Dinâmica da utilização de energia em matrizes de frango de corte ao longo do período de postura
Data
2023-03-27
Autores
Teofilo, Guilherme Ferreira da Silva
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Compreender a dinâmica de utilização energética em matrizes de corte permite propor estratégias nutricionais e melhorarias no desempenho reprodutivo. Baseado nisso, o presente estudo objetivou descrever a utilização e o particionamento da energia ingerida em matrizes de corte durante o período de postura e propor modelos de exigências de energia. Para tal, foram conduzidos dois ensaios experimentais utilizando matrizes de corte da linhagem Cobb 500. O primeiro ensaio teve como objetivo fracionar a energia ingerida em: mantença e energia retida (ER) no corpo e no ovo. Foram utilizadas 50 aves de 27 a 63 semanas de idade, sendo 5 aves avaliadas a cada 4 semanas. Cada ave foi alojada individualmente em câmaras respirométricas e alimentada com base nas recomendações do guia de manejo. A produção total de calor total (PCT) e em jejum (PCJ) foram calculadas pela equação de Brouwer. O consumo de ração (CR), excretas produzidas e a massa de ovo (MO) foram registrados diariamente. Ao final desse período a composição corporal das aves foi estimada pelo DEXA. Os dados foram analisados em função da idade por meio de regressões lineares (P≤0,05). O segundo ensaio objetivou determinar a utilização energética e propor modelos de exigências. Foram utilizadas 60 aves de 29 a 65 semanas de idade, sendo 6 aves avaliadas a cada 4 semanas. Oito dias anteriores às medições, as aves foram adaptadas a três níveis de ingestão energética e em seguida, as aves foram alojadas em câmaras respirométricas. O CR, peso corporal, MO e coleta de excretas foram realizados diariamente. Ao final das avaliações de respirometria, as aves foram eutanasiadas para mensuração da massa visceral. Para avaliar o efeito da idade e energia metabolizável ingerida (EMAi) nos dados do balanço energético foi ajustada uma regressão multifatorial. Além disso, foi realizada a correlação de Pearson entre a massa visceral e os parâmetros do metabolismo energético. Para obter a exigência de energia metabolizável (EM) e líquida (EL), quatro modelos mistos foram ajustados, incluindo ou não o efeito de idade. Para o primeiro ensaio o CR e consequentemente o EMAi foram decrescentes com o avanço da idade (P<0,001), com maiores valores durante pico de produção (31 e 35 semanas). Não houve efeitos significativos (P>0,05) da idade na PCJ, PCT e incremento calórico. A MO e o ER no ovo como gordura e proteína foram constantes ao longo das idades (P>0,05), enquanto o ER no corpo como proteína aumentou linearmente (P=0,0011) conforme as aves envelheceram. A maior EMAi no pico de produção resultou em aumento da ER como gordura no corpo (P<0,0001). Para o segundo ensaio, os resultados mostraram que a PCJ (259 kJ/kg0,75*d) permaneceu constante durante todo o ciclo de produção independente do nível de EMAi (P>0,05). A PCJ e o PCT apresentaram correlação positiva com os órgãos digestivos e reprodutivos (P<0,05). A eficiência de utilização de energia para depositar proteína e gordura no corpo mudou com a idade da ave. Os modelos de EL e EM desconsiderando o efeito da idade apresentou menor erro. As eficiências de utilização de energia foram 0,89; 0,78 e 0,80 para mantença, ganho e produção de ovos, respectivamente. O modelo de EL não foi afetado pela idade e apresentou menor erro quando comparado ao de EM. Conclui-se que para matrizes de corte a EMAi é usada principalmente para suportar a demanda de EL para mantença e produção de ovos, e o restante é depositado nos tecidos corporais em maior eficiência como gordura, enquanto a ER como proteína no corpo aumenta com a idade da ave. Os modelos mistos são viáveis para construir modelos de recomendações energéticas para os sistemas de EM e EL, sendo a EL mais acurada em expressar as exigências energéticas de matrizes pesadas.
