Meat quality of “Nero Siciliano” pigs fed with different diets

The effects of two different feeding strategies used during the fattening period on the meat quality of 24 “Nero Siciliano” pigs were examined. Animals were divided into two groups called Acorn (A) and Barley (B), consisting of 12 animals each, homogenous for live weight and sex. The trial was carried out over a period of 90 days. After slaughtering, Longissimus lumborum (Ll) muscle samples were taken from the left half of each carcass and examined for: pH1 (after 45’) and pHu (after 24h), colour parameters, cooking loss, Warner-Bratzler shear force, chemical and fatty acid composition. Results showed that pH1 (A 6.28 vs. B 6.12), pHu (A 5.77 vs. B 5.63), cooking loss (A 24.60 vs. B 20.68), lightness (L*) (A 46.44 vs. B 48.61), C18:1ω9 (A 50.47 vs. B 43.91), MUFA (A 59.93 vs. B 48.90), SFA (A 34.04 vs. B 39.66), and PUFA (A 6.03 vs. B 11.44) between the two diets were statistically different. Introduction The “Nero Siciliano” pig is an autochthnous genetic type of the rural areas in north Sicily (Italy), traditionally reared under extensive conditions. Its presence is proved by fossil remains and by references of ancient writers in the Greek period (VII-VI b.C.). It is characterised by rusticity and good adaptability to the environment, and it grows with difficulty. It eats grasses, leaves, acorn, tubers, roots, and wild fruits. Because of its conformation (long muzzle, presence of strong bristles in dorsal trait) and habits, this pig is often confused with wild boars. Recently, the number of breeding animals increased, because of an enhanced demand of “Nero Siciliano” products. The aim of this work was to assess the effect of two different diets, on chemical-physical characteristics of meat and fatty acid composition of intramuscular fat of “Nero Siciliano” pigs. Material and methods The trial was carried out on 24 “Nero Siciliano” pigs, reared in the Nebrodi mountain region of Sicily. Animals were assigned to two groups called Acorn (A) and Barley (B), consisting of 12 animals each, homogenous for sex (castrated males) and body weight (BW, 79.48 ± 0.15 kg). Animals of group A were kept in a wooded area of 12 hectares, appropriately enclosed, and fed with acorn during the fattening period (90 days). Animals of group B were reared within an open-air system in the same rural region and fed with germinated barley on a basis of 2.5 kg/pig/d during the fattening period. After 90 days and a fasting period of 18 hours (ASPA, 1991), animals were slaughtered. At 45 minutes and at 24 hours post-mortem, pH1 and pHu were respectively measured. Determinations on Longissimus lumborum muscle (Ll), carried out according to ASPA (1996), were: 1) chemical composition (moisture content, intramuscular fat percentage (IMF) as ether extract, protein percentage and ash); 2) water-holding capacity, determined by cooking loss in a water bath; 3) shear force measurements, by Warner-Bratzler Instron 5542 apparatus (WBS) on cooked meat in water bath; and 4) colour parameters L*, a* and b*, with a Minolta chromameter CR200. Fatty acid composition was analysed on intramuscular fat. In addition, the atherogenic index (AI) and the thrombogenic index (TI) were calculated by means of the equations proposed by Ulbricht and Southgate (1991). Data were analysed by using the GLM procedure of SAS (2001). Results and discussion Measurements of intramuscular pH values offer some useful provisional information about the possible defects of pork meat (PSE, DFD). In this case, the pH1 (Table 1) was lower in pigs fed with barley (6.12) compared to those fed with acorns (6.28). In both groups, pH1 values were similar to those reported by Zumbo et al. (2002) in the same breed. However, the pH1 measured in group A was slightly lower than the one reported by Hansen et al. (2002) in pigs reared outdoors and fed with a similar diet (6.28 vs. 6.41). This difference, however, might be due to the different genetic types. The pHu resulted higher in group A (5.77) than in group B (5.63).