title: The effects of porcine somatotropin on muscle fibre morphology and meat quality of pigs of known stress susceptibility.
abstract: To study the effects of porcine somatotropin (pST) administration on muscle fibre characteristics and meat quality, 48 pigs of the Lacombe breed (equal numbers of barrows and gilts) of known halothane genotype (NN, Nn or nn) were randomly assigned to either a control (excipient buffer) or pST (3.0 mg d(-1)) treatment. At a pen average animal weight of 106 kg, pigs were slaughtered and muscle samples were collected post mortem for determination of fibre type, glucidic metabolites and meat quality. There was a 16% increase in muscle weight of the semimembranosus (SM) and psoas major (PM) in pST-treated animals (p ≤ 0.01). However, there was no significant change in fibre type associated with the pST treatment in either the SM or PM (p > 0.05). In the PM muscle there was a 65-70% increase in fast, oxidative, glycolytic (FOG) and fast, glycolytic (FG) fibre areas in pST-treated gilts (p ≤ 0.05). These cellular changes were manifest in meat colour that was lighter and spectrally shifted towards yellow (significantly higher L (∗) and hue angle values), higher drip loss, lower moisture content and a tendency towards higher Kramer-Press shears (p = 0.06) in the PM of pST-treated gilts. Although these changes were in the same direction as pale, soft, exudative meat, the average values fell within the normal range. Based on the observed gender by pST treatment interactions, administration of pST (timing, dosage and protein requirements in the feed) may need to be tailored to suit different genders and breeds to achieve the maximal response.
authors: Meat Research Section, Lacombe Research Centre, Agriculture and Agri-Food Canada, Lacombe, Alberta, Canada T4L 1W1.
authors: J L
authors: JL
authors: Aalhus
authors: D R
authors: DR
authors: Best
authors: F
authors: F
authors: Costello
authors: A L
authors: AL
authors: Schaefer