Níveis de lisina digestível da ração e temperatura ambiente para frangos de corte em crescimento

Este estudo foi conduzido para avaliar os efeitos dos níveis de lisina digestível da ração e da temperatura ambiente sobre o desempenho e as características de carcaça de frangos de corte dos 22 a 42 dias de idade. Foram utilizados 672 frangos Ross®, machos, com peso médio de 726 g, em delineamento inteiramente casualizado segundo arranjo fatorial 4 × 4, com seis repetições de sete aves. Os frangos foram mantidos nas temperaturas de 18,5; 21,1; 24,5 e 27,0ºC e foram alimentados com rações com diferentes níveis de lisina digestível (0,934; 1,009; 1,084 e 1,159%). Não houve interação temperatura ambiente × níveis de lisina da ração para as variáveis estudadas. O consumo de ração (CR) e o ganho de peso (GP) não foram influenciados pelos níveis de lisina. O consumo de ração reduziu linearmente com a temperatura ambiente e o ganho de peso aumentou até a temperatura estimada de 21,5ºC. A conversão alimentar melhorou até o nível estimado de 1,085% de lisina digestível. Os pesos de carcaça (PC), peito com osso (PPO), coxa (PCX) e sobrecoxa (PSCX) aumentaram até as temperaturas estimadas de 21,9; 21,0; 22,7 e 23,7ºC, respectivamente. Os rendimentos de carcaça (RC), coxa (RCX) e sobrecoxa (RSCX) aumentaram, enquanto o peso do peito sem osso (PPSO) e os rendimentos de peito com osso (RPO) e sem osso (RPSO) reduziram linearmente com a temperatura ambiente. O PCX e o RCX aumentaram, mas o RSCX reduziu linearmente com os níveis de lisina da ração. O PC, PPO, PSCX, RC, RPO e o RPSO não foram influenciados pelos níveis de lisina. A temperatura ambiente no intervalo de 18,5 e 27,0ºC não influenciou as exigências de lisina das aves. A condição para melhor conversão alimentar no período de 22 a 42 dias foi obtida com o nível de 1,085% de lisina digestível na ração e com a temperatura ambiente estimada de 23,3ºC.

Jejum Pré-abate em Frangos de Corte

As condições ideais dos frangos de corte no momento do abate devem ser conhecidas a fim de possibilitar a produção de carne de excelente qualidade, uma vez que diversos fatores pré e pós-abate estão envolvidos na qualidade final. em condições normais de abate e processamento, a retirada de ração é feita de 6 a 8 horas antes da apanha das aves, resultando em um período total de jejum de 8 a 12 horas antes do abate, para esvaziar o intestino e com isso minimizar a contaminação no abatedouro. A escalda, depena e evisceração são pontos importantes de contaminação cruzada no abatedouro devido à grande quantidade de microorganismos aderidos às penas, pele e patas das aves e ao rompimento das vísceras durante a evisceração. Entretanto, a desidratação da carcaça começa imediatamente após o início do jejum. Períodos prolongados de jejum podem afetar o pH das diversas partes do intestino, aumentando a presença de Salmonella e outros microorganismos patogênicos. Além disso, determinam uma maior contaminação pela bile, e são, subjetivamente, associados à fragilidade dos intestinos durante a evisceração mecânica. Portanto, os esquemas de processamento devem ser estabelecidos levando-se em conta a integridade e o esvaziamento do intestino e da vesícula biliar, bem como a desidratação e os seus efeitos sobre o bem estar das aves, contaminação da carcaça e qualidade da carne. Como alguns efeitos do jejum ainda não são bem conhecidos, sugerem-se pesquisas nas seguintes áreas: definir o tempo ótimo de jejum para atender o bem estar das aves, minimizar a contaminação e otimizar os parâmetros de qualidade de carcaça; estudar os efeitos de períodos prolongados de jejum sobre o pH e a colonização do papo, pró-ventrículo, moela, intestino delgado, intestino grosso e cecos por enterobactérias, como Salmonella, por exemplo; efeito do jejum sobre o tamanho e cor do fígado. O resultado esperado é um aumento na qualidade final dos produtos aliado a uma redução nas perdas e no custo de produção.

