Absence of a causal relationship between environmental and body temperature in dairy cows (Bos taurus) under moderate climatic conditions

Verwoerd, W.S.; Wellby, Martin P.; Barrell, Graham K.

doi:10.1016/j.jtherbio.2006.07.001

Cited by 21 publications

(22 citation statements)

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“…Base de regras da taxa de detecção de estro de vacas leiteiras em função do índice de temperatura e umidade (ITU), período após último cio (PAUC) e número de comportamentos observados (NCO) Na simulação proposta, a base de regras foi ajustada para valores de entrada ideais. Desta forma, o índice de temperatura e umidade (ITU) assumiu valor igual a 70, segundo sugestão de VERWOERD et al (2006) e MARTELLO (2006. No caso de vacas que não sofreram estresse térmico ou qualquer outro tipo de disfunção, segundo VANZIN (2006) o dia mais provável para que este animal entre no cio é 21º dia.…”

Section: Resultsunclassified

Desenvolvimento De Um Modelo Para Estimativa Do Estro De Gado Leiteiro Usando Lógica Fuzzy

Santos

Nääs

Labigalini³

2007

Revista Brasileira De Engenharia De Biossistemas

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IRENILZA DE ALENCAR NÄÄS MARCELO RICARDO LABIGALINI RESUMOA ambiência é uma ferramenta que vem ao encontro das necessidades dos produtores, por reunir os conhecimentos necessários sobre produção animal e avaliação ambiental, principalmente através dos índices de conforto. É também através desta ciência que passa a ser possível se propor opções de observação de todo manejo da produção, com base na interação animal/ ambiente, por meio de seus indícios fisiológicos e comportamentais. A carência existente no setor da pecuária leiteira brasileira, tanto de aumentar a produtividade, quanto de diminuir os custos de produção, tem induzido os produtores a buscarem novos conhecimentos. Desta forma, as relações entre fatores ambientais e respostas fisiológicas do gado leiteiro são de extrema importância durante o processo produtivo. Assim, informações como a época correta de ocorrência do estro não deve ser analisada como uma variável absoluta, já que fatores ambientais, sistema de criação e tipologia das instalações influenciam nas reações fisiológicas do animal. O objetivo desse trabalho foi descrever um modelo multivariável com a utilização da lógica fuzzy que estimasse o cio de vacas leiteiras. Foram utilizadas informações pertinentes a gado holandês alojados em confinamento total com intervalos de idade, peso e produção pré-definidos. Serviram como variáveis de entrada o índice de temperatura e umidade (ITU), período após último cio (PAUC) e número de indícios de estro (NCO). Como variável de saída foi considerada a taxa de detecção de cio (TDC). Foi possível concluir que, em situação de ITU elevado, o modelo baseado na lógica fuzzy estimou com alto grau de exatidão, a possibilidade de uma vaca estar entrando na fase de estro.

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Section: Resultsunclassified

Desenvolvimento De Um Modelo Para Estimativa Do Estro De Gado Leiteiro Usando Lógica Fuzzy

Santos

Nääs

Labigalini³

2007

Revista Brasileira De Engenharia De Biossistemas

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“…Robertshaw (1985) indicated that controlling and maintaining the temperature of the central nervous system, particularly the brain, is the most important function of the body, as the brain is highly susceptible to changes in temperature. In a study conducted by Verwoerd et al (2006), the authors showed that cattle were able to isolate their body temperature from the thermal environment during moderate temperatures, however when conditions become hot cattle are no longer able to cope with increasing ambient conditions. Furthermore Spiers et al (2004) indicated that rectal temperature of beef cattle increased within 24 hours after the introduction of thermal stress.…”

Section: Core Body Temperaturementioning

confidence: 99%

“…digestion and locomotion, also result in an increase in core body temperature and therefore the diurnal pattern exhibited. Verwoerd et al (2006) showed that cattle are able to isolate their body temperature from the thermal environment during moderate temperatures. When conditions become hot, however, cattle are no longer able to cope with increasing ambient conditions.…”

