Modelagem do crescimento, composição do corpo e das penas em frangos de corte
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Data
2017-06-07
Autores
Gonçalves, Camila Angelica [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O escâner absorciometria de raios-X de dupla energia (DXA) consiste em uma técnica não invasiva para obter informações sobre a composição corporal dos animais, que permite avaliar a dinâmica de crescimento dos mesmos sem que haja a necessidade de abate. Foram conduzidos três experimentos com frangos de corte, realizados com os objetivos de determinar equações que predizem a composição corporal in vivo das aves no equipamento DXA (experimento I), e estimar o potencial genético de três linhagens comerciais (experimentos II e III). No experimento I foram utilizados 720 frangos de corte Cobb (360 machos e 360 fêmeas) distribuídos em delineamento inteiramente casualizado (DIC), dividido em esquema de parcelas subdivididas 3×2×2 (três níveis de proteína bruta nas dietas, dois sexos e duas técnicas nas sub-parcelas) com seis repetições de 20 aves cada. As dietas foram formuladas com o objetivo de alterar a composição corporal das aves, variando a proteína bruta em 70, 100, e 130% da exigência de cada fase avaliada, mas mantendo a relação entre os aminoácidos. Ao todo 216 aves foram digitalizadas no DXA para quantificação dos dados fornecidos pelo equipamento: massa magra, massa gorda, conteúdo mineral ósseo e massa total. Em seguida, as mesmas aves foram mantidas em jejum alimentar de 24h e depois, abatidas e depenadas. Foi realizada a análise química do corpo livre de penas (FFB) das aves para os conteúdos de proteína, água, lipídeos e matéria mineral. Os dados foram submetidos à análise de variância (ANOVA), sendo constatadas diferenças na quantificação da composição corporal pelas diferentes técnicas. Devido à essas diferenças, foram ajustadas regressões para cada componente químico do corpo. Todas as equações estabelecidas apresentaram alta correlação e podem ser utilizadas na avaliação da composição corporal por DXA, de forma direta, em ensaios futuros envolvendo diferenças entre grupos de frangos de corte e de indivíduos ao longo da vida. Através da condução dos experimentos II e III as equações DXA foram validadas e objetivou-se estimar os parâmetros da função Gompertz para avaliar o potencial genético de crescimento do peso vivo, dos constituintes químicos do FFB e das penas para as linhagens comerciais de frangos de corte Cobb, Hubbard e Ross, machos e fêmeas. Em ambos os ensaios, 336 frangos de corte de cada linhagem e sexo foram distribuídos em delineamento inteiramente casualizado, distribuído em esquema fatorial de 3 linhagens × 2 sexos, com quatro repetições (totalizando 24 unidades experimentais). As aves foram alojadas em ambiente termoneutro de 1 a 105 dias de idade e alimentadas com dieta única para machos e fêmeas divididas em quatro fases, contendo 3100 kcal EMAn/kg, formuladas acima das outras exigências nutricionais. As avaliações envolveram 12 aves por linhagem e sexo ao longo do crescimento para obtenção dos dados de composição do corpo livre de penas determinados in vivo por DXA (experimento II) e abate comparativo realizado em 48 aves por linhagem e por sexo ao longo de todo período experimental para a composição química das penas (experimento III). Os dados foram ajustados à curva de crescimento Gompertz e as taxas de deposição calculadas pela equação derivada. Relações alométricas entre os pesos dos componentes químicos do corpo livre de penas e das penas com o peso proteico dos mesmos foram determinadas para descrever as taxas de crescimento dos componentes nos diferentes genótipos. Os resultados evidenciaram o potencial dos machos em atingir maior peso na maturidade, maior crescimento e deposição proteica em comparação às fêmeas. Constatou-se que as linhagens comerciais atuais apresentam maior peso corporal na maturidade e consequentemente taxas de deposição dos componentes em relação a estudos prévios encontrados na literatura. Por alometria, observou que a gordura corporal foi depositada a uma taxa de 22% e 15% superior nas fêmeas e nos machos, respectivamente, em relação à deposição proteica no corpo. Esses resultados mostram as diferenças no potencial de crescimento das linhagens envolvidas e atualizam as curvas de crescimento para cada linhagem de frangos de corte.