Life cycle and host specificity of Amblyomma triste (Acari : Ixodidae) under laboratory conditions

We report biological data of two generations of Amblyomma triste in laboratory and compared the suitability of different host species. Infestations by larval and nymphal stages were performed on guinea pigs (Cavia porcellus), chickens (Gallus gallus), rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus), wild mice (Calomys callosus), dogs (Canis familiaris) and capybaras (Hydrochaeris hydrochaeris). Infestations by adult ticks were performed on dogs, capybaras and rabbits. Tick developmental periods were observed in an incubator at 27degreesC and RH 90%. Guinea pigs were the most suitable hosts for larvae and nymphs, followed by chickens. The remaining host species were less suitable for immature ticks as fewer engorged ticks were recovered from them. Mean larval feeding periods varied from 3.8 to 4.7 d between different host species. Mean larval premolt periods ranged from 8.9 to 10.4 d. Nymphal mean feeding periods varied from 4.2 to 6.2 d for ticks fed on different host species. Premolt period of male nymphs (mean: 15.4 d) was significantly longer than that of female nymphs (14.7 d). Female nymphs were significantly heavier than male nymphs. The overall sex ratio of the adult ticks emerged from nymphs was 0.9:1 (M:F). Capybaras were the most suitable host for the tick adult stage as significantly more engorged females were recovered from them and these females were significantly heavier than those recovered from dogs or rabbits. The life cycle of A. triste in laboratory could be completed in an average period of 155 d. The potential role of guinea pigs, birds and capybaras, as hosts for A. triste in nature, is discussed.

Effect of acute heat stress on heat shock protein 70 messenger RNA and on heat shock protein expression in the liver of broilers

1. The synthesis of heat shock protein 70 (Hsp70) mRNA and the expression of Hsp70 in the liver of broiler chickens submitted to acute heat stress (35 degrees C for 5 h) was investigated.2. Hsp70 expression was detected by SDS-PAGE and Western blot analysis using a polyclonal antiserum against Hsp70 of Blastocladiella emersonii. The specific signal of Hsp70 mRNA was analysed by Northern blot using as probe a Hsp70 cDNA of B. emersonii.3. An increase in the amount of Hsp70 was detected from the first up to the fifth hour of acute heat exposure. This increase in the amount of Hsp70 was accompanied by an increase in Hsp70 mRNA which peaked at 3 h.4. This study shows that the heat induced increase in Hsp70 mRNA and protein in broiler liver, in vivo, are time dependent, similar to that in mammals.

Inhibition between Salmonella-strains - A new aspect of Salmonellosis control in poultry

Freshly hatched chickens show a very high susceptibility to Salmonella infections and control measures are therefore frequently focused on the period shortly after hatching. Experimental investigations using one strain against itself, differentiated by different antibiotic resistance markers, have shown that colonisation with Salmonella prevents the establishment of subsequently inoculated challenge organisms in the chicken gut. The inhibition effect lasts for several days and is detectable even when a challenge dose of 10(8) organisms is used. It is independent of the breed of bird. Chickens colonised with Salmonella shed a subsequently inoculated challenge strain with significant lower numbers for several weeks than do non colonised control birds. The phenomenon is strain specific but not serovarspecific as has been shown in investigations using different strains of the same and other serovars for colonisation and challenge. The phenomenon shows a large variability between strains. Using other Enterobacteriaceae strains comparable inhibition against Salmonella was not observed.One important topic for further investigation is the capability of Salmonella live Vaccines given orally to establish a protection effect, based on the inhibition phenomenon in the first few days of live, developing into a long-lasting immunity when the birds reach immunological maturity.

