Pig Breeding in Hot Climates
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Data
2010
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Os suínos são animais muito sensíveis a elevadas temperaturas. Em presença de elevadas temperaturas, acima da sua zona de termo neutralidade, eles accionam mecanismos fisiológicos e comportamentais que permitem facilitar as perdas de calor para o ambiente ou minimizar ganhos de calor do ambiente. A sua ingestão de alimento, bem como a sua performance reprodutiva são afectadas quando as porcas são expostas ao stress térmico.
Nesta dissertação, em primeiro lugar, foram determinados os dias que têm um maior impacto negativo na performance reprodutiva em duas linhas de porcas distintas, linha Yorkshire (linha D) produzida principalmente em climas temperados, e a linha Large White (linha I) produzida maioritariamente em climas quentes. Em segundo lugar foi estudada a relação dos dados de temperatura e humidade recolhidos na exploração e recolhidos em estações meteorológicas localizadas a diferentes distâncias da exploração. Em terceiro lugar, foi estudada a importância de novos parâmetros para implementar na estimativa de valores genéticos com a finalidade de aperfeiçoar a selecção de porcas reprodutoras baseada na sua capacidade de ingestão de alimento após o parto e na sua mobilização de reservas durante a lactação.
Com esta dissertação pode-se concluir que porcas sujeitas a elevados valores do Índice de Temperatura e Humidade (ITH) diminuem a sua performance reprodutiva traduzindo-se numa diminuição do tamanho da ninhada e da taxa de parto. A taxa de parto da linha D foi afectada significativamente pelo ITH, no entanto a taxa de parto da linha I não foi afectada. O maior impacto negativo do ITH no tamanho da ninhada foi registado 14 dias após a inseminação para a linha D e para a linha I foi registado 5 dias antes da inseminação. A linha D mostrou maiores quebras na performance reprodutiva que a linha I com o aumento do ITH. Dados de temperatura e humidade registados na exploração são mais precisos no estudo das quebras da performance reprodutiva associadas ao stress térmico, no entanto, a estação meteorológica mais próxima da exploração, até uma distância de 117 km, pode também fornecer informação útil para utilizar em estudos relacionados com o stress térmico. No terceiro objectivo, a classificação da ingestão de alimento após o parto mostrou ser um parâmetro interessante para usar no aperfeiçoamento da estimativa de valores genéticos sendo que foi claramente afectado pela temperatura e estação.
Pigs are very sensitive to high temperatures, when they are exposed to high temperature, above the thermo-neutral zone, they respond invoking physiological and behavioral mechanisms to facilitate heat losses to the environment or to minimize heat gain from the environment. Feed intake and reproductive performance are affected when sows are exposed to heat stress. Firstly, it was studied on which day heat stress had the greatest impact on reproductive performance in two different sow lines, a Yorkshire line (D-line) producing mainly in temperate climates and a Large White line (I-line) producing mainly in hot climates. Secondly, the relationship of temperature and humidity collected on-farm and collected on weather stations located at different distances from the farm was studied. Thirdly, new indicator traits, feed intake score and losses in back fat during lactation, to use in Breeding Value Estimation were studied. From the first analysis, it was possible concluded that total number born (TNB) was negatively affected by Temperature Humidity Index (THI) for D-line and for I-line. Farrowing rate (FR) of D-line was significantly affected by THI and FR of I-line was not significantly affected by the class effect of THI. Temperature Humidity Index had a largest negative effect on TNB of D-line at 14 days after insemination and the largest effect of THI on TNB of I-line was at 5 days before insemination. D-line showed higher losses in reproductive performance than I-line sows when THI increased. These differences may be an indication of genetic differences in heat stress tolerance in sow lines. From the second objective, it was possible concluded that data from on-farm records were more accurate for predict losses in reproduction performance than information from weather station; however, weather station until 117 km far from the farm also provide satisfactory information for quantify losses in reproduction performance under heat stress conditions. From the third objective, feed intake score is a trait affected by high temperature and season. Feed intake score showed a low heritability; however may be introduced at Breeding Value Estimation to improve selection on start up of sows in Spain and Portugal. Losses in back fat during lactation was not a heritable trait.
Pigs are very sensitive to high temperatures, when they are exposed to high temperature, above the thermo-neutral zone, they respond invoking physiological and behavioral mechanisms to facilitate heat losses to the environment or to minimize heat gain from the environment. Feed intake and reproductive performance are affected when sows are exposed to heat stress. Firstly, it was studied on which day heat stress had the greatest impact on reproductive performance in two different sow lines, a Yorkshire line (D-line) producing mainly in temperate climates and a Large White line (I-line) producing mainly in hot climates. Secondly, the relationship of temperature and humidity collected on-farm and collected on weather stations located at different distances from the farm was studied. Thirdly, new indicator traits, feed intake score and losses in back fat during lactation, to use in Breeding Value Estimation were studied. From the first analysis, it was possible concluded that total number born (TNB) was negatively affected by Temperature Humidity Index (THI) for D-line and for I-line. Farrowing rate (FR) of D-line was significantly affected by THI and FR of I-line was not significantly affected by the class effect of THI. Temperature Humidity Index had a largest negative effect on TNB of D-line at 14 days after insemination and the largest effect of THI on TNB of I-line was at 5 days before insemination. D-line showed higher losses in reproductive performance than I-line sows when THI increased. These differences may be an indication of genetic differences in heat stress tolerance in sow lines. From the second objective, it was possible concluded that data from on-farm records were more accurate for predict losses in reproduction performance than information from weather station; however, weather station until 117 km far from the farm also provide satisfactory information for quantify losses in reproduction performance under heat stress conditions. From the third objective, feed intake score is a trait affected by high temperature and season. Feed intake score showed a low heritability; however may be introduced at Breeding Value Estimation to improve selection on start up of sows in Spain and Portugal. Losses in back fat during lactation was not a heritable trait.
Descrição
Dissertação de Mestrado em Engenharia Zootécnica
Palavras-chave
Índice de temperatura e humidade , Ingestão de alimento , Performance reprodutiva , Porca , Stress térmico , Feed intake , Heat stress , Reproductive performance , Sow , Temperature Humidity Index