Comparison of meat quality from Naïma and DanBred hybrid sows mated with P-76 boars. Comparison of meat quality from Naïma and DanBred hybrid sows mated with P-76 boars

: The objective of this study was the comparative analysis of selected attributes of nutritional and technological quality of pork from Naïma and DanBred gilts mated with P-76 boars. The research was carried on 50 pigs (25 in each group) reared under the same environmental conditions and slaughtered at about 115±5.0 kg. Both analyzed crossbreds populations were characterized by overall good nutritional and technological quality. However the loins from DanBred×P-76 compared with those from Naïma×P-76 had significantly greater glycogen and less lactate concentration in early post mortem period, higher pH at all measurement points (besides no statistical differences in pH measured 2 hours post mortem), lower thermal drip and drip loss measured 96 and 144 hours post mortem and lower lightness (except no differences measured 48 hours post mortem). Additionally loins from DanBred×P-76 contained more protein and less water. No statistical differences in IMF content between both analysed groups were noted (their average values were below 2%). Aforementioned may suggest that crossing both Naïma and DanBred hybrids with P-76 boars may not improve IMF content or increase marbling scores to the levels preferred for culinary purposes.


INTRODUCTION
Meat is an important component of human diet that provides proteins, vitamins and minerals required both for health and disease prevention (BIESALSKI, 2005). In Europe, the per capita meat consumption has reached 69 kg whereby pork is still most frequently consumed meat with 31.3 kg on average (EC, 2009). Nonetheless, the level of consumption is strongly associated with consumer preferences and expectations for meat (FONT-I-FURNOLS & GUERRERO, 2014). Recently, consumers are mostly interested in lean meat but nutritious aspects, safety and quality issues (i.e. colour, drip loss, juiciness and tenderness) also plays a major role in choices and purchasing behaviour (FONT-I-FURNOLS & GUERRERO, 2014). The quality of pork is determined by variety of factors such as breed, production system, nutrition, pre-slaughter handling and slaughter procedure (WARNER et al., 2010). Over the past ten years many European countries have introduced different strategies to improve meat quality although production of high quality pork is constantly a big challenge for meat producers and Zybert et al. processors (VERBEKE ET AL., 2010;MORTIMER & PRZYBYLSKI, 2016).
Many pork producers use different hybrid pigs in fattening that are created by breeding companies from high performing lines. Among variety of commercial hybrid lines offered in Europe Naïma (Choice Genetics) and DanBred (DanBred International) hybrids are often use in Poland. The Naïma hybrid is maternal line created by combining of Gallia and Redone lines that merge excellent maternal performance and good carcass quality (PRZYBYLSKI et al., 2010). The Choice breeding programme assumes mating of P-76 sires with Naïma hybrids. The P-76 is a sire line issued from the Laconie (Hampshire, Piétrain and Large White in equal proportion) and Penshire (Hampshire, Large White and Duroc) lines that combines high growth potential and lean meat content with good meat quality (PRZYBYLSKI et al., 2010;LEBRET et al., 2011). DOKMANOVIC et al. (2015 and RYBARCZYK et al. (2016) indicated high lean meat content and low variability in meat quality of Naïma sows mated with P-76 boars. However the remaining majority of surveys focused on this topic are obsolete and the results may vary in comparison to quality traits of modern hybrid population. DanBred hybrid is maternal line created by crossing of Danish Landrace (L) and Danish Yorkshire (Y). DanBred hybrids, as reported by RYBARCZYK et al. (2018), SCHILD S.L. A.et al. (2020) and KASPRZYK & BOGUCKA (2020) may ensure high reproductive performance with high lean meat content and an excellent meat quality. The DanBred breeding programme assumes mating of DanBred hybrid sows (L×Y) with Duroc (D) boars. Several studies have shown the efficiency of (L×Y) × D hybrids in production of high quality pork (ZYBERT et al., 2015;CHOI et al., 2016;RYBARCZYK et al., 2018). However no data is still available regarding meat quality of DanBred hybrids mated with P-76 boars.
Because pig genotype has high impact on pork quality, the knowledge about meat quality of different pig lines and they potential to production high quality pork is an important issue both for pig producers and meat processors. Therefore, the objective of this study was the comparative analysis of selected attributes of nutritional and technological quality of pork from two commercial hybrid lines (e.g. Naïma and DanBred) mated with P-76 boars.

