Estimation of genetic parameters for teat number and reproduction and production traits from different data sources for Czech dam breeds

Genetic parameters for total number of teats (TNT), total number of piglets born (TNB), number of weaned piglets (NW), lean meat content, and average daily gain were estimated for the populations of Czech Large White and Czech Landrace pig breeds. TNT was defined as sum of all measurable teats without taking into account of between teats and was counted during the identification of piglets up to 10 days after birth. Two main resources of data for TNT were analyzed: (1) TNT recorded only for breeding pigs in the national performance testing scheme (animals with at least 14 teats in total) as the pre-selected performance data set (PT; 94,500 animals); and (2) TNT recorded in nucleus and multiplier farms (F). In this data set (40,160 animals), whole litter information, including negatively selected piglets, was considered. Only 6.7% of animals from farmers' data set showed optimal production in the performance test. The average number of piglets evaluated in the PT and F data sets per litter was 2.7 and 9.4, respectively. The TNT was analyzed using single-trait and five-trait animal models by using production and reproduction data to determine heritability and genetic correlations between TNT and production and reproduction traits. As expected, the farmers' data set was characterized by higher variability of TNT than the performance data set. The estimated heritability for TNT ranged from 0.28 to 0.30 (regarding the data and models used). The genetic correlations of TNT with production and reproduction traits were negligible and varied from −0.096 to 0.080 depending on the datasets and models used. A very high significant genetic correlation (0.782 and 0.793) was found between TNB and NW. Our hypothesis of impact of raw data inclusion on estimated genetic parameters for the trait TNT was rejected. Our findings suggested no significant differences for the estimated heritabilities of TNT among the analyzed datasets and models. The breeding values for TNT can be estimated by using single as well as multi-trait animal models, because no genetic correlations with production and reproduction traits were found.