Many plant protein leaf meals (LM) remain unassessed for their rumen bypass potential following heat treatment. This study aimed to evaluate whether heat treatment could reduce ruminal degradability and improve bypass protein availability in five LMs—ipil-ipil (ILM), kakawate (KaLM), moringa (MLM), kudzu (KuLM), and gumamela (GLM). A total of 60 nylon bags (3 replicates per treatment) containing untreated or heat-treated LMs were incubated for 24 h in a rumen-fistulated Brahman bull using a completely randomized design. Heat treatment reduced mean crude protein degradability (CPD) by 7.6% (81.41% untreated vs. 73.77% treated; P = 0.006), with the largest reductions recorded in ILM (−23.9%), KuLM (−14.7%), and GLM (−6.8%). In contrast, dry matter degradability (DMD: 69.76% vs. 68.65%) and organic matter degradability (OMD: 74.44% vs. 70.56%) were not significantly affected. Among the LMs, moringa consistently exhibited the highest degradability (CPD = 98.27%, DMD = 94.98%, OMD = 97.00%), whereas kudzu had the lowest (CPD = 68.69%, DMD = 48.52%, OMD = 54.21%). Degradability trends were influenced by drought-resistance, botanical classification (legume vs. non-legume), and growth form (tree, shrub, creeping). Legume LMs were 16% less digestible in protein content than non-legumes, and creeping types were 19% less digestible than non-creeping types. Heat treatment further lowered CPD in both categories, indicating its capacity to enhance bypass protein potential. These findings suggest that targeted application of heat treatment, especially for ipil-ipil, kudzu, and gumamela, offers a practical strategy to improve protein utilization efficiency in ruminant feeding systems by increasing post-ruminal protein supply. Keywords: Brahman cattle, Heat-treatment, In situ degradation, Leaf meal, Rumen.
CORTEZ et al. (Mon,) studied this question.