Effects of dietary magnesium and short-duration transportation on stress response, postmortem muscle metabolism, and meat quality of finishing swine1

Abstract

Crossbred pigs, heterozygous for the halothane gene, were used to determine the effects of long-term dietary supplementation of magnesium mica (MM) and short-duration transportation stress on performance, stress response, postmortem metabolism, and pork quality. Pigs were blocked by weight, penned in groups (six pigs per pen), and pens (three pens per diet) were assigned randomly either to a control corn-soybean meal diet or the control diet supplemented with 2.5% MM (as-fed basis; supplemented at the expense of corn). Diets were fed during the early-finisher (0.95% lysine, as-fed basis; 43.7 to 68 kg) and late-finisher (0.85% lysine, as-fed basis; 68 to 103 kg) periods. At the conclusion of the 71-d feeding trial, 12 pigs from each dietary treatment were selected randomly and subjected either to no stress (NS) or 3 h of transportation stress (TS). Dietary MM had no effect (P > or = 0.40) on ADG or ADFI; however, G:F was improved (P < 0.05) during the early-finisher period when pigs were fed MM-supplemented diets. Plasma glucose concentrations were increased in TS pigs fed the control diet, but transportation did not affect plasma glucose in pigs fed 2.5% MM (diet x transportation stress; P = 0.02). Dietary MM did not affect blood lactate, cortisol, insulin, NEFA, Ca, or Mg concentrations in response to TS (diet x transportation stress; P > or = 0.13); however, circulating lactate, cortisol, and glucose concentrations increased in TS pigs (transportation stress x time; P < 0.01). The LM from TS pigs fed MM had higher initial (0-min) and 45-min pH values than the LM from NS pigs fed the control diet (diet x transportation stress x time; P = 0.07). Lactic acid concentration and glycolytic potential were greater in the LM of TS pigs fed MM than TS pigs fed control diets (diet x transportation stress; P < or = 0.01). Although some trends were identified, neither MM (P > or = 0.15) nor TS (P > or = 0.11) altered the color or water-holding capacity of the LM and semimembranosus. The transportation model elicited the expected changes in endocrine and blood metabolites, but dietary MM did not alter the stress response in pigs. Conversely, although pork quality traits were not improved by dietary MM, delaying postmortem glycolysis and elevating 0- and 45-min muscle pH by feeding finishing diets fortified with MM may benefit the pork industry by decreasing the incidence of PSE pork in pigs subjected to short-duration, routine stressors.

Magnesium supplementation in swine finishing stage: performance, carcass characteristics and meat quality

“…The magnesium and lactic acid concentration do not show any effects from the dietetic supplementation with MgO during the last week before the slaughter. This is similar to the observed by Apple et al (2005) that reported no alteration on serum magnesium concentration by a dietetic supplementation with magnesium mica in animals submitted to stress by transportation. However, D'Souza et al (1998) reported evidences that the supplementation with magnesium aspartate for swine reduce the acid lactic concentration in the muscular tissue 40 minutes before slaughter, that mean a reduced stress effect on the muscular glycogenolysis.…”

“…Peeters, Driessen and Geers (2006) also treat swine with Mg (by water) and do not have significant results for initial and final pH values. In a contrary way, Apple et al (2005) found in swine transported during 3 hours and supplemented with magnesium mica a higher initial pH value that those ones not submitted to transportation independently from consumed diet; however the final pH measures were not affected by the treatments. The water retention capacity is a very important characteristic because affect the appearance of meat before cooking, the behavior during the cooking process, the juiciness during the chew process and the technologic yield for preparation of meat products (LAWRIE, 2005).…”

“…D'Souza et al (1998,1999), Hamilton et al (2003) and Lahucky et al (2004) had verified a reduction in drip losses for longissimus dorsi muscle for swine supplemented with MgO during a short time period. However, Apple et al (2000bApple et al ( , 2002Apple et al ( , 2005 and Caine et al (2000) that had supplemented diets with magnesium for longer time periods had observed no differences in the same parameter For the water losses during the defrosting, there was observed a quadratic effect (Table 7) and the point of minimum loss was for 0.35% of MgO inclusion on feed. The water losses during the cooking process had no influence from the treatments (Table 7).…”

Growth performance, carcass characteristics, meat quality, and tissue histology of growing pigs fed crude glycerin-supplemented diets1

“…Concentrations of most plasma metabolites were different between pretransport and at the time of slaughter (P < 0.01). Transporting pigs has been shown to cause stress in pigs (Pérez et al, 2002;Apple et al, 2005). Increases in plasma cortisol, glucose, lactate, and creatine phosphokinase are correlated with increased stress in pigs (Brown et al, 1998;Pérez et al, 2002;Apple et al, 2005).…”

Serum stress parameters in pigs transported to slaughter under commercial conditions in different seasons

“…Variations of cortisol, despite possible diurnal variations, and glucose (Table 3) suggest that short journeys did not permit a total recovery from the initial stress caused by loading, which is known to have a negative impact on the welfare of animals (Broom, 2000) independently from the loading method used (Brown et al, 2005). Furthermore, Bradshaw et al (1996) found a raise in cortisol levels 30 min after loading, and a gradual decrease after 4.5 h of transportation, and Apple et al (2005) found that cortisol levels matched up with an increase in plasmatic glucose. These assertions would justify our results, so that, in the case of short transportations, initial stress caused by sample size is provided between brackets *P < 0.05; **P < 0.01; ***P < 0.001; ns = non sgnificant Table 2).…”