Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia
The aim of this study was to determine the effects of severe extreme thermal stress on the respiratory rate (panting) of unsheared and sheared rams in standing and lying position, and to analyse two temperature-humidity indices (THIs). Six mature Australian Merino rams from Northern Patagonia, three...
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| Format: | Article |
| Language: | English |
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Universidade de São Paulo
2017-05-01
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| Series: | Brazilian Journal of Veterinary Research and Animal Science |
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| Online Access: | http://www.revistas.usp.br/bjvras/article/view/108524 |
| _version_ | 1811250775113859072 |
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| author | María Fernanda López Armengol Ronina Paola Freund Gustavo Néstor Giménez Natalia Rubio |
| author_facet | María Fernanda López Armengol Ronina Paola Freund Gustavo Néstor Giménez Natalia Rubio |
| author_sort | María Fernanda López Armengol |
| collection | DOAJ |
| description | The aim of this study was to determine the effects of severe extreme thermal stress on the respiratory rate (panting) of unsheared and sheared rams in standing and lying position, and to analyse two temperature-humidity indices (THIs). Six mature Australian Merino rams from Northern Patagonia, three unshorn and three shorn, were subjected to 40 hours (8 hours each day for five days) of gradual increase in temperature from 25°C to 40°C, guaranteeing 4h daily at 40°C in a heat chamber. Respiratory rate (RR) was registered continuously by counting flank movements, and the ambient air temperature and relative humidity were recorded every five minutes inside the heat chamber. From 1413 RR measurements, descriptive and modelling analyses were performed. Panting as a response variable was distributed into five categories, and fixed effects such as THI, wool (unshorn/shorn), and position (standing/lying) were considered. No significant differences were observed between the panting score in the unshorn (standing or lying) and standing (unshorn or shorn) sheep, but significant differences were observed in shorn and lying rams. The explanations could be that heat production from muscle activity was lower and the transfer and heat lost by conduction to the floor was easier in the rams with shorter fleece (at least 0.7 inches long). However, in the unshorn rams, their wool acted as an insulator, both with air as well as the floor. Australian Merino rams from Northern Patagonia are heat tolerant to an environment between 31.5°C and 42°C, and 32% to 48% humidity for 40 hours over five days. The rams were in the first phase of panting, and the normal rectal temperatures registered daily when leaving the heat chamber confirmed that regulation of body temperature was possible. The LPHSI’s THI was adjusted to improve the analysis of the RR more than the National Research Council’s THI. |
| first_indexed | 2024-04-12T16:10:53Z |
| format | Article |
| id | doaj.art-45f8af04c6df45a4862e06c0295268e5 |
| institution | Directory Open Access Journal |
| issn | 1413-9596 1678-4456 |
| language | English |
| last_indexed | 2024-04-12T16:10:53Z |
| publishDate | 2017-05-01 |
| publisher | Universidade de São Paulo |
| record_format | Article |
| series | Brazilian Journal of Veterinary Research and Animal Science |
| spelling | doaj.art-45f8af04c6df45a4862e06c0295268e52022-12-22T03:25:55ZengUniversidade de São PauloBrazilian Journal of Veterinary Research and Animal Science1413-95961678-44562017-05-0154110.11606/issn.1678-4456.bjvras.2017.108524113308Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern PatagoniaMaría Fernanda López Armengol0Ronina Paola Freund1Gustavo Néstor Giménez2Natalia Rubio3Universidad Nacional del Comahue, Facultad de Ciencias Agrarias, Laboratorio de Teriogenología “Dr. Héctor H. Morello” Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue (CITAAC)Universidad Nacional del Comahue, Facultad de Ciencias Agrarias, Laboratorio de Teriogenología “Dr. Héctor H. Morello”Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue (CITAAC) Universidad Nacional del Comahue, Facultad de Economía y Administración, Departamento de EstadísticaUniversidad Nacional del Comahue, Facultad de Economía y Administración, Departamento de EstadísticaThe aim of this study was to determine the effects of severe extreme thermal stress on the respiratory rate (panting) of unsheared and sheared rams in standing and lying position, and to analyse two temperature-humidity indices (THIs). Six mature Australian Merino rams from Northern Patagonia, three unshorn and three shorn, were subjected to 40 hours (8 hours each day for five days) of gradual increase in temperature from 25°C to 40°C, guaranteeing 4h daily at 40°C in a heat chamber. Respiratory rate (RR) was registered continuously by counting flank movements, and the ambient air temperature and relative humidity were recorded every five minutes inside the heat chamber. From 1413 RR measurements, descriptive and modelling analyses were performed. Panting as a response variable was distributed into five categories, and fixed effects such as THI, wool (unshorn/shorn), and position (standing/lying) were considered. No significant differences were observed between the panting score in the unshorn (standing or lying) and standing (unshorn or shorn) sheep, but significant differences were observed in shorn and lying rams. The explanations could be that heat production from muscle activity was lower and the transfer and heat lost by conduction to the floor was easier in the rams with shorter fleece (at least 0.7 inches long). However, in the unshorn rams, their wool acted as an insulator, both with air as well as the floor. Australian Merino rams from Northern Patagonia are heat tolerant to an environment between 31.5°C and 42°C, and 32% to 48% humidity for 40 hours over five days. The rams were in the first phase of panting, and the normal rectal temperatures registered daily when leaving the heat chamber confirmed that regulation of body temperature was possible. The LPHSI’s THI was adjusted to improve the analysis of the RR more than the National Research Council’s THI.http://www.revistas.usp.br/bjvras/article/view/108524Australian Merino ramsHeat stressRespiratory rateUnshorn / shornStanding / lying down |
| spellingShingle | María Fernanda López Armengol Ronina Paola Freund Gustavo Néstor Giménez Natalia Rubio Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia Brazilian Journal of Veterinary Research and Animal Science Australian Merino rams Heat stress Respiratory rate Unshorn / shorn Standing / lying down |
| title | Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia |
| title_full | Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia |
| title_fullStr | Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia |
| title_full_unstemmed | Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia |
| title_short | Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia |
| title_sort | effect of extreme severe heat stress on respiratory rate in unshorn and shorn australian merino rams from northern patagonia |
| topic | Australian Merino rams Heat stress Respiratory rate Unshorn / shorn Standing / lying down |
| url | http://www.revistas.usp.br/bjvras/article/view/108524 |
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