Mountain mahogany and cottonseed meal as supplements for grass hay

Abstract

Sixteen wether lambs (avg weight 34.5 kg) were used to study the influence of 2 sources of supplemental protein, leaves of mountain mahogany (Cercocarpus montanus Raf.) and cottonseed meal, on N digestibility and balance, forage digestibility, and voluntary intake by sheep fed a low-quality grass hay. Treatments were grass hay alone (C), C plus cottonseed meal, C plus mountain mahogany, and C plus mountain mahogany and cottonseed meal. All supplements provided 42 g of supplemental crude protein per head daily. Treatments were assigned to wethers within blocks according to a randomized complete block design. Supplemental N increased (P < 0.01) N digestibility and balance regardless of source; however, lambs supplemented with mountain mahogany digested less (P < 0.01) N, but their N balance did not differ (P > 0.10) from those supplemented with cottonseed meal. Wethers supplemented with mountain mahogany plus cottonseed meal ate more (P < 0.05) organic matter (OM) than the average consumed by those given either of the 2 supplements alone. Protein supplementation did not affect (P > 0.05) OM or fiber digestibility. Range management practices that encourage dormant season utilization of mountain mahogany by ruminants in the Southwest could reduce supplemental protein needs; such practices might include reserving mountain mahogany sites for winter use as well as greater use of mountain mahogany (and other palatable, highly nutritive shrubs) in range restoration programs in mountainous areas.