Use of multivariate analyses for determining heat tolerance in Brazilian cattle |
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Authors: | Concepta McManus Marlos Castanheira Samuel Rezende Paiva Helder Louvandini Maria Clorinda Soares Fioravanti Giane Regina Paludo Eliandra Bianchini Patricia Spoto Corrêa |
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Institution: | 1.Faculdade de Agronomia e Medicina Veterinária,Universidade de Brasília,Brasília,Brazil;2.Escola de Veterinária,Universidade Federal de Goiás,Goiania,Brazil;3.EMBRAPA Recursos Genéticos e Biotecnologia,Brasília,Brazil;4.Secretaria de Vigilancia em Saúde,Ministério da Saúde,Brasília,Brazil |
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Abstract: | Adaptability can be evaluated by the ability of an animal to adjust to environmental conditions and is especially important
in extreme weather conditions such as that found in tropical Brazil. A multivariate analysis using physical and physiological
traits in exotic (Nellore and Holstein) and naturalized (Junqueira, Curraleira, Mocho Nacional, Crioula Lageana, and Pantaneira)
cattle breeds was carried out in the Federal District of Brazil to test and determine which traits are important in the adaptation
of animal to heat stress as well as the ability of these traits and statistical techniques to separate the breeds studied.
Both physical and physiological traits were measured on three occasions and included body measurements, skin and hair thickness,
hair number and length, pigmentation, sweat gland area as well as heart and breathing rates, rectal temperature, sweating
rate, and blood parameters. The data underwent multivariate statistical analyses, including cluster, discriminate, and canonical
procedures. The tree diagram showed clear distances between the groups studied, and canonical analysis was able to separate
individuals in groups. Coat traits explained little variation in physiological parameters. The traits which had higher discriminatory
power included packed cell volume, shoulder height, mean corpuscular volume, body length, and heart girth. Morphological and
physiological traits were able to discriminate between the breeds tested, with blood and size traits being the most important.
More than 80% of animals of all breeds were correctly classified in their genetic group. |
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