The objective of this experiment was to investigate the effects of inclusion of dragon fruit peel pellet (DFPP) and dietary non-protein nitrogen (NPN) on nutrients digestibility, rumen fermentation efficiency, plasma antioxidant activity, microbial protein synthesis, milk yield and composition in lactating Holstein-Friesian crossbred cows. Four animals were randomly allotted to 4 dietary treatments according to a 2 × 2 factorial arrangement in 4 × 4 Latin square design. The treatments were as follows: 300 g DM of DFPP +100 g of urea (T1), 300 g DM of DFPP + 200 g of urea (T2), 400 g DM of DFPP + 100 g of urea (T3), and 400 g DM of DFPP + 200 g of urea (T4), respectively. The results showed that intake of rice straw was increased (P < 0.01) by the DFPP addition. Including DFPP and urea did not affect (P > 0.05) the NDF and ADF digestibilities, but increased the apparent digestibilities of dry matter, organic matter, and crude protein (P < 0.01). Rumen fermentation process, especially the propionate concentration, was significantly increased by the DFPP levels. The plasma antioxidant activity was increased (P > 0.05) with the addition of DFPP. The DFPP improved (P < 0.01) microbial protein synthesis. The supplementation of DFPP and urea increased (P < 0.05) milk fat, whereas milk yield and 3.5% fat corrected milk were only increased (P < 0.05) by the DFPP supplementation. Based on these results, addition of DFPP at 400 g/animal per day with urea at 100 g/animal per day improved rumen fermentation, plasma antioxidant activity, milk yield and milk fat percentage.
Keywords: Food waste; Livestock; Plasma antioxidant capacity; Tropical fruit peel.
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