Evaluation of Cicer Milkvetch and Alfalfa Cultivars for Nutritive Value, Anti-Quality Factors and Animal Preference

摘要

Cicer milkvetch (CMV; Astragalus cicer L.) is an alternative non-bloat legume to managing alfalfa. A 2-yr study was conducted to compare three CMV cultivars (Oxley II, Oxley, and Veldt) to AC Grazeland alfalfa (ALF; check forage) for nutritive value and animal preference. Each yr, replicate samples (n = 4) of each forage type were harvested late summer and analyzed for nutrient profile. Oxley II had lower (p 0.05) fiber content than AC Grazeland, while Oxley and Veldt were similar (p = 0.48) to AC Grazeland for neutral detergent fibre (NDF), acid detergent fibre (ADF) and starch. In contrast, Oxley II had higher (p 0.05) net energy for gain (NEg) than AC Grazeland, and Oxley and Veldt were similar (p 0.05) to AC Grazeland for NEg. All three CMV varieties had similar levels of total digestible nutrients (TDN) (63.6 ± 0.6%; p 0.05), but had higher (p = 0.01) energy content than AC Grazeland alfalfa (54.9 ± 1.4% TDN). Selenium (Se) concentrations were similar (p 0.05) among CVM cultivars and less than 1 mg/kg DM, and no swainsonine or nitrotoxins were detected in the CMV cultivars. The Oxley II CMV tended (p = 0.06) to have a higher (139) relative feed value (RFV) compared to AC Grazeland (94), while Oxley and Veldt had moderate RFV values (128). Dry matter intake of Oxley II, Veldt, and Oxley CMV was 4, 18, and 28% greater than AC Grazeland, respectively. Based on the relative preference index (ratio of forage DMI to AC Grazeland alfalfa DMI), forage types are ranked as follows: AC Grazeland (1.0) Veldt (1.2) Oxley (1.4) Oxley II (1.7). Study results suggest that CMV cultivars harvested late summer, maintained higher forage quality with greater preference compared to alfalfa.