Nutritional compositions of Katuk leaves and their supplementation to hays of different quality: an in vitro study

Abstract

Katuk leaves (Sauropus androgynus (L.) Merr.; KL) are widely consumed by breast-feeding Indonesian mothers as it has been reported to increase breast milk production. It is hypothesized that supplementing KL in diets might increase crude protein (CP) concentration and fibre digestibility in the diet. The KL had high CP and non-fibre carbohydrate concentrations (333 and 332 g/kg dry matter; DM, respectively), but low neutral detergent fibre assayed with heat, a stable amylase and expressed exclusive of residual ash (aNDFom; 200 g/kg DM). Fibre digestibility linearly increased with increasing of KL supplementation in low-quality hay (LQH) diets. The KL did not contain a considerable amount of tannins. In LQH diets, gas production after 24 h incubation (GP24) linearly increased with increasing of KL supplementation (P < 0.001). Meanwhile, GP24 linearly decreased with increasing of KL supplementation in medium- and high-quality hays (MQH and HQH; P < 0.001). Metabolizable energy tended to linearly increase in LQH diets, but tended to linearly decrease with increasing of KL supplementation in MQH and HQH diets (P = 0.078). Therefore, this study suggested that KL can be a potential supplement in the ruminant diet due to its abundant dietary proteins but low fibre concentration in its leaves. However, further studies (e.g. in vitro or in vivo) investigating other rumen parameters after incubation should be performed to validate how KL can be supplemented in the diet of ruminant livestock.