Effect of early feed restriction and enzyme supplementation on digestive enzyme activities in broilers

The effect of feed restriction and enzymatic supplementation on intestinal and pancreatic enzyme activities and weight gain was studied in broiler chickens. Quantitative feed restriction was applied to chickens from 7 to 14 d of age. An enzyme complex mainly consisting of protease and amylase was added to the chicken ration from hatching to the end of the experiment. Birds subjected to feed restriction whose diet was not supplemented showed an increase in sucrase, amylase, and lipase activities immediately after the restriction period. Amylase, lipase, and chymotrypsin activities were higher in chickens subjected to feed restriction and fed a supplemented diet than in those only subjected to feed restriction. Trypsin activity increased after feed restriction and after supplementation, but there was no interaction between these effects. Early feed restriction had no effect on enzyme activity in 42-d-old chickens. Chickens subjected to early restriction and fed the supplemented diet presented higher sucrase, maltase, and lipase activities than nonsupplemented ones (P < 0.05). There was no effect of early feed restriction or diet supplementation on weight gain to 42 d. Percentage weight gain from 14 to 42 d of age was equivalent in feed-restricted and ad libitum fed birds. Feed-restricted broilers fed a supplemented diet showed a higher percentage weight gain than nonsupplemented birds. We conclude that enzymatic supplementation potentiates the effect of feed restriction on digestive enzyme activity and on weight gain.

Farelo de trigo e complexo enzimático na alimentação de poedeiras semipesadas na fase de produção

The study was carried out with the objective to evaluate the effects of the inclusion of the wheat bran (WB) with or without supplementation of an enzymatic complex (EC) on the performance of semi-heavy hens in the egg-production phase. A total of 288 Lohmann Brown pullets were used, distributed to a completely randomized design in 4 x 2 factorial arrangement, composed by four WB levels (0, 3, 6 and 9%) in the ration and enzymatic complex supplementation (0 or 100g/100 kg diet), with eight treatments and six replicates of six birds. The enzymatic complex contained the enzymes beta-galactosidase, galactomananase, xilanase and alpha-glucanase. Feed intake, final body weight, egg production, egg weight, egg mass, egg mass feed conversion or egg dozen feed conversion was not affected by WB inclusion in the diets. Egg shell specific gravity deteriorated as WB levels increase in the diets. None of the characteristics was affected by the enzymatic complex supplementation, except for egg weight, that improved from 62.74 to 64.28 g. Then, the use up to 9.0% of wheat bran in the ration is recommended for semi-heavily chickens in the production phase. The supplementation of alpha-galactosidase, galactomannanase, xylanase and alpha-glucanase improve egg weight.

Maternal antibody transfer to broiler progeny varies among strains and is affected by grain source and cage density

Two experiments were conducted to examine the effects of broiler breeder dietary grain source and cage density on maternal antibody (MatAb) transfer to progeny in 2 genetic strains (A and B). Broiler breeders were assigned to 16 litter floor pens and fed either corn- or wheat-based diets. Breeders were administered 4 live vaccines against Newcastle disease virus (NDV). At 23 wk of age, pullets and cocks, which reflected the full BW distribution from each treatment, were moved to a cage breeder house and placed at 1 or 2 hens/cage. Breeders were artificially inseminated at 44 wk (experiment 1) and 52 wk of age (experiment 2). Eggs were collected for 8 d, incubated, and placed in individual pedigree bags at d 19 of incubation. Blood samples from 5 chicks per treatment combination were collected at hatch in both experiments. Spleen and bursa were collected from the same chicks for histomorphometry analyses in experiment 2. In the second experiment, 12 chicks per treatment were placed in cages. Progeny were provided diets based on the same grain (corn or wheat) as their parents. Serum samples were collected at 5, 9, and 13 d of age and analyzed for anti-NDV MatAb. Data were analyzed as a 2 x 2 x 2 factorial design considering strain, dietary grain source, and cage density as main factors. Interaction effects were observed in breeders and progeny. Experiment 1 showed that strain A chicks had lower levels of MatAb when hens were housed at 2 hens/cage rather than 1 hen/cage. The MatAb levels of strain B chickens were not affected by cage density in either experiment. Experiment 2 demonstrated similar effects of cage density on MatAb levels and the area of bursa follicles for both strains. Progeny of breeders fed corn-based diets had smaller spleen white pulp only when hens were housed at 2 hens/cage compared with 1 hen/cage. The results of these experiments suggest that breeder strain and cage-density conditions affected MatAb transfer to progeny and embryo development of spleen and bursa.

