Get reliable rangeland science

Cattle in the Chihuahuan Desert are exposed to extreme temperatures during certain times of year. We examined relationships between temperature and behavior for Angus Hereford (AH) and Raramuri Criollo (RC) cattle. We monitored 10 mature nursing cows of each breed that grazed separately in each of two adjacent pastures (1190ha, 1165ha) during July 2015 for 26 days. Five individuals per group were fitted with Lotek 3300 GPS collars set to record location and temperature at 10 min intervals. Collar temperature sensors were located on the GPS motherboards within plastic encasements that hung below the animals� necks. Sensors were presumed to record ambient temperature in the proximity of the collared animal. We calculated distance traveled, movement velocity, time spent within 100m of water, vegetation selection, and collar temperature during the hottest (1:00-3:00PM; H) and coolest (6:00 � 8:00AM; C) hours of each day. We also calculated the difference between temperature readings recorded by the collars and by a weather station located 3 km away.� We used a repeated measures mixed ANOVA to quantify differences between the breeds� distribution, behavior, and temperature. Each collared cow was treated as an experimental unit. During H hours, RC cows traveled 40 m farther (P<0.01), moved 4.7 m/min faster (P<0.01), spent less time close to water (-18 min; P<0.01), exhibited higher preference for vegetation types with least shade (bare ground, P<0.01), and had collar temperatures that were 1.3 oC hotter (P<0.01) than AH counterparts. Temperature differences between collar and weather station records for H hours was also greater for RC (+ 2.7 oC) than for AH (+1.5 oC) cows (P<0.01). During C hours, differences between breeds were either considerably smaller or non-existent. With our preliminary data analysis, RC cows may be better able to withstand the hot summers of the Chihuahuan Desert compared to commonly-used British crossbreds.