@article{frederick_heugten_see_2006, title={Effects of pig age at market weight and magnesium supplementation through drinking water on pork quality}, volume={84}, ISSN={["1525-3163"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33744927165&partnerID=MN8TOARS}, DOI={10.2527/2006.8461512x}, abstractNote={Thirty-two halothane-negative pigs (109 +/- 0.6 kg of BW) were used to determine the effect of pig age at marketing (and thus growth rate), and magnesium supplementation through drinking water, on pork quality. Two initial groups of 50 pigs that differed by 30 +/- 2 d of age were fed diets to meet or exceed nutrient requirements beginning at 28 kg of BW. Sixteen average, representative pigs were selected from each group to represent older, slow-growing pigs and younger, fast-growing pigs. For the duration of the study, pigs were individually penned, provided 2.7 kg of feed (0.12% Mg) daily, and allowed free access to water. After 7 d of adjustment, pigs were blocked by sex and BW and allotted to 0 or 900 mg of supplemental Mg/L as MgSO4 in drinking water for 2 d before slaughter. All 32 pigs were then transported (110 km) to a commercial abattoir on the same day and slaughtered 2.5 h after arrival. Longissimus and semimembranosus (SM) chops were packaged and stored to simulate display storage for fluid loss and Minolta color determinations at 0, 2, 4, 6, and 8 d. Two remaining sections of the LM were vacuum-packaged and stored at 4 degrees C for 25 or 50 d. Fast- (younger) and slow- (older) growing pigs differed by 27 +/- 0.3 d of age (153 and 180 +/- 0.3 d; P < 0.001) at similar BW (108 and 110 +/- 0.6 kg of BW; P = 0.13). Supplementation of Mg tended to increase plasma Mg concentration (24.1 vs. 21.8 +/- 0.8 ppm; P = 0.06) but did not affect Mg concentration in LM or SM. Fluid loss of displayed LM or SM, and purge loss, color, and oxidation of vacuum-packaged LM or SM were not affected by age or Mg (P > 0.10). Surface exudate of the SM from older pigs was lower than that of younger pigs (61 vs. 74 +/- 6 mg; P = 0.05) but was not different for the LM (P = 0.22). The LM from older pigs displayed for 4 and 8 d; P < 0.05) were less yellow (lower b*) than younger pigs. The SM from older pigs had lower lightness (L*) initially (47.9 vs. 49.5 +/- 0.4) and after 2 d (49.7 vs. 51.1 +/- 0.4), 6 d (52.1 vs. 53.7 +/- 0.4) and 8 d (54.5 vs. 55.9 +/- 0.4) of display storage. Younger pigs had greater oxidation of the LM than older pigs on d 8 of display (P < 0.01), and Mg decreased oxidation on d 8 within younger pigs (P < 0.05). Pork quality was improved in older pigs as indicated by less exudate, reduced yellowness of the LM, reduced paleness of the SM, and reduced oxidation of the LM. However, Mg supplementation through the water for 2 d did not affect pork quality of either older, slower growing pigs or younger, faster growing pigs.}, number={6}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Frederick, B. R. and Heugten, E. and See, M. T.}, year={2006}, month={Jun}, pages={1512–1519} }
 @article{frederick_heugten_hanson_see_2006, title={Effects of supplemental magnesium concentration of drinking water on pork quality}, volume={84}, ISSN={["1525-3163"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33744906659&partnerID=MN8TOARS}, DOI={10.2527/2006.841185x}, abstractNote={Thirty-two barrows were used to determine the effects of supplemental Mg in drinking water on pork quality. Pigs were determined to be free of the halothane and Napole mutations and were individually penned. After a 7-d adjustment period, barrows (111 +/- 1 kg BW) were blocked by BW and allotted randomly within block to 0, 300, 600, or 900 mg of supplemental Mg from Mg sulfate/L of drinking water for 2 d before slaughter. Pigs were not allowed access to feed (0.13% Mg) for 15 h before slaughter but continued to have access to experimental water treatments. Pigs were loaded and transported 110 km (1.75 h) to a commercial abattoir and remained in lairage for 5 h before slaughter. The LM was removed 24 h postmortem. Retail storage was simulated for 8 d, and the remaining LM was vacuum-packaged for 25 or 50 d at 4 degrees C. Plasma Mg concentration increased linearly (P = 0.001) with Mg supplementation; however, Mg concentration of the LM was not affected (P = 0.99) by Mg supplementation. Surface exudate, drip loss, and retail fluid loss of the LM were not affected (P > 0.10) by Mg. Lightness (L*) and redness (a*) of the LM were not affected (P > 0.10) by