Animals, slaughter and carcass treatment
The experiment was performed according to the recommended EU Directive 2010/63/EU for animal experiments (EU, 2010). The investigation was carried out on 50 pigs (25 gilts in each group) derived from crossing of Naïma and DanBred hybrid sows with P-76 boars. The animals were kept on the same farm in non-bedding system with an unrestricted access to water and fed ad libitum with a growing diet up to 60 kg (13.1 MJ metabolic energy, 170 g crude protein, 11.50 g lysine/kg) and then up to 115 kg with finished diet (12.9 MJ metabolic energy, 150 g crude protein, 9.9 g lysine/kg). Loading was performed by qualified personnel with use of sort boards. The pigs were transported to slaughterhouse (approximately 30 km) in specialised for pig transport trucks. After transport, the pigs were allowed for 2 hours rest before slaughter in lairage pens (without mixing from other transports) in accordance with density standards and constant access to water. The pigs were stunned electrically and exsanguinated in a horizontal position. Each carcass was classified according to EUROP grading system with Sydel CGM opticneedle apparatus (Sydel, France) and weighed on an electronic scale. Carcasses were chilled in chilling tunnel (-22 °C for 40 min.) and then stored at 4 °C up to 24 hours after slaughter.

Meat quality traits
The quality of pork from 45 min. to 24 hours post mortem was evaluated directly in carcasses in the Longissimus lumborum (LL) behind the last rib and then in meat samples taken at 1 st -4 th lumbar vertebra. The samples were separated from the bone, external fat and epimysium and then stored in plastic bags at 0-4 °C. Three chops were used: one to determine drip loss and colour, second to determinate pH and third for measuring of thermal drip, chemical composition and Warner-Bratzler shear force (WBSF). The pH was measured 45 min. (pH 45 ), 2 (pH 2 ) and 24 hours post mortem (pH 24 ) directly in the right halves in the cold room and 48 (pH 48 ), 96 (pH 96 ) and 144 (pH 144 ) hours post mortem in the laboratory using temperature-compensating pH meter pH-Star (Ingenieurbüro Matthäus, Nobitz, Germany). Electrical conductivity (EC) was recorded 2 (EC 2 ) and 24 (EC 24 ) hours post mortem directly in right halves using LF-star (Ingenieurbüro Matthäus, Nobitz, Germany). Meat colour was measured 24, 48, 96 and 144 hours post mortem after a 10 min. blooming period by measuring of L * (lightness), a * (redness) and b * (yellowness) with a Minolta portable chroma meter (model CR 310, Minolta, Osaka, Japan) with 50 mm aperture and D65 illuminant. Drip loss (DL) was determined according to PRANGE et al. (1977) 48 (DL 48 ), 96 (DL 96 ), and 144 (DL 144 ) hours post mortem Water holding capacity (WHC) was determined 24 hours post mortem by the filter paper method according to POHJA & NINIVAARA (1957). Thermal drip was determined 48 hours post mortem Muscle samples (50 g) were placed in plastic bags and heated in a water bath until the internal temperature of the samples reached 72 °C. After cooling to 20 °C meat samples were reweighed. Weight loss was calculated as the difference before and after heating and expressed in percentages.
Shear force was measured using the TA-XT2 Texture Analyzer (Stable Micro Systems) with Warner-Bratzler attachment. Meat samples previously cooked to internal temperature of 72 °C and cooled to room temperature were cut out parallel to muscle fibres as cylinders with 14 mm diameter and 15 mm height. Blade speed during test was 1.5 mm/s. From the each sample, the average peak force of four cores was used for the statistical analysis. The results were presented as force per area (N/cm 2 ).
The chemical composition of Longissimus muscle was determined in accordance to the official analytical methods of the AOAC (2012), water content by oven-drying 2-gram samples at 102 °C to a constant weight, crude protein content by the classic macro-Kjeldahl method, ash content by the incineration at 550 °C and lipid content by petroleum ether extraction using a Soxhlet extractor.
The mineral content (potassium K, phosphorus P, iron Fe, zinc Zn, sodium Na) was determined by atomic emission spectrometry with excitation in the inductively-coupled plasma (ICP-AES) using an Optima 3200RL camera (Perkin Elmer, USA).

