Jochen Wolf

Simultaneous estimation of the covariance structure of traits from field test, station test and litter recording in pigs

Abstract The covariance structure was estimated by REML for a joint genetic evaluation of traits from field test, station test and litter recording with data from the Czech Landrace (LA, 86 833 records) and the Slovak White Meaty breed (WM, 58 348 records). Production traits from the field test (average daily gain [ADGF], lean meat percentage [LMF], and backfat thickness [BFF]) and from the station test (average daily gain [ADGS], valuable cuts [VCS], and backfat thickness [BFS]) as well as reproduction traits (number of piglets born alive in the first litter [NBA1] and number born alive in the second and higher litters [NBA2+] as a trait with repeated measurements) were analyzed jointly in a six-trait (LA) or seven-trait (WM) animal model. The estimated genetic correlations between NBA1 and NBA2+ (0.83 for LA and 0.78 WM) support the decision to treat first and further litters separately in genetic evaluation. The proportions of variances and correlations were also estimated for nongenetic effects in the models for both breeds (herd or herd–year–season, station–year–season, litter effects, and permanent effect of sow). For ADGF, a very high proportion of variance (0.43) was observed in WM for the herd–year–season effect and in LA (0.27) for the herd effect. The herd–year–season effects for reproduction traits were low (0.05–0.06 in WM, 0.01–0.02 in LA). The estimated genetic correlations between production and reproduction traits were small with the highest absolute values between NBA2+ and ADGS (−0.12 for LA and −0.28 for WM). As not all of them were zero, a separate genetic evaluation of reproduction would be incorrect. Also, because of the low heritabilities of the reproduction traits any additional information will be useful making a joint evaluation of production and reproduction traits preferable. Covariance estimates and parameters for genetic and nongenetic effects in the models were widely discussed with special attention to the most recent literature sources.

Economic weights for beef production traits in the Czech Republic

Abstract The economic weights for net daily gain, dressing percentage and average class of fleshiness and fat covering were calculated for Czech Pied cattle. They were defined as the partial derivatives of the discounted profit function with respect to the evaluated traits. A closed herd model was assumed. For fleshiness and fat covering, which were measured as ordered categorical traits, the threshold model was applied. A modified procedure for calculating the economic weight of an ordered categorical trait was developed. Population and production parameters valid in the Czech Republic in 1992 were used. The economic weights were (per standard female unit): Kc 8.04 per g/d (1 US

Incidence and economics of clinical mastitis in five Holstein herds in the Czech Republic.

= 28Kc) for net daily gain, Kc 182 per 1% of dressing percentage, Kc 1.01 and Kc 0.65 for decreasing the mean class in fleshiness or fat covering, respectively, by 0.01 points where lower class numbers stand for better quality. As the economic weights for quality classes of fleshiness and fat covering are very low, these traits will only be of interest for selection programs, if they are positively correlated with other economically important traits.