Fibre optic probe measurements in landrace pigs of different halothane phenotypes

Fibre Optic Probe (FOP) measurements were made in the longissimus dorsi muscle of 70 halothane-positive (HP) and 70 halothane negative (HN) pigs of a synthetic Landrace strain at 45 min (FOP₁), 3 h (FOP₃) and 17h (FOP₁₇) post mortem. Measurements of pH, rigor and temperature were also made in the slaughterline. Carcasses were sampled (longissimus dorsi, 2–4 lumbar vertebrae) at 18h post mortem and meat quality objectively assessed.The incidence of slight PSE (visual score) was 49% in HP and 10% in HN pigs, while the incidence of serious PSE was 20% and 4%, respectively. Yet, the percentage drip loss during 48 h storage in HN/PSE pigs was higher than in HP/PSE pigs (10·2 vs 7·5%), which was associated with a lower ultimate pH (5·25 vs 5·44). Therefore, it is suggested that the remaining PSE problem in HN Landrace pigs, although less in frequency, might be more serious.In the whole population, of all FOP measurements taken correlations with colour (Hunter L¹-value) and percentage drip loss were highest for the FOP₁₇ measurements (r = 0·82 and 0·69, respectively). FOP₁ was better related than pH₁ to colour, while the relationships with drip loss were of a similar magnitude.Differences in FOP values between HP and HN pigs were larger for FOP₁ (148 vs 108) than for FOP₃ (148 vs 125) or FOP₁₇ (153 vs 130). The relationship between FOP1 and ultimate meat colour (L¹-value) appeared to be higher in HP (0·60) than in HN (0·48) pigs, while for the relationship between FOP₁ and percentage drip loss the reverse was true (0·48 and 0·60, respectively). The effect of halothane phenotype on the relationships found, may partially explain the different results of reflectance measurements reported in the literature as to their predictive value for ultimate meat quality.The results suggest that the measurement of reflectance in the slaughterline offers opportunities for identifying (potential) PSE carcasses. The large genetic influence of halothane phenotype on this parameter, may eventually justify its use as a base for payment for meat quality to the producer.