Understanding the dynamics of energy utilization in broiler breeders allows proposing nutritional strategies and improvements in reproductive performance. Based on this, the present study aimed to describe the utilization and partitioning of energy intake in broiler breeders during the laying period and to propose models of energy requirements. For this purpose, two experimental trials were carried out using Cobb 500 broiler breeders. The first trial aimed to partitioning the energy intake into: maintenance and retained energy (RE) in the body and in the egg. Fifty birds from 27 to 63 wks of age were used, with 5 birds evaluated every 4 wks. Each bird was individually housed in respirometric chambers and fed based on the guideline recommendations. Total heat production (THP) and fasting (FHP) were calculated using the Brouwer equation. Feed intake (FI), excreta produced, and egg mass (EM) were recorded daily. At the end of this period, the body composition of the birds was estimated by DEXA. Data were analyzed as a function of age using linear regressions (P≤0.05). The second trial aimed to determine energy utilization and propose models of energy requirements. Sixty birds from 29 to 65 weeks of age were used, with 6 birds evaluated every 4 wks. Eight days prior to the measurements, the birds were adapted to three levels of energy intake. Then, the birds were housed in respirometric chambers. The FI, body weight, EM and excreta collection were performed daily. At the end of the respirometry evaluations, the birds were euthanized to measure the visceral mass. To assess the effect of age and apparent metabolizable energy intake (AMEi) on energy balance data, a multifactor regression was fitted. In addition, Pearson's correlation between visceral mass and parameters of energy metabolism was performed. To obtain metabolizable (ME) and net (NE) energy requirements, four mixed models were fitted, including, or not including the effect of age. For the first trial, the FI and consequently the AMEi decreased with the age of the birds (P<0.001), with higher values during peak production (31 and 35 wks). There were no significant effects (P>0.05) of age on FHP, THP and heat increment. The EM and RE in the egg as fat and protein were constant across ages (P>0.05), while RE in the body as protein increased linearly (P=0.0011) as the birds aged. Higher AMEi at peak production resulted in increased RE as body fat (P<0.0001). For the second trial, the FHP (259 kJ/kg0.75*d) remained constant throughout the production cycle regardless of the AMEi level (P>0.05). The FHP and THP showed a positive correlation with digestive and reproductive organs (P<0.05). The efficiency of energy utilization to deposit protein and fat in the body changed with bird age. The NE and ME models disregarding the effect of age showed the lowest error. Efficiencies of energy utilization were 0.89; 0.78 and 0.80 for maintenance, gain and egg production, respectively. The NE model was not affected by age and presented a smaller error when compared to the ME. It is concluded that for broiler breeders AMEi is mainly used to support the NE demand for maintenance and egg production, and the remainder is deposited in body tissues more efficiently as fat, while RE as protein in the body increases with the age of the bird. Mixed models are feasible to build energy recommendation models for ME and NE systems, with NE being more accurate in expressing the energy requirements of broiler breeders.
Understanding the dynamics of energy utilization in broiler breeders allows proposing nutritional strategies and improvements in reproductive performance. Based on this, the present study aimed to describe the utilization and partitioning of energy intake in broiler breeders during the laying period and to propose models of energy requirements. For this purpose, two experimental trials were carried out using Cobb 500 broiler breeders. The first trial aimed to partitioning the energy intake into: maintenance and retained energy (RE) in the body and in the egg. Fifty birds from 27 to 63 wks of age were used, with 5 birds evaluated every 4 wks. Each bird was individually housed in respirometric chambers and fed based on the guideline recommendations. Total heat production (THP) and fasting (FHP) were calculated using the Brouwer equation. Feed intake (FI), excreta produced, and egg mass (EM) were recorded daily. At the end of this period, the body composition of the birds was estimated by DEXA. Data were analyzed as a function of age using linear regressions (P≤0.05). The second trial aimed to determine energy utilization and propose models of energy requirements. Sixty birds from 29 to 65 weeks of age were used, with 6 birds evaluated every 4 wks. Eight days prior to the measurements, the birds were adapted to three levels of energy intake. Then, the birds were housed in respirometric chambers. The FI, body weight, EM and excreta collection were performed daily. At the end of the respirometry evaluations, the birds were euthanized to measure the visceral mass. To assess the effect of age and apparent metabolizable energy intake (AMEi) on energy balance data, a multifactor regression was fitted. In addition, Pearson's correlation between visceral mass and parameters of energy metabolism was performed. To obtain metabolizable (ME) and net (NE) energy requirements, four mixed models were fitted, including, or not including the effect of age. For the first trial, the FI and consequently the AMEi decreased with the age of the birds (P<0.001), with higher values during peak production (31 and 35 wks). There were no significant effects (P>0.05) of age on FHP, THP and heat increment. The EM and RE in the egg as fat and protein were constant across ages (P>0.05), while RE in the body as protein increased linearly (P=0.0011) as the birds aged. Higher AMEi at peak production resulted in increased RE as body fat (P<0.0001). For the second trial, the FHP (259 kJ/kg0.75*d) remained constant throughout the production cycle regardless of the AMEi level (P>0.05). The FHP and THP showed a positive correlation with digestive and reproductive organs (P<0.05). The efficiency of energy utilization to deposit protein and fat in the body changed with bird age. The NE and ME models disregarding the effect of age showed the lowest error. Efficiencies of energy utilization were 0.89; 0.78 and 0.80 for maintenance, gain and egg production, respectively. The NE model was not affected by age and presented a smaller error when compared to the ME. It is concluded that for broiler breeders AMEi is mainly used to support the NE demand for maintenance and egg production, and the remainder is deposited in body tissues more efficiently as fat, while RE as protein in the body increases with the age of the bird. Mixed models are feasible to build energy recommendation models for ME and NE systems, with NE being more accurate in expressing the energy requirements of broiler breeders.
Descrição
Palavras-chave
Zootecnia, Aves criação, Animais nutrição, Metabolismo energético, Gasto energético