Robert Eckert

The expression pattern of myogenic regulatory factors MyoD, Myf6 and Pax7 in postnatal porcine skeletal muscles.

The MyoD, Myf6 genes, which belong to the family of muscle regulatory factors (MRFs) play a major role in muscle growth and development. Therefore, they are considered as candidate genes for meat production traits in pigs. These basic helix-loop-helix (bHLH) transcription factors regulate myogenesis: they initiate the formation of muscle fibres and regulate the transcription of muscle specific genes. The paired-box transcription factor Pax7 plays critical roles during fetal development and this protein is essential for renewal and maintenance of muscle stem cells. In particular, expression of Pax7 and MyoD is correlated with presence of active satellite cells, important in hyperplastic and hypertrophic growth in skeletal muscle. The objective of the study was to investigate the level of expression of MyoD, Myf6 and Pax7 genes in porcine skeletal muscles (m. semimembranosus, m. biceps femoris, m. gracilis) in breeds differing in muscularity. Moreover, we investigated expression profile of these genes during ontogenesis in Polish Large White (PLW) and Pietrain pigs in the largest ham muscle (m.semimembranosus). Analysis of several ham muscles showed higher expression of MyoD in the Polish Landrace (PL) breed than in Pietrain and PLW pigs (m. semimembranosus P<0.001; m. biceps femoris P<0.05 and P<0.01, respectively; m. gracilisP<0.01). The level of Pax7 transcript depended on type of muscle and breed. The highest expression was in m. gracilis in Pietrain and the lowest in Polish Landrace. Our results indicate that MyoD and Pax7 genes had higher expression levels in the early stages of development in both investigated breeds. The total expression profile of MyoD and Pax7 genes suggests that higher muscularity in Pietrain pigs is associated with the presence of a greater number of active satellite stem cells compared to other breeds. The expression level of Myf6 gene does not indicate significant differences between muscles, ages and breeds.

Comprehensive analysis of the whole transcriptomes from two different pig breeds using RNA-Seq method

Next-generation sequencing RNA-Seq technology is a powerful tool that creates new possibilities for whole-transcriptome analysis. In our study, the RNA-Seq method was applied to analyze global changes in transcriptome from muscle tissue (m. semimembranosus) in two pig breeds (Pietrain and Polish Landrace, PL). The breeds differ in terms of muscularity, growth rate and reproduction traits. Using three different approaches (deseq, cufflinks and edger) and taking into account the most restrictive criteria, 35 genes differentially expressed between Pietrain and PL pigs were identified. In both breeds, the most abundant were transcripts encoding ribosomal and cytoskeletal proteins (TPM3, TCAP, TMOD4, TPM2, TNNC1) and calcium-binding proteins involved in muscle contraction, calcium-mediated signaling or cation transport (CASQ1, MLC2V, SLC25A4, MYL3). In PL pigs, we identified up-regulation of several genes that play crucial roles in reproduction: female gamete generation (BDP1, PTPN21, USP9X), fertilization (EGFR) and embryonic development (CPEB4). In the Pietrain breed, only seven genes were over-expressed (CISH, SPP1, TUBA8, ATP6V1C2, IGKC, predicted LOC100510960 and LOC100626400), and they play important roles in, for example, negative regulation of apoptosis, immune response, cell-cell signaling, cell growth and migration as well as the metabolic process. The functions of the majority of selected genes were consistent with phenotypic variation in investigated breeds; thus, we proposed a new panel of candidate genes that can be associated with economically important pig traits.

Expression and imprinting analysis of the NESP55 gene in pigs

Most imprinted genes play important roles in a mammalian development. One of them is GNAS complex locus which codes for several imprinted or biallelically expressed transcripts. The function of some of them are well understood (for example GSα-guanine nucleotide binding, α -stimulating protein is essential element of cell signaling), whereas the others are little known. The function of NESP55 (Neuroendocrine secretory protein 55) remains elusive, although there are suggestions about its role in brain development. Imprinted genes are currently being studied as potential candidate genes for quantitative trait loci (QTLs) in farm animals. In our study, we analyzed tissue distribution of NESP55 mRNA in pigs and established imprinting status of this gene in the brain stem, muscle, kidney and liver at several developmental stages. NESP55 mRNA was most abundant in central nervous system (CNS) and pituitary. Substantial expression was also noticed in the kidney, testis and muscle. Moreover, we identified a 12-nucleotides deletion within the coding region of NESP55 (accession number ss#342570450) which was used in imprinting analysis. The deletion was very rare in the analyzed populations and present only in heterozygous form. The imprinting analysis showed that NESP55 is maternally expressed in young and adult pigs, similar to what was obtained in humans, mice and cattle.

