Modern pig breeds, which have been genetically improved to achieve fast growth and a lean meat deposition, differ from local pig breeds with respect to fat deposition, fat specific metabolic characteristics and various other properties. The present review aimed to elucidate the mechanisms underlying the differences between fatty local and modern lean pig breeds in adipose tissue deposition and lipid metabolism, taking into consideration morphological, cellular, biochemical, transcriptomic and proteomic perspectives. Compared to modern breeds, local pig breeds accumulate larger amounts of fat, which generally contains more monounsaturated and saturated fatty acids; they exhibit a higher adipocyte size and higher activity of lipogenic enzymes. Studies using transcriptomic and proteomic approaches highlighted several processes like immune response, fatty-acid turn-over, oxidoreductase activity, mitochondrial function, etc. which differ between local and modern pig breeds.

The effect of linseed oil supplementation on performance, fatty acid composition and oxidative status of rabbits The objective of the present study was to determine the effect of linseed oil supplementation on performance, fatty acid composition and oxidative status of rabbits. Twelve male SIKA rabbits were divided into two groups. The control group (n = 4) received commercial diet and the linseed group (n = 8) received commercial diet containing 9% of linseed oil, which was sprayed onto the pellet. rabbits were slaughtered at 115 days of age, 52 days after the start of the experiment. Live weight, weight gain, feed intake and feed efficiency were recorded. The fatty acid composition of muscle, adipose tissue and liver was determined by the in situ transesterification method and gas chromatography-flame ionisation detection (GC-fId). In order to evaluate the oxidative status of rabbits, the malondialdehyde (mdA) concentration in plasma, liver and muscle were measured. The results show that it is possible to enhance proportion of n-3 polyunsaturated fatty acids (pufA) in rabbit's muscle, adipose tissue and liver by adding linseed oil in the diet without detrimental effect on productive performance. Linseed oil addition improved fatty acid composition in all tissues by increased pufA proportion and decreased proportion of saturated and monounsaturated fatty acid. Linseed oil also reduced n-6/n-3 pufA ratio in all tissues. However, linseed oil addition led to significantly higher mdA concentrations in plasma, liver and muscle. Since pufA are highly susceptible to oxidation, further research is needed to focus on protecting animal and their products from lipid oxidation by adding various natural antioxidants to the diet.

14Data on production traits of the only Slovenian autochthonous pig breed, the 15 Krškopolje pig, is very scarce. Krškopolje pigs are reared in conventional and organic 16 production systems, which were compared in the present study. After weaning, 24 17 barrows were assigned within litter to either conventional (CON) or organic (ECO) 18 rearing system. Group CON (n=12) was housed indoors in two pens (7.5 m 2 ) with 19 partly slatted floor. Group ECO (n=12) was held in a sty with sheltered area (concrete 20 floor, bedded with straw, 16 m 2 ) and outdoor paddock area (100 m 2 ). The trial started 21 when pigs had 68±8 kg BW and 157±6 days of age. Two diets were formulated with 22 equivalent ingredients and composition. For ECO diet the ingredients used were 23 ecological. Group ECO received a diet with 12.4 MJ metabolisable energy (ME) per 24 kg and 12.9% CP and group CON a diet with 12.7 MJ ME per kg and 13.6% CP. 25This manuscript has been published in a revised form in journal ANIMAL Feed distribution was limited to 3.5 kg per pig daily. In line with the rules for organic 26 production, ECO pigs were additionally given alfalfa hay ad libitum. After 73 days on 27 trial, the pigs were slaughtered and carcass, meat and fat quality was evaluated. 28Meat quality traits (pH, colour, water holding capacity), fatty acid composition, lipid 29 and protein oxidation, collagen content and solubility were analysed in longissimus 30 lumborum (LL) muscle. Fatty acid composition, lipid oxidation, and vitamin A and E 31 concentrations were determined in backfat. There were no significant differences in 32 growth rate and carcass traits between ECO and CON pigs, however ECO pigs 33 tended (P<0.10) to have higher daily gain and lower dressing percentage, higher 34 (P<0.001) pH 45 min and lower (P<0.01) pH 24 h post mortem, affecting (P<0.10) 35 also water holding capacity and objective colour parameters (P<0.05) of LL muscle. 36There were no differences in intramuscular fat (IMF) content of LL muscle, however 37 IMF of ECO pigs had lower (P<0.05) proportion of saturated and higher (P<0.01) 38proportion of monounsaturated fatty acids accompanied by higher (P<0.001) values 39 of thiobarbituric reactive substances (TBARS). In backfat, ECO pigs showed lower 40 (P<0.05) vitamin E content, higher (P<0.001) TBARS, higher (P<0.01) degree of 41 unsaturation (percentage of polyunsaturated fatty acids ), and also higher (P<0.05) 42 vitamin A concentration than CON pigs, which can be related to alfalfa hay 43 supplementation of ECO pigs. In brief, organic rearing of Krškopolje pigs did not 44 affect performances but had an effect on meat and fat quality. 45 46 47

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There are indications of reduced meat quality in entire male pigs (EMs) in comparison to surgically castrated pigs (SCs); however, the differences are not strongly confirmed, and the etiology is not clarified. In the present study, samples of the longissimus dorsi, pars lumborum muscle (LL) from EMs (n = 12) and SCs (n = 12) of the same age and weight were evaluated at the physico-chemical and proteomic level. EMs exhibited lower intramuscular fat content, higher collagen content with higher solubility, a higher level of protein carbonyl groups (indicating higher protein oxidation), lower water holding capacity, and tougher meat than SCs. Proteomic analysis revealed differences in heat shock proteins expression, while a greater abundance of several other identified proteins (malate dehydrogenase, Na/K-transporting adenosintriphosphatase (ATP-ase) subunit alpha-1, and blood plasma proteins) indicates that EMs have a more oxidative metabolic profile than that of SCs. More abundant protein fragments (mainly actin and myosin heavy chain) suggest a higher degree of proteolysis in EMs, which was not followed by lower meat toughness.