Predicting body and carcass characteristics of 2 broiler chicken strains using support vector regression and neural network models

As a new modeling method, support vector regression (SVR) has been regarded as the state-of-the-art technique for regression and approximation. In this study, the SVR models had been introduced and developed to predict body and carcass-related characteristics of 2 strains of broiler chicken. To evaluate the prediction ability of SVR models, we compared their performance with that of neural network (NN) models. Evaluation of the prediction accuracy of models was based on the R-2, MS error, and bias. The variables of interest as model output were BW, empty BW, carcass, breast, drumstick, thigh, and wing weight in 2 strains of Ross and Cobb chickens based on intake dietary nutrients, including ME (kcal/bird per week), CP, TSAA, and Lys, all as grams per bird per week. A data set composed of 64 measurements taken from each strain were used for this analysis, where 44 data lines were used for model training, whereas the remaining 20 lines were used to test the created models. The results of this study revealed that it is possible to satisfactorily estimate the BW and carcass parts of the broiler chickens via their dietary nutrient intake. Through statistical criteria used to evaluate the performance of the SVR and NN models, the overall results demonstrate that the discussed models can be effective for accurate prediction of the body and carcass-related characteristics investigated here. However, the SVR method achieved better accuracy and generalization than the NN method. This indicates that the new data mining technique (SVR model) can be used as an alternative modeling tool for NN models. However, further reevaluation of this algorithm in the future is suggested.

Anticoccidial effects of coumestans from Eclipta alba for sustainable control of Eimeria tenella parasitosis in poultry production

The aim of this study was to evaluate the anticoccidial efficacy of a product containing coumestans from Eclipta alba. Experimental conditions were set up as to reproduce the environment conditions for husbandry adopted in commercial broiler farms. Broilers were raised in broiler chicken shed provided with feeders, drinkers, illumination and temperature control systems and floor covering to afford an adequate nourishing environment. Male Cobb broilers (240) were assigned to four experimental groups being each experimental group set apart in rice straw-covered shed isolated with wire mesh. One-day-old broilers were reared in a coccidian-free environment with ad libitum supply of filtered water and freely available standard feed, from the 1st to the 35th day of life. The T1 group received standard feed (negative control); T2 was treated with standard feed supplemented with 66 ppm of salinomycin (positive control); groups T3 and T4 had standard feed supplemented with the ethyl acetate fraction from methanolic extract of E. alba aerial parts, which contains the coumestans WL and DWL (120 and 180 ppm, respectively). The chicken broilers were individually infected with 2 x 104 oocysts of Eimeria tenella when they were 14 days old and were monitored weekly to evaluate zootechnical parameters such as weight gain and food conversion ratio. Counting of coccidial oocyst in chiken feces was assessed from random samples, from the 21st to 28th days of life, which corresponded to 7-14 days after the infection. Five chickens selected at random from each experimental group were subsequently euthanized at 21, 28 or 35 days of life to determine the lesion score in the cecal region and to excise a cecum portion for histopathological evaluation. The group treated with coumestans from E. alba presented an average weight gain and food conversion ratio higher than the negative control group and similar to the mean value of the positive control group. Coumestan-treated groups showed a significant decrease in the oocyst counting since the 21th day of life and displayed a reduced number of macroscopic lesions. Histopathological evaluations of cecum fragments showed that both treatments induced the migration of defense cells at the site of infection. A severe destruction of the cecal lining was found in the intestinal tract of broilers fed with a coumestans dose of 180 ppm. Overall, our results validate the use of a phytotherapy containing E. alba coumestans at a dose of 120 ppm as a therapeutic or prophylactic agent against avian coccidiosis. (C) 2010 Elsevier B.V. All rights reserved.

