Resumo em Inglês:

This article describes the genetic evolution of commercial broilers between 1990 and 2009, considering live performance, in particular, in terms of weight gain and feed conversion ratio. In order to determine if the assumption that the relationship between body weight gain and feed conversion ratio is increasing and positive, information on all broiler strains reared in Brazil were collected from several companies present in five Brazilian regions. This survey aimed at evaluating broiler live performance as a function of genetic improvement with time. Broiler performance improved, as shown by the statistical differences obtained for the following parameters: livability, live weight, daily weight gain, feed conversion ratio, and production efficiency index between 1990 and 2009. However, live weight gain and feed conversion ratio are emphasized due to the significant differences found along the studied period.

Resumo em Inglês:

The present study was carried out to examine the effect of vitamin premix reduction or withdrawal in finisher diet (29 to 42 days of age) on the performance and meat quality of chicks fed a wheat/barley based diet and reared on floor pens. A total of 504 male broiler chicks (Ross® 308) were allocated to seven treatment groups, with four replicates per treatment and 18 birds per replicate. All data were analyzed according to a completely randomized design. Results showed that the reduction or withdrawal of the vitamin premix from diets in different weeks of finisher period did not affect chicken performance (p>0.05). There were no significant differences in TBARS values of thigh samples of birds slaughtered at 35 days of age. However, the TBARS value of the treatment without vitamin premix was significantly higher than in the other treatments (p < 0.05) when birds were slaughtered at 42 days of age. Finally, the results of this study demonstrated that it is not possible withdrawal all premix vitamin of the diet. However, it may be possible to reduce vitamin supplements in finisher broiler diets without any negative effects on performance or meat quality during freezing.

Resumo em Inglês:

Storing hatchable eggs is a common practice in commercial hatcheries. However, storage time may negative effects on several performance parameters. An experiment was carried out to evaluate inverting egg position during storage of eggs laid by young and old layer breeders. Fertile eggs of 32 and 58-week-old breeders were stored for seven, 14, and 21 days at 18ºC ± 2ºC and 80% ± 10% relative humidity (RU). The following parameters were evaluated: egg weight loss, hatchability and hatchling weight, and embryodiagnosis results. Eggs stored with the small end up lost less weight during storage compared with the control eggs. Storing eggs for 14 days with the small end up reduced early embryo mortality, improving hatchability. In addition, hatchling weight increased. These results show that the detrimental effects of long storage periods may be alleviated when eggs are stored with the small end up to 14 days of storage.

Resumo em Inglês:

The study was conducted to evaluate carcass yield and chemical composition of thigh and breast muscles of broilers fed three different lysine requirement levels: high lysine (+10% NRC), standard (NRC) and low lysine (-10% NRC) and two ways of expressing amino acids in feedstuffs (total or digestible amino acids). The results of this study showed that diet formulation based on digestible amino acids significantly influenced breast yield and abdominal fat deposition. The study showed that increasing lysine level (+10% NRC) of diet significantly increased both carcass and breast percentage and also carcass, breast and thigh weight. The interaction between digestible amino acids and lysine requirement levels affected carcass and breast percentage. Feeding broilers high lysine diets (+10% NRC) significantly increased lysine content in breast and thigh. The response to formulation based on digestible amino acids was maximized when broilers received the high lysine level diet.

Resumo em Inglês:

Levamisole hydrochloride (Lev.HCl) has been acclaimed to boost immune response particularly in immunocompromised state. Its routine use as an immunomodulator in poultry production is yet to be well embraced, thus its effects of on cellular immunity and flock performance of commercial broilers were evaluated. One hundred and fifty Anak broiler chicks were separated into two groups of 75 each. Broilers in group 1 were sensitized with 150µg of Staphylococcus aureus antigen each at 4 and 5 weeks, while those in group 2 were not sensitized. Each group was further divided into subgroups A, B, and C. Levamisole hydrochloride (40 mg/kg) was administered orally to 1A and 2A at 45 and 46 days of age and to 1B and 2B at 47 and 48 days of age, while 1C and 2C were not treated. At 47 days of age, 12 broilers from all subgroups were challenged with 75µg of S. aureus antigen each at the right wattle. Wattle thickness was measured till 72 hours post challenge (pc) and delayed wattle reaction (DWR) was determined. Tissues were harvested at 72 hours pc for histopathology. Morbidity, mortality and live weights at 8 weeks of age were recorded. DWR peaked at 4 hours pc in 1A (2.22 ± 0.21 mm) and 1B (2.96 ± 0.21 mm) and 24 hours pc in 1C (3.39 ± 0.34 mm), the difference being significant (p<0.05). Inflammatory lesions were observed in wattles of sensitized subgroups and were more severe in 1C. Mortality rates were 4.17% and 29.17% in 1A and 1C respectively. Mean live weights in A and B i.e. 1.57± 0.06 kg and 1.56 ± 0.06 kg respectively, were significantly higher (p<0.0) than 1.43 ± 0.08 kg in C. Levamisole enhanced DTH via an early response, improved broiler liveability, and its anti-inflammatory property was confirmed.

