Salomea Grajewska

Polymorphism in Coding and Non-coding Regions of the MyoD Gene Family and Meat Quality in Pigs*

The aim of the study was to evaluate the relations between genotype effects at porcine loci MYF3, MYF4, MYF5 and MYF6 on meat quality traits in pigs of the CC genotype at the RYR1 locus. Meat traits were analysed in longissimus lumborum muscle in 98 pigs (75 of PLW PL and 25 [PLW PL] Pietrain crosses). The determined meat characteristics covered the pH1 and pHu records, visual assessment of colour and exudation on fresh meat samples, water holding capacity, drip loss, spectrophotometric measurements of dominant wavelength, colour saturation and lightness, L, a*, b* values according to the CIE system, basic chemical constituents (water, protein, intramuscular fat and ash) and soluble protein fraction in meat. The distribution of animals within particular MyoD genotypes only in the MYF4 and MYF5 genotypes were spread uniformly. The gene effects at particular MyoD loci on studied meat traits were significant. The most pronounced effect on meat quality was exerted by the myogenin gene (MYF4). Individuals of the BB genotype in respect to the MYF4 locus showed a better water holding capacity (P<0.01), lower drip loss (P<0.05), darker colour score (P<0.01) and better wateriness score (P<0.01), darker and more desirable colour characteristic (P<0.01) than pigs with the AA genotype, whereas AB genotype animals had intermediate values. In respect to meat protein solubility the AA genotype pigs had a significantly lower level of soluble protein in meat than AB and BB (P<0.01). On basis of the present study it may be inferred that mutations in coding and the non-coding regions of MyoD genes exert significant effects on muscle traits related to oxidative metabolism, as well as related to glycolysis and contractile muscle properties, and thereby on meat quality.

Morphometric Characteristics of the Reproductive System in Polish Large White and Polish Landrace Gilts at 100 Kg Body Weight / Charakterystyka morfometryczna układu rozrodczego loszek wielkiej białej polskiej i polskiej białej zwisłouchej przy masie ciała 100 kg

Abstract The study involved an analysis of the developmental stage of reproductive organs collected at slaughter from 160 gilts (Polish Large White (PLW), n = 80; Polish Landrace (PL), n = 80) at 100 kg body weight. Due to a large variation in slaughter age (140-190 days), three groups of animals were set up: A (less than 160 days), B (160 to 180 days) and C (more than 180 days). PL gilts reached their slaughter weight earlier than PLW gilts (P≤0.05). Uterine weight increased with the age of animals but due to high variability and large deviations from the mean value, statistically significant differences were demonstrated only between gilt groups A and B for both breeds together (120.57 g vs. 148.83 g; P≤0.05). Larger differences related to the age of the gilts were found for cervical length between the groups compared (P≤0.01). The total length of the right and left uterine horns showed a significant increase with age in PLW gilts (P≤0.05). The ratio between uterine weight without ligament and the length of uterine horns (g/cm) was significantly higher in group B than in group A in gilts of both breeds together (P≤0.05), which might indicate thickening of the uterine walls. Uterine capacity was significantly higher in older animals yet due to a large variability of this trait, no significant differences between the groups were shown. The length and diameter of oviducts, the weight of each ovary, their sum and dimensions did not reveal any consistent changes associated with the age or breed of pigs. However, the size of the ovaries determined volumetrically and reported as the volume of ovaries in gilts of both breeds was significantly larger in group B compared with C (P≤0.01). No significant differences related to the studied traits were stated between PLW and PL prepubertal gilts. However, the effect of age on morphometric development of the reproductive system was more pronounced in PLW than in PL gilts. STRESZCZENIE W niniejszej pracy oceniano u 160 loszek (wbp n = 80; pbz n = 80) stan rozwoju narządów rodnych pobranych przy uboju przy masie ciała 100 kg. Ze względu na duże zróżnicowanie wieku przy uboju (140-190 dni) utworzono trzy grupy zwierząt: A (poniżej 160 dni), B (od 160 do 180 dni) i C (powyżej 180 dni). Nieco wcześniej osiągały masę ubojową loszki rasy pbz niż rasy wbp (P≤0.05). Masa macicy zwiększała się wraz z wiekiem zwierząt, jednak ze względu na dużą zmienność i dużą wartość odchylenia od średniej, statystycznie istotne różnice wykazano tylko między grupą loszek A i B obu ras łącznie (120.57g wobec 148.83 g; P≤0.05). Większe różnice związane z wiekiem loszek wykazano dla długości szyjki macicy między porównywanymi grupami (P≤0.01). Długość prawego i lewego rogu macicy podana łącznie wykazała istotny wzrost wraz z wiekiem zwierząt u loszek rasy wbp (P≤0.05). Proporcja masy macicy bez więzadła do długości rogów (g/cm) była istotnie większa w grupie B, niż w grupie A u loszek obu ras łącznie (P≤0.05), co może wskazywać na pogrubienie ścian macicy. Pojemność macicy była wyraźnie większa u zwierząt starszych, lecz ze względu na dużą zmienność tej cechy nie wykazano istotności różnic między grupami. Długość i średnica jajowodów, masa poszczególnych jajników, ich suma i wymiary nie wykazały systematycznych zmian związanych z wiekiem i rasą świń. Jednak wielkość jajników określona metodą wolumetryczną i podana jako objętość jajników u loszek obu ras była istotnie większa w grupie B w porównaniu z C (P≤0.01). Nie wykazano istotnych różnic związanych z rasą w morfometrycznej budowie układu rozrodczego niedojrzałych płciowo loszek wbp i pbz. Jednak wpływ wieku na badane cechy był bardziej wyraźny u loszek rasy wbp niż pbz.

BONE STRENGTH (ossis tibiae) OF NATIVE PIGS ZŁOTNICKA SPOTTED BREED AND CROSSBREDS OF POLISH LARGE WHITE AND PoLISH LANDRACE PIGS

The purpose of this study was to compare the bone strength traits in two groups of pigs different in terms of genetic value, fast growth capability and meat deposition in the body. The study covered 33 fatteners of the Zlotnicka Spotted breed (ZŁP) and 20 crossbreds F1 (Polish Large White x Polish Landrace). Tibial bones were obtained following slaughter and evaluated in terms of properties and geometry, as well as bending and compressive strength. Mineral composition of the bone tissue was also established, i.e.: ash, Ca, P, Na, K, Zn and Mg. The significance of differences between the traits demonstrated by pigs in both groups subject to the study was estimated, with calculated overall correlations between the primary bone properties. The results confirmed significant differences in terms of geometry of the bones in both animal groups. In the ZŁP breed pigs, compared to the F1 crossbred group (PLW x PL), the outside and inside diameters of the tibial shaft were smaller (P ≤ 0.01), yet the average thickness of the wall of the bone was slightly larger. The bending force required to fracture the bone turned out to be lower in Zlotnicka Spotted pigs, the opposite of the results obtained with regard to the compressive strength. Furthermore, calcium content, calcium-phosphorus ratio (Ca : P) and sodium content were highly statistically or significantly larger in the bone tissue of the Zlotnicka Spotted pigs. Consequently, the final results show that the bone strength demonstrated by modern pig breeds subject to intensive selection focused on high growth rate and increased meat deposition is in no way lower than the same trait recognized in the Zlotnicka Spotted breed kept in preservative breeding conditions.