Effect of Dietary Non‐Fiber Carbohydrate Sources and Sulfur Supplementation on in vitro Ruminal Fermentation and Digestibility of the Dairy Ration

Synchronization of rumen degradable protein (RDP), non-fiber carbohydrate (NFC), and sulfur availability are needed for optimum microbial protein synthesis (MPS), rumen fermentation activity, and feed digesti-bility. Cassava and corn are rich in NFC content and have different carbohydrate characteristics. Most of the tropical feedstuff is deficient in sulfur, thus it needs to be supplemented in the ration. This study aimed to compare the effect of corn and cassava as NFC sources and sulfur supplementation on fermentability and digestibility using in vitro study. The experiment used a 2 × 3 factorial randomized block design with four different dairy cattle rumen liquor as replications (block). The first factor was NFC sources (corn and cas-sava), and the second factor was the level of sulfur supplementation (0%, 0.1%, 0.2%). Parameters ob-served include fermentability (rumen pH, NH3 concentration, total volatile fatty acids (VFA), molar propor-tion of VFA, MPS, rumen bacteria, and protozoa population) and in vitro digestibility (dry matter (IVDMD) and organic matter (IVOMD)). Data were tested using ANOVA followed by the Duncan test. The result showed an interaction between rumen pH (P 0.05). The NH3 concentration was low in cassava treatment, while total VFA did not have a significant effect. Corn treatment produced a higher iso-butyrate and iso-valerate than cassava treatment (P 0.05). The rumen microbes, MPS, IVDMD, and IVDMD, did not differ among the treatments. Cassava could replace corn as an NFC source for tropical dairy ration along with providing RDP in balance ratio and sulfur supplementation.