The Impact of Ammoniation Treatment on the Chemical Composition and In Vitro Digestibility of Rice Straw in Chinese Holsteins

SIMPLE SUMMARY: Rice straw has many essential uses as a byproduct of agriculture. As a feed source, due to low digestibility, low crude protein and minerals contents, the pretreatment of rice straw is required before use in ruminant feeding. To enhance the nutritive value of rice straw, different methods are practiced. Among them, treatment with ammoniation might be effective regarding the rice straw intake, enhancement of straw digestibility and crude protein levels, which are essential for enhancing the productive ability of dairy cattle. In the current study, we experimentally proved the efficiency of ammoniation treatment to enhance the different feed value parameters (dry matter digestibility, neutral detergent fiber, crude protein, gas production, acetic acid, butyric acid, and total volatile fatty acid) of rice straw. ABSTRACT: The current study was conducted to explore the ammoniation treatment effects on the chemical composition and in vitro digestibility of rice straw in Chinese Holsteins. For this purpose, rice straw was stored in polyethylene bags (35 × 25 cm, 350 g per bag) including (i) no additives (RS); (ii) 5% urea (5U, dry matter (DM) basis); (iii) 9% corn steep liquor + 5% urea (9C5U, DM basis); (iv) 9C2.5U; and (v) 9C2.5U + 3% molasses (9C2.5U3M, DM basis). The air-dry matter of the mixture was kept at the same level at 55% for all treatments. Fifteen bags (5 treatments × 3 repeats) were prepared and stored at ambient temperature (25 ± 3 °C). The chemical composition and in vitro digestibility were measured at day 60 after storage. Our analysis revealed that all the four ammoniation treatments improved the in vitro DM and neutral detergent fiber (IVNDFD) digestibility. In addition, all the four ammoniation treatments significantly (P < 0.001) increased the levels of crude protein (CP), gas production (GP), acetic acid (AA), butyric acid (BA) and total volatile fatty acid (TVFA) contents of the rice straw and decreased the neutral detergent fiber (NDF) and acid detergent fiber (ADF) of the rice straw compared to the control. Within four treated groups, the 9C5U treatment was most effective. Finally, we concluded that ammoniation treatments increased the nutritive value of rice straw. In addition the 9C5U treatment could be an effective ammoniation treatment for the better utilization of rice straw.