Desempenho reprodutivo, características do pelame e taxa de sudação em vacas da raça Braford

Abstract

RESUMO -Foram investigados os efeitos das características do pelame e da taxa de sudação (TS) sobre o intervalo de partos (IEP, n = 423) e os dias para o parto (DPP, n = 1.202) de vacas da raça Braford criadas em sistema extensivo em região tropical úmida no Mato Grosso do Sul, Brasil. As análises foram realizadas pelo método dos quadrados mínimos considerando para intervalo de partos os seguintes efeitos das classes de idade da vaca ao parto: grupo genético; pai; e regressão sobre a refletância da superfície da capa (R), a espessura da capa (E), o comprimento dos pêlos (C), o número de pêlos por unidade

Thermoregulatory responses related to coat traits of Brazilian native ewes: an adaptive approach

“…By contrast, when the animals had coat traits that makes heat loss difficult, such as longer hair and higher hair density, these animals tended to reduce T 4 hormone concentrations to reduce heat production (Table 2), probably due to the difficulty in dissipating heat through evaporative skin thermolysis (Maia et al , 2009). Bertipaglia et al (2008) found a relationship between coat traits and reproductive indices, in which the animals that had short HL showed shorter calving intervals. However, this response does not increase lineally over the environmental conditions imposed on the groups.…”

“…This protection differs according to many factors such as coat thickness (CT) and hair characteristics (Silva 2008;Maia et al 2009). Substantial research has been conducted to analyse the relationship between coat characteristics and livestock productivity and other traits that are not directly related to thermoregulation (Bertipaglia et al 2007(Bertipaglia et al , 2008. McManus et al (2009), analysing five sheep groups, found that animals that showed lower respiratory rate (RR), rectal temperature (RT) and heart rate are characterized by better coat traits to heat adaptation.…”

“…However, this decrease in metabolic processes can affect the productive performance, such as growth and fattening (West 2003). Undesirable hair coat traits can cause overheating in animals and can be related to variations in hormone concentrations (Bertipaglia et al 2008). On the other hand, it has been established that low CT and less dense coats composed of short and thick hairs can promote the dissipation of excessive body heat and contribute to homeostasis and better performance (Cena & Monteith 1975;Finch et al 1984).…”

Genetic assessment of rectal temperature and coat score in Brahman, Angus, and Romosinuano crossbred and straightbred cows and calves under subtropical summer conditions

“…Prayaga and Henshall (2005) reported permanent environmental variance as a fraction of the phenotypic variance to be 0.19 for rectal temperature and 0.08 for coat score. Estimates of heritability for a variety of coat/hair characteristics ranged from 0.08 (number of hairs per cm 2 ) to 0.3 (measure of reflectance) in Braford cows (Bertipaglia et al, 2008). An estimate for heritability for the condition of the coat (subjectively scored as shiny, dull, or very dull) in dairy cows was 0.05 (Jørgensen et al, 2010).…”

Levantamento comparativo do desempenho reprodutivo de vacas com diferentes níveis de produção de leite

“…On the other hand, the heritability for milk production at 305 days was estimated at 0.27 by Freitas et al (2000). Bertipaglia et al (2008) reported almost zero heritability to the interval between partum and days for calving. The relatively minor role of genetics and the largest domain of non-genetic factors on reproductive phenotype was reported by Silva et al (1998) whose results of heritability estimates were 0.35 for milk production in the first lactation and 0.05 for age at first calving.…”