The influence of boar breed and applied method on the meat content

The aim of this study was to determine the influence of the applied method of
 the quality carcass in 201 descendants, both sexes (n=108 male castrated
 animals and n=93 females), of studied boar-sires. For the determination of
 the meat yield (JUS1) and the share of meat (JUS 2) in carcass sides, on the
 basis of the performed measurements, tables for meat pigs, which are an
 integral part of the Rulebook on the quality of slaughtered pigs and
 categorization of pork meat (OG SFRY, 1985), were used. Share of meat (EC 94
 and EC 06) was determined on cooled left carcass sides by method of partial
 dissection (according to methodology recommended by EU- Walstra and Merkus,
 1996). Research was carried out on pig farm and in experimental
 slaughterhouse of the Institute for Animal Husbandry, Belgrade-Zemun.
 Housing, care and nutrition of animals were in accordance to breeding
 technology in investigated herd. The average share of meat determined by the
 application of the Rulebook (JUS2) was 43.58% with a lower absolute
 variation compared to the EU regulation from 1994 (EC 94; 53.56%) and from
 2006 (EC 06; 56.55%). The estimated lean meat content by the application of
 the Rulebook (JUS 2) was by 9.98% lower compared to the EC 94 regulation and
 by 12.97% lower compared to EC 06. If we are talking about the selection of
 offspring for breeding, if we consider only the estimated leanness, we see
 that within the Landrace (L) breed we have high and very significant
 (P<0.001) differences between the sires for the assessed meat content
 according to EC 94 and EC 06. By implementing new methods of assessment of
 lean meat content (EC 94 and EC 06), a higher share of meat (9.98%
 respectively 12.97%) was determined compared to the Rulebook (1985). This
 research indicates the necessity of changing the current method for the
 establishment of meat content of pigs in the Republic of Serbia.


Introduction
The most important factors determining the carcass quality are genetic and environmental factors. The quantitative and qualitative properties of the carcass depend on the selection methods. By cross-breeding of pigs a heterosis effect is achieved for major productive properties. Finding the best combinations of crosses is a continuous process, since the frequency of certain genes continuously changes by the selection (Senčić et al., 2003). It is known that certain quantitative properties of pigs are unevenly inherited, which means that the possibilities for their improvement in selection are different. The pig genotype, in addition to the nutrition, has the greatest effect on carcass quality and meatiness. The prerequisite for work on the genetic improvement of pig quality is knowledge of the variability of the production properties of the breeding animals. Regardless of the significance of the evaluation of the carcass quality and meat quality on the slaughter line, there is a problem in our country that in most slaughterhouses (except for some) no automatic or semi-automatic devices for their assessment are used. For more than 20 years the economic environment in the country has been too dynamic and insecure, which has put domestic pig breeding in difficult situations. In the process of joining the European Union, Serbia must implement the qualification of pig carcases under the (S)EUROP system. This system is obligatory for each member of EU (Zapryanova, 2019). In our country, the Rulebook (OG SFRY, 1985), according to which the total mass of muscular tissue without the belly-rib meat is determined, is still applicable. Due to the above, the content of meat determined according to the Rulebook (OG SFRY, 1985) is lower by 8 to 12% compared to evaluation using FOM or dissection according to the methodology recommended by the EU (Walstra and Merkus, 1996). Given the fact that total dissection of the carcass side is expensive and complicated, the EU has recommended a short procedure. According to this procedure, the left carcass side is cut into 12 parts, and only on 4 parts (leg, shoulder, back-loin and belly-rib part) the total dissection is performed. In the research of Radović et al. (2009), the difference in the values for share of meat established according to the Rulebook (OG SFRY, 1985) and dissection (according to the method recommended by the EU) was 8.83% for the genotype Large White (LW) and 10.02% for the genotype Swedish Landrace (SL).

