Quality of meat from lambs grazed on seven pasture species in Hawkes Bay

Abstract

Eating quality attributes of lean meat were examined for lambs from two growth performance trials. The lambs had grazed one of seven pure-sward pastures—ryegrass, tall fescue, cocksfoot, Phalaris, lucerne, chicory, and prairie grass—in Hawkes Bay during late summer in 1992 and 1993. The Phalaris diet caused a 73% incidence of staggers in 1992 and a 52% incidence in 1993. Ryegrass staggers was minimal in 1992 and absent in 1993. Frozen meat (m. longissimus thoracicus et lumborum) from 10 animals in each treatment was cooked to a 75°C endpoint and served to panelists who assessed samples for intensity of grass flavour, sheepmeat flavour, and foreign flavour, and also tenderness and overall acceptability. In 1992, panelists recorded a marked foreign flavour, described as “fishy” or “rancid” in the Phalaris treatment, accompanied by significantly increased tenderness. Overall acceptability was lowest for this treatment, indicating that the foreign flavour dominated perceptions. Panelists’ comments were particularly unfavourable for the Phalaris treatment. In 1993, similar results were obtained, but differences between treatments were less marked. Considered over both years, the cocksfoot treatment was the most favoured in terms of comments, but panel score differences between that treatment and others (except Phalaris) were slight. It was also concluded that the seven pastures had no important effect on sheepmeat flavour as an attribute. Eleven of the 60 meat samples in 1993 had a high ultimate pH (> 6.0). Six of these were raised on Phalaris. It is argued that the foreign flavour in the Phalaris treatment stems from an intrinsic effect on sheep metabolism, through staggers, rather than from pH per se. The high pH condition induced by Phalaris was almost certainly caused by hyperexcitability or other condition of the staggers, and raises the wider question of the nation-wide effect of grass staggers on pH, a major quality determinant of meat. © 1994 Taylor & Francis Group, LLC.