Muscle metabolites concentration
The glycolytic potential (GP) was calculated according to simplified formula of MONIN & SELLIER (1985) as the sum of 2[glycogen] + [lactate]. A 1g samples from thoracic part of Longissimus muscle (at the hight of the last rib) were collected 45 min. and 24 hours post mortem and then immersed into tubes with 10 ml 0.5M HClO 4 and homogenized to inhibit glycolytic changes in muscles. Samples were stored at 20 ºC until measurement. Glycogen content was determined by the enzymatic method according to DALRYMPLE & HAMM (1973) using amyloglucosidase derived from the yeast Aspergillus niger. Lactate content was determined according to BERGMEYER (1978) using lactate dehydrogenase. The glycolytic potential was expressed as μmol of lactic acid equivalent per g of fresh muscle.

Statistical analysis
Data were analysed by one-way ANOVA in STATISTICA 13.1 (StatSoft, Tulsa, OK, USA). The significance of the differences in meat quality between the two crossbreed groups was evaluated using Student's t-tests. All data were expressed as least square means and standard deviations.

Carcass characteristics, chemical composition and mineral content
In present study no statistical differences were found between hot carcass weight (HCW) and lean meat content between DanBred×P-76 and Naïma×P-76 ( The chemical composition of longissimus muscles from Naïma and DanBred hybrids mated with P-76 were presented in table 1. The Naïma crossbreed pigs had significantly (P≤0.01) higher water but lower protein, dry matter and ash content than DanBred hybrids mated with P-76 (Table 1). In contrast to our findings, no statistical differences in protein, moisture and ash were noted by KASPRZYK & BOGUCKA (2020) between Naïma and DanBred hybrids. The reference data shows, that protein content in Naïma x P-76 varies between 22 and 23% while water between 72 and 74% (GRZEŚKOWIAK & BORZUTA, 2004, STRZELECKI et al., 2017 In DanBred hybrids, however mated with Danish Duroc, an average protein content varies between 20 and 22 % (RYBARCZYK et al., 2018;ZHANG et al., 2018). Total lipids is an important attribute of pork quality (HOCQUETTE et al., 2010). The amount of total lipids may positively enhance flavour, juiciness and tenderness, if they levels increase above approximately 2.5% (FERNANDEZ et al., 1999;JANKOWIAK et al., 2019). However, the consumers' acceptance of intramuscular fat (IMF) level varies in dependence of country. In Europe the acceptable amount of IMF in pork ranges from 2 to 3% (HOCQUETTE et al., 2010). There were no statistical differences (P≥0.05) in total lipids content between Naïma and DanBred hybrids mated with P-76 and its average values did not exceed 2% (Table 1) Pork is an important source of minerals but their concentrations may vary in dependence of breed, age, feeding, production system or muscle (TOMOVIC et al., 2015). NIKOLIC et al. (2015) analysed the content of selected minerals in three different pork cuts from the Serbian market. They found, that in pork Longissimus muscle, Zn content ranged from 1.4 to 6,7 mg/kg. The similar Zn levels in pork loins from Serbian market reported also DJINOVIC-STOJANOVIC et al. (2017). Thus, these levels are similar to those in this study (Table 1). REN et al. (2008) found that loins from Yorkshire and   Duroc breeds contained respectively 3.7 and 3.5 g/kg K and 6.5 and 5.1 g/kg Fe without the effect of breed on minerals content. Similar to those in this study K levels in loins from (L×Y)×D also detected HAM et al. (2021). VALAITIENË et al. (2017) compared several pure bred and crossbreed pigs (Large White, Landrace, Yorkshire, Piétrain, Landrace×Large White, Yorkshire×Large White, Yorkshire×Piétrain and Landrace×Yorkshire) but found no differences in Zn concentration. In cited study however Landrace×Large White contained more iron than any other examined purebreds and crossbreds. Lower concentrations in Zn and Fe with in average 0.7 mg/100g Zn and 1.5 mg/100g Fe were determined by GERBER et al. (2009) in pork loins purchased from local supermarkets and butcheries in Swiss market. According to NIKOLIC et al., (2015) and GERBER et al. (2009) such variability in comparison to reference data, probably may be associated with differences in animal husbandry and applied feeding systems, or differences between breeds. As presented in table 1 Naïma hybrids had significantly (P≤0.05) less sodium but contained more (P≤0.01) phosphorus, iron and zinc than DanBred hybrids mated with P-76.