Mg, with the exception of initial redness (cubic; P = 0.05). Pigs supplemented with 300 or 900 mg of Mg/L had lower yellowness (b*) values of the LM displayed for 0 to 6 d than pigs supplemented with 0 or 600 mg of Mg/L (cubic; P < 0.05). Lightness of the LM after 25 (quadratic; P = 0.03) or 50 (quadratic; P = 0.04) d of vacuum-packed storage was greater at 300 and 600 mg of Mg/L than at 0 or 900 mg/L. Yellowness tended to be greater after 50 d, but not after 25 d, of vacuum-packaged storage for 300 or 600 mg of Mg/L compared with 0 or 900 mg/L (quadratic; P = 0.08). Oxidation of the LM, determined by thiobarbituric acid reactive substances after 4 d of retail storage, increased linearly (P = 0.05) as Mg increased in the drinking water. Furthermore, oxidation of the LM after 8 d of retail storage tended to increase linearly (P < 0.10), primarily because of the high oxidation of LM from pigs supplemented with 900 mg of Mg/L compared with controls (224 vs. 171 +/- 19 microg/kg, respectively). Oxidation of the LM was greater for pigs supplemented with 300 or 900 mg/L compared with 0 or 600 mg of Mg/L (cubic; P < 0.06) after 25 d of vacuum-packed storage. Magnesium did not improve pork quality characteristics of practical significance in pigs without the halothane and Rendement Napole mutations.}, number={1}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Frederick, BR and Heugten, E and Hanson, DJ and See, MT}, year={2006}, month={Jan}, pages={185–190} }
 @article{van heugten_frederick_2004, title={Magnesium supplementation and pork quality}, volume={25}, ISBN={0143-9014}, number={3}, journal={Pig News and Information}, author={Van Heugten, E. and Frederick, B. R.}, year={2004}, pages={101} }
 @article{frederick_heugten_see_2004, title={Timing of magnesium supplementation administered through drinking water to improve fresh and stored pork quality}, volume={82}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2442473252&partnerID=MN8TOARS}, DOI={10.2527/2004.8251454x}, abstractNote={Thirty-two pigs were used to determine the timing effect of magnesium (Mg) supplementation given through drinking water on pork quality. Pigs (16 barrows and 16 gilts) were individually penned, provided 2.7 kg of feed (0.12% Mg) daily (as-fed basis), and allowed free access to water via a nipple waterer for the duration of the study. After 5 d of adjustment, pigs (120 +/- 0.8 kg BW) were allotted randomly by weight and sex to 900 mg/L of supplemental Mg from magnesium sulfate heptahydrate in drinking water for -6, -4, -2, or 0 d relative to slaughter. The LM and semimembranosus (SM) muscles were removed 24 h postmortem. Retail display storage was simulated for 8 d, and the LM was vacuum-packaged for 25 or 50 d at 4 degrees C. Magnesium did not affect the pH of the LM at either 45 min (P = 0.15) or 24 h postmortem (P = 0.23). However, the pH of the SM at 24 h postmortem tended to be greater (P = 0.08) for pigs consuming Mg for 2 d than for those not supplemented. Fluid loss after 8 d of storage was less (P < 0.05) in the LM of pigs supplemented with Mg for 6 d than in those without supplementation. Furthermore, fluid loss from the SM of pigs provided supplemental Mg for 2 d, but not for 4 or 6 d, was lower (P < 0.05) on each day of retail display than the SM of unsupplemented pigs. Minolta L*, a*, and b* color measurements of the LM during display storage were not (P > 0.10) affected by Mg supplementation. However, Mg supplementation for 2 or 4 d decreased paleness (lower L* value) after 25 d (P < 0.05), but not 50 d (P > 0.10) of vacuum-packaged storage. Magnesium addition for 2 d decreased the extent of oxidation (thiobarbituric acid-reactive substances) of the LM after 4 d of display storage compared with 0 d of Mg (P < 0.05). Oxidation of the SM during 8 d of display storage increased linearly (P < 0.05) as duration of supplementation increased from 2 to 6 d but did not differ (P = 0.22) from 0 d of Mg supplementation. Although the response to Mg supplementation was variable, supplementation for 2 d before slaughter was considered most efficacious because of the following: decreased fluid loss from the SM, and lower lipid oxidation formation in the LM during retail storage; a darker, more desirable LM color after 25 d of vacuum-packaged storage; and cost reductions compared with longer durations.}, number={5}, journal={Journal of Animal Science}, author={Frederick, B. R. and Heugten, Eric and See, M. T.}, year={2004}, pages={1454–1460} }