Abstract
Finishing diets in intensive beef production systems are mainly based on cereals, which does not take advantage of the capacity of the ruminant digestive system to digest fibrous feeds, cannot be considered sustainable and does not contribute to the circular bioeconomy. Our aim was to investigate the effects of an alternative concentrate rich in agro-industrial by-products for finishing crossbred Limousine heifers. Four pens with 12 heifers and four pens with 13 heifers were randomly allocated to one of two treatments: control (CON), a commercial concentrate with a 43.3% cereal composition, and alternative (ALT), a concentrate with a composition of 26% cereals and up to 73.5% agro-industrial by-products. Growth performance data were collected along the 91 days of the experimental period. Carcass characteristics were collected after slaughter and 24 h later. Vacuum-packaged samples from longissimus muscle were aged for 7, 21 or 28 days to study meat quality traits. Feed intake was higher and feed conversion rate was lower in the ALT treatment, but no differences were found in average daily gain and feeding costs. Treatment had no effects on any of the measured carcass traits (grading, hot and cold carcass weight, dressing out, chilling losses, subcutaneous fat depth, pH, temperature and lean and fat colour) nor on the meat quality traits (drip loss, cooking loss, shear force, oxidative stability, chromatic indices and pigment contents). Ageing time decreased drip loss and shear force, increased lightness and did not affect redness or surface colour stability. In conclusion, feeding crossbred Limousine heifers a finishing diet rich in agro-industrial by-products did not have any negative effects on performance, carcass and meat quality traits, which might be considered positive from the point of view of sustainability of beef production. Under the conditions assayed, ageing for 21 and 28 days improved tenderness of meat, without detrimental effects on oxidative stability or traits related to visual acceptability.