Section: New Technologies In the Measurement Of Body Temperaturementioning

confidence: 99%

Biological responses of feedlot cattle to heat load

Lees¹

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Heat load is a significant animal welfare and cost of production issue worldwide. In the US alone heat load is reported to have an annual economic burden of > $300 million in the beef sector.Furthermore animal growth is often depressed during summer resulting in heat related decreases in weight gain of approximately 10 kg which coincides with a 7 day increase in days on feed. The reduced growth rate increases days on feed, thereby increasing the cost of production. Whilst the effects of heat load on cattle has been researched for a number of years, there is speculation as to the interactions between hot environmental conditions and livestock performance, reproduction, health and overall wellbeing. Therefore there is a need to develop a more comprehensive understanding of the dynamic responses of animals to heat load. The key focus of heat load research is to develop effective management strategies to support animal comfort and performance during hot periods.While heat load can occur in pasture raised cattle, it is mostly observed within the intensive grain feed feedlot industry. Heat load occurs where a combination of environmental conditions exceed the animals ability to regulate body temperature, thus impacting on homeostasis. However how an animal responds to heat load is also dependent on a number of individual characteristics, including genotype, coat characteristics, health status and days on feed. Therefore no two animals will respond to hot climatic conditions in exactly the same manner. There are numerous responses to heat load that can be measured and/or observed in cattle, including changes in behaviour, respiratory dynamics, blood metabolites and body temperature. The experiments within this thesis were focused on investigating the; A key aspect in managing heat load is that feedlot personnel are able to recognise the responses of cattle to high heat load. Improvements in animal management have contributed to alleviating some of the negative effects of heat load. However summer conditions are still responsible for significant production losses and welfare concerns worldwide. Furthermore heat load cannot be completely eradicated where there are animal production operations in tropical and sub-tropical regions.Therefore the primary purpose of heat load research becomes focused on the effective use of mitigation strategies prior to and during heat related stress events, thus improving animal survivability and welfare during these events.iii Declaration by author Publications included in this thesisNo publications included. Contributions by others to the thesis

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“…Apenas correlações fracas ou não significativas foram verificadas para os hormônios IGF-I e cortisol, entre eles e com as variáveis fisiológicas e ambientais. (FUQUAY, 1981;JONHSON, 1980;MAYER et al, 1999;VERWOERD et al, 2006;WEST, 1999). Entretanto, esses limites máximos podem variar devido a inúmeros fatores como grau de aclimatação do animal, tempo de exposição ao estresse, prenhez e nível de produção.…”

Section: Resultsunclassified

Capacidade termolítica e respostas comportamentais e hormonais em vacas Holandesas.

Titto¹,

Negrão²

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Capacidade termolítica e respostas comportamentais e hormonais em vacas Holandesaslactations with average production of 20 kg/day divided into two experimental groups after birth, with and without an evaporative cooling system in a free-stall.Environmental parameters were evaluated by temperature and humidity index (THI).Collection of physiological data (rectal temperature, body surface, internal base of tail, respiratory rate), hormonal (cortisol and IGF-I), behavioral and production and milk quality were conducted in five climatic conditions (autumn, winter, spring, dry summer and rainy summer) characterized by air temperature, relative humidity and solar radiation. In summer the animals were subjected to Thermolysis Capacity Test (CT) and a comparative study of a period of seven days under heat stress in climatic chamber and challenged with ACTH administration. In experiment 1 the Thermolysis Capacity Test was validated. The CT was the same for dry or lactating animals (P>0.05) and higher for cows kept in evaporative cooling system throughout the year (P<0.01). The results showed influence of sun exposure on all physiological variables (P<0.01). Plasma levels of cortisol were higher before sun exposure and after the one hour rest under shade for lactating cows (P=0.03) and for no cooled animals (P=0.03). IGF-I was higher in dry cows in late gestation (P<0.01). In experiment 2 the evaporative cooling system did not show influence on rectal temperature, with both groups having values below 38.56 ºC throughout the year (P=0.11). It was observed an upward trend (P<0.01) in plasma cortisol concentrations between autumn and winter, starting the decline until the beginning of dry summer and a further increase during rainy summer, and an opposite pattern for IGF-I. Rectal temperature showed a moderate and positive correlation (P<0.01) with the body surface temperature (0.46) and respiratory rate (0.35). The air temperature and THI showed moderate to high positive correlations with rectal temperatures, and the internal base of tail, and 9 also with the respiratory rate (P<0.01). In experiment 3 cows spent most of the day standing in the shade (84.2%) regardless of season. Cooled cows had a higher feeding frequency and milk production during summer (P<0.05) and fat content 17.9% higher (P<0.01). In experiment 4, cows were subjected to the short stress caused by the ACTH administration and prolonged heat stress in climatic chamber.Both the administration of ACTH as prolonged exposure to heat in climatic chamber increased the levels of plasma cortisol. During heat stress a decrease in plasma IGF-I and milk production was observed, and an increase in physiological variables related to thermoregulation.

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Absence of a causal relationship between environmental and body temperature in dairy cows (Bos taurus) under moderate climatic conditions

Cited by 21 publications

References 13 publications

Desenvolvimento De Um Modelo Para Estimativa Do Estro De Gado Leiteiro Usando Lógica Fuzzy

Desenvolvimento De Um Modelo Para Estimativa Do Estro De Gado Leiteiro Usando Lógica Fuzzy

Biological responses of feedlot cattle to heat load

Capacidade termolítica e respostas comportamentais e hormonais em vacas Holandesas.

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