Four, lactating dairy cows were randomly assigned according to a 2 x 2 Factorial arrangement in a 4 x 4 Latin square design to study supplementation of malate two levels as 500 and 1,000 g and cassava hay in high-quality feed block. The treatments were as follows T1 (supplementation of high-quality feed block without cassava hay + malate at 500 g); T2 (supplementation of high-quality feed block without cassava hay + malate at 1,000 g); T3 (supplementation of high-quality feed block with cassava hay + malate at 500 g); and T4 (supplementation of high-quality feed block with cassava hay + malate at 1,000 g), respectively. The cows were offered the treatment concentrate at a ratio to milk yield at 1:2 and ruzi grass was fed ad libitum. The results have revealed that rumen fermentation and blood metabolites were similar for all treatments. The populations of protozoa and fungal zoospores were significantly different as affected by malate level and cassava hay supplementation. In conclusion, the combined use of cassava hay and malate at 1,000 g in high-quality feed block with concentrates containing high levels of cassava chip at 65% DM could highest improved rumen ecology and nutrients digestibility in lactating cows.
Key words: Malate, cassava hay, high-quality feed block, rumen ecology, lactating cows.
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