birds in MG-F and MG-ts11 reacted at 42 days P1E, while MG-70 and MG-6/85 groups yielded positive results only after challenge; MG-70 birds reacted at 56 days P1E at the rate of 17% against 63 days P1E for 100% of MG-6/85 birds. The time lag for positive serologic response was monitored on a weekly basis and was statistically different among groups (p<0.05) by Analysis of Variance (ANOVA). No clinical signs or gross lesions were seen in the control, vaccinated or MG-70 infected birds. Tracheitis and airsaculitis were observed in birds in the MG-R group. MG was isolated from all studied groups.
Abstract in English:This study evaluated two enzyme-linked immunosorbent assays (ELISA) in the detection of chicken serologic response against Salmonella enterica sorotype Typhimurium. The assays have used as detecting antigen the soluble bacterial proteins of a non-flagellated strain of Salmonella Typhimurium (AgTM), and antibody conjugated to peroxidase or alkaline phosphatase. According to the results, optimal dilutions of antigen (concentration 5.49 mg/mL) and serum samples in both assays were 1:20,000 and 1:1,000, respectively. In such conditions, the ELISA/AgTM was able to detect serological response to Salmonella Typhimurium. Cross-reactions to Salmonella serotypes Gallinarum and Pullorum were seen, but not with other serotypes such as Enteritidis.
Abstract in English:This study aimed to evaluate broiler responses to increases in feed energy (2,870, 3,000 and 3,100 kcal ME/kg) and the inclusion of Acidulated Soybean Soapstock (ASS) when compared to Degummed Soybean Oil (DSO) in feeds from placement to 7 days of age. From 7 to 42 days ASS or DSO were included in diets that contained similar energy and nutrient levels. Metabolizable energy values used to formulate the diets for ASS and DSO were 8,351 and 7,701 kcal ME/kg in the first week and 9,314 and 8,559 kcal ME/kg afterwards, respectively. Diets were based on corn and soybean meal and were fed to 1,600 one-d-old male broiler chicks randomly placed in 40 floor pens. No differences in performance due to fat source were seen at 7 days. However, the increase in energy levels to 3,100 kcal ME/kg reduced feed intake, whereas feed conversion was improved with energy at 3,000 kcal ME/kg. Live performance, and the yields of carcass and commercial cuts were not affected by the type of fat included in the feeds from 7 to 42 days, except for increased body weight at 21 and 35 days with ASS supplementation. Litter moisture at 7, 21, 35 and 42 days was not affected by any of the factors and there were no residual effects of treatments at 21, 35 and 42 days of age. On the other hand, body weight at 35 days was affected by the interaction of diets fed in the first week with those provided afterwards. The results showed that ME values used for DSO and ASS are adequate and that ASS may be used as fat source in broiler feeds from placement to 42 days of age.
Abstract in English:Bovine meat and bone meal (MBM) was widely used in animal diets until outbreaks of Bovine Spongiform Encefalopathy (BSE) occurred in some countries. It has not been confirmed yet whether or not BSE may be transmitted to man through chicken meat originated from poultry that had been fed diets containing MBM. Therefore, consumers nowadays express preference for meat originated from birds fed exclusively vegetable diets. This study analyzed samples of major breast muscle (Pectoralis major) using mass spectrometry of stable isotopes (carbon and nitrogen) as a means to assess the presence of MBM in broiler diets, a technique that might be used in the certification of poultry quality. A total of 150 day-old chicks were reared in five randomized treatments with increasing MBM dietary inclusion levels (0, 1, 2, 4 and 8%). On day 42, breast muscle samples were collected from three birds per treatment and used in the determination of 13C/12C and 15N/14N isotope ratios. The breast muscle isotope values were expressed as delta in parts per thousand (delta‰). The following carbon isotope values (13C) were found: 18.74‰±0.11, 18.51‰±0.19, 18.24‰±0.10, -17.79‰ ±0.12, and -17.15‰±0.15 for 0, 1, 2, 4 and 8% MBM dietary levels, respectively. Nitrogen isotope values (15N) were 1.65‰±0.14, 1.65‰±0.28, 1.72‰±0.08, 1.95‰±0.16, and 2.52‰ ± 0.09 for 0, 1, 2, 4 and 8% MBM dietary levels, respectively. This study showed important differences in delta13C and delta15N values in breast meat, evidencing a simultaneous enrichment of this isotopic pair, which allowed tracing MBM in bird diets. Analysis of carbon and nitrogen stable isotopes may be used to ensure feeding with exclusively vegetable diets, and might also be used as a reliable evaluation tool in broiler meat certification. The diet with 1% inclusion level of MBM and the exclusively vegetable diet showed similar results.