Relationships between chemical composition of colostrum and milk and rearing performance of piglets during a 21-day lactation

Abstract Normal development of piglets is determined principally by the milking ability of the sows. This study attempted to determine the relationships between sow’s milk quality and rearing performance of the piglets. The experiment was carried out under uniform conditions, with standard feeding of the sows and a similar number of piglets per litter. The study accounted for 109 lactations of second- and third-parity Polish Large White (PLW ) sows and 123 lactations of second- and third-parity Polish Landrace (PL) sows. Colostrum and milk were collected from the sows at 1, 7, 14 and 21 days of lactation and analysed for solids, crude protein, fat, lactose and somatic cell count (SCC). Rearing performance of second- and third-litter piglets was determined based on the number and weight of piglets at birth and at 7, 14 and 21 days of age. The coefficients of correlation, estimated between basic composition of milk and rearing performance of the piglets over subsequent weeks of lactation were low and exceeded r = 0.200 only for some traits. The experiment showed that a higher content of basic milk components, in particular protein, may be one of the factors contributing to an increase in weight gain of piglets during a 21-day lactation. Milk fat content may be of significance for rearing performance of piglets only during their first week of life. Rearing performance of the piglets is unrelated to udder health expressed as milk SCC. STRESZCZENIE Prawidłowy rozwój prosiąt determinowany jest głównie przez mleczność odchowujących je macior. Podjęte badania stanowią próbę określenia zależności pomiędzy jakością mleka loch a wynikami odchowu prosiąt. Przeprowadzono je w ujednoliconych warunkach, standardowym żywieniu loch, jak również przy wyrównanej liczbie prosiąt w miotach. W badaniach uwzględniono 109 laktacji loch rasy wielkiej białej polskiej (wbp) oraz 121 laktacji loch rasy polskiej białej zwisłouchej (pbz). Były to laktacje po urodzeniu drugich i trzecich miotów tych loch. Od zwierząt zdajano siarę i mleko w 1., 7., 14. i 21. dniu laktacji. W siarze i mleku oznaczano: suchą masę, białko ogólne, tłuszcz, laktozę oraz komórki somatyczne (LKS). Wyniki odchowu prosiąt z drugiego i trzeciego miotu określone były na podstawie: liczby prosiąt oraz ich masy w dniu urodzenia oraz w 7., 14. i 21. dniu ich życia. Oszacowane współczynniki korelacji pomiędzy podstawowym składem mleka a wynikami odchowu prosiąt w kolejnych tygodniach laktacji były niskie i przewyższały wartość r = 0,200 jedynie dla niektórych cech. Badania wskazują, że większa zawartość podstawowych składników mleka, w szczególności białka i suchej masy, może być jednym z czynników wpływających na zwiększenie przyrostów prosiąt w czasie 21-dniowej laktacji. Zawartość tłuszczu w mleku może mieć znaczenie na odchów prosiąt tylko w pierwszym tygodniu ich życia. Wyniki odchowu prosiąt nie są zależne od liczby LKS w mleku.

Histological profile of the longissimus dorsi muscle in Polish large white and Polish landrace pigs and its effect on loin parameters and intramuscular fat content

Abstract The objective of this study was to analyse differences in individual fibre types in the histological profile of the longissimus dorsi muscle and their effect on pork carcass lean content and level of intramuscular fat (IMF) content, which determines palatability of meat and meat products. Analysis showed that the amount of type IIB fibres had a statistically significant (P<0.05) effect on the IMF content of the longissimus dorsi muscle. Animals with more than 70% of type IIB fibres in this muscle were also characterized by larger loin eye area (P<0.01) and loin eye height (P<0.05). Analogous relationships were noted when the analysed group of animals was divided according to the diameter of type IIA fibres. IMF was negatively correlated to the percentage of type IIB fibres (rP= -0.162). Relationships with the other two fibre types were positive (IIA - rP= 0.097; I - rP= 0.187). It was found that increased percentage of type IIB fibres resulted in a slightly greater loin weight (rP= 0.176), higher loin eye height (rP= 0.136), larger loin eye area (rP= 0.265) and higher carcass lean content (rP= 0.204). Likewise, the increase in the number of type IIA and type I fibres decreased these parameters.