Meat quality traits
Initial glycogen concentration in muscles at the slaughter or in the early post mortem period has an important role in development of pork quality. Glycogen content in muscles is determined by variability of factors such as breed, breeding strategy, feeding, pre-slaughter handling or slaughter procedures (PRZYBYLSKI et al., 2006).
An average estimates of glycogen and lactate concentrations and glycolytic potential for Naïma and DanBred hybrids mated with P-76 were shown in table 2. DanBred hybrids had significantly (P≤0.01) greater GP, more glycogen (at 45 min. and 24 hours post mortem) and less lactate (45 min. post mortem) than Naïma mated with P-76. An average GP estimates although typical for normal meat were lower than those previously reported by TRAORE et al. (2012) andTARCZYŃSKI et al. (2018).
Naïma compared with DanBred hybrids had significantly lower pH at all measurement points ( Table 2). The only exception was no noted statistical differences in pH measured 2 hours post mortem . The results may be partly explained by a higher rate of muscle glycolysis and lactate production in early post mortem hours in Naïma fatteners.
No statistical differences were found in DL 48 and WHC between analysed groups. However more favourable DL 96 (3.98±1.11% vs. 5.16±1.50%) and DL 144 (4.97±1.21 vs. 6.96±1.83) were noted in DanBred×P-76 than in Naïma×P-76 fatteners. Similarly to our findings no statistical differences    (2020) noted no statistical differences in thermal drip loss between DanBred and Naïma hybrids besides its lower value in latter group. As suggested by PRZYBYLSKI et al. (2010) average consumer's satisfaction is based mainly on visual impression (appearance) during product purchase while sensory quality and culinary usefulness is its secondary criteria. Then meat lightness is of high importance. In present study statistically lower (P≤0.01) L * 24 and b * but higher a * 24 were obtained in DanBred×P-76 than in Naïma×P-76 (Table 3). Contradictory results were noted by KASPRZYK & BOGUCKA (2020) between DanBred and Naïma hybrids. Cited authors did not found however statistical differences in b *

24
. As suggested by KARPIESIUK et al. (2013) the higher the water content the brighter the meat colour. It is due to muscle structure which does not let the light penetrate into deeper meat layers resulting in much more intense reflection and thus higher brightness. Abovementioned is in accordance both with study of KASPRZYK & BOGUCKA (2020) and present survey. Additionally higher L * 24 in Naïma×P-76 reported in this study probably occurred also due to lower pH 24 as well as higher lactate content than in Naïma×P-76 (Table 2).

CONCLUSIONS
Both Naïma and DanBred hybrids mated with P-76 boars are high lean meat crossbreeds with an overall good nutritional and technological quality. DanBred hybrids however, due to significantly better estimates for nutritional and technological quality may be more beneficial for processing and culinary purposes than Naïma×P-76 fatteners. It has Table 3 -Least square means and standard deviation for the colour of Longissimus lumborum muscle from Naïma and DanBred hybrids.