Estimation of the Genetic Parameters for Semen Traits in Spanish Dairy Sheep

Abstract

Simple Summary:The limited studies addressing the estimation of genetic parameters for ram semen traits in different breeds show a wide variation, highlighting the importance of studying these traits for individual breeds. Therefore, this work aimed to estimate genetic parameters for traits related to semen production and quality in five dairy sheep breeds. For that, ejaculates of rams from Assaf, Churra, Latxa Cara Negra, Latxa Cara Rubia, and Manchega breeds were analyzed. Estimates of the genetic covariance structure were obtained with multiple-trait animal models using the average information REML (restricted maximum likelihood) method in the BLUPF90 family of programs. Repeatability estimates for all the traits were also calculated. Heritability estimates were of low to moderate magnitude, although the estimates differed among the breeds. The estimated genetic correlations among the three semen traits showed adequate precision only in the Manchega (MAN) breed. The heritability estimates reported here suggest that improvement of these traits may be achieved by genetic selection.Abstract: This work aimed to estimate genetic parameters for traits related to semen production and quality in Spanish dairy sheep breeds. For that, ejaculates of rams from Assaf, Churra, Latxa Cara Negra, Latxa Cara Rubia, and Manchega breeds were analyzed to measure volume, semen concentration, and motility. Estimates of variance components were obtained with multiple-trait animal models using the average information REML method in the BLUPF90 family of programs. Repeatability estimates for all the traits were also calculated, with values ranging from 0.077 to 0.304 for the motility and the semen concentration traits, respectively. Heritability estimates were of low to moderate magnitude, ranging from 0.014 (motility in Latxa Cara Rubia) to 0.198 (volume in Churra), although the estimates differed among the breeds. The estimated genetic correlations among the three semen traits showed adequate precision only in the MAN breed. The heritability estimates for the semen traits reported in the present paper suggest an adequate response to selection. The practical extension of these results to the other breeds studied here will be secondary to the estimation of more reliable genetic correlations in these breeds.

Heritability and genetic correlation estimates of semen production traits with litter traits and pork production traits in purebred Duroc pigs

“…On the other hand, for ratio-defined traits such as PROP and MWB, theoretical investigations and computer simulations have been conducted ( Iwaisaki and Wilton, 1993 ; Ogawa and Satoh, 2020 ; Yazaki et al, 2021 ), and the results should be interpreted with caution. The results of genetic parameter estimation for semen production traits may contain bias due to both selection at a young age and data editing ( Tusell et al, 2012 ; Atagi et al, 2017 ; Pelayo et al, 2019 ; Olsen et al, 2021 ). Furthermore, genetic correlations of semen production traits may differ among breeds ( Wolf, 2010 ; Li et al, 2019 ).…”

Low-density SNP panel for efficient imputation and genomic selection of milk production and technological traits in dairy sheep

“…The phenotypic data used in this study involved 2,020 ewes belonging to the Assaf (n = 1,039; number of flocks = 4) and Churra breeds (n = 981; number of flocks = 2). These samples were previously analyzed by Sánchez-Mayor et al (2019) for the Assaf breed and Pelayo et al (2019) for the Churra breed. After consultation with the Research Ethics Committee of the University of León, as the animals have been sampled within the routine practices carried out on commercial farms, formal ethical approval was deemed not necessary.…”

Heritability and Genetic Parameters for Semen Traits in Australian Sheep

“…The few studies that do exist indicate that heritability of semen traits is generally low to moderate. For example, a study on Spanish dairy rams estimated the heritability for common ejaculate quality traits including volume, concentration and motility to range from 0.077 to 0.304 using a dataset consisting of ejaculates from 3289 rams across five breeds [ 18 ]. Similarly, a study focused on 9- and 12-month old Ethiopian rams estimated the heritability for ejaculate volume to be 0.07 and 0.11, for gross motility to be 0.32 and 0.27, for individual motility to be 0.32 and 0.16, and for concentration to be NA and 0.17 respectively [ 19 ].…”

“…Several studies in livestock species have also estimated the genetic correlation between different combinations of semen traits [ 10 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Specifically, in sheep, previous studies vary considerably in terms of the reported estimates for genetic correlations between different traits.…”

“…Specifically, in sheep, previous studies vary considerably in terms of the reported estimates for genetic correlations between different traits. The correlation between gross motility and concentration, for example, has been estimated to be as high as 0.98 in 9-month-old rams [ 19 ], and as low as −0.04, in rams of Latxa Cara Negra breed [ 18 ]. Similarly, the correlation estimates between ejaculate volume and gross motility has been reported to vary from 0.51 in 12-month rams [ 19 ] to −0.37 in Latxa Cara Rubia [ 18 ], and the correlation between volume and concentration has been reported to vary between −0.71 and 0.02 in Latxa Cara Rubia and Churra rams respectively [ 18 ].…”