Effect of substituting concentrate mix with Cajanus cajan leaf on growth performance traits and carcass components of yearling rams and its potential in mitigating methane production

The main challenges in ruminant production are to reduce feeding costs and to improve product quality while minimising environmental impact. The use of unconventional feedstuffs may contribute to decrease feeding costs and environmental impact. A study was conducted to investigate the supplementation effect of Cajanus cajan leaves (CCL) on the growth performance and carcass characteristics of yearling rams and its association with methane (CH4) reduction in vitro. Thirty yearling rams with an initial body weight of 15.1±0.68 kg were randomly allocated to five treatment diets with six rams each. A basal diet was prepared to contain 300 g/head/d concentrate mix (CM) for the control group (T1) and treatment (T) diets were formulated by replacing the CM with CCL at 5% (T2), 10% (T3), 15% (T4) and 20% (T5). Data were collected on feed intake, body weight, carcass components, and CH4 production from 24h in vitro gas production (GP). The digestible organic matter (dOM) and metabolizable energy (ME) were estimated from 24h GP. The CCL content of ash was 126 g kg-1 DM of ether extract 43 g kg-1 DM, and crude protein 240 g kg-1 DM. The feed intake, body weight gain, feed efficiency and carcass components were not affected by treatment diets. The 24 h GP (ml g-1 DM) was significantly higher for T1 and T2 diets than that of T4 and T5. The lowest CH4 was obtained from T5 and differed significantly with that of T1 and T2. The ME and dOM values in T1 and T2 diets were higher than those of T4 and T5. The supplementation of CCL considerably reduced the CH4 production across treatment diets without affecting the voluntary feed intake, weight gain and carcass components suggesting its potential as alternative supplement to poor quality forages while keeping CH4 production at a minimum level.