Effect of grazing and dietary protein on eating quality of Podolian beef1,2

Abstract

Twenty-four young Podolian bulls were used to evaluate the effect of rearing system (extensive vs. intensive) in relation to postmortem aging (11 and 18 d) on the eating quality of the meat, with the diet of outdoor animals adjusted to the protein content of the indoor system (15% CP) or to the minimum protein content required for satisfactory growth (12% CP). At 415 ± 9.35 (SE) d of age, with a mean BW of 337.5 ± 16.51 (SE) kg, animals were allotted to 3 groups for the finishing period (172 d): 1) indoor group receiving a diet at 15% CP; 2) grazing animals receiving a diet at 15% CP of DM; and 3) grazing animals receiving a diet at 12% CP of DM. Longissimus dorsi lumborum muscle sampled from the right half and divided longitudinally into 2 sections was aged in vacuum packaging at 4°C until 11 and 18 d postmortem, respectively. Rearing system did not affect (P > 0.05) color, Warner-Bratzler shear force, texture profile, water-holding capacity, and most of the sensory attributes of the beef steaks. However, sensory tenderness was less in the meat from outdoor animals receiving a diet with 15% CP than in meat from outdoor animals receiving a diet with 12% CP or from the indoor group (P < 0.05). Meat aged 18 d showed decreased Warner-Bratzler shear force (P < 0.001), hardness (P < 0.001), cohesiveness (P < 0.05), springiness (P < 0.05), gumminess (P < 0.01), chewiness (P < 0.01), and thawing loss (P < 0.01) compared with meat aged for 11 d. Prolonging the aging time up to 18 d significantly increased b* (yellowness; P < 0.05), cooking losses (P < 0.001), and the intensity of all the texture sensory attributes, namely, juiciness and fatness (P < 0.05), chewiness, tenderness, and flavor (P < 0.01). Significant correlations were found between instrumental and sensory variables (range of r = -0.55 to -0.85, P < 0.05 to 0.001). Overall, in the present study, the rearing system did not markedly affect meat sensory and physical properties. Thus, we conclude that an outdoor system, even with reduced protein supplementation, may represent a valid farming system for local breeds in Mediterranean areas characterized by poor-quality pastures. However, an extended aging period is suggested to improve the main factor limiting the quality of this product, namely, reduced tenderness.