と畜前の飲料水にビタミン D を補給すると、酸化状態、生理的ストレス、および豚肉の品質が改善される

Vitamin D Supplementation in Drinking Water Prior to Slaughter Improves Oxidative Status, Physiological Stress, and Quality of Pork.

• Ana I Rey
• José Francisco Segura
• David Castejón
• Encarnación Fernández-Valle
• Mª Isabel Cambero
• Luis Calvo

抄録

本研究の目的は、食肉処理前のレイヤード時間帯に飲料水にビタミンDを投与することが、生理的ストレス、酸化状態、および豚肉の品質特性に及ぼす影響を調べることであった。実験は2つ実施した。1つ目は飲用水中のビタミンD補給の効果を調べるために、2つ目は補給量（50万IU/L vs. 70万IU/L）の効果を調べるために行った。血清カルシウム濃度は、対照群と比較して、水中ビタミンDを投与された豚の方が高かった。実験１では、ビタミンＤを補給した群（５００，００００ＩＵ／匹）の肉にα-トコフェロールが４０％増加し、冷蔵保存後５日目と８日目に肉のマロンジアルデヒド（ＭＤＡ）値が低下する傾向が見られた。実験2では、水分摂取量が多かったため（ビタミンD摂取量が800,000IUと1,120,000IU/匹）、酸化状態への影響がより深く、ビタミンDの補給は血清α-トコフェロールを増加させ、コルチゾールと血清TBARSを減少させた。これらの効果は肉にも観察された；TBARS レベルは冷蔵保存 3 日後に低下した。いずれの実験においても、飲料水にビタミンDを添加した豚の肉は、未添加豚に比べて遊離多価不飽和脂肪酸（主にn-6）の割合が低く、これらは冷蔵保存5日目のTBARS産生と正の相関を示した（実験1および2ではそれぞれ=0.53および0.38）。ビタミンDを水中で摂取した豚の肉は、対照群と比較して、凝集力、歯ごたえ、噛み応えが低下していた。筋肉の磁気共鳴イメージング試験では、ビタミンDを補給した豚の方が横方向の弛緩時間が少なく、保水性への効果が確認された。

The aims of this study were to investigate the effect of vitamin D administration in drinking water during lairage time prior to slaughter on physiological stress, oxidative status, and pork quality characteristics. Two experiments were carried out. The first one was performed to examine the effect of vitamin D supplementation in drinking water, and the second one to check the effect of supplementation dose (500,000 IU/L vs. 700,000 IU/L). Serum calcium concentration was greater in pigs receiving vitamin D in water when compared to the control group. In experiment 1, a 40% α-tocopherol increase in meat from the group supplemented with vitamin D (500,000 IU/animal) was observed, that resulted in a tendency of decreased meat malondialdehyde (MDA) values at days 5 and 8 after refrigerated storage. In experiment 2, since water intake was higher (800,000 IU and 1,120,000 IU/animal of vitamin D consumption) effects on oxidative status were more profound and vitamin D supplementation increased serum α-tocopherol and decreased cortisol and serum TBARS. These effects were also observed in meat; TBARS levels were decreased after 3 days of refrigerated storage. In both experiments meat from pigs that received vitamin D in drinking water had a lower proportion of total free-polyunsaturated fatty acids (mainly n-6) when compared to the unsupplemented pigs, and these were positively correlated with TBARS production at day 5 of refrigerated storage ( = 0.53 and 0.38 for experiments 1 and 2, respectively). Meat from pigs receiving vitamin D in water showed reduced cohesiveness, gumminess, and chewiness values compared to the control group. The magnetic resonance imaging study of muscle confirmed the effects on water retention with lesser transverse relaxation time in pigs supplemented with vitamin D. No vitamin D dose effect was observed, apart from muscle α-tocopherol concentration that was higher in pigs supplemented with 700,000 compared to those supplemented with 500,000 UI/L.