V. J. M. Savino

Resistência ao Estresse Calórico em Frangos de Corte de Pescoço Pelado

Birds of two lineages, a carrier of the Naked Neck gene (Na_) that determines reduction in the feathering and other non-carrier (normal feathering, nana), were submitted to thermal stress (38, 40 and 42oC) in climatic chambers at 28, 35 and 42 days of age to verify the resistance to the thermal stress. Significant differences were verified among the mean rectal temperature of the normal feathered lineage when compared with the naked neck lineage, in all the ages and stress periods, with higher values in the normal feathered birds. The same result was found for mean respiratory rate. Significant difference was found for weight loss between the two lineages only at the age of 35 days. The results obtained suggest that the Naked Neck lineage possesses higher resistance to the thermal stress in relation to the normal feathered lineage.

Behavior and performance of broiler strains reared under semi-intensive system with shaded areas

The matter of animal welfare has led to studies in order to evaluate alternative rearing systems for livestock in order to improve well-being. The semi-intensive system is an alternative method of rearing broilers in which the birds are kept in a poultry house and have free access to a pasture area during the day. It is known that ambient conditions may directly affect the behavior of birds reared in the semi-intensive system. Therefore, this research evaluated the behavior of four broiler strains reared under a semi-intensive system with a shaded area (provided by a black plastic screen - 50%) and the bioclimatic characteristics of this environment when compared with the non-shaded pasture. Thirty-five birds were reared in pens with 4.5 m2 and 35 m2 of pasture. Ambient variables were measured throughout the day to calculate the indexes of thermal comfort (BGHI and enthalpy). Data was analyzed in a 4 x 2 factorial (4 strains and 2 rearing environments) with 2 repetitions, in order to establish the rate of bird permanence in the pasture. There was an improvement in the ambient conditions of the shaded pasture in the hottest hours of the day (from 10:00 to 14:00 h), i.e., there was a reduction in the mean values of BGHI (approximately 26%) and enthalpy (36%). As a consequence, there was an increase in the rate of permanence in this environment if compared with the non-shaded pasture. Three out of four evaluated strains showed better adaptability to the semi-intensive rearing system.

Influence of The Genotype and Sex on The Hematocrit Value of Meat-Type Chicken

The objective of this research was to evaluate the effect of the genotype and sex on the value of meat-type chicken hematocrit (percentage packed cells volume). One hundred and eighty breeders of 18 experimental genotypes were used. Individual samples of blood were collected and the percentage packed cells volume was determined. For the factor genotype, it was possible to distinguish two different groups with averages changing from 45,83 to 41,69% and 41,24 to 37,21%. For sex, the values showed significant difference with values of 46,20 ± 4,14% for males and 35,74 ± 3,16% for females. In conclusion the genotype and sex influenced the hematocrit value in meat-type chickens, above to cluster every genotypes in two groups.

Influence of egg pre-storage heating period and storage length on incubation results

This experiment aimed at evaluating the influence of different heating times of settable eggs of Cobb 500® broiler breeders before submitting them to different storage periods on egg weight loss, embryo mortality, and hatchability. A total number of 1,980 eggs were distributed in a completely randomized experimental design with a 3 x 3 factorial arrangement, comprising nine treatments with 22 replicates of 10 eggs each. The following factors were analyzed: pre-storage heating periods (0, 6, 12 hours at 36.92°C) and storage periods (4, 9, 14 days at 12.06°C). After storage, eggs were incubated under usual conditions, and were transferred to the hatcher at 442 hours of incubation. Eggs were weighed before heating, incubation, and transference to determine weight loss. Partial hatchability was determined at 480 hours, and total hatchability at 498 hours of incubation. Embryo mortality was determined in non-hatched eggs. It was concluded that heating eggs for six hour before storage improves incubation results as it decreases incubation length and late embryo mortality, therefore its use can be indicated in commercial operations. Storing eggs for 14 days and pre-heating for 14 days and pre-heating for 12 hours severely impair incubation results, and therefore are not recommended.

Adaptação de linhagens de galinhas para corte ao sistema de criação semi-intensivo

Birds of four meat-type chicken lines were reared at the semi-intensive system with the objective of evaluate the adaptation to these breeding systems through environmental and behavioural parameters. The experimental period took place between 35 and 75 days of age during which it was collected data of number of broilers in the pasture, air temperature and relative humidity inside the boxes and in the pasture areas, and percentage of shadow in the pasture areas. Environmental factors influenced the behaviour of the evaluated lines. The bioclimatic analysis and the observation of the chicken behaviour allowed to discriminate the studied lines regarding to the adaptation to the semi-intensive breeding system. The broilers of the evaluated lines showed adaptation to the semi-intensive system, presenting the expected behaviour for this breeding system.

Influence of egg pre-storage heating period and storage length on the digestive tract of newly-hatched broiler chicks

Universidade de Sao Paulo Faculdade de Zootecnia e Engenharia de Alimentos Departamento de Zootecnia