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This Article Full Text (PDF) All Versions of this Article: jas.2008-1486v1 87/8/2700    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Shibata, M. Articles by Chikuni, K. Search for Related Content PubMed PubMed Citation Articles by Shibata, M. Articles by Chikuni, K.

Differential expression of the skeletal muscle proteome in grazed cattle

M. Shibata^*, K. Matsumoto^*, M. Oe^#, M. Ohnishi-Kameyama, K. Ojima^#, I. Nakajima^#, S. Muroya^# and K. Chikuni^#

^* National Agricultural Research Center for Western Region (WeNARC), Ohda-shi, Shimane-ken, 694-0013 , National Food Research Institute, Tsukuba-shi, Ibaraki-ken, 305-8642 ^# National Institute of Livestock and Grassland Science, Tsukuba-shi, Ibaraki-ken, 305-0901, Japan

shibatam{at}affrc.go.jp

Abstract

The objective of this study was to investigate the differences in the muscle proteome of grass-fed and grain-fed cattle. Eight Japanese Black Cattle aged 10 mo were separated randomly into two groups: 1) grazing (grass-fed), and 2) concentrate (grain-fed) groups. All cattle were first housed individually in a stall barn and fed a combination of concentrate ad libitum and Italian ryegrass hay until 21 mo of age. After this control period, the four grass-fed cattle were placed on outdoor pasture, while the other four grain-fed cattle continued on the concentrate diet. The cattle were slaughtered at 27 mo of age, and tissues from the M. semitendinosus muscle were obtained for use in proteome analysis. Differential expression of muscle proteins in the two groups was carried out using two-dimensional gel electrophoresis (2DE) and Western blot analyses, with subsequent mass spectrometry. Approximately 200 individual protein spots were detected and compared in each group using 2DE, of which 20 and 9 spots respectively showed differences in the spot intensity for the sarcoplasmic fraction and myofibrillar fraction. In the grazing group, the relative intensity of spots were significantly higher for both adenylate kinase 1 and myoglobin in the sarcoplasmic fraction, and for slow-twitch myosin light chain 2 in the myofibrillar fraction (P<0.05), than the concentrate group. The relative spot intensity of several glycolytic enzymes were significantly higher in the grazing group, such as beta-enolase 3, fructose-1,6-bisphosphate aldolase A, and triosephosphate isomerase, and heat shock 27 kDa protein (P<0.05). Moreover, significantly higher slow twitch of troponin T, troponin I, and myosin heavy chain of ST muscle were detected in the grazing group than in the concentrate group using Western blot analysis (P<0.05). Several previous reports have described that the slow-twitch muscle contents affect elements of nutrition, flavor and food feeling of meat. This study revealed muscle fiber type conversion to slow-twitch tissues from fast-twitch tissues occurring with change in the energy metabolic enzyme when cattle were grazed in the latter fattening period. Although analyses of the influence on elements of nutrition, flavor and food texture were not done for this study, these results show that slow-twitch converted muscle resulting from the grazing of cattle might modify several meat characteristics.

Key Words: beef cattle • grazing • muscle • myofibrillar protein • proteome analysis • sarcoplasmic protein