Vegetation selection by Angus crossbred vs. Raramuri Criollo nursing cows grazing Chihuauan Desert rangeland in summer

TitleVegetation selection by Angus crossbred vs. Raramuri Criollo nursing cows grazing Chihuauan Desert rangeland in summer
Publication TypeConference Paper
Year of Publication2016
AuthorsNuamuryeking'e S., Cibils AF, Estell R.E., Gonzalez A
Conference Name69th Annual Meeting of the Society for Range Managment
Date Published12/2016
PublisherSociety for Range Management
Conference LocationCorpus Christi, TX
ARIS Log Number332017
Abstract
We examined vegetation selection patterns of nursing Angus X Hereford crossbred (AH) and Raramuri Criollo (RC) cows grazing Chihuahuan Desert vegetation during the growing season. Eleven cows of each group grazed separately in two large pastures (1190ha, 1165ha) from mid-July until mid-August 2015 (28 days). GPS coordinates were recorded at 10 min intervals on five cows of each group. Vegetation in the pastures included honey mesquite (Prosopis glandulosa) intermixed with perennial grasses on sandy soils or tobosa (Pleuraphis mutica) and burrograss (Schleropogon brevifolius) in lower areas with clayey soils. GPS data were overlaid on a vegetation map of the pastures in ArcGIS. Mapped vegetation types were: bare ground, burrograss, mesquite, mesquite dunes, other shrubs, Sporobolus spp., and tobosa. Ivlev’s electivity index (E) for each vegetation type was calculated for all collared cows (n=10). A t-test revealed statistical differences in E between groups for all seven vegetation types. Compared to AH cows, RC showed higher preference for bare ground areas presumably dominated by annuals (ERC = 0.34; EAH = -1.00; P<0.01) and burrograss areas (ERC = 0.19; EAH = -0.25; P<0.01), lower preference for mesquite (ERC = 0.03; EAH = 0.13; P = 0.02), mesquite dunes (ERC = -0.08; EAH = 0.02; P<0.01), and tobosa grasslands (ERC = -0.11; EAH = 0.12; P<0.01), and lower avoidance of other shrubs (ERC = -0.26; EAH = -0.70; P= 0.04) and Sporobolus areas (ERC = -0.42; EAH = -0.88; P<0.01). Our preliminary results suggest that RC cows employ foraging strategies during the growing season that differ significantly from AH cows which are commonly used in our region.