Estimativas de parâmetros genéticos para produção e composição do leite de vacas da raça Holandesa no estado do Paraná

Abstract

RESUMO -Estimaram-se as herdabilidades e as correlações genéticas para as produções de leite (PL), de gordura (PG) e de proteína (PP) e para os percentuais de gordura (%G) e de proteína (%P) no leite de vacas da raça Holandesa no estado do Paraná. Foram analisados 117.082 registros de lactações encerradas para estimativa das características PL, PG e PP e 116.747 registros de lactações para %G e de %P. Todos os animais foram controlados oficialmente pelo Serviço de Controle Leiteiro Mensal da Associação Paranaense de Criadores de Bovinos da Raça Holandesa entre janeiro de 1992 e dezembro de 2003. A estimação dos componentes de co-variância e dos parâmetros genéticos foi realizada por meio de inferência Bayesiana em análises uni e tricaracteres utilizando-se um modelo animal que incluiu os efeitos fixos de grupo de contemporâneos e número de ordenhas, além dos efeitos linear e quadrático da idade da vaca ao parto e os efeitos aleatórios genéticos aditivos, permanente de ambiente e residual. As médias e os respectivos desvios-padrão para as PL, PG e PP, em kg, foram 8.181,23 ± 1.903,51; 270,88 ± 67,58 e 249,01 ± 55,65, respectivamente, e para os %G e %P foram 3,33 ± 0,45 e 3,06 ± 0,19, respectivamente. As estimativas de herdabilidade para PL, PG, PP, %G e %P obtidas nas análises unicaracteres foram 0,26; 0,28; 0,25; 0,60 e 0,58, respectivamente, e indicam que as características possuem variação genética aditiva que garante boa resposta à seleção. As estimativas das correlações genéticas entre PL e PG, PL e PP, PG e PP, PL e %G, PL e %P, %G e %P foram 0,56; 0,89; 0,67; -0,42; -0,39 e 0,56, respectivamente, portanto, a seleção realizada para aumentar a PL promoverá aumento na PG e PP e redução nos %G e %P.Palavras-chave: amostrador de Gibbs, componentes do leite, correlação genética, herdabilidade, inferência Bayesiana Estimates of genetic parameters for yield and composition of milk of Holstein cows in Paraná StateABSTRACT -The objectives of this study were to estimate heritabilities and genetic correlations for milk (MY), fat (FY) and protein (PY) yields and for percentages of fat (%F) and protein (%P) in milk of Holstein cows in Paraná State. Data consisted of 117,082 lactation records for MY, FY and PY and 116,747 records for %F and %P from herds supervised by the Milk Recording Service of the Holstein Breeders Association of Paraná from January 1992 to December 2003. Covariance components and genetic parameters were estimated by Bayesian inference using an animal model including the fixed effects of contemporary group, number of milking, linear and quadratic effects for calving age and the additive genetic, permanent environmental and residual random effects. Averages and respective standard deviations for MY, FY and PY (kg) were respectively 8,181.23 ± 1,903.51, 270.88 ± 67.58 and 249.01 ± 55.65 and for %F and %P they were 3.33 ± 0.45 and 3.06 0.19, respectively. Heritability estimates for MY, FY, PY, %G and %P obtained from single-trait analyses were 0.26, 0.28, 0.25, 0.60 and 0.58, respectively. They indicat...

Genetic parameters for dystocia, milk yield and age at first calving in Brazilian Holstein cows

“…The heritability estimates were 0.15 (0.01), 0.27 (0.02), and 0.17 (0.03) for MY305, AFC and dystocia, respectively (Table 3). The heritability of MY305 was slightly lower to those found in the literature for Holstein cows, ranging from 0.19 to 0.27 (Paula et al 2008;Irano et al 2014;Stefani et al 2018). The heritability for AFC was slightly higher to those found in the literature, ranging from 0.19 to 0.20 (Muir et al 2004;Canaza-Cayo et al 2018).…”

Genotype by environment interaction for fat and protein yieldsviareaction norms in Holstein cattle of southern Brazil

“…We observed that FY heritability was always moderate, varying from 0.21 to 0.27, reinforcing the absence of GEI. Similar heritability estimates have been reported by Moreira et al (2018) and Paula et al (2008) for Holstein herds in Brazil and by van der Laak et al (2016) for herds in Netherlands. However, higher FY heritability has been reported elsewhere for Holstein cattle.…”

“…(2018) and Paula et al . (2008) for Holstein herds in Brazil and by van der Laak et al . (2016) for herds in Netherlands.…”

Chemical profile, somatic cell count and milk production of Holstein, Girolando and Jersolando cows

“…The result of this study in relation to the fat percentage of milk from Holstein cows (2.93%) was lower than that found by Santos et al (2009), who observed high fat content in the milk from Holstein cows (4.30%) using soybean oil in the diets of cows during the transition period. Paula et al (2008) and Stelzer et al (2009) observed similar fat contents (3.40%), but higher than those found in this work.…”