Linhas genéticas e sistema de alimentação de precisão como alternativa sustentável para produção de suínos em países de clima tropical
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Data
2019-02-05
Autores
Santos, Luan Sousa dos
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Universidade Estadual Paulista (Unesp)
Resumo
A criação de suínos em países em desenvolvimento, localizados em regiões de clima tropical predominantemente quente com investimento reduzido em infraestrutura, expõem os animais a condições de estresse por calor. Por sua vez, o estresse por calor gera perdas significativas na produção animal, principalmente para suínos, devido à sua capacidade limitada de dissipar calor. Além disso, as disseminações de vetores de doenças devido à alta temperatura também aumentam os desafios na suinocultura. O investimento para climatização completa de uma instalação pode acarretar no aumento do custo de produção e preços menos competitivos para o suinocultor. Nesse sentido, a escolha de uma genética adequada atreladas a um bom plano nutricional torna-se indispensável na suinocultura mundial. Dessa forma, com essa tese objetivou-se avaliar os efeitos do estresse por calor primeiramente em diferentes genéticas. Após definir-se a genética mais sensível ao estresse por calor, foi realizado um segundo estudo utilizando duas técnicas de nutrição (convencional e de precisão) para avaliação das respostas de desempenho e composição corporal dos animais. No primeiro estudo o objetivo foi avaliar a robustez no desempenho e composição corporal de progênies provenientes de duas genéticas pai (G) comumente utilizadas mundialmente (AGPIC 327: Hampshire puro e AGPIC 337: linhagem sintética) submetidos ao estresse por calor (33ºC). Um total de 24 suínos machos castrados (peso inicial de 32,0 ± 2,0 kg) foram alojados em baias individuais e então submetidos a um dos dois ambientes (AT), sendo eles termoneutro a 22ºC (TN) e alta temperatura a 33ºC (HT). O consumo de ração e ganho de peso foram avaliados semanalmente durante todo período experimental (55 dias). A composição corporal foi avaliada durante os dias 27 e 55 do experimento por meio de um equipamento de densitometria óssea de raio-X duplo. Durante os dias 0 e após cada avaliação de composição corporal, a gordura de cobertura e a profundidade de músculo também foram mensuradas por meio de um equipamento de ultrassonografia. Como esperado, animais submetidos ao estresse por calor reduziram o consumo de ração (35%; P < 0,01) em relação aos animais em ambiente termoneutro durante ambas fases experimentais (0-27 e 28-55 dias). Ainda em ambiente de estresse por calor, animais de linhagem sintética reduziram o consumo de ração em 50%, enquanto em animais Hampshire, essa redução foi de aproximadamente 24% (P < 0,05 para a interação G × AT). Nos dias 27 e 55, o peso corporal, teor de lipídios, fósforo e conteúdo mineral ósseo reduziram (P < 0,05) em animais submetidos ao estresse por calor quando comparados com animais em ambiente termoneutro. Nesses mesmos dias, sob estresse por calor a gordura de cobertura foi 26% menor em animais sintéticos quando comparados com Hampshire (P < 0,10 para a interação G × AT). Temperaturas elevadas influenciaram ambas as genéticas avaliadas. Nesse primeiro estudo pode-se concluir que potenciais interações entre linhas comerciais e ambiente podem influenciar o desempenho e a composição de carcaça de suínos em estresse por calor de maneira inversa ao esperado em condições termoneutras. No segundo estudo objetivou-se avaliar as respostas dos suínos submetidos a sistemas de nutrição de precisão individual diária (IPF) e convencional de alimentação por fases (CON) em termos de desempenho, balanço de nutrientes, parâmetros séricos e padrões de refeição de animais criados em condições termoneutras (TN: 23 °C) e condições de estresse térmico (HT: 30 °C). Os animais em cada tratamento