| Production of market-ready poultry products results in co-production of millions of tons of wastes. Some, such as poultry litter, poultry by-product meal, and feather meal, are well known and have high acceptance. Others, like spent laying hens and dissolved air flotation skimmings, are less well known and therefore may not be utilized to their full potential. Our research demonstrated that spent laying hens can be mechanically deboned to yield a soft tissue fraction (66% of carcass weight) which could be valuable as a monogastric feedstuff. It also produced a hard tissue fraction (largely feathers and bones and 34% of carcass weight) which could be further processed into a proteinaceous meal for ruminant feeds. Steam hydrolysis of the hard tissue improved pepsin digestibility from 74 to 85%. True amino acid digestibility in the hydrolyzed hard tissue averaged 77% (SEM = 1.9%). Subsequent keratinase enzyme addition did not improve either pepsin or true amino acid digestibility beyond levels achieved by steam hydrolysis (P > 0.10). Co-extrusion of the steam hydrolyzed hard tissue with soybean hulls resulted in feather-bone meal (FBM) which had handling characteristics similar to those of soybean hulls; contained 94% dry matter, 23% protein, 55% neutral detergent fiber, and 7% fat; and which was well accepted when incorporated into concentrate pellets for meat goats to provide up to 60% of added nitrogen. Animals which received FBM in place of a portion of the traditional protein source, soybean meal, had a tendency for higher dry matter intake (703, 710, 673, and 779 g/d intake for 0, 20, 40, or 60% FBM substitution, respectively; P = 0.11) and had higher nitrogen retention than control goats (2.2, 1.4, 2.1, 2.5g N/d for 0, 20, 40, and 60% FBM substitution, respectively; P = 0.06). Dissolved air flotation skimmings (90% water, 6% fat, and 4% non-fat solids) are a product of waste water treatment in poultry processing facilities. Partial fat extraction and dehydration yields a proteinaceous meal called secondary protein nutrients (SPN; 5% moisture, 46.5% protein, 27.8% fat, 28,200 ppm Fe). Evaluation of secondary protein nutrients confirmed that it can be utilized in diets for meat goats and beef steers to supply up to 40% of supplemental protein. Inclusion rates above 50% in steer diets resulted in reduced dry matter intake (6.8, 7.3, 6.9, 60, and 5.2 kg DM/d for 0, 25, 50, 75, and 100% SPN substation, respectively; P < 0.001) and average daily gain (1.26, 1.21, 1.11, 0.94, and 0.67 kg/d for 0, 25, 50, 75, and 100% SPN substitution, respectively; P < 0.01). Reductions were likely the result of a combination of factors including reduced fiber degradation caused by inadequate supplies of ruminally degradable protein, increasing levels of fat in the diet, and elevated iron content. Goats receiving up to 40% of added N as SPN had similar N retention (g/d) to control animals (P = 0.11). Changes in ruminal parameters varied with species, but reflected the dietary addition of rumen undegradable protein and changes in fat and Fe content. Our research established that wastes from the poultry industry can successfully be converted into novel feedstuffs, offering the opportunity to recycle nutrients and reduce their release into the environment. The novel feedstuffs evaluated supported animal growth, supplying supplemental protein. Although detailed economic analysis was not conducted, we hypothesize that use of novel feedstuffs produced from wastes could reduce feed costs and increase the value of waste, thus improving the profitability of animal and poultry production. |
