Effect of magnesium sulphate and l-tryptophan and genotype on the feed intake, behaviour and meat quality of pigs

Is Magnesium Supplementation an Effective Nutritional Method to Reduce Stress in Domestic Pigs? A Systematic Review

In commercial pig production, stressful events are common and can have detrimental impacts on the pig's health and welfare, as well as on the performance of the farm. Supplementary magnesium may reduce stress, and subsequent harmful and aggressive behaviors, that occur during stressful events, such as regrouping. However, reports on the efficacy of this treatment are mixed. We aimed to systematically review the studies in which magnesium was given to pigs to examine the effects on measures of stress. Of the 16 studies included in the final corpus, 10 reported at least one statistically significant beneficial effect of supplementary magnesium on reducing stress. However, two studies found that magnesium significantly increased stress suggesting supplementary dietary magnesium may be harmful in some cases. Overall, there are a limited number of studies investigating the possible effect of magnesium on reducing stress in pigs, and although results were varied, the majority found beneficial effects of supplementary magnesium.

Elemental Composition of Swine Manure from 1997 to 2017: Changes Relevant to Environmental Consequences

There have been revisions in the composition of swine diets in the last two decades that not only improved production profitability but also had potential environmental benefits. Among other changes, the use of phytase in feed has enabled lower total P concentrations. Nitrogen, specifically protein, concentrations are expected to be lower, and certain trace elements were also expected to change. In this study, analyses of 1195 swine slurry manure samples from various barn types in Manitoba, Canada, collected from 1997 to 2002 were compared with similar analyses from 2010 and 2017. Concentrations of P were significantly lower in 2017, from a median in sow barns of 28.0 g kg dry weight (dw) in 1998 to 2002 to 20.6 g kg dw in 2010 and 2017, and from a median in feeder finisher barns of 24.1 g kg dw in 1998 to 2002 to 18.7 g kg dw in 2010 and 2017. Total N levels did not change with time, but the fraction of manure N that was NH decreased. Zinc concentrations were consistently higher in nursery manures than in other swine manures and increased from a median of 2800 mg kg dw in nursery barns in 1998 to 2002 to 5580 mg kg dw in nursery barns in 2010 and 2017. Concentrations of most other trace elements decreased over this time period. With the exception of Zn from nursery barns, these temporal changes should lessen the potential for environmental consequences from swine manure application to land.

Effects of Short-term Feeding Magnesium before Slaughter on Blood Metabolites and Postmortem Muscle Traits of Halothane-carrier Pigs

Fifty-four, mixed-sex, halothane-carrier crossbred (Yorkshire×Landrace) pigs with an average initial BW of 108.2±0.8 kg were randomly allotted to one of three dietary treatments for 5 d before slaughter: i) a control corn-soybean meal finisher diet devoid of supplemental magnesium; ii) a diet supplemented with 1.5 g/kg of elemental Mg from magnesium acetate; and iii) a diet supplemented with 1.5 g/kg of elemental Mg from magnesium sulfate heptahydrate. Serum creatine kinase (CK), lactate and glucose were analyzed at slaughter. Muscles from longissimus (LM) were packaged and stored to simulate display storage for muscle lactate and glycogen determinations at 0, 1, 2, 3, and 4 d. Mg supplementation reduced (p<0.05) serum CK and lactate concentration, but had no effect (p>0.05) on serum glucose. Daily change of muscle lactate concentration linearly increased (p<0.01), while glucose concentration linearly decreased (p<0.05) as storage time increased in all treatments. However, dietary Mg acetate and Mg sulfate supplementation in pigs elevated (p<0.05) muscle glycogen and reduced (p<0.05) muscle lactate concentrations, especially during the first 2 d of display, compared with pigs fed the control diet. This study suggests that short-term feeding of magnesium acetate and magnesium sulfate to heterozygous carriers of the halothane gene has beneficial effects on stress response and pork quality by improving blood and muscle biochemical indexes.

Effects of water supplementation with tryptophan and vitamin B6 or feeding hydrogenated fat on reducing hunger-induced drinking pre-slaughter in pigs

Faucitano, L., Torrey, S., Matte, J. J., del Castillo, J. R. E. and Bergeron, R. 2012. Effects of water supplementation with tryptophan and vitamin B6 or feeding hydrogenated fat on reducing hunger-induced drinking pre-slaughter in pigs. Can. J. Anim. Sci. 92: 319–326. A current food safety challenge at pig slaughter plants comes with the presence of stomachs filled with liquid induced by hunger-related drinking in lairage. With the objective to reduce hunger-related excess drinking, 30 barrows were assigned to three treatments (10 pigs per treatment): (1) unsupplemented water or feed regimen (CONT), (2) L-Tryptophan (3 g L−1) and vitamin B6 (10 mg L−1) in the drinking water for 5d (TRP-B6), (3) hydrogenated fat (HF) supplemented at 10% in the diet for the last day of feeding before pre-slaughter fasting. As compared with CONT, neither TRP-B6 nor HF supplementation influenced behaviour in lairage and water intake at anytime over the pre-slaughter fasting period as reflected on stomach weight and its liquid content at slaughter (P>0.10). However, in HF-fed pigs plasma non-esterified fatty acids concentrations tended to be lower (P=0.09) while carcass yield was higher (P=0.04) than CONT pigs. It appears, therefore, that neither drinking water supplementation with TRP-B6 for 5 d nor feeding HF the last day before slaughter can be recommended strategies to limit excess water drinking prior to slaughter and liquid stomach content at slaughter. However, dietary HF supplementation the last day before slaughter may attenuate the effects of fasting on body energy reserves and improve carcass yield.

The impact of short-term feeding of magnesium supplements on the quality of pork packaged in modified atmosphere

This study compared the effect of dietary magnesium (Mg) supplementation on pork quality during 13 days of storage at 4±1°C under modified atmosphere. The experiment was conducted with 40 gilts (Pietrain×(Landrace×Large White)) which were fed one of four diets five days prior to slaughter: 1) control diet; 2) Mg oxide; 3) Mg sulphate; or 4) Mg chelate. Dietary Mg supplementation did not affect 24-h pH, colour, and Warner-Bratzler shear force values. Pork from pigs fed the Mg chelate-supplemented diet had the lowest (P≤0.05) drip, exudative, and cooking losses. Furthermore, pork from pig supplemented with Mg oxide had the lowest TBARS values. Visual assessment of pork from pigs supplemented with Mg chelate received higher colour and lower exudative scores, as well as overall acceptability scores, throughout display. Thus, Mg chelated supplementation could be effective in improving pork quality during 13 days of storage under modified atmosphere conditions.