foram distribuídos nos tratamentos experimentais de acordo com os pesos iniciais (12 animais por tratamento com 41,0 ± 4,87 kg de peso corporal). O experimento durou 55 dias (fase I – 0 ao 27º dia e fase II – 28º ao 55º dia). Os suínos no grupo CON receberam em cada fase uma mistura constante de dietas com alta e baixa densidade de nutrientes suprindo as exigências nutricionais estimadas do grupo, enquanto os animais IPF receberam diariamente uma mistura personalizada fornecendo a quantidade estimada de nutrientes. O conteúdo mineral ósseo, massa magra e gorda foram avaliados por meio de absorciometria de raio-X duplo no início e final de cada fase. Os dados foram analisados incluindo os seguintes efeitos fixos: sistema de alimentação (FS), temperatura ambiente (AT) e suas interações. Os suínos sob HT apresentaram redução (P < 0,01) no consumo diário de ração em 28%, no ganho diário de peso em 25%, no ganho de proteína em 14% e o ganho de lipídio em 14% em comparação aos animais sob TN. Em relação ao tratamento CON, animais IPF reduziram (P < 0,05) a ingestão de lisina (19%), proteína (16%) e P (14%) sem prejudicar (P > 0,05) a composição corporal. A excreção de nitrogênio foi 24% menor (P < 0,05) nos animais do grupo IPF, quando comparada com os suínos CON, com a mesma eficiência de retenção de nitrogênio durante todo o período. O tempo de alimentação, a taxa de consumo de ração e o consumo de ração por refeição foram 15% menores (P < 0,05) em suínos criados sob HT do que sob condições TN. Os níveis de haptoglobina foram afetados pela AT, mostrando um aumento de 70% e 43% na HT aos 28 dias e 55 dias do experimento, respectivamente. Os suínos criados sob condições de HT apresentaram concentração de albumina sérica 10% menor (P < 0,05) aos 55 dias do que aqueles em condições TN. Para as concentrações séricas de ureia, animais no sistema IPF apresentaram níveis 28% menores (P < 0,01) do que os suínos CON. Embora as condições de HT tenham reduzido consideravelmente o crescimento dos animais e ativado suas respostas inflamatórias, foi demonstrado que o sistema IPF é uma excelente ferramenta para alcançar a adequada utilização de nutrientes tanto em condições HT como em TN, sem comprometer a composição corporal dos animais.
Developing countries, located in regions of predominantly warm tropical climate with little investment in infrastructure, expose animals to heat stress conditions. In turn, heat stress generates significant losses in animal production, especially for pigs, because of their limited ability to dissipate heat. In addition, the spread of disease vectors by heat also increases the challenges in swine farming. The investment for complete climatization of a facility can lead to an increased production costs and less competitive prices for the pig farmer. Because of this, the choice of an appropriate genetic linked to a good plan of nutrition become indispensable in the swine industry worldwide. Thus, with this thesis we aimed to evaluate the effects of heat stress first on different genetics. After defining the genetics most sensitive to heat stress, a second study was performed using two nutrition techniques (conventional and precision feeding) to evaluate the performance responses and body composition of the animals. In the first study the objective was to evaluate the robustness in the performance and body composition of progenies from two sire genotypes (G) commonly used worldwide (AGPIC 327: pure Hampshire and AGPIC 337: synthetic line) under heat stress (33 ºC). A total of 24 barrows (initial weight 32.0 ± 2.0 kg) were housed in individual pens and then submitted to one of two environments (AT), being thermoneutral at 22 ºC (TN) and high temperature at 33 ° C (HT). Feed intake and weight gain were evaluated weekly throughout the experimental period (55 days). The pigs’ body composition was assessed at 28 and 56 days of the experiment