The nine samples from each slaughterhouse were pooled and sub-sampled to make three samples per slaughterhouse. Dried PSW samples were ground through a 1 mm screen (Wiley mill, Arthur H. Thomas, Philadelphia, PA), and samples analyzed for amino acids, total nitrogen, fat, ash and organic matter (AOAC, 1990). The CNCPS protein fractions of the PSW was determined according to standardized procedure of Licitra et al. (1996) at the University of Bahonar, Kerman. The B2 fraction was calculated by difference and results are reported as CP percentage. Phosphate buffer soluble nitrogen (PBSN) was determined using the phosphate buffer. Neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) were determined as the nitrogen content of the residual after neutral and acid detergent procedures. The analysis of 11 amino acids i.e. arginine, cysteine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine in three different PSW samples was performed using NIRS, FOSS 5000 Denmark at the Paya Amin Mehr Company (Tehran, Iran).The generation of poultry slaughterhouse waste from poultry production is not only unavoidable but the amount and kinds of waste can cause environmental problems. In the present study, the potential rumen digestion of poultry slaughterhouse waste which consists of protein-rich organic residues was evaluated. The chemical composition, amino acid profile and Cornell Net Carbohydrate and Protein System fractions of these wastes was determined. Rumen digestion of poultry slaughterhouse waste was compared with two common protein sources (fish meal and roasted soybean). Three poultry slaughterhouse waste samples were collected from industrial poultry slaughter-houses and the in situ degradation was done using rumen cannulated sheep. The protein (50e63%), ether extracts (18e27%) and ash (9e15.5%) contents of different poultry slaughterhouse waste samples were different (P < 0.05). Methionine and lysine contents were similar among different poultry slaughterhouse waste sources. Difference were observed for cystine (1.2e1.7%), threonine (1.9e2.2%), arginine (3e3.5%), leucine (3.5e4.1%) and valine (2.8e3.3%) (P < 0.05). Ruminal degradation rate for dry matter, organic matter and protein were different among poultry slaughterhouse waste, fish meal and roasted soybean. The degradation parameter for protein degradation was 76% for poultry slaughterhouse waste, 79% for fish meal and 98% for roasted soybean (P < 0.05). Results revealed that there was great variation in chemical composition, protein fractioning, and amino acid profiles of different poultry slaughterhouse waste sources. Poultry slaughterhouse waste is slowly-degraded protein in the rumen and thus can be an economical and rich source of rumen undegradable protein in ruminant nutrition. This implies that the use of poultry slaughterhouse waste in ruminant nutrition has a huge potential as a cleaner product of animal feeding and prevention environmental pollution. However, further studies are warranted to evaluate the digestibility of poultry slaughterhouse waste amino acids escaping the rumen into the intestine in ruminants and to compare the biological values for the amino acids in these waste material with common ruminant feedstuffs
