D. E. Faria Filho

Performance and carcass characteristics of broiler chickens with different growth potential and submitted to heat stress

In order to evaluate the effects of broiler genotype and of heat exposure on performance, carcass characteristics, and protein and fat accretion, six hundred one-day-old male broilers were randomly assigned in a 2 x 3 factorial arrangement, according to the following factors: genetic group (selected and non-selected broilers) and pair-feeding scheme (Ad 32 - reared under heat stress and fed ad libitum; Ad 23 - reared at thermoneutrality and fed ad libitum; Pf 23 - reared at thermoneutrality and pair fed with Ad 32 ), with a total of six treatments with four replicates of 25 birds each. Independent of pair-feeding scheme, selected broilers showed better feed conversion, higher carcass yield, and lower abdominal fat deposition rate. However, as compared to non-selected broilers, they reduced more intensively feed intake when heat exposed, which promoted significant breast-yield decrease, and more pronounced changes on carcass chemical composition. These findings allows concluding that, in both genetic groups, both environmental temperature and feed-intake restriction influence abdominal fat deposition rate and other carcass characteristics; however, the impact of heat exposure on broiler performance is more noticeable on the selected line.

Effect of energy intake on performance and carcass composition of broiler chickens from two different genetic groups

In order to evaluate the effect of energy intake and broiler genotype on performance, carcass yield, and fat deposition, 600 one-day-old male chicks from two different genetic groups (AgRoss 308 - commercial line and PCLC - Embrapa non-improved line) were fed diets with different metabolizable energy level (2950, 3200 and 3450 kcal/kg). A completely randomized experimental design in a 2X3 factorial arrangement with four replications of 25 birds per treatment was applied. In order to ensure different energy intake among treatments within each strain, feed intake was daily adjusted by pair-feeding schemes. AgRoss 308 broilers had better performance and carcass yield, and presented lower abdominal fat deposition rate. In both genetic groups, the highest dietary energy level increased weight gain, heart relative weight, and fat deposition. However, it reduced the difference between AgRoss 308 and PCLC for feed conversion ratio and carcass protein deposition. These findings allow concluding that genetic improvement had a significant effect on broiler energy metabolism, and that the highest performance differences between genetic groups are found when low-energy intake is imposed.

Effect of mannanoligosaccharides and/or enzymes on antibody titers against infectious bursal and Newcastle disease viruses

The effect of including mannanoligosaccharides (MOS) and/or enzymes in broiler diets on antibody titers against infectious bursal disease virus (IBDV) and Newcastle disease virus (NDV) was evaluated. A total of 750 broilers were distributed into a completely randomized experimental design in a factorial arrangement 2 x 2 + 1 with two levels of MOS (0 and 0.1% until 21 days and 0.05% from 22 to 42 days of age), two levels of enzymes (0 and 0.05%) and a positive control diet containing antibiotic, totaling five treatments with five replicates each. For antibody analyses, blood samples were weekly collected by jugular vein puncture in the same two birds per replicate. The first and last collections were done at 7 and 42 days of age, respectively. The inclusion of MOS resulted in increased antibody titers against IBDV in the fourth (P<0.03) and fifth (P<0.02) weeks, and against NDV in the third (P<0.01), fourth (P<0.03) and fifth (P<0.03) weeks of age. MOS was effective in stimulating the humoral immune responses against IBDV and NDV vaccine viruses.

Classification of coefficients of variation in experiments with commercial layers

This study aimed at determining a specific classification of coefficients of variation in experiments with commercial layers. Coefficients of variation were collected from papers published in Brazilian journals between 2000 and 2009 for performance, internal egg quality, and eggshell quality parameters. The coefficients of variation of each parameter were classified as low, intermediate, high, and very high according to the ratio between the median and the pseudo-sigma. It was concluded that the parameters used in experiments with commercial layers have a specific classification of coefficients of variation, and that this must be considered to evaluate experimental accuracy.

Breeder age and bone development in broiler chicken embryos.