Ileal and caecal microbial populations in broilers given specific essential oil blends and probiotics in two consecutive grow-outs

Specific essential oil (EO) blends and probiotics used as feed additives have been shown to promote healthy digestive microbials resulting in improved poultry production. Two consecutive experiments were conducted with broilers fed corn-soybean meal diets to determine comparative effects of feed additives on ileal and caecal microbial populations (MP). Ross 708 broilers were placed in 84 pens with previously used litter and treatments maintained in the same pens for both experiments. Eight treatment groups were fed diets containing: Bacitracin methylene disalicylate (BMD) as positive control (PC); no additives as negative control (NC); three probiotics: BC-30; BioPlus 2B (B2B); and Calsporin; and the essential oil blends Crina Poultry Plus (CPP) at 300 or 150 ppm in the first experiment; and CPP at 300 ppm and Crina Poultry AF at 100 ppm in experiment 2. Starter and grower diets contained the ionophore (Coban). Ileal and caecal samples were collected at 43 days of age from male broilers. The DNA of microbial populations was isolated from digesta samples and analysed by denaturing gradient gel electrophoresis to generate percentage similarity coefficients (%SC) from band pattern dendrograms. Differences were observed in ileal and caecal populations depending on treatment, respectively, and especially between experiments. Broilers fed diets with probiotics had very similar MP. The EO CPP at 300 ppm resulted in ilea! MP similar to those observed in chickens fed probiotics. We concluded that antibiotic treatment affected ileal, but no caecal MP. More pronounced changes in ileal and caecal MP were seen in broilers at 43 days of age following probiotic and essential oil treatments.

Effects of broiler breeder genetic, diet type, and feeding program on maternal antibody transfer and development of lymphoid tissues in chicken progeny

Maternal antibody (MatAb) transfer is important for early chicken survivability. Diet composition and the amount of feed given to breeder pullets during rearing may affect the development of immunity and the transfer of MatAb to progeny, and could affect progeny performance and resistance to disease. The effects of broiler breeder nutrition and feeding management practices were evaluated for the transfer of MatAb to progeny and for spleen and bursa development at hatching in 2 genetic strains (A and B). In this experiment, the levels of MatAb against Newcastle disease virus were assessed by enzyme-linked immunosorbent assays in serum samples taken of pedigreed chicken progeny from hatching to 13 d of age. Chickens were fed corn-and wheat-based diets, as were their parents. The breeder feeding program and diet type altered the Newcastle disease virus MatAb found in progeny at hatching and affected how long these antibodies were maintained in circulation. Bursal follicle size at hatching was influenced by an interaction among all factors evaluated. Percentage of white pulp in the spleen was affected mainly by genetic strain and diet type, but responses varied according to the breeder feeding program. It was concluded that breeder feeding programs influence MatAb transfer and half-life, and may also affect the early development of lymphoid tissues.

In vitro characterization of intra-generic inhibition of growth in Salmonella typhimurium

The intra-generic inhibition of bacterial growth observed previously in vivo and in vitro with strains of Salmonella, Citrobacter and E. coli was studied in vitro using S. typhimurium strain F98. There was complete inhibition of multiplication of S. typhimurium when it was added to stationary-phase broth cultures of different Salmonella serotypes, but only partial inhibition when added to broth cultures of E. coli. The degree of inhibition between different mutants of F98 was affected by the numbers of bacteria of the inhibiting strain, but this was not the only factor, since exponential-phase bacterial cells were less inhibitory than stationary-phase cells. The inhibitory effect was produced at temperatures between 20°C and 40°C. The complete inhibition of growth observed between F98 mutants was abolished by ampicillin, rifampicin and streptomycin, but not by nalidixic acid. Inhibition was also prevented by separating the two cultures by a dialysis membrane. A Tnpho A Insertion mutant of F98 was produced which did not show inhibition in vitro but was still inhibitory in vivo. It is suggested that this complete inhibition of bacterial multiplication between organisms of the same genus, which is greater than that produced between organisms from different genera, is mediated by a cell surface protein.