Material and Methods
Research was carried out on pig farm and in experimental slaughterhouse of the Institute for Animal Husbandry, Belgrade-Zemun. Housing, care and nutrition of animals were in accordance to breeding technology in investigated herd. The quality of the carcass was tested in 201 descendants, both sexes (n=108 male castrated animals and n=93 females), of studied boar-sires. For the determination of the meat yield (JUS 1) and the share of meat (JUS 2) in carcass sides, on the basis of the performed measurements, tables for meat pigs, which are an integral part of the Rulebook on the quality of slaughtered pigs and categorization of pork meat (OG SFRY, 1985), were used. Share of meat (EC 94 and EC 06) was determined on cooled left carcass sides by method of partial dissection (according to methodology recommended by EU- Walstra and Merkus, 1996). Left carcass sides were cut into 12 parts (Figure 1). Based on quantity of meat in four major parts -leg, shoulder, loin-rump and belly-rib part (skin with subcutaneous tissue, intermuscular fat and bones), which contain 75% of total musculature mass of carcass side, and mass of tender loin, percentage of meat in carcass sides was calculated using two formulas/equations: Data processing was carried out using the appropriate computer package "LSMLMW and MIXMDL, PC-2 VERSION" (Harvey, 1990), using the procedure of the least squares method in order to determine the significance (P<0.05) of the systematic effects on the growth traits, the quality of the carcass sides and meat. Properties of carcass quality were analysed by using models (1 and 2) that included the following factors: sire's race, sire, sex, offspring birth season and linear influence of warm carcass side weight. Table 1 shows the average values for meat yield and share (JUS 1 and JUS 2) as well as the share of meat obtained using the forms of EC No 3127/94 and EC No 1197/06 regulations for the assessment of lean meat content. The average share of meat determined by the application of the Rulebook (JUS2) was 43.58% with a lower absolute variation compared to the EU regulation from 1994 (EC 94; 53.56%) and from 2006 (EC 06; 56.55%). The estimated lean meat content by the application of the Rulebook (JUS 2) was by 9.98% lower compared to the EC 94 regulation and by 12.97% lower compared to EC 06. The effect of the sire breed, sires within breed, sex and season on the variation of meat content in carcass sides assessed under the Regulation (JUS2) and two EU Regulations (EC 94 and EC 06) is shown in Table 2. The general average for meat share in carcass sides determined by application the aforementioned methods was 43.62, 55.18 and 58.07%, respectively.

Results and Discussion
Quality of pig carcasses, i.e. the presence of muscle and fatty tissue, depends on the sex (Renaudeau et al., 2005;Renaudeau and Mourot, 2007;Serrano et al., 2007;Radović et al., 2008, Carabús et al., 2017, which was also found in our studies of fat thickness, yield and meat share. According to Wagner et al. (1999), male and female animals had almost the same share of fat tissue with 25 kg (6.92 and 7.00%), but with 100 kg it was higher in boars (16.33%) than in gilts (13.92 %). This difference between the sexes increased at a weight of 152 kg, so the share of belly fat tissue in males was 20.00 and in the gilts 16.91%. The results The influence of boar breed and applied … 21 of our research on the effect of sex on the quality of pig carcasses are in agreement with the results of Latorre et al. (2003,2004) and Radović et al. (2008). On the basis of a total dissection of four carcass parts, estimated leanness [Commission Regulation EC No 3127/94, (1994)] of genotypes 1 (SL), 6 [Px (SLxLW)], 8 [SLx (SLxLW)] and 9 [LWx (SLxLW)] in our trials was higher (+ 10.88%, + 6.66%, + 4.56% and + 5.10%) than shown by Kosovac et al. (2009a) for the same genotypes.  The highest yield (JUS 1) and the share of meat in the carcass sides (JUS 2, EC 94 and EC 06) were determined in offspring of sires of Pietrain breed (Table 2). In these animals, the largest difference in the estimation of lean meat between JUS2 and EC94 was found (difference was 15.88%) and between JUS 2 and EC 06 (the difference was 18.51%). In regard to the share of meat in the carcass side using the Rulebook (JUS 2), a smaller difference was found between offspring of sires of P and L breeds (0.16%), and P and LW (1.76%). The offspring originated from the sires of Pietrain breed had 60.14% of the meat in carcass side determined by the application of Regulation EC 94. The determined mean value was by 10.17 and 4.71% higher than for the offspring of the LW and L sires, respectively. By using the equation for the calculation of the lean meat content using EC 06, it was established that the offspring of the sires of Pietrain breed had a higher share of meat than the offspring of L sires (4.05%) and LW sires (10.04%).