Resumo em Inglês:

This study investigated the effects of arginine (Arg) supplementation on broiler breeder egg production and egg quality. Male (30) and female (360) Ross® breeders, totaling 390 birds, were studied. A completely randomized design with five Arg levels (0.943%, 1.093%, 1.243%, 1.393%, 1.543% digestible Arg) and six replicates of 12 females and one male per experimental unit was applied. The following performance and egg quality were evaluated: lay percentage, albumen and yolk contents, average egg weight, egg specific gravity, and eggshell percentage and thickness. Hatchability and and embryo mortality were also determined. The applied dietary digestible Arg levels quadratically influenced egg production (p<0.05), with the highest production obtained when 1.262% digestible Arg was supplemented. Egg weight linearly increased (p<0.05) with digestible Arg dietary level; however, egg specific gravity linearly decreased (p<0.05). Hatchability was not affected (p<0.05) by digestible Arg level. The supplementation of broiler breeder diets with Arg improved egg production and egg weight without any effect on hatchability. Further research is needed to determine the effect of dietary Arg supplementation on the performance of the progeny.

Resumo em Inglês:

Carcass quality is one of the main parameters to evaluate broiler welfare, and the presence of back scratches indicates that the birds were submitted to stress. The objective of this study was to identify the best management practices during rearing and catching, taking into consideration broiler genetic differences (genetic lines A and B) and sexes. The survey was carried out in 351 broiler houses belonging to an integrated company and located in the region of Dourados, MS, Brazil. Between January and October, 2010, 2% of broilers of all ages (one to 43 days old) in all flocks were sampled. The sampled flock was evaluated in 21 d intervals. Scratches were classified as present or absent. The results indicated that catching management has the strongest influence on back scratches (73%), followed by rearing management (17%) and equipment management (10%). In general, strain A females presented the lowest probability of presenting scratches after weighing, equipment management, and catching. It was concluded that, although rearing and equipment management practices affected the presence of scratches, catching caused the highest percentage of lesions in birds of both strains, and therefore, it is considered critical. Broilers from distinct that genetic strains reacted differently to management practices due to their temperament and growth rate. Therefore, broilers should be housed according to genetic strain due to their different temperaments.

Resumo em Inglês:

In this study, the effects of boric acid and humate supplementation into hen diets on egg production and quality parameters and blood cholesterol levels were examined. For this aim, totally 160, 40 weeks of age, Hyline-White 98 layers were randomly divided into control and 3 treatment groups each containing 40 birds and 10 replicates (each with 4 birds). There was no boric acid or humate supplementation to control group diets (basal diet) where as treatment groups were supplemented with (basal diet plus) 90 ppm boric acid or 1 g/kg humate, or combination of these two feed additives, respectively. The experimental period lasted in 14 weeks. End of the trial there were no significant effects of dietary boric acid and humate inclusion on feed intake, egg weights and yields, egg quality parameters (shell thickness, breaking strength, and shape index) compared with control. But feed conversion ratio for hens which were supplemented with humate showed negative results while combination humate and boric acid were showed positive result compare with control (p < 0.05). It was also determined that there were no effects of treatments on blood cholesterol levels. As a result, since hens which were fed with basal diet plus boric acid and humate combination showed better feed conversion ratio, these feed additives combination can added diets without any adverse effect for laying hens.

Resumo em Inglês:

Marigold flower extract, a natural pigment, was used to determine its effect on carcass and skin pigmentation, immunity and growth performance of broiler chickens. Two hundred and forty 1-day-old Arbor Acres broiler chicks were randomly distributed into four treatment groups with six replicates in a randomized block design. Birds were fed basal diet for 42 d with or without supplementation of marigold flower extract at various concentrations, i.e., 0 (MG0, control), 100 (MG100), 150 (MG150) and 200 (MG200) mg/kg of feed, respectively. Feed intake and live body weight were weekly recorded. Carcass and shank color, and antibody titers against Newcastle and Influenza viruses were measured. Results showed that marigold flower extract significantly (p<0.05) improved live body weight and relative thymus weight. However, feed intake, feed conversion ratio (FCR), and spleen and bursa weights were not significantly affected. Yellowness (b*) of breast and thigh muscles increased by the dietary supplementation of marigold flower extract compared with the control diet. However, lightness (L*), redness (a*) and redness to yellowness ratio (a/b) were not influenced by the treatments. Moreover, Roche color fan scores of the shank skin were increased at market age (d 42). The results revealed that marigold extract enhanced antibody titers against Newcastle and influenza viruses. It was possible to conclude that the dietary supplementation with marigold flower extract at the rate of 200 mg/kg of feed enhanced carcass and shank color, antibody titers against ND and AI, and growth performance of broiler chickens.

Resumo em Inglês:

In order to estimate the crude protein (CP) equivalence value of Natuzyme-p (NP) enzyme by using regression response equations, two experiments were carried out using Ross (308) broiler chicks. Graded levels of dietary CP (while amino acids levels were kept constant) and NP enzyme were used to derive the regression equation in the first experiment. Four levels of dietary CP and NP enzyme were fed to 160 feather-sexed male broiler chicks during the starter (0-28 d of age) and grower (28-42 d of age) period. Each diet was offered to four replicates of five chicks in a completely randomized design. Results obtained in experiment one failed to fit a regression equation between BW, dietary CP levels and NP enzyme. In experiment two, graded levels of CP changed along with the levels of lysine (Lys), Met+Cys and threonine (Thr). Regression equations between BW and dietary CP and NP enzyme were derived. Nonlinear and linear equations were generated for enzyme and CP. Based on an assessment of r² and P value, nonlinear equations were used to determine enzyme equivalence. The derived regression equations of body weight for CP were set to be equal with those obtained for NP and were solved; enzyme equivalence value for CP was calculated by subtracting the obtained value from CP content of basal diet. Crude protein equivalence value of NP at 28 and 42 d of age was estimated to be 0.96 and 0.38 %, respectively.