through a dual X-ray bone densitometry equipment. During days 0 and after each assessment of body composition, the back fat thickness and the muscle depth were also measured by an ultrasound equipment. As expected, animals submitted to heat stress reduced feed intake (35%; P < 0.01) in relation to the animals in the thermoneutral environment during both experimental phases (0-27 and 28-56 days). Also in a heat stress environment, synthetic line animals reduced their feed intake by 50%, while in Hampshire animals, this reduction was approximately 24% (P < 0.05 for G × AT interaction). On days 27 and 55, body weight, composition of lipids, phosphorus, and bone mineral content reduced (P < 0.05) in animals submitted to heat stress when compared to animals in thermoneutral environment. On these same days, under heat stress the back fat thickness was 26% lower in synthetic animals when compared to Hampshire (P < 0.10 for the G × AT interaction). Higher temperatures influenced both genetics evaluated. In this first study, it can be concluded that potential interactions between commercial lines and the environment might influence the performance and composition of pig carcasses in heat stress inversely as expected under thermoneutral conditions. The objective of the second study was to evaluate the responses of individual daily precision feeding (IPF) and conventional phase systems (CON) in terms of performance, nutrient balance, serum parameters and meal patterns of pigs raised under thermoneutral conditions ( TN: 23 °C) and heat stress conditions (HT: 30 °C). The animals in each treatment were distributed in the experimental treatments according to their initial weights (12 animals per treatment and 41.0 ± 4.87 kg body weight). The experiment lasted 55 days (phase I - 0 to 27 days and phase II - 28 to 55 days). The pigs in the CON group received at each phase a constant mixture of diets with high and low nutrient density, meeting the nutritional requirements of the group, while the IPF animals received daily a personalized mixture providing the estimated amount of nutrients. Bone mineral content, lean and fat mass were assessed by a dual X-ray bone densitometry equipment at the beginning and at the end of each phase. The data were analyzed including the following fixed effects: feed system (FS), ambient temperature (AT) and their interactions. The effects of AT were significant (P < 0.01), reducing daily feed intake by 28%, daily weight gain by 25%, protein gain by 14% and lipid gain by 14% in animals under HT compared to TN. In relation to CON treatment, IPF animals reduced their lysine intake (19%), protein intake (16%) and P intake (14%) without compromising (P > 0.05) the body composition. Nitrogen excretion was 24% lower (P < 0.05) in the IPF group when compared to CON pigs, with the same nitrogen retention efficiency throughout the experimental period. Feeding time, feed intake rate and feed consumption per meal were 15% lower (P < 0.05) in pigs raised under HT than under TN conditions. During the second growth phase, only feeding time, feed intake rate and feed consumption per meal decreased (P < 0.05) in pigs under HT conditions during the nocturnal and diurnal periods. Haptoglobin levels were affected by AT, showing a 70% and 43% increase in HT at 28 and 55 days of the experiment, respectively. The pigs raised under HT conditions presented a 10% lower serum albumin concentration (P < 0.05) at 55 days than those in TN conditions. For serum urea concentrations, animals in the IPF system presented 28% lower levels (P < 0.01) than the CON pigs. Although HT conditions have considerably reduced the growth of the animals and activated their inflammatory responses, it has been demonstrated that the IPF system is an excellent tool to achieve adequate nutrient utilization in both HT and NT conditions without compromising the animals' body composition.
