Reducing the impact of feedstuff transport by a better utilization of plant wastes for livestock: a way to improve meat quality?

The effect of feeding plant by-products (cardoon meal (CM), dried corn gluten feed (CGF), corn (CDGS) and wheat (WDGS) distillers’ grains with solubles, and citrus pulp (DCP)) on the quality of meat from ruminant animals (lambs and beef cattle) was investigated. The first experiment examined the response of rumen function to diets rich in phenolic compounds (i.e. tannins), which are secondary metabolites prevalent in several plant by-products. Concentrate diet supplemented with 4% of two hydrolysable (chestnut and tara) and condensed (mimosa and gambier) tannin extracts did not impair ruminal fermentation traits and microbiome in lambs. The second and third experiments indicated that replacement of 15% dehydrated alfalfa with CM did not influence lamb performance and carcass traits. Feeding CM promoted ruminal biohydrogenation of fatty acids (FA) through a modulation of the rumen bacterial community and consequently, reduced the proportion of t-11 18:1 and c-9,t-11 conjugated linoleic acid (CLA) in lamb meat. Moreover, dietary CM did not influence the oxidative stability of lamb meat whereas a phenolic-rich CM extract reduced lipid oxidation in an ovine muscle model system. The fourth, fifth and sixth experiments assessed the quality indices of beef from grass silage-fed steers offered concentrate supplements in which barley/soybean meal was replaced with varying levels of CGF (25%, 50% and 75%), CDGS and WDGS (80%), and DCP (40% and 80%), respectively. The inclusion of up to 75% CGF improved the FA profile of beef by decreasing the proportion of C14:0 and increasing CLA, C18:3 n-3, C20:5 n-3 and C22:5 n-3 without negatively influencing the shelf-life and eating quality of beef. Dietary CDGS or WDGS increased the proportion of CLA and total polyunsaturated fatty acids (PUFA) in beef but decreased beef shelf-life by increasing lipid oxidation and discolouration in fresh beef patties stored in modified atmosphere packs (80% O2:20% CO2). The inclusion of up to 80% DCP improved the FA profile of beef by increasing the percentage of CLA and PUFA in beef without compromising the oxidative stability and consumer acceptability of beef