Biotransforming of Poultry and Swine Slaughterhouse Waste as an Alternative Protein Source for Ruminant Feeding

The biotransformation of poultry (PSW) and swine (SSW) slaughterhouse waste might provide protein feedstuffs, ensuring efficient ruminant systems while safeguarding the environment. The present study aimed to evaluate the potential of PSW and SSW as alternative protein feed for ruminant animals. A total of 24 lambs [25.4 ± 3.13 kg of body weight (BW), mean ± SD] were randomly allocated to one of three groups (n = 8): a control diet formulated with typical protein ingredients (CTRL) and two diets formulated with PSW or SSW meal as a protein source. Dietary inclusion of PSW or SSW did not alter (p = 0.05) dry matter intake or final BW. However, animals fed SSW showed the highest average daily gain (ADG, p = 0.04). In addition, substituting PSW and SSW improved the feed conversation ratio (FCR, p = 0.05). There were no diet effects (p = 0.05) on N intake, while fecal N excretion increased (p = 0.03) with SSW feeding. Compared to CTRL and PSW, ingestion of SSW decreased (p = 0.001) and retained N. The digestibility of crude protein and organic matter remained unchanged (p = 0.05). Additionally, there were no differences (p = 0.05) in potential microbial protein synthesis based on either protein content (SPMp) or energy content (SPMe). Similarly, potential metabolizable protein by protein (PMp) and potential metabolizable energy by protein (PMe) were not affected (p = 0.05). Overall, both PSW and SSW positively influenced the growth performance of ewe lambs. However, further studies are warranted to explore the impact of PWS or SSW feeding on rumen function, nitrogen pollution, and protein escaping the rumen into the intestine in ruminants.