18. Estimation of Meat Content in the Carcasses of Young Pigs Based on Performance Testing of Live Animals and Carcass Evaluation

Abstract The aim of the study was to develop new equations for the estimation of meat percentage in the carcasses of young pigs, based on examination of the current pig population. In addition, new regression equations were constructed to predict the weight of meat in primal cuts. In both cases, the estimates were based on performance testing of live animals and post-slaughter evaluation of carcass traits in these animals. The study was conducted on 654 gilts of six breeds. Performance testing of live animals and carcass evaluation were performed at the Pig Testing Station (SKURTCh). Performance records in live animals included body weight (BW [kg]), age (A [days]), daily weight gain (DG [g/day]), and ultrasonic measurements, using a Piglog 105 ultrasound apparatus: backfat thickness at P2 and P4 and loin eye height P4M (at P4). Then the gilts were slaughtered and, after being chilled for 24 hours at 4°C, the right half-carcass was dissected into primal cuts. These cuts were then subjected to detailed dissection, which provided the basis for determination of the weight of meat in the primal cuts E2 [kg] and meat percentage in the carcass E1 [%]. An array of linear models based on multiple regression was constructed to estimate meat percentage in the carcass [%] and weight of meat in primal cuts [kg]. It was found that the developed linear regression equations for all breeds, which estimated meat content in the carcass based on three variables (classical model: P2, P4 and P4M), were characterised by the following values of standard error of the estimate RSE and correlation coefficient R: for E1[%], RSE=3.33; R=0.63; for E2 [kg], RSE=1.65; R=0.58. The addition to the classical model of a variable describing the breed greatly improved the parameters of the equation predictive of E1 (RSE=3.02; R=0.71). The model predictive of E2 was obtained by the addition of two variables: breed and carcass weight on the day of measurement (RSE=1.37; R=0.73). In general, the present studies indicate that equations estimating the weight of meat in a carcass (E2 [kg]) based on performance testing of live animals are characterised by a much lower value of standard error (RSE) than equations estimating meat percentage in the carcass of the same pigs (E1[%]), including those currently used in practice.

Prediction of carcass meat percentage in young pigs using linear regression models and artificial neural networks.

Abstract One of the approaches to improving performance testing of pigs is to look for mathematical solutions to increase the accuracy of calculations. This is mainly done through improvement of linear regression equations based on current data on performance tested pigs in Poland. The advances in computer technology and the improvements in mathematical analysis have made it possible to use artificial neural networks (ANNs) for prediction of carcass meat percentage in young pigs. The aim of the study was to compare the potential for live estimation of carcass meat percentage in pigs using two computational methods: linear regression equations and ANNs. The experiment used 654 gilts of six breeds, which were subjected to performance testing and slaughter analysis at the Pig Performance Testing Station (SKURTCh). The collected data were used to train ANNs to estimate carcass meat percentage in young pigs. Training was performed using the Levenberg- Marquardt algorithm. Next, meatiness estimated by ANNs was compared with the results obtained using linear modelling. It is concluded that based on the fattening and slaughter performance test results of live pigs, artificial neural networks (SSN23) are significantly more accurate in estimating carcass meat percentage in young pigs compared to the three-variable linear regression model 1. The difference in meatiness estimation between SSN23 and the four-variable linear regression model 2 was statistically non-significant in most of the breeds except Duroc and Pietrain, where the meatiness of young animals was estimated more accurately by the linear regression model.

New Polymorphisms in Regulatory Regions of Porcine μ-Calpain Gene and Their Association with CAPN1 Transcript Abundance

Abstract The activity of calpains, in particular μ-calpain, is associated with several processes occurring in muscle tissue postmortem and influences meat quality parameters. Therefore, the CAPN1 gene coding for large subunit of μ-calpain is considered as a candidate gene associated with meat quality traits. The aim of our study was to identify new polymorphisms in regulatory regions of the porcine CAPN1 gene and to estimate their impact on CAPN1 transcript abundance. In the present study, 7 polymorphisms in the porcine CAPN1 gene were identified, of which 5 were localized in introns (g.1195_1197insCCT; g.1429G>A; g. [4479A>G; 4526A>T; 4529_4530delAG]), one in 3’ untranslated region (g.25676C>T) and one microsatellite sequence in promoter region (c.-155- AGGG [3_5]). The analysed populations (a total of 451 gilts representing three pure breeds: Pietrain, P lish Landrace, Polish Large White and one conservation breed Pu.awska) were not in Hardy-Weinberg equilibrium according to mutation g.25676C>T in 3’ untranslated region (all breeds), g.1429G>A (Pu.awska pigs) and g. [4479A>G; 4526A>T; 4529_4530delAG] (PLW pigs). Furthermore, the analysed SNPs in the porcine CAPN1 gene were in linkage disequilibrium (P≤0.05). The CAPN1 transcript abundance was also estimated in two important muscles (m. longissimus dorsi, m. semimembranosus). In longissimus dorsi muscle, a significant effect of c.-155- AGGG [3_5] polymorphism in promoter region on CAPN1 expression levels was determined. The c.-155AGGG [3/3] pigs showed a statistically higher (P≤0.05) expression level of the CAPN1 gene when compared to c.-155AGGG [4/4] homozygotes. The results obtained suggested that detected SNPs within regulatory regions of the CAPN1 gene could be related to transcript level and activity of μ-calpain. The selected polymorphisms areproposed to be associated with meat production traits.