Hand-held lactate analyzer as a tool for the real-time measurement of physical fatigue before slaughter and pork quality prediction

The objectives of this study were to assess the relationship between blood lactate variation measured at the plant, and pork quality variation on a large sample size and under commercial preslaughter handling conditions. A total of 600 pigs were randomly chosen on arrival at a commercial slaughter plant and blood samples taken from the ear vein at unloading (UN), after lairage (LA), in the restrainer (RE; before stunning) and at exsanguination (EX) were analysed for lactate content using a Lactate Scout Analyzer (LSA). In order to have a large range of measures, pigs were distributed into two groups; one kept in lairage overnight (G1) and the other for 2 to 3 h (G2) before slaughter. Meat quality was assessed in the Longissimus thoracis (LT), Semimembranosus (SM) and Adductor (AD) muscles by measuring the pH 30 min postmortem (pH1) and at 24 h postmortem (pHu), the colour and the drip loss. Blood lactate levels did not differ between G1 and G2 (P>0.05). A reduced muscle lactate and glucose contents (P=0.02 and P=0.004, respectively) resulting in a lower (P<0.001) glycolytic potential (GP) was observed in the LT muscle of G1 pigs when compared with G2 loins. In the LT muscle of G1 pigs, the lower GP resulted in an increased pHu (r= 120.67; P<0.001), decreased drip loss (r=0.57; P<0.001) and darker colour (r=0.50; P<0.001) compared with G2. In both G1 and G2 pigs, the lower GP was correlated to higher pHu value in the SM and AD muscles (r= 120.73; P<0.001). The greatest correlation was observed in G2 between blood lactate levels at LA and pHu value of the SM and AD muscles (r=0.46 and r=0.44, respectively; P<0.001 for both muscles). The second greatest correlation was found between blood lactate levels at EX and pH1 value in the SM muscle in both groups (r= 120.37 and r= 120.41, respectively; P<0.001 for both groups). Based on the results of this study, it appears that blood lactate levels, as measured by the LSA, reliably reflect the physiological response of pigs to perimortem stress and may help explain the variation in pork quality

Composition of exudates from meat drip loss and microbial spoilage differences between various pork quality classes

This study aimed at elucidating the differences in the composition of meat exudates and determining which constituents contribute the most to microbial growth between five pork quality classes (DFD=Dark, Firm, Dry; RFN=Reddish-pink, Firm and Non-exudative; RSE=Red, Soft and Exudative; PFN=Pale, Firm and Non-exudative and PSE=Pale, Soft and Exudative). A total of 65 Longissimus muscle samples (n=15/pork quality class; n=5 for DFD meat class) were analyzed in triplicate for glucose, glucose-6-phosphate, lactate and protein content, and microbial growth. Differences between pork quality classes were assessed using the MIXED procedure of SAS. Surprisingly, after storage at -80°C, the greatest pH value was observed in the purge of RFN pork (P0.05). Volume of drip loss was a major limit with the methods used. High throughput mass spectroscopy is currently under investigation as a more effective tool to study drip loss composition and effect on microbial growth

The effects of handling and group size on welfare of pigs in lairage and their influence on stomach weight, carcass microbial contamination and meat quality

At unloading and on the way to stunning, 800 barrows were exposed to either gentle handling (GH: slowly with a plastic board or whip) or rough handling (RH: quickly with an electric prod). Pigs were kept in large or small groups (30 or 10 pigs) during lairage. Compared with GH, RH increased climbing (P < 0.05), slipping (P < 0.01) and turning around (P < 0.001) behaviours during unloading, and climbing (P < 0.05) on the way to stunning. RH also reduced drinking behaviour during lairage (P < 0.01). Pigs kept in large groups were observed more often standing (P < 0.05) and fighting (P < 0.001) than pigs kept in small groups, but, in contrast, had a slightly lower level of urinary cortisol at slaughter. Stomach weight and microbial contamination at slaughter were not affected by treatments. RH tended to increase skin bruise score on the carcass (P < 0.06) and produced more exudative meat (P < 0.05). In conclusion, the response of pigs to the two specific stressors applied prior to slaughter in this study did not seem to contribute to stomach weight variation at slaughter, but it did influence pork quality. Key words: Pigs, pre-slaughter handling, group size, stress, stomach weight, microbial contamination, behaviour, meat qualit

