Comparison of two feeding finishing treatments on production and quality of organic beef

Abstract

The study compared growth and slaughter performance and meat quality of organic beef cattle finished with or without pasture grazing. One group of 10 Limousin heifers was finished under confined conditions and fed ad libitum a total mixed ration based on maize silage, hay and cereal grains. A second group of 10 Limousin heifers rotationally grazed two contiguous pasture plots of 1.5 ha each with a daily supplementation of a concentrate mix based on cereal grains and roasted soybeans. Heifers were slaughtered at commercial finishing and meat quality traits were assessed on Longissimus thoracis muscle. The grazing group, due to a lower average daily gain (0.74 vs. 0.95 kg/day; P<0.05), required a prolonged finishing period (172 vs. 155 days; P<0.05) than the confined animals. Meat samples from grazing cattle were less tender (shear force: 3.92 vs. 3.24 kg/cm2; P<0.05) and showed a lower lightness (L*: 33.0 vs. 35.8; P<0.001) and a higher redness (15.4 vs. 13.7; P<0.01) and yellowness (15.6 vs. 14.6; P<0.05). Fatty acid composition of the intramuscular fat was significantly affected by the finishing system. Grazing heifers had a higher content of polyunsaturated fatty acids (4.06 vs. 3.66% of total fatty acids; P<0.05), conjugated linoleic acids (0.16 vs. 0.10% of total fatty acids; P<0.01) and ω-3 (0.44 vs. 0.30% of total fatty acids; P<0.001) than confined animals. The detrimental effects of pasture grazing on growth performance and on some important meat quality traits explain the limited adoption of this finishing system in organic beef production.