The aim of this study was to provide information on the fatty acid profile of different adipose depots -subcutaneous (upper and inner backfat layers) and intramuscular (m. Longissimus dorsi) in East Balkan pigs. The animals were reared in free-range conditions and slaughtered at an average live weight of 107±1.65kg. The results of the study showed that the various adipose tissues in pigs have different lipid metabolism and hence differ in their fatty acid composition. Intramuscular fat had significantly higher content of the saturated C16:0 and C18:0 (P<0.001), as well as the C16:1 (P<0.001) than the subcutaneous fat. In regards to the content of the polyunsaturated fatty acids, the latter displayed considerably higher content of both C18:2 and C18:3 (P<0.001) in comparison to the intramuscular fat in m. Longissimus dorsi. The differences between the subcutaneous and intramuscular adipose tissue in the individual fatty acids determined the similar trend of change in the total content of saturated and polyunsaturated fatty acids. Significant differences between the backfat layers were detected for C16:1, C18:0 and C18:3 (P<0.001). Stearic acid (C18:0) displayed higher content of the inner, while both C16:1 and C18:3 had higher proportion in the outer backfat layer in the East Balkan pigs. Except for C20:2, the long chain polyunsaturated n-6 and n-3 fatty acids had significantly higher proportions in the intramuscular fat, however no differences were determined between the two backfat layers.

The aim of this study was to describe and compare the fatty acid profile of the backfat layers in four pig breeds – Landrace, Pietrain, Duroc and Large White. Six gilts per breed were used for the analysis. While differences between the examined breeds were limited to the content of C18:1n-9 and the total level of monounsaturated fatty acids (MUFA), which were highest in the inner backfat layer of Duroc pigs, the two layers differed substantially. Generally, the inner backfat layer was more saturated when compared to the outer layer. On the other hand, the content of the polyunsaturated fatty acids (PUFA) was higher in the outer layer. The differences in the fatty acid profile between the two backfat layers were most visible in the Landrace pigs. The latter showed significantly higher content of C18:0 (P<0.001), which was also found in Duroc (P<0.05), as well as total saturated fatty acids (SFA) (P<0.01) in the inner layer. Furthermore, higher levels of C18:2n-6 (P<0.05), C18:3n-3 (P<0.01) and the total amount of PUFA (P<0.05) were found in the outer backfat layer in the animals of the Landrace breed.

Twelvehematological and fifteen serum biochemical parameters were determined in indigenous East Balkan pigs at different ages and two seasons. The experiment was carried out in the Scientific Centre of Agriculture- Sredets aiming to characterize the health status of the animals when reared organically. Blood samples were taken from pre-weaned piglets (n=10), growers (n=10) and sows (n=10) in spring and summer. The results were analysed through two way ANOVA to assess the influence of the age, season and their interaction on the hematological and serum biochemical profile of the animals. Both age and season interacted significantly in regard to the red blood cells count (RBC) (P0.001), hemoglobin (HGB) (P0.001) and hematocrit (HCT) (P0.01), as well as in the most biochemical parameters including creatinine(P0.001), total protein (TP) (P0.001), albumin (ALB) (P0.001), alanine aminotransferase (ALT) (P0.001), aspartate aminotransferase (AST) (P0.01), uric acid (UA) (P0.01), Mg (P0.001), triglycerides (TG) (P0.05) and cholesterol (P0.01). Regardless of the season, the white blood cells (WBC) including lymphocytes and granulocytes, as well as platelets (PLT)decreased with age, while mean corpuscular volume (MCV) increased.The content of glucose, urea, gamma-glutamil transferase (GGT), alkaline phosphatase (ALP), Ca and P which displayed maximal values in preweaned pigs (P0.05) compared to the other age groups (P0.05). The season affected the number of lymphocytes (P0.01), their percent (P0.001), mean corpuscular hemoglobin (MCH) andmean corpuscular hemoglobin concentration (MCHC) (P0.001), as well as the concentration of GGT (P0.001) which increased during summer,and also granulocytes (P0.01), their percentage (P0.001), PLT (P0.05), glucose, urea, ALP, Ca (P0.001) and P (P0.01) whichwere higher in spring.

The aim of our study was to assess the dynamics of the characteristics in pig carcasses as affected by the season and year of slaughter. A total of 106 027 carcasses of growing-finishing pigs of commercial production, slaughtered in the same abattoir in 2014 and 2015 were included in the study. The carcasses were classified using UltraFOM 200 device, as the characteristics controlled were back-fat thickness at two locations and the depth of m. Longissimus dorsi. These measurements were used to further determine the lean meat percentage. The results of the study showed significant differences in the dynamics of changes of carcass characteristics during the seasons and the years. The highest lean meat percentage was found in summer (56.48%), followed by spring (56.34%), autumn (56.29%) and winter (56.10%). On the other hand, the pigs slaughtered in winter displayed highest carcass weight and back-fat thickness at both locations.

Abstract(An experiment with two groups of East Balkan pigs – castrated males (n=10) and females (n=10), was carried out to study the growth performance and fattening abilities of the animals from the weaning until slaughter. The pigs were included in the trial at 60 day age. The average live weight of the castrated males was 8. 65±1.08 kg and for the females, 8.5±0.62 kg.The pigs were reared using traditional technology, grazing on natural pastures in the Strandzha mountain, Bulgaria. In autumn, acorns were naturally present in their diet. According to the category, the animals additionally received ground organic feed (50% barley and 50% wheat). The trial lasted 304 days (from February to November, 2019). During this period the final live weight of the male castrated pigs reached 88.00 kg while that of the females was 84.4 kg. The difference, however, was not significant. Furthermore, no significant differences in the growth performance characteristics that could be attributed to the sex of the animals were observed. The average daily gain of both sexes tended to be lower in summer and higher in autumn. The feed conversion ratio was higher in summer. The animals showed high average daily weight gain at pasture when their live weight was over 50 kg.