Shelf life of pork from five different quality classes

A total of 117 loins were selected on the cutting line at 24 h post-mortem to study the long term shelf life (35 days, 4 °C) of vacuum packaged pork from five different quality classes (PSE: pale, soft, exudative; PFN: pale, firm, non-exudative; RSE: red, soft, exudative; RFN: red, firm, non-exudative; and DFD: dark, firm, dry). The microbial load at 0 d was not significantly different (P > 0.05) among the pork quality classes, indicating that the initial microflora was influenced by the dressing conditions at the plant, not by the meat quality class. But after 35 d of storage, total aerobic mesophilic and presumptive lactic acid bacteria counts were higher (P < 0.05) in DFD pork due to its higher ultimate pH. RSE was the second quality class most susceptible to spoilage, whereas PFN, RFN and PSE pork had similar microbial loads. Further research is needed to elucidate the causes of the shorter shelf life in RSE pork

Meat quality of pigs submitted to diferent water spray periods.

Projeto/Plano de Ação: 02.06.01.001

Stress levels of pigs submitted to three water spray periods.

Projeto/Plano de Ação: 02.06.01.001

Comportamento dos suínos submetidos a diferentes períodos de aspersão e descanso.

Projeto/Plano de Ação: 02.06.01.001

Hand-held lactate analyzer as a tool for the real-time measurement of blood lactate during slaughter and pork quality prediction

A total of 600 pigs was randomly chosen on arrival at a commercial slaughter plant and sampled for lactate analysis from the ear vein using a Lactate Scout Analyzer (LSA) at unloading (UN), after lairage (LA), in the restrainer (RE; before stunning), and from the ear vein (EX1) and the bleeding incision (EX2) at exsanguination. Pigs were distributedinto two pen groups, one kept in lairage overnight (G1) and the other kept between 2 and 3 h before slaughter (G2).Meat quality was assessed in the Longissimus dorsi(LD), Semimembranosus (SM) and Adductor(AD) muscles. Data were analyzed using Spearman correlations and the MIXED procedure of SAS. Greater (P=0.009) levels of blood lactate were found in pigs laired longer, which resulted in LD and SM muscles with greater pHu (P=0.03 and P=0.001, respectively), as well as lower L* (P=0.005and P=0.008, respectively)and drip loss (P=0.01 and P=0.02, respectively). The greatest correlation with lactate levels was observed at LA with pHu value of the SM and AD muscles (r=0.40; P<0.001). LSA lactate levels reliably reflect the physiological response of pigs to preslaughter procedures and may help explain the variation in pork quality as measured in the ham muscles

Use of the spectrophotometric color method for the determination of the age of skin lesions on the pig carcass and its relationship with gene expression and histological and histochemical parameters

The presence of lesions on the pig carcass is an indicator of poor animal welfare and has economic impact as it downgrades the carcass value. The assessment of the age of lesions on the carcass may help identify risk factors and ultimately prevent their occurrence. The aim of this study was to assess the age of lesions on pig carcasses through spectrophotometric color evaluation and to relate the results with gene expression and histological and histochemical parameters. A total of 96 barrows were mixed 4 times over 3 d before slaughter and 80 lesions were selected after skin lesion observations to define 4 age categories: < 7 h (T1), 7\u201325 h (T2), 25\u201330 h (T3), and 49\u201354 h (T4). A nonlesioned skin area was used as a control. At slaughter, 3 biopsies per lesion and control skin were taken immediately after bleeding for analyses of gene expression (CCL2, COX2, IL6, IL8, IL10, ITGA3, MMP1, TNF\u3b1, TIMP1, SERPINE1), skin histological characteristics (inflammation, erosion or ulceration, and necrosis), and enzyme activity (alkaline phosphatase and adenosine triphosphatase). The number of lesions was counted on each carcass, and the color was assessed visually by a pictorial chart and instrumentally through a spectrophotometer. Delta values (\u394) were calculated as the difference between the value of the lesion and the value of the control for all measures, except for the histological analysis. Results indicated that visual color observation was not sufficiently accurate to discriminate lesions by time of infliction (P > 0.10), while the spectrophotometer \u394L* and \u394a* values variation allowed the identification of 25 h old lesions (P < 0.05). Similarly, the expression of CCL2, IL6, ITGA3, MMP1, and SERPINE1 genes was higher (P 25 h old lesions; P < 0.05). To conclude, the spectrophotometric color assessment of the carcass lesions at slaughter appears to be a reliable method to discriminate between fresh and older lesions on the carcass at the abattoir