Effect of Lime (Citrus aurantifolia) Waste Powder Supplementation on in Vitro Fermentability and Digestibility in Male Goats

Abstract

Goat production in tropical areas faces significant challenges due to seasonal forage scarcity and high feed costs, necessitating alternative feed resources. This study aimed to evaluate the effect of lime (Citrus aurantifolia) peel meal supplementation on the digestibility and fermentability of male goat rations in vitro. The experiment was conducted using a Completely Randomized Design with five supplementation levels: R0 (0%), R1 (5%), R2 (10%), R3 (15%), and R4 (20%) using a basal diet of Taiwan Napier grass and concentrate. The parameters evaluated included in vitro dry matter digestibility (IVDMD), in vitro organic matter digestibility (IVOMD), total volatile fatty acids (total VFAs) concentration, and rumen ammonia-nitrogen (NH3). The results showed that the treatments significantly affected (P < 0.05) all parameters. The R3 treatment (15%) provided the most optimal results, yielding the highest IVDMD (64.08%), maximum IVOMD (72.06%), peak total VFA (171.89 mM), and ideal NH3 (10.08 mM). This efficiency was triggered by a substrate shift, where the high crude fiber of Taiwan Napier grass (27.12%) was substituted by lime peel meal which had lower crude fiber (11.92%), thereby reducing the total lignin proportion of the ration and optimizing fermentation. However, the 20% level (R4) induced a threshold effect that decreased the IVOMD (64.24%) and total VFA (141.92 mM) values due to the accumulation of bioactive compounds (saponins and limonene) that began to inhibit microbial activity. In conclusion, supplementing male goat rations with 15% lime peel waste meal optimizes rumen fermentation and feed digestibility, offering a sustainable alternative feed strategy to mitigate feed price instability.