Genetic variability of some Italian and Polish duck breeds

This study is aimed to estimate and compare the inter- and within-breed variability of duck populations under genetic conservation programmes. The following four duck breeds were analysed: Germanata Veneta (AGV) and Mignon (AMG) from Italy, Pekin Krajowy (33P) and Pomniejszona (2K) from Poland. The characterisation of the four populations was carried out through a panel of 23 microsatellite markers. The analysis involved 180 individuals: 39 for AGV, 41 for AMG, 50 for 33P and 50 for 2K. An average of 11.36 alleles per locus was identified. Twenty-two loci showed high values of polymorphism information content from 0.575 to 0.912, while CAUD136 was monomorphic for the Italian breeds. The breeds showed relatively high heterozygosity: higher for the Polish populations (0.6920 for 33P and 0.6521 for 2K), and lower for the Italian (0.4497 and 0.3718 for AGV and AMG, respectively). The inbreeding coefficient was higher for the Italian breeds, AMG in particular (0.133, 0.097 and 0.121), as well as the differentiation index (0.253). The Nei’s minimum distances (DM) and Reynolds distances (DR) were low between the Polish populations (0.131 and 0.088, respectively); these were associated to AGV (DM = 0.191 and DR = 0.259 for 33P; DM = 0.174 and DR = 0.226 for 2K). Finally, AGV was distant from AMG (DM = 0.259 and DR = 0.317). The molecular coancestry, or mean kinship was higher for the Italian breeds compared to Polish populations. The Italian populations showed intermediate values. The obtained results can be perceived as an important tool for the applied genetic conservation programmes

Single-gene Effects on Body Weight in Selected and Unselected Mouse Lines Detected by Bayesian Marker-free Segregation Analysis

Segregation analysis of body weight at 21, 42, and 63 days in eleven generations of unselected (2813 individuals  of C line) and selected (1410 individuals of HGC line, derived from C line) mice was performed.  The Gibbs sampling algorithm was applied to obtain posterior density distributions of model parameters.  Moderate heritability via polygenic model was estimated. The results suggest a mixed inheritance model  (major gene + polygenic) for the body weight. The proportion of single gene variance to phenotypic variance  ranged from 9.7 to 41 percent. The estimated additive heritabilities for these traits varied between 0.25  and 0.47 for the C line and 0.37 and 0.41 for the HGC line. Considerable differences in estimated major  gene frequencies were found between unselected and selected lines.

The search for SNPs and genes associated with the feed conversion ratio using entropy analysis.

The aim of this study was to detect the chromosomal regions connected with feed conversion ratio and point out the respective genes in meat-type chicken. Analysis covered 862 genotyped commercial line of broiler using 60K Illumina iSelect chicken array and obtained information about 57636 SNPs. Feed conversion ratio between 39-46 days were registered. Finally, 42770 SNPs were analysed. The information theory is employed to detect the association between SNPs and recorded traits. The following parameters were estimated: entropy coefficient, conditional entropy, portion of information and mutual information. Important regions at chromosomes 1 and Z were identified. They are mainly located within genes determining the nervous system and expressed also in gastrointestinal tract

The effects of line crossing following selection in mice

The objective of this study was to evaluate selection responses and heterotic effects in mouse line crosses after ten generations of selection. Four mouse lines were analyzed: G, L, W and C, selected for growth (body weight at 42 days [BW42]), tail length at 42 days [TL], litter size at birth [LS], and the control line, respectively. After 10 generations of selection the first set of crosses was created; in generation 12, backcrosses and three-way crosses were made. In the crosses the following traits were analyzed: body weight at 21, 42, 63 days, tail length at 42 days, litter size and litter mass at birth. Additive genetic effects of all lines were significant for BW (at all three measurement times) and TL. Heterosis was found for BW42 for the WxC combina- tion, whereas the CxL combination tended to have a BW42 lower than expected from the line means. The same effect was observed for the CxG cross at day 63 with the effect increasing with age. With the exception of a maternal heterotic effect in the GxL cross, there was no significant effect on reproductive traits. The results show that 10 generations of line separation with selec- tion on different traits (rather than divergent selection on a single trait) are enough to create tic differences between the lines which result in a significant amount of heterosis for some parameters

Genetic Diversity of Old Chicken Breeds Kept in Poland

The aim of this study was to compare the genetic variation of five local chicken breeds reared in Poland. Twenty-seven microsatellite markers were investigated in 138 birds belonging to five breeds: Miniature Cochin (MCO), Gold Italian (GI), Green Legged Partridge (GLP), Silver Italian (SI) and White Leghorn (WL). One hundred eighty five alleles were detected in the overall population, with a mean number of 6.85 ± 3.32 alleles per locus. For the local breeds, the observed and expected heterozygosity ranged from a minimum of 0.287 to a maximum of 0.458 and from 0.397 to 0.499 for the GI and SI breeds, respectively. The overall population heterozygote deficiency was 0.430, the average Wright’s inbreeding coefficient (FIS) was 0.061 and the heterozygote deficiency due to breed subdivision was 0.393. Wright’s fixation index was slightly positive for all breeds excluding MCO (FIS = -0.476) and the estimated molecular inbreeding (fij) within breed ranged from 0.296 (GLP and SI) to 0.361 (WL) evidencing limited coancestry. Mean allelic richness, obtained with rarefaction method based on sixteen observations, was 2.12 being the WL the less variable (1.79). Tomiuk and Loeschcke’s DTL genetic distance values were used to draw a neighbornet network which separated the cluster made of MCO and GLP from the cluster of GI, WL and SI. The results arising from our microsatellites analysis represent a starting point for the valorization of these local Polish chicken breeds for monitoring and preserving their genetic variability

Detection of SNP effects on feed conversion ratio in pigs based on entropy approach.

