Breeding for reproduction traits in context of multiplication herds efficiency in swine

HUMPOLICEK PETR, TVRDOŇ ZDENĚK, URBAN TOMAS: Breeding for reproduction traits in context of multiplication herds effi ciency in swine. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 3, pp. 647–650 Presented study is a follow-up to the studies focused on eff ect of diff erent selection pressure applied on two subpopulations of purebred Czech Large White sows on performance in multiplication herds. Higher selection pressure particularly on litter size and number of function nipples, while lower pressure on growth performance was applied in one population. About 1214 farrows of 393 F1 Czech Large White sows were included into statistical evaluation. The mixed linear models using the procedure REML in SAS for Windows 9.1.2. was used. The hypothesis that progeny of sows from hyper-prolifi c subpopulation breed in multiplier herds have diff erent performance was not confi rmed which is in contrast to previous studies. This non-homogeneity can be related to non-additive genetic eff ects which are caused by crossbreeding while selection methods are based on additive models. selection, crossbreeding, reproduction In swine, the selection criteria and breeding methods are mainly focused on the purebred populations in breeding herds but the focus on economic effi ciency of multiplier herds are insuffi cient if we consider profi t in swine industry. In spite of this the litter size traits or more generally prolifi cacy of F1 sows seems to be crucial. Achieving satisfactory reproduction level is complicated by the fact that reproduction traits are infl uenced by a complex of genetical and internal and external environmental factors. This leads to the problematic advancement even in breeding herds let alone in multiplication herds. During past decades diff erent selection strategies were tested: hyperprolifi c lines creation (Bidanel and Ducos, 1994), direct selection based on the evaluation of breeding value (Holl and Robinson, 2003), marker assisted selection (Distl, 2007) or introgression (Piyasatian et al., 2008), combination of molecular data into the BLUP-AM procedure (Baruch and Weller, 2009) and genomic selection (Noguera et al., 2009). Mentioned strategies were focused mainly on the progress in purebred populations without regarding the impact on multiplication herds. In previous studies (Tvrdoň and Humpolicek, 2010; Humpolicek and Tvrdoň 2011) it was described that despite maximal selection pressure using hyperprolifi c line, which can be applied in breeding herds without negative eff ects, the progress in litter size traits in multiplication herds was insuffi cient. We noticed that incorporation of some auxiliary selection traits can be very eff ective. In present study we are concerning that breed specifi c eff ect can be crucial if progresses in multiplication herds are taken into account. MATERIAL AND METHODS Experimental procedure In the study the progeny of Czech Large White sows bred at one breeding herd were used. The parental generation breed in breeding herd was divided into either hyperprolifi c (HP) or normal 648 Petr Humpolicek, Zdeněk Tvrdoň, Tomas Urban (N) subpopulation according to their performance. To be incorporated into the HP subpopulation, the sows had to meet the following criteria: excellent breeding value for litter size (number of piglets born alive in the second and subsequent litters) among the top 15%; have on her fi rst to third litter an average of 12 or more live-born piglets per litter; at least 7 functional nipples on either side, maximal back fat thickness of 12 mm and the sow must be MHS negative (Brenig and Brem, 1992). Sows which failed to meet these criteria belonged to the N subpopulation. Breeding values for individual traits were computed for both populations using the same method. The aggregate breeding values were computed separately for both populations using diff erent weight coeffi cients. The aggregate breeding value comprises 60% (HP) and 55% (N) of litter size on the second and following litters, 30 % (HP) or 40% (N) of average daily gain and 10% (HP) or 5% (N) of lean meat content. In HP subpopulations aggregate breeding values were used for planned mating. The sows of parental generation were mated or inseminated with the purebred boars of Large White breed while the sows of F1 generation were inseminated with purebred Landrase boars. In contrast to the sows from normal population the HP sows were mated or inseminated only with boars with excellent breeding values for reproduction (> 5% of population). These schemes of selection and mating were practised for six years. During this time 393 gilts from F1 generation were moved, at age of six months to the multiplier herd where their performances were recorded and subsequently analysed. All studied sows from F1 generation were bred under the same living conditions. Several performance traits were recorded in the F1 generation. The prolifi cacy was specifi ed by the total number of piglets born (TNB; defi ned as the number of all fully formed fetuses expelled at farrowing, dead or alive), number of piglets born alive (NBA; defi ned as the number of piglets alive immediately a er birth), number of piglets weaned (NW; defi ned as the number of piglets available on the 28-th day of the piglets’ age), age of sows at the fi rst parity (AFP) and number of functional nipples (FN). As the traits describing the growth performance the ultrasonic back fat thickness (BF; Sonomark 100) and lean meat content (LMC; calculated from ultrasonic measurements without any live weight pre-adjustment) and average daily gain from birth to test end (g/day) (ADG) were used. Statistical Analyses The mixed linear models using the procedure REML in SAS for Windows 9.1.2. were conducted to estimate the diff erences between the performance of F1 off spring and the eff ect of insemination or natural mating on litter size. As very diff erent traits are included in the study, the independent analyses were carried out for each trait. Individual models used to detect the eff ect of diff erent pedigree are defi ned in the Tab. I. RESULTS AND DISCUSSION Presented study is a follow-up to the studies focused on eff ect of diff erent selection pressure applied on two subpopulations of purebred Czech Large White sows on performance in multiplication herd (Tvrdoň and Humpolicek, 2010; Humpolicek and Tvrdoň, 2011). In these studies there was described that despite maximal selection pressure, which can be applied in breeding herds using hyperprolifi c line creation, the progress in litter size traits in multiplication herds was insuffi cient. In the Tab. II the non-signifi cant diff erences between the total number of piglets born, number of piglets born alive, number of piglets weaned, age at fi rst farrowing and functional niplets is presented. In previous studies the progress on the growth traits as well as on the number of functional nipples were found. Those results corresponded to the heritability of studied traits when only traits with middle or high heritability coeffi cient show progress in multiplication herds. Mutually in present study I: Specifi cation of models used for detection of diff erences between sows of HP or N population Litters Pop YS AFF Dam Sire Boar BF Mat PN