The dual-energy X-ray absorptiometry (DXA) consists of a noninvasive technique to obtain information about the body composition of the animals, which allows evaluating the growth dynamics of the animals without the need for slaughter. Three experiments were carried out with broilers, with the objective of determining predictive equations for the in vivo body composition of birds in the DXA equipment (experiment I), and to estimate the genetic potential of three commercial strains (experiments II and III). In the experiment I, 720 Cobb broilers (360 males and 360 females) were distributed in a completely randomized design (DIC), divided into split plot design 3 × 2 × 2 (three crude protein levels in the diets, two sexes and two methods of body evaluation at sub parcels) with six replicates of 20 birds each. The diets were formulated with the objective of altering the body composition of the birds, varying the crude protein in 70, 100, and 130% of the requirement of each evaluated phase, but maintaining the relation between the amino acids. A total of 216 birds were digitized in the DXA to quantify the data provided by the equipment: lean mass, fat mass, bone mineral content and total mass. Then, the same birds were kept in a 24-hour fasting meal, slaughtered and plucked. The chemical analysis of the feather free body (FFB) of birds was carried out for protein, water, lipids and mineral matter content. The data were submitted to analysis of variance (ANOVA), being observed differences between diets, sexes and in the quantification of body composition by the different techniques. Due to the differences between the techniques, regressions were adjusted for each chemical component of the body and for each sex. All the established equations presented an R2 <0.96 and allow the evaluation of body composition by DXA to be determined directly and rapidly in future scans involving broiler chickens. Through the conduction of experiments II and III we aimed to estimate the parameters of the Gompertz function to evaluate the genetic potential of growth of live weight, chemical constituents of FFB and feathers for the commercial lines of broilers Cobb, Hubbard and Ross, males and females. In both trials, 336 broilers of each lineage and sex were distributed in a completely randomized design, distributed in a factorial arrangement of 3 lines × 2 sexes, with four replications (totaling 24 experimental units). The birds were housed in a thermoneutral environment from 1 to 105 days of age and fed a single diet for males and females divided into four phases, containing 3100 kcal ME/kg, and formulated above nutritional requirements. The evaluations involved 12 birds per strain and sex throughout the growth to obtain feather free body composition data determined in vivo by DXA (experiment II) and a comparative slaughter performed in 48 birds per strain and sex throughout experimental period for the chemical composition of feathers (experiment III). The data were adjusted to the Gompertz growth curve and the deposition rates calculated by the derived equation. Allometric relationships between the weights of the chemical components of the FFB and the feathers with their protein weight were determined to describe the growth rates of the different strains. Numerically, the results evidenced the potential of males to reach higher weight at maturity, higher growth and protein deposition compared to females. It was observed that the current commercial lines present higher body weight at maturity and consequently deposition rates of the components in relation to previous studies found in the literature. In general, body fat was deposited at a rate of 22% and 15% higher in females and males, respectively, in relation to protein deposition in the body. The proportion of water and minerals deposited in the body has decreased relative to the protein. These results show the differences in the growth potential of the strains involved and update the growth curves of modern broiler chickens.
The dual-energy X-ray absorptiometry (DXA) consists of a noninvasive technique to obtain information about the body composition of the animals, which allows evaluating the growth dynamics of the animals without the need for slaughter. Three experiments were carried out with broilers, with the objective of determining predictive equations for the in vivo body composition of birds in the DXA equipment (experiment I), and to estimate the genetic potential of three commercial strains (experiments II and III). In the experiment I, 720 Cobb broilers (360 males and 360 females) were distributed in a completely randomized design (DIC), divided into split plot design 3 × 2 × 2 (three crude protein levels in the diets, two sexes and two methods of body evaluation at sub parcels) with six replicates of 20 birds each. The diets were formulated with the objective of altering the body composition of the birds, varying the crude protein in 70, 100, and 130% of the requirement of each evaluated phase, but maintaining the relation between the amino acids. A total of 216 birds were digitized in the DXA to quantify the data provided by the equipment: lean mass, fat mass, bone mineral content and total mass. Then, the same birds were kept in a 24-hour fasting meal, slaughtered and plucked. The chemical analysis of the feather free body (FFB) of birds was carried out for protein, water, lipids and mineral matter content. The data were submitted to analysis of variance (ANOVA), being observed differences between diets, sexes and in the quantification of body composition by the different techniques. Due to the differences between the techniques, regressions were adjusted for each chemical component of the body and for each sex. All the established equations presented an R2 <0.96 and allow the evaluation of body composition by DXA to be determined directly and rapidly in future scans involving broiler chickens. Through the conduction of experiments II and III we aimed to estimate the parameters of the Gompertz function to evaluate the genetic potential of growth of live weight, chemical constituents of FFB and feathers for the commercial lines of broilers Cobb, Hubbard and Ross, males and females. In both trials, 336 broilers of each lineage and sex were distributed in a completely randomized design, distributed in a factorial arrangement of 3 lines × 2 sexes, with four replications (totaling 24 experimental units). The birds were housed in a thermoneutral environment from 1 to 105 days of age and fed a single diet for males and females divided into four phases, containing 3100 kcal ME/kg, and formulated above nutritional requirements. The evaluations involved 12 birds per strain and sex throughout the growth to obtain feather free body composition data determined in vivo by DXA (experiment II) and a comparative slaughter performed in 48 birds per strain and sex throughout experimental period for the chemical composition of feathers (experiment III). The data were adjusted to the Gompertz growth curve and the deposition rates calculated by the derived equation. Allometric relationships between the weights of the chemical components of the FFB and the feathers with their protein weight were determined to describe the growth rates of the different strains. Numerically, the results evidenced the potential of males to reach higher weight at maturity, higher growth and protein deposition compared to females. It was observed that the current commercial lines present higher body weight at maturity and consequently deposition rates of the components in relation to previous studies found in the literature. In general, body fat was deposited at a rate of 22% and 15% higher in females and males, respectively, in relation to protein deposition in the body. The proportion of water and minerals deposited in the body has decreased relative to the protein. These results show the differences in the growth potential of the strains involved and update the growth curves of modern broiler chickens.
Descrição
Palavras-chave
Alometria, Análises químicas, Linhagens, Peso proteico, Taxa de crescimento, Allometry, Chemical analysis, Growth rate, Protein weight, Strains