The objectives of the study were to classify SNPs according to their contribution to the feed conversion ratio and to indicate interactions between the most informative SNPs using entropy analysis. The records of 1296 pigs were included. Two selection criteria for molecular data were applied: call rate 0.95 and minor allele frequency 0.05. After this, 50 951 SNPs were included into the entropy analysis. For each SNP entropy and conditional entropy were estimated. For interaction analyses the most informative SNPs were selected. For each pair of SNPs, the mutual information was assessed. A majority of the loci studied showed relatively small contributions. The most informative SNPs are mainly located on chromosomes: 1, 4, 7, 9 and 14. Whereas important interactions between SNP pairs were detected on chromosomes: 1, 14, 15 and 16. High mutual information was registered for SNPs located nearby.

Inter and Intra Subpopulation Genetic Variability of Roe Deer (Capreolus capreolus L.) Assessed by I and II Class Genetic Markers

This article is published as Kamieniarz, Robert, Anna Wolc, Mirosław Lisowski, Mirosława Dabert, Bartosz Grajewski, Ryszard Steppa, and Tomasz Szwaczkowski. "Inter and intra subpopulation genetic variability of roe deer (Capreolus capreolus L.) assessed by I and II class genetic markers." Folia biologica 59, no. 3-4 (2011): 127-133. doi: 10.3409/fb59_3-4.127-133.</p

The effects of line crossing following selection in mice

The objective of this study was to evaluate selection responses and heterotic effects in mouse line crosses after ten generations of selection. Four mouse lines were analyzed: G, L, W and C, selected for growth (body weight at 42 days [BW42]), tail length at 42 days [TL], litter size at birth [LS], and the control line, respectively. After 10 generations of selection the first set of crosses was created; in generation 12, backcrosses and three-way crosses were made. In the crosses the following traits were analyzed: body weight at 21, 42, 63 days, tail length at 42 days, litter size and litter mass at birth. Additive genetic effects of all lines were significant for BW (at all three measurement times) and TL. Heterosis was found for BW42 for the WxC combina- tion, whereas the CxL combination tended to have a BW42 lower than expected from the line means. The same effect was observed for the CxG cross at day 63 with the effect increasing with age. With the exception of a maternal heterotic effect in the GxL cross, there was no significant effect on reproductive traits. The results show that 10 generations of line separation with selec- tion on different traits (rather than divergent selection on a single trait) are enough to create tic differences between the lines which result in a significant amount of heterosis for some parameters.This article is published as Wolc, Anna, Werner Schlote, and Tomasz Szwaczkowski. "The effects of line crossing following selection in mice." Scandinavian Journal of Laboratory Animal Science 41, no. 11 (2015): 1-13. doi: 10.23675/sjlas.v41i0.334. Posted with permission.</p

Genetic variability of traits recorded during 100-day stationary performance test and inbreeding level in Polish warmblood stallions

The objectives of this study were to estimate direct heritability of 30 conformation and performance traits evaluated during 100-day stationary performance test and to predict the genetic effects in Polish Warmblood stallions. Inbreeding coefficients were estimated as well. Moreover, phenotypic and genetic trends were derived. The data were extracted from the database of the Polish Horse Breeding Association. The analysis included 494 warmblood stallions, which performed during 100-day test in the years 2002-2008 at two Polish Training Centres. Pedigree data comprised 8 512 individuals. Restricted maximum likelihood was employed to estimate parameters under an additive genetic model (including fixed effects: age of stallion, breed, year and place of performance test). Nonzero inbreeding coefficients were estimated for 88 stallions with performance records as well as for 458 unrecorded ancestors. Average inbreeding level for the stallions with records was 0.29 %, whereas for all inbred individuals – 1.69 %. The average completeness of the pedigrees, expressed as Cassell coefficient, for the recorded stallions was 42.47 %. The heritability estimates varied from 0.14 (character) to 0.87 (total index). Relatively high heritabilities were found for jumping-ability traits. In general, the genetic trends for studied traits were negligibly positive.This article is published as Borowska, A., Wolc, A., and Szwaczkowski, T.: Genetic variability of traits recorded during 100-day stationary performance test and inbreeding level in Polish warmblood stallions, Arch. Anim. Breed., 54, 327–337, doi: 10.5194/aab-54-327-2011, 2011. </p

Synergy factors in the analysis of lamb survival

Survival is one of the most important traits in genetic improvement programmes in livestock. The objective of this study is to determine sex, inbreeding, and birth type effects as well as their interactions on birth survival in lambs of two breeds. Records of 6356 Polish Merino (PM) breed and 9143 Wielkopolska sheep (WS) were taken into the analysis. Relationships between survival and three binary variables (sex, inbreeding, type of birth) were estimated by the use of logistic regression. Interactions among these variables were also included in the model. Thus, the odds ratios and synergy coefficients were estimated. Lowest birth mortality was registered for inbred females from single birth. Differences in survival between the studied breeds were observed. Negligible single effects of sex, inbreeding and birth type for PM were estimated, whereas for WS these effects were significant (P&lt;0.01). Opposite dependencies were obtained for interactions among these variables. In the case of PM, synergy between birth survival and joint effects of sex-inbreeding, sex-birth type, sex-inbreeding-birth type were highly significant, but for WS only inbreeding-birth type interaction was considerable. Hence, a generalisation of the obtained results seems to be difficult: they exhibit a very complex background of lamb survival