Developing countries, located in regions of predominantly warm tropical climate with little investment in infrastructure, expose animals to heat stress conditions. In turn, heat stress generates significant losses in animal production, especially for pigs, because of their limited ability to dissipate heat. In addition, the spread of disease vectors by heat also increases the challenges in swine farming. The investment for complete climatization of a facility can lead to an increased production costs and less competitive prices for the pig farmer. Because of this, the choice of an appropriate genetic linked to a good plan of nutrition become indispensable in the swine industry worldwide. Thus, with this thesis we aimed to evaluate the effects of heat stress first on different genetics. After defining the genetics most sensitive to heat stress, a second study was performed using two nutrition techniques (conventional and precision feeding) to evaluate the performance responses and body composition of the animals. In the first study the objective was to evaluate the robustness in the performance and body composition of progenies from two sire genotypes (G) commonly used worldwide (AGPIC 327: pure Hampshire and AGPIC 337: synthetic line) under heat stress (33 ºC). A total of 24 barrows (initial weight 32.0 ± 2.0 kg) were housed in individual pens and then submitted to one of two environments (AT), being thermoneutral at 22 ºC (TN) and high temperature at 33 ° C (HT). Feed intake and weight gain were evaluated weekly throughout the experimental period (55 days). The pigs’ body composition was assessed at 28 and 56 days of the experiment through a dual X-ray bone densitometry equipment. During days 0 and after each assessment of body composition, the back fat thickness and the muscle depth were also measured by an ultrasound equipment. As expected, animals submitted to heat stress reduced feed intake (35%; P < 0.01) in relation to the animals in the thermoneutral environment during both experimental phases (0-27 and 28-56 days). Also in a heat stress environment, synthetic line animals reduced their feed intake by 50%, while in Hampshire animals, this reduction was approximately 24% (P < 0.05 for G × AT interaction). On days 27 and 55, body weight, composition of lipids, phosphorus, and bone mineral content reduced (P < 0.05) in animals submitted to heat stress when compared to animals in thermoneutral environment. On these same days, under heat stress the back fat thickness was 26% lower in synthetic animals when compared to Hampshire (P < 0.10 for the G × AT interaction). Higher temperatures influenced both genetics evaluated. In this first study, it can be concluded that potential interactions between commercial lines and the environment might influence the performance and composition of pig carcasses in heat stress inversely as expected under thermoneutral conditions. The objective of the second study was to evaluate the responses of individual daily precision feeding (IPF) and conventional phase systems (CON) in terms of performance, nutrient balance, serum parameters and meal patterns of pigs raised under thermoneutral conditions ( TN: 23 °C) and heat stress conditions (HT: 30 °C). The animals in each treatment were distributed in the experimental treatments according to their initial weights (12 animals per treatment and 41.0 ± 4.87 kg body weight). The experiment lasted 55 days (phase I - 0 to 27 days and phase II - 28 to 55 days). The pigs in the CON group received at each phase a constant mixture of diets with high and low nutrient density, meeting the nutritional requirements of the group, while the IPF animals received daily a personalized mixture providing the estimated amount of nutrients. Bone mineral content, lean and fat mass were assessed by a dual X-ray bone densitometry equipment at the beginning and at the end of each phase. The data were analyzed including the following fixed effects: feed system (FS), ambient temperature (AT) and their interactions. The effects of AT were significant (P < 0.01), reducing daily feed intake by 28%, daily weight gain by 25%, protein gain by 14% and lipid gain by 14% in animals under HT compared to TN. In relation to CON treatment, IPF animals reduced their lysine intake (19%), protein intake (16%) and P intake (14%) without compromising (P > 0.05) the body composition. Nitrogen excretion was 24% lower (P < 0.05) in the IPF group when compared to CON pigs, with the same nitrogen retention efficiency throughout the experimental period. Feeding time, feed intake rate and feed consumption per meal were 15% lower (P < 0.05) in pigs raised under HT than under TN conditions. During the second growth phase, only feeding time, feed intake rate and feed consumption per meal decreased (P < 0.05) in pigs under HT conditions during the nocturnal and diurnal periods. Haptoglobin levels were affected by AT, showing a 70% and 43% increase in HT at 28 and 55 days of the experiment, respectively. The pigs raised under HT conditions presented a 10% lower serum albumin concentration (P < 0.05) at 55 days than those in TN conditions. For serum urea concentrations, animals in the IPF system presented 28% lower levels (P < 0.01) than the CON pigs. Although HT conditions have considerably reduced the growth of the animals and activated their inflammatory responses, it has been demonstrated that the IPF system is an excellent tool to achieve adequate nutrient utilization in both HT and NT conditions without compromising the animals' body composition.
Descrição
Palavras-chave
Estresse por calor, Melhoramento genético, Nutrição de precisão, Robustez