Potato processing waste in beef finishing diets; effects on performance, carcass and meat quality

Potato by-products are frequently fed to cattle in many parts of the World. This paper considered the effect of feeding very high proportions of potato processing waste (PPW) to finishing beef cattle. One-hundred crossbred steers (Continental × British) were assigned to one of five finishing diets where rolled barley was replaced by PPW to give diets containing 0%, 20%, 40%, 60% or 80% PPW in the dry matter. Diets were fed ad libitum for 79, 107 or 135 days before steers were slaughtered and assessed for carcass and meat quality characteristics. Increasing the proportion of PPW in the diet resulted in a positive quadratic response in liveweight gain (P = 0.027). Inclusion level of PPW had no effect on carcass traits, although carcass weights declined linearly from 327 to 312 kg as PPW level in the diet increased (P = 0.016). Overall, effects of increasing the level of PPW on physical and sensory characteristics of meat were small and considered unlikely to affect consumer acceptance. Potentially due to inherent genetic variation in the cattle, some grew more slowly and were on feed for longer. Thus there was a linear decline in liveweight gain (P = 0.001) and a linear increase in grade fat (P = 0.039) as days to finish increased. Steers finished after 107 days had smaller loin eye area and lean meat yield, which resulted in negative quadratic effects for these characteristics (P = 0.014 and 0.024, respectively). We conclude that PPW can fully substitute for rolled barley in finishing diets without any negative implications for growth performance or meat quality and that the effect of days to finish were more important than the effect of the proportion of PPW in the diet.