The use of by-products from the potato processing industry in beef finishing diets.

Abstract

13A The use of by_products from the potato processing industry in beef finishing diets J.L. Duynisveld and E. Charmley Agriculture and Agri_Food Canada, Crops and Livestock Research Centre, Nappan, Nova Scotia B0L 1C0, Canada edward.charmley@csiro.au Over 2 million tonnes of potato processing waste (PPW) is produced annually in Canada. Depending on the type of processing, PPW ($1025/t DM) is low and variable in dry matter (DM) content (100 to 300 g/kg), low in crude protein (CP; <100 g/kg DM), high in starch (>500 g/kg DM) and can have widely varying fat concentration (5 to 100 g/kg DM). Ninety steers with initial liveweight (LW) 420 kg were allotted to 5 diets, fed for 79, 107 or 135 d, comprising 20% grass silage and 80% concentrate which was rolled barley decreasing from 100% to zero with the inclusion of 0, 25, 50, 75 and 100% PPW. Steers fed 50% PPW in the concentrate had the highest gains (P<0.05) but LW and carcass weight at slaughter were similar for all treatments (Table 1). DM intake declined as % PPW increased, thus influencing feed to gain ratio (P<0.05). There were no effects of diet on any carcass or meat quality attributes. As time on feed increased, LW gain declined ( P <0.05), carcass attributes were unaffected, and meat flavour and texture improved (P<0.05). In a 3 x 3 Latin square digestibility trial steers were fed ad libitum diets containing 0, 40 or 80% of a concentrate that was a 50/50 mixture of PPW and barley (DM basis); thus the 80% concentrate diet was the same as the 50% PPW diet in the production trial. A quadratic response in dry matter digestibility (DMD) to concentrate inclusion suggested a depressing effect of concentrate on silage DMD. However, the 80% concentrate diet had a high digestibility (77%), and ad libitum DM intake increased linearly as the concentrate proportion increased. The production trial showed that high proportions of PPW can be fed to finishing cattle without detrimental effects on performance, carcass or meat characteristics. Moderate inclusion of PPW may depress forage digestibility, but this is not of concern in highPPW diets. Table 1 Effect of PPW and days on feed on performance, carcass meat quality of steers and diet digestibility. % PPW in concentrate 0 Final LW, kg LW gain, kg/d DM intake, g/kg LW Feed:gain Carcass weight, kg Backfat, mm Raw meat moisture, % 581 1.68a 21.5c 6.33b 325 7.25 73.4 25 583 1.70a 21.9c 6.43b 326 6.90 72.9 50 595 1.93b 20.1bc 5.16a 329 7.19 72.9 75 582 1.61a 18.7ab 5.61a 322 7.25 73.1 100 573 1.69a 17.1a 5.34a 317 6.42 73.2 SEM 8.19 0.06 0.73 0.18 5.35 0.54 0.16 80% concentrate 21.8 77.4 16.9 79 587 1.72c _ _ 324 6.53 73.4c Days on feed 107 584 1.54b _ _ 325 7.18 72.7a SEM 135 580 1.43a _ _ 325 7.45 73.1b SEM 6.63 0.05 _ _ 4.36 0.43 0.07 0% concentrate DM intake, g/kg LW DM digestibility, % Digestible DM intake, g/kg LW 16.7 67.2 11.2 40% concentrate 19.6 64.1 12.6 Response (P<0.001) Linear Quadratic Quadratic 0.46 1.15 0.42 Means in a row with different superscripts differ (P<0.05) Recent Advances in Animal Nutrition in Australia, Volume 14 (2003)