The nutritive quality of cholla cactus as affected by burning

Abstract

Cholla cactus may serve as an emergency feedstuff for livestock when forage availability is low. A study was conducted at the Corona Range and Livestock Research Center to evaluate the nutritive quality of cholla cactus (Opuntia imbricata) after spine removal. Six samples were collected for each treatment in a completely randomized design. Treatments consisted of spine removal by burning with a propane torch (BURN), or leaving spines intact (UN). Each sample consisted of 2 burned and 2 unburned cladodes from each of 5 plants. One sample from each treatment was weighed immediately after collection and used solely for dry matter (DM) determination. Remaining samples were evaluated for crude protein (CP), organic matter (OM), neutral detergent fiber (NDF), and mineral composition. Rate and extent of ruminal DM and OM disappearance were estimated in situ for 20 and 68 hours in the rumen of each of 2 cannulated cows grazing native rangeland. Dry matter contents of burned and unburned cholla were 12.7% and 12.4% respectively. Crude protein was not affected by burning (P > 0.6; 13.0% UN, 13.6% BURN, SE +/- 0.7). Burning reduced OM (82.4% UN, 81.0% BURN; SE +/- 0.4) and NDF (48.6% UN, 39.2% BURN; SE +/- 1.8) content (P < 0.03). Reduced NDF contributed to increased rate and extent of ruminal OM disappearance for burned cholla (P 0.03). Mineral content was minimally affected by burning. Measurements indicate that cholla has relatively high nutrient quality, but the high moisture content would require large amounts to be fed as an emergency feed source.