Nyamplung seed cake as a dietary supplement for dairy goats: In vitro digestibility and fermentability analysis

Abstract

The crude oil industry derived from Nyamplung seeds (Calophyllum inophyllum) in Indonesia is rapidly developing. A byproduct of crude oil industry from Nyamplung seed is called Nyamplung Seed Cake (NSC). This research was undertaken to examine the biochemical constituents and in vitro digestibility and fermentability analysis of NSC, alongside the effects of NSC supplementation on dairy goat feed. In terms of biochemical composition, NSC exhibited 90.59% dry matter, 84.87% organic matter, 21.93% crude protein, 6.70% ether extract, 10.07% hemicellulose, 42.32% neutral detergent fiber, and 32.25% acid detergent fiber. Regarding secondary plant metabolites, NSC contained a total flavonoid content of 1.65%, 6.58% total phenols, and 0.87% saponins. The total tannin content in NSC was 0.95%, comprising 0.44% condensed tannins and 0.44% hydrolyzable tannins. NSC supplementation at 15% and 20% resulted in dry matter digestibility, organic matter digestibility, and fermentation metrics similar to those of standard feed.  Meanwhile, supplementation at the level of 25% significantly increased the digestibility of dry matter to 77.38% and the digestibility of organic matter to 74.99% and produced the lowest methane emission of 48,756.06 ppm compared with other feed treatments. This study concluded that the addition of NSC to dairy goat feed improved feed digestibility and lowered methane emissions without negatively affecting rumen digestion. This study supports the use of NSC as a substitute for protein source diet ingredients in dairy goat feed, recommending its inclusion at levels of up to 25% of the total ration.