Effect of Two Dietary Concentrate Levels on Tenderness, Calpain and Calpastatin Activities, and Carcass Merit in Waguli and Brahman Steers

¹ Department of Animal Sciences, University of Arizona, Tucson Arizona

^* To whom correspondence should be addressed. E-mail: jam{at}ag.arizona.edu.

	Abstract

The objective of this study was to compare carcass characteristics of a newly introduced breed, the Waguli (Wagyu x Tuli), with the carcass characteristics of the Brahman breed. Brahman cattle are used extensively in the Southwest of the United States because of their tolerance to adverse environmental conditions. However, Brahman carcasses are discounted according to the height of their humps because of meat tenderness issues. The Waguli was developed in an attempt to obtain a breed that retained the heat tolerance of the Brahman but have meat quality attributes similar to the Wagyu. Twenty-four animals were used. Six steers from each breed were fed a 94% concentrate diet (94C) and 6 steers from each breed were fed an 86% concentrate diet (86C). Eight steers, 2 from each group, each were harvested after 128 d, after 142 d, and after 156 d on feed. Waguli steers had larger LM, greater back fat thickness, higher marbling scores, and higher quality grades than the Brahman steers (P < 0.05). It is well known that the Japanese Wagyu breed is highly marbled and has tender meat, and these traits are also present in the Waguli. The Waguli had significantly lower Warner-Bratzler shear force values than the Brahman steers after 7 and 10 d of postmortem aging (P<0.05); this difference decreased after 14 d postmortem (P =0.2) when tenderness of the slower aging Brahman had increased to acceptable levels. Toughness of the Brahman has been associated with high levels of calpastatin in Brahman muscle, and the Waguli longissimus had significantly less at 0-h postmortem calpastatin activity (P=0.02) than the Brahman longissimus. At 0-h postmortem the total LM calpain activity did not differ between Brahman and Waguli (P = 0.57). Neither diet nor days on feed had any significant effect on at 0-h postmortem calpain or at 0-h postmortem calpastatin activity, and had no effect on Warner-Bratzler shear-force values. In conclusion, longissimus muscle from the Waguli steers has a high degree of marbling, had lower shear force values, and had low calpastatin activity that is related to tender meat.

Key Words: Waguli, Brahman, calpain, calpastatin, carcass characteristics, tenderness