CNCPS-based carbohydrate and protein fractionation of feed ingredients commonly used in tropical ruminant diet formulation

Abstract Precision diet formulation for tropical ruminants requires feed ingredient characterisation beyond proximate composition, yet comprehensive Cornell Net Carbohydrate and Protein System (CNCPS) fractionation data for concentrate ingredients used in South Asian livestock systems remain scarce. This study evaluated the chemical composition, fibre fractions, and CNCPS carbohydrate and protein fractions of seven protein concentrates (alfalfa residue, coconut oil cake, sesame oil cake, groundnut cake, soybean meal, sunflower cake, and corn gluten feed) and six energy concentrates (maize, de-oiled rice bran, wheat bran, rice polish, tapioca starch waste, and black gram husk). Six samples of each ingredient were analysed in duplicate and data are expressed as means ± standard error (SE). Carbohydrate fractionation revealed wide variation in ruminal degradability: maize was dominated by the intermediately degradable starch fraction (CB1: 71.53% of total carbohydrate), while coconut oil cake and rice polish contained predominantly unavailable cell wall (CC: 58.42% and 67.43%, respectively). Among protein ingredients, soybean meal was rich in intermediately degradable true protein (PB2: 78.91% of crude protein), while alfalfa residue was dominated by the slowly degradable fraction (PB3: 75.08%). Rumen-degradable protein ranged from 36 per cent in coconut oil cake to 74 per cent in corn gluten feed. These CNCPS fraction profiles provide a regional reference dataset for tropical concentrate ingredients, enabling diet formulation based on ruminal degradation kinetics and supporting more precise energy–protein synchronisation in tropical ruminant production systems. Keywords: CNCPS fractionation, concentrate feed ingredients, rumen degradability, tropical ruminants, South Asia.