Use of multivariate analyses for determining heat tolerance in Brazilian cattle

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.

Access to shade changes behavioral and physiological attributes of dairy cows during the hot season in the subtropics

“…Reduced heat production is usually achieved with decreased feed intake, less physical activity as walking or ruminating and lowered milk production (Silanikove, 2000;Berman, 2011;Renaudeau et al, 2012). The choice of which strategy to be used may change depending on weather conditions and on the cow's own characteristics, such as size, body surface, hair coat length and color, as well as metabolic rate (McManus et al, 2011).…”

Cellular immune response of Curraleiro Pé-duro and Nellore calves following Mycobacterium bovis-BCG vaccination

“…Further, the semi-arid region poverty makes health and nutritional care for animals minimal or nonexistent at all. The bovine originated in this scenario is highly rustic and believed to be more resistant (Serrano et al 2004, Mariante & Cavalcante 2006, Azevêdo et al 2008, McManus et al 2011. So far, a single study, Moraes et al (2009), provided some physiological aspects of Curraleiro Pé-duro calves showing that Curraleiro Pé-duro animals presente increased levels of total leukocyte in the bloodstream.…”

“…During five centuries the European cattle underwent natural selection in those specific environments originating four new bovine breeds showing unique adaptive traits for different backgrounds. Curraleiro Pé-duro was the first bovine breed arisen in Brazil, since it was based where the settles introduced the breeding (Mariante & Egito 2002, Serrano et al 2005, McManus et al 2011. During the last century, exotic breeds were introduced in Brazil aiming the increase of the commercial production.…”

Maternal offspring behaviour in Curraleiro Pé Duro naturalized cattle in Brazil

“…These introductions occurred initially in 1550, in São Paulo, Pernambuco and Bahia States; these introduced breeds are now called naturalized or local, with various names depending on where they are reared and now form several different breeds. The most important trait of these breeds is their adaptation potential, and some such as the Curraleira Pé Duro have shown natural resistance to a hostile environment (McManus et al, 2011) without interference from man, while others have been exposed to a process of extinction (Primo, 1992). The Curraleira Pé Duro breed is thought to have descended from the Portuguese Mirandesa and in particular the Beiroa lineage, which can be found in Portugal and the Spanish province of León.…”

“…It is unlikely that only the Mirandesa breed was responsible for the origin of the Curraleira Pé Duro, and it is believed that several different genetic groups contributed, not established as breeds at the time of colonization, to the formation of this breed (Carvalho & Girão, 1999). The Curraleira Pé Duro is the smallest naturalized breed (Bianchini et al, 2006) with high heat tolerance (McManus et al, 2011) and disease resistance (Juliano et al, 2007). The slow growth and small size of these cattle is in harmony with the harsh conditions of the Brazilian semi-arid northeast and savannah (Cerrado) regions.…”