• Enhancement of pigmeat quality by altering pre-slaughter management

      Lawlor, Peadar G; Lynch, P Brendan; Mullane, J.; Kerry, Joseph P.; Hogan, S.A.; Allen, Paul (Teagasc, 25/10/2005)
      The studies presented in this report were conducted to investigate the effect of breed, slaughter weight, castration of male pigs and strategic feeding strategies on the performance of pigs to slaughter and on their carcass quality. The effect of breed, gender and feeding regimen on the performance of pigs and their carcass quality was examined in the first study (Section 3). From weaning to slaughter Landrace-sired pigs grew at a similar rate but had a better feed conversion efficiency compared with Duroc-sired pigs. Landrace-sired pigs also had a higher carcass lean and greater muscle depth than Duroc-sired pigs. Entire male pigs grew more efficiently, had lower lean content in their carcasses and had a reduced kill out yield when compared with gilts. The eye muscle depth was greater for gilts than entire males. Diluting the diet with grass-meal (GM) reduced growth rate, caused a deterioration in feed conversion efficiency, reduced back fat thickness, reduced eye muscle thickness and reduced kill out yield compared to the control feeding regimen of a cereal based diet. Compensatory growth was observed during a re-alimentation period following a period of diet dilution with grass-meal. However, where it did occur, in most cases it was only partial. Adding 5% rapeseed oil instead of lard to the finisher diet increased nitrogen utilization efficiency and phosphorous utilization efficiency. The effect of gender (boar, castrate, gilt) and slaughter weight (80 to 120kg) on pig performance, carcass quality, meat quality, and nitrogen excretion was investigated in the second study (Section 4). Boars grew faster than gilts and more efficiently than castrates or gilts. Castrates had a higher kill out yield than boars. Nitrogen excretion from castrates was similar to gilts which were both higher than that from boars. The processing value of carcasses from castrates may be higher than that of boars and gilts. In particular castrates had heavier loins and bellies than either boars or gilts. Carcasses from castrates and gilts had a higher temperature (recorded 24 hours post slaughter) than boars. However, pH24 was not affected by gender. The intramuscular fat content of the l. dorsi in castrates was higher than that of boars or gilts, however at 1.65% this was well below the level (2.0%) above which any noticeable sensory attributes might be detected. Feed intake increased with increasing slaughter weight and feed conversion efficiency deteriorated. N excretion also increased with each increment in weight. Carcass lean content increased up to 90kg live EOP 4939.doc 4 25/10/2005 weight then reached a plateau and declined after 110kg live weight. Heavier carcasses yielded more product for approximately the same slaughtering cost and the associated larger muscles could make it easier to use seam butchery techniques that result in lean, well-trimmed, attractive cuts and joints. The pH45 and pH24 were reduced with increasing slaughter weight and drip loss increased. Heavier pigs may be more prone to the development of PSE than lighter pigs as their carcass temperature remains higher for longer than that of lighter pigs.