Abstract in English:Growth curves models provide a visual assessment of growth as a function of time, and prediction body weight at a specific age. This study aimed at estimating tinamous growth curve using different models, and at verifying their goodness of fit. A total number 11,639 weight records from 411 birds, being 6,671 from females and 3,095 from males, was analyzed. The highest estimates of a parameter were obtained using Brody (BD), von Bertalanffy (VB), Gompertz (GP,) and Logistic function (LG). Adult females were 5.7% heavier than males. The highest estimates of b parameter were obtained in the LG, GP, BD, and VB models. The estimated k parameter values in decreasing order were obtained in LG, GP, VB, and BD models. The correlation between the parameters a and k showed heavier birds are less precocious than the lighter. The estimates of intercept, linear regression coefficient, quadratic regression coefficient, and differences between quadratic coefficient of functions and estimated ties of quadratic-quadratic-quadratic segmented polynomials (QQQSP) were: 31.1732±2.41339; 3.07898± 0.13287; 0.02689±0.00152; -0.05566±0.00193; 0.02349±0.00107, and 57 and 145 days, respectively. The estimated predicted mean error values (PME) of VB, GP, BD, LG, and QQQSP models were, respectively, 0.8353; 0.01715; -0.6939; -2.2453; and -0.7544%. The coefficient of determination (R²) and least square error values (MS) showed similar results. In conclusion, the VB and the QQQSP models adequately described tinamous growth. The best model to describe tinamous growth was the Gompertz model, because it presented the highest R² values, easiness of convergence, lower PME, and the easiness of parameter biological interpretation.
Abstract in English:The objective of this experiment was to evaluate the effect of diet supplementation with vitamins C and E and organic minerals Zn and Se on the performance of 1 to 35 day-old broilers from, kept under cyclic heat stress (25 to 32ºC). Four levels of vitamin-mineral supplementation were used (T1-control diet (60/30 IU of vit E for starter and growing diet, respectively, zero vit. C, 80 ppm of inorganic Zn, 0.3 ppm of inorganic Se); T2-control diet + 100 UI vit E and 300 ppm vit C/kg; T3-control diet + 40 ppm Zn and 0,3 ppm Se/kg; T4-control diet + T2 and T3 levels) and two environments - thermoneutral and cyclic heat stress (TN and HS) from 14 to 35 days of age. In the period when part of the birds was submitted to HS, from 14 to 35 days, it was observed lower feed intake (FI) and better feed conversion (FC) for HS birds receiving supplementation compared to the group without supplementation. Evaluating the total period, all the types of supplementation provided lower FI and better FC than the control treatment, but not affected weight gain (WG). The supplementation of vitamins C and E and/or organic minerals Zn and Se improved the performance of birds due to a lower FI resulting in better FC, independently on the environment.
Abstract in English:This experiment aimed at verifying the effect of different diets and thermal environments on the performance, carcass yield, and diet digestibility of 21 to 42-day-old broilers. A total number of 288 21-day-old male Ross broilers were distributed in a 2 x 2 + 2 factorial arrangement, with six replicates, including the following factors: two environments (TNE - thermoneutral: 21-25ºC and 73% RH; CHS - cyclic heat stress: 25-32ºC and 65%RH), and two diets (control: 2.4% soybean oil and 19.5% protein; summer: 4.0% soybean oil and 18.5% protein). In TNE, two additional treatments were included with feed restriction of birds fed both the control and summer diets (pair-feeding), thereby maintaining the same feed intake level for both types of diet. Diet did not influence performance, dry matter and protein digestibilities, or carcass and part yields. TNE birds had better performance (p<0.001) as compared to CHS birds, but FCR was not different. CHS birds had lower breast yield (p<0.0001), and higher thigh yield (p<0.02) than TNE birds. In the pair-feeding treatments, environment did not influence performance, but dry matter digestibility was significantly lower in CHS (p<0.03), whereas protein digestibility was not affected. The difference in feed intake was the main responsible factor for the variation in the performance of heat-stressed birds.
Abstract in English:Several changes in amino acid levels occur during an infection. As a rule, glycine, taurine and serine levels diminish considerably, while cysteine levels increase. Such changes may be attributed to the intense consumption of sulfur amino acids (SAA- methionine+cysteine) during infectious challenge. Methionine plays an important role in humoral and cellular immune responses. It has been suggested that such effect is exerted by intracellular glutathione and cysteine levels. Four-hundred thirty-two day-old Ross male broiler chickens were fed (from 1 to 42 days of age) three SAA levels in the diet (0.72, 0.82, and 0.92% from 1 to 21 days of age; 0.65, 0.75, and 0.85% from 22 to 42 days of age) and submitted to two immunological stimulus series. Vaccines against Marek's disease, Fowlpox, Infectious Bronchitis and Infectious Bursal disease, Freund's Complete Adjuvant, and avian tuberculin were used as immunological stimuli. The experiment comprised 6 treatments, with 6 replications using 12 birds per replicate. Performance data were collected weekly. Gumboro antibodies were measured by ELISA, and the cellular immune response by the tuberculin test. SAA levels tested did not influence immune response. Nevertheless, the vaccines applied on the 1st day impaired chick performance up to the 21 days of age. The SAA levels generally adopted in poultry husbandry may not be enough to assure weight gain, especially when birds are raised if a low-challenge infectious environment.
Abstract in English:Trachea, lung, and conjunctive samples from 51 commercial layer farms from Bastos region, São Paulo, Brazil, were submitted to nested-PCR and virus isolation in SPF chicken embryos for ILT diagnosis. This region experienced an outbreak characterized by respiratory signs, decrease in egg production and increased mortality. Out of the 51 tested field samples, 23 were positive for ILT by nested-PCR, 22 were positive after the virus isolation, and 24 were positive when both techniques were used. Newcastle disease virus, Avian pneumovirus, or Mycoplasma gallisepticum were not detected. Infectious bronchitis virus was detected in one farm and Mycoplasma synoviae was detected in eight farms. The high incidence of infectious laryngotracheitis virus (ILTV) detection, the high correlation between the observed clinical signs and the ILTV detection, and the results of differential diagnosis demonstrated that ILTV was the causative agent of the outbreak of respiratory disease observed in Bastos region, São Paulo, Brazil.
Abstract in English:The association of human foodborne salmonellosis with poultry products enhanced the efforts to control Salmonella Enteritidis in poultry farms. Dietary organic acid supplementation is one of the measures currently used to reduce the presence of undesirable microorganisms. Another method to control enteric Salmonella in poultry is competitive exclusion using defined or undefined microorganisms products. Organic acids and microbiological methods to accelerate the development of the intestinal microbiota can be used individually or in combination. The present study evaluated the effect of dietary supplementation of an acidifier and of a defined multi-strain microbial mixture (Biomin® PoultryStar) via drinking water in the control of the intestinal colonization of broilers by Salmonella Enteritidis. Four experiments were performed. The first experiment showed that the organic acids mixture was able to prevent Salmonella Enteritidis colonization of ceca in both inclusion rates applied (p<0.05). In the second and third experiments the probiotic either individually or in combination the acidifier, both in high and low doses reduced the incidence of Salmonella Enteritidis in the cecal contents (p<0.05). In these three experiments, birds were orally challenged. Similar results were obtained in a fourth trial, in which challenge was made by contact.