The variation of the meat content by the application of the Rulebook (JUS 2) between the sires of L and P breeds was low (from 43.12 to 44.87% and from 43.67 to 44.85%) and was not statistically significant (Table 2). Between the descendants of three LW boars, the variation in the lean meat content was greater (from 41.17 to 43.66%) and statistically very significant (P<0.001; Table 4). The highest estimated lean meat content with the application of EU regulations (EC 94 and 06), within the L breed, was established for sire No. 9 (58.53% and 62.26%), while the lowest in offspring of sire No. 3 (50.33 and 53.94%). The determined difference between the offspring of these sires amounts to 8.20% and 8.32% of the muscle tissue in the carcass sides. The lowest mean values of these traits were recorded in animals originating from sire No.5 of the LW breed (46.14 and 49.06%), while the highest values were determined for the offspring of sire No.19 of Pietrain breed (64.92 and 65.78%). The difference in mean values of the meat content in the carcass sides between the offspring of these two boars-sires was 18.78% (EC 94) and 16.72% (EC 06).
Female animals had higher values (Table 3) for yield and meat share in carcass sides compared to male castrated animals. The meat content of carcass sides in female animals was estimated to be by 1.18 (JUS2), 4.22 (EC 94) and 4.62% (EC 06) higher compared to male castrated animals. The differences were statistically significant at the level of 99.9% (Table 4). When we observe the season of birth we see that the animals born in the winter period had higher average values of meat content in carcass sides determined by using the EC 94 (57.45%) and EC 06 (61.07%) Regulations compared to animals born in other seasons.
The sire breed, sires within the LW breed and the sex/gender had a very high statistically significant influence (P<0.001) on the yield and share, i.e. the meat content of carcass sides (Table 4). Sires within the L breed showed no influence only on the lean meat content of the carcass sides determined by the application of the Rulebook (JUS2), while the other properties were influenced (P<0.01 and P <0.001). ± 0.64 1) M-male castrates, F-females; 2) JUS 1-yield of meat in carcass sides, JUS 2 -share of meat in carcass sides, EC 94 -share of meat in carcass sides, EC 06 -share of meat in carcass sides The yield traits and the share of meat in the carcass sides, determined by the application of the Rulebook (JUS1 and JUS2), did not vary between the sires of Pietrain breed and the season of birth (P> 0.05). However, the estimated values for leanness obtained by applying the EC 94 and EC 06 regulations varied between the boars -sires of Pietrain breed (P<0.001). The interaction between the sex within the sire race for JUS 1 and JUS 2 was statistically significant (P <0.001), but in case of share of meat in carcass sides according to EC94 and EC06 it was not significant (P>0.05). By comparing the two regulations EC94 and EC06, the average estimated meat content of the tested fatteners in our trials was 53.56% and 56.55%, which means that the difference between them is 2.99% of the meat. The established difference in the average estimated meat content by applying the above regulations is lower (4.13%) than results presented by Kosovac et al. (2009b). For hybrid combinations of crosses with three [(LWxL) xJ and (LxD) xJ] and four breeds [(LWxL) x (JxP) and (LWxL) x (HxP)], Bahelka et al. (2005), for both sexes (f = 61 animals and m = 62 animals), assessed the average meat content [Commission Regulation EC No 3127/94, (1994)] on the basis of a total dissection of four carcass parts of 55.54%, which is by 1.98% higher value compared to our result (53.56%).