Temperature Acclimation and Its Effects on Porcine Muscle Properties in Two Humidity Environments

Abstract

SUMMARY— The effects of temperature and humidity on postmortem and associated muscle properties during growth of “stress susceptible” pigs were evaluated. Exposure to ambient temperatures of 32 and 21°C for alternating 3‐day periods caused rapid post‐mortem glycolysis, high percent light reflectance, and increased light to dark fiber ratios in the longissimus dorsi muscle as compared to constant (27°C) temperature, but only in moderate (38–42% relative) humidity environments. The above events due to temperature acclimation were masked when the humidity was low (17–23% relative). Humidity effects that were independent of temperature acclimation resulted in high percent light reflectance and high muscle temperature in the post‐mortem muscle of pigs reared in low humidity. No significant differences were found in lactic dehydrogenase or succinic dehydrogenase enzyme activities of longissimus dorsi or gluteus medius muscles.

Environmental Influence on High Energy Phosphate Metabolites in Porcine Muscle

“…This relation between rate of pH decline and muscle color agrees with previous reports in the literature (Wismer-Pedersen, 19.59;Briskey et al, 1961;Sayre et al, 1963). Howe et al (1968) have additionally demonstrated that more rapid rates of post-mortem muscle pH decline can be induced in Poland China pigs reared in alternating temperature as compared to constant temperature rearing environments. The more rapid glycolysis was associated with higher light reflectance values of the longissimus dorsi muscle.…”

“…Other authors have reported that environmental temperature and humidity both influence muscle characteristics (Thomas et al, 1966;Addis et al, 1967;Howe et al, 1968). As noted earlier, it was not possible to regulate humidity in the present experiment therefore no definite conclusions can be drawn about humidity effects upon muscle phosphate compounds.…”

“…Howe et al (1968) have additionally demonstrated that more rapid rates of post-mortem muscle pH decline can be induced in Poland China pigs reared in alternating temperature as compared to constant temperature rearing environments. The more rapid glycolysis was associated with higher light reflectance values of the longissimus dorsi muscle.…”

“…It has subsequently been demonstrated that alternating temperature environments induce more rapid post-mortem glycolysis, higher percentage of light reflectance and increased light to dark fiber ratios in the longissimus dorsi muscle of pigs as compared to constant temperature environments, (Howe et al, 1968), but only at moderate relative humidities. LOW humidity contributed to more rapid muscle pH decline at either constant or alternating temperatures.…”

“…Kastenschmidt et al (1968) have demonstrated that muscles which undergo rapid pH decline are more highly anaerobic at the time of exsanguination. A higher proportion of dark muscle fibers (Howe et al, 1968) and higher myoglobin levels (Thomas et al, 1970) no specifications were given for the method of removing cores. Previous studies did not reflect that any objective control was exercised to insure uniform, consistent samples to be measured by the various tenderness machines.…”