Genetic parameters for type score traits and milk production in Brazilian Jersey herds

Mayara Andressa Sabedot,Luís Fernando Batista Pinto,Gabrieli De Souza Romano,Victor Breno Pedrosa

doi:10.1590/rbz4720170093

Mayara Andressa Sabedot, Luís Fernando Batista Pinto + Show 2 more

Open Access

https://doi.org/10.1590/rbz4720170093

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Abstract

This study aimed to estimate the heritability coefficients for ten functional type traits and milk production in the Jersey breed in Brazil, besides the genetic and phenotypic correlations between them. The present study utilised data from 1,567 records of linear type traits, including stature (ST), body depth (BD), loin strength (LS), rump width (RW), rump angle (RA), fore udder attachment (FUA), front teat placement (FTP), rear udder height (RUH), central ligament (CL), and final score (FS). Milk yield (MY) adjusted to 305 lactation days was also calculated. Covariance components were estimated by the restricted maximum likelihood approach using the PEST and VCE6 programs on the animal model. Heritability coefficients thus assessed were as follows: 0.22±0.01 (ST), 0.35±0.07 (BD), 0.17±0.01 (RW), 0.55±0.05 (RA), 0.09±0.01 (LS), 0.20±0.02 (FUA), 0.40±0.06 (FTP), 0.40±0.06 (RUH), 0.15±0.02 (CL), 0.21±0.02 (FS), and 0.16±0.02 (MY). Therefore, the higher genetic gain will be obtained for BD, RA, FTP, and RUH, while the other traits would need a medium or long-term period to show improvement. The genetic correlations fell in the range from 0.01 (FTP × FS) to 0.87 (RW × CL), and the only genetic correlation noted between FS and RA was negative (−0.10±0.06). Thus, in the Jersey breed in Brazil, the type traits are genetically associated, and the selection of any one of them may elicit an indirect response in another.

Highlights

The linear type traits form an interesting set of traits for dairy farmers as they are related to appearance, breed pattern as well as productive performance of cows, throughout their lifetimes (Kern et al, 2015)
Traits associated with rump, feet and legs, dairy strength, and mammary system have been monitored since the time the Jersey breeding programs commenced across the world (Norman et al, 1978)
Stature (0.22±0.01) and body depth (BD) (0.35±0.07) revealed moderate heritability coefficients (Table 2), while the genetic correlations of ST with the other traits were in the range of 0.15 to 0.74 (Table 3); for BD, the genetic correlations ranged from 0.20 to 0.84

Summary

Introduction

The linear type traits form an interesting set of traits for dairy farmers as they are related to appearance, breed pattern as well as productive performance of cows, throughout their lifetimes (Kern et al, 2015). Some estimates of heritability reported in these studies were moderate, in a few instances, they were high, reiterating that most type traits possess the potential to be used as selection criteria. Until now, no reports of the estimation of genetic parameters are available for the type score traits in Brazilian Jersey herds, which reveal difficulties in establishing selection criteria for these cows in the country. This study aimed at determining the heritability coefficient for the type traits and milk yield in Jersey cows from the Brazilian herds, as well as genetic and phenotypic correlations between these traits

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