The use of the 15N tracer technique for estimating the protein value of pea seeds in goats

摘要

This study aimed to evaluate the metabolisable protein value (called PDI in the Inra 2018 system) of pea seeds. Eight mid-lactating goats were fed two iso-PDI diets both containing 227 g pea/kg DM but differing in Rumen Protein Balance (L: RPB—4.2, vs h: RPB=18.2 g/kg DM). Faeces and urine were totally collected and the 15N enrichment and total N content of the samples were measured after feeding 15N-pea. The PDI value of the peas was estimated by the difference between intake and losses in faeces and urine during the 72 h after the 15N-pea allowance. Results showed a higher PDI value of peas in the L- than in the H-diet (114 vs 98 g PDF/leg DM) in agreement with the difference in the in sacco nitrogen degradability of the diets. The PDI value of peas in the H-diet was similar to that in the 2018 Inra tables, but the PDI value in the L-diet was higher.