O efeito da idade da matriz sobre o desenvolvimento dos ossos longos foi estudado em embrioes de frango de 12 dias de incubacao ate o nascimento. Ovos ferteis foram incubados e distribuidos em delineamento inteiramente casualizado em arranjo fatorial 2 x 6 (duas idades de matriz - 38 e 60 semanas e seis dias de incubacao - 12, 14, 16, 18, 20 e 21 dias). Determinou-se a atividade enzimatica das fosfatase alcalina e acida-resistente ao tartrato no peso e nas epifises da tibia, no comprimento e na largura da tibia e do femur. A atividade das fosfatases nao foi afetada pela idade da matriz. O peso absoluto e a largura de femur e tibia foram maiores nos embrioes das matrizes com 60 semanas de idade. Atividade enzimatica e medidas morfometricas aumentaram com o dia de incubacao independentemente da idade da matriz. Concluiu-se que o processo de ossificacao endocondral durante os dois ultimos tercos de desenvolvimento embrionario nao foi influenciado pela idade das matrizes. No entanto, em termos de peso absoluto, os ossos longos de embrioes provenientes de matrizes velhas foram mais pesados o que foi associado a maior largura e nao ao maior comprimento dos ossos.

Response surface models to predict broiler performance and applications for economic analysis

A study was carried out to elaborate response surface models using broiler performance data recovered from literature in order to predict performance and elaborate economic analyses. Nineteen studies published between 1995 and 2005 were retrieved using the systematic literature review method. Weight gain and feed conversion data were collected from eight studies that fulfilled the pre-established inclusion criteria, and a response surface model was adjusted using crude protein, environmental temperature, and age as independent variables. The models produced for weight gain (r2 = 0.93) and feed conversion (r2 = 0.85) were accurate, precise, and not biased. Protein levels, environmental temperature and age showed linear and quadratic effects on weight gain and feed conversion. There was no interaction between protein level and environmental temperature. Age and crude protein showed interaction for weight gain and feed conversion, whereas interaction between age and temperature was detected only for weight gain. It was possible to perform economic analyses to determine maximum profit as a function of the variables that were included in the model. It was concluded that the response surface models are effective to predict the performance of broiler chickens and allow the elaboration of economic analyses to optimize profit.

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.

Crude protein and metabolizable energy levels for layers reared in hot climates

The objective of the present study was to evaluate the effects of different dietary crude protein (CP) and metabolizable energy (ME) levels on the performance, internal and external egg quality, and cloacal temperature of commercial layers reared in hot climate. In this trial, 100 commercial Hy-Line W-36 layers between 20 and 32 weeks of age were distributed according to a completely randomized experimental design with a 2 x 2 factorial arrangement, consisting of two CP levels (15 e 18%) and two ME contents (2700 and 3100 kcal/kg) with five replicates per treatment and 10 birds per replicate. Performance (feed intake, egg production, egg mass, and feed conversion ratio), internal (Haugh units and albumen and yolk percentage) and external (eggshell % and thickness) egg quality parameters were evaluated. Cloacal temperature was measured in two birds per replicate at 8:00 h and 13:00 h. The diet containing 2700 kcal ME/kg promoted the best performance, whereas the worse performance observed in birds fed the diet with 3100 ME/kg was partially recovered when the diet contained 18% CP. Haugh units worsened as dietary CP level increased. The other external and internal egg quality parameters were not affected by dietary CP or ME levels. The cloacal temperature of birds fed 15% CP was lower in the morning and higher in the afternoon relative to those fed 18% CP, which temperature did not change during the day. It was concluded that dietary CP and ME levels influenced the performance and the body temperature of commercial layers.

The inclusion of coffee in commercial layer diets

This experiment aimed at evaluating the effect of the dietary inclusion of caffeinated and decaffeinated coffee on the performance and internal and external egg quality of commercial layers. One hundred and twenty 25-week-old Hy-line Brown layers, with 1575 ± 91 average body weight, were distributed according to a completely randomized experimental design with three treatments (control, 1.2% caffeinated coffee, or 1.2% decaffeinated coffee) of five replicates of eight birds each. The inclusion of 1.2% caffeinated coffee was calculated to supply 6mg caffeine per kg body weight, which is considered a moderate dose. The applied treatments did not influence (p>0.05) feed intake, egg production, egg weight, egg mass, feed conversion ratio, Haugh units, yolk color or albumen and yolk percentages. The eggs of hens fed 1.2% caffeinated coffee presented lower (p<0.05) eggshell thickness and egg specific density. The eggs of layers fed 1.2% caffeinated coffee tended (p=0.0637) to present lower eggshell percentage. It was concluded that feeding caffeinated coffee to commercial layers does not affect their performance or internal egg quality; however, eggshell quality is impaired.

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