Open access publications in the SLU publication database

Abstract

Beef production is performed in varying systems, with or without grazing, but the common goal is to obtain high-quality carcasses. Semi-natural grasslands are characterized by specific flora and fauna and they are dependent on grazing management to be maintained. The aim of this thesis was to evaluate factors influencing nature conservation, animal performance and meat quality in beef production using semi-natural grasslands in summer. In a first study, effects of breed and season on foraging behaviour and diet composition were studied in heifers grazing semi-natural grasslands. In two further studies, effects of feed intensity and length of rearing period on feed intake, weight gain, feed conversion and carcass traits were investigated. One of these studies included finishing dairy steers, which had grazed semi-natural grasslands in previous summer, and the other study included beef heifers, which were reared from weaning until slaughter including a grazing period on semi-natural grasslands. For the heifers also meat quality, as affected by feed intensity, slaughter age and suspension method, was studied. Foraging behaviour and diet composition were more influenced by season than by breed. Over the grazing period, the heifers decreased their levels of activity, but increased their time spent grazing. The grazing time composed of more eating jaw movements and fewer pauses as the grazing period progressed. Wet areas, dominated by Deschampsia cespitosa (tufted hairgrass), were consistently avoided for grazing, whereas browsing on Alnus glutinosa (alder) increased over the grazing period. Increased indoor feed intensities were accompanied by increased weight gains and improved feed conversions. In the steers, an intermediate length of finishing resulted in the best feed conversion. Carcass traits were more affected by length of rearing period than by feed intensity. A prolonged rearing period resulted in heavier and fatter carcasses with increased dressing percentages and improved conformation. Meat from pelvic suspended sides was tenderer than meat from sides suspended by Achilles tendon after 14 days of ageing. Production of quality-grade carcasses with tender meat can be combined with the management of semi-natural grasslands on the conditions of regular controls of animal weights, strategic grazing regimes and proper post-slaughter procedures.