Comparison of Nutritional Components, Ruminal Degradation Characteristics and Feed Value from Different Cultivars of Alfalfa Hay

SIMPLE SUMMARY: The nutrient contents and rumen degradation of alfalfa hay rely highly on cultivars and grown regions. Moreover, the evaluation of alfalfa hay with respect to nutritional components in conjunction with the selection of feed resources according to local condition is necessary and essential for dairy farms to obtain an efficient and economic formula. Thus, this study was conducted to investigate the variations of different alfalfa hay cultivars grown in China and the US in terms of nutritional components, ruminal degradation characteristics and feed value. The results showed that the cultivar of American Golden Empress (GE) had the greatest rumen degradation characteristics; meanwhile, the indicators of total digestible nutrients (TDN), dry matter intake (DMI), digestible dry matter (DDM), relative feed value (RFV) and relative forage quality (RFQ) of GE were better than China Zhongmu No. 1 (ZM1) and China Gongnong No. 1 (GN1) cultivars. ABSTRACT: The objective of this study was to evaluate the effects of different cultivars of alfalfa hay, including American Anderson (AA), American Golden Empress (GE), China Zhongmu No. 1 (ZM1) and China Gongnong No. 1 (GN1), on conventional nutrient composition, rumen degradation characteristics and feed value. Four healthy Holstein cows (137 ± 14 days in milk, 2.40 ± 0.50 parity) equipped with permanent ruminal cannulas were examined for the nylon-bag technique. The alfalfa hay samples were incubated in the rumen for 0, 4, 8, 12, 24, 36, 48 and 72 h according to the “gradual in/all out” schedule to detect the ruminal nutrients’ degradability. Our results showed that various cultivars of alfalfa hay from different planting regions had significant differences on nutrient contents, rumen degradability and feed value. For nutritional components of alfalfa hay, the highest dry matter (DM) content was found in GE and the lowest in GN1 (p < 0.001); however, GN1 had the greatest concentration of ether extract (EE, p = 0.01), Ca (p < 0.001) and the lowest Ash (p < 0.001). Additionally, the lowest neutral detergent fiber (NDF), acid detergent fiber (ADF) and highest starch contents were observed in AA and GE (p < 0.001). Meanwhile, the cultivar of ZM1 represented the highest NDF, ADF and Ash contents, in conjunction with minimal CP and P concentrations (p < 0.001). In terms of rumen degradation characteristics, the effective degradation rate (ED) of DM in GE and ZM1 was significantly higher than that in AA and GN1 (p = 0.013). The NDF effective degradation was lower in ZM1 than the other three cultivars (p = 0.002), and in addition ZM1 also showed lower CP and ADF effective degradation than GE (p < 0.001). As far as feed value was concerned, the cultivar of alfalfa hay imported from the US, including AA and GE, exhibited higher relative feed value (RFV) and relative forage quality (RFQ) than Chinese alfalfa based on ZM1 and GN1 (p < 0.001). In conclusion, the results suggested that the cultivar of GE exhibited greater rumen degradable characteristics and feed value, while ZM1 showed the opposite status.