The glutamate metabotropic receptor 5(GRM5)gene is associated with beef cattle home range and movement tortuosity

Background:The grazing behaviour of herbivores and their grazing personalities might in part be determined genetically,but there are few studies in beef cattle illustrating this.In this study,we investigated for first time the genetic variation within a candidate‘grazing gene',the glutamate metabotropic receptor 5 gene(GRM5),and tested associations between variation in that gene and variation in grazing personality behaviours(GP-behaviours)displayed by free-ranging cows during winter grazing in the steep and rugged rangelands of New Zealand.Mature beef cows(n=303,from 3 to 10 years of age)were tracked with global positioning system(GPS)and,with 5-minutes(min)relocation frequency,various GP-behaviours were calculated.These included horizontal and vertical distances travelled,mean elevation,elevation range,elevation gain,slope,home range and movement tortuosity,variously calculated using daily relocation trajectories with repeated measurements(i.e.,7 to 24 days(d))and satellite-derived digital elevation models(DEM).The different GP-behaviours were fitted into mixed models to ascertain their associations with variant sequences and genotypes of GRM5.Results:We discovered three GRM5 variants(A,B and C)and identified the six possible genotypes in the cattle studied.The mixed models revealed that A was significantly associated with elevation range,home range and movement tortuosity.Similarly,GRM5 genotypes were associated(P<0.05)to home range and movement tortuosity,while trends suggesting association(P<0.1)were also revealed for elevation range and horizontal distance travelled.Most GP-behaviour models were improved by correcting for cow age-class as a fixed factor.The analysis of GP-behaviours averaged per cow age-class suggests that grazing personality is fully established as beef cows reached 4 years of age.Home range and movement tortuosity were not only associated with GRM5 variation,but also negatively correlated with each other(r=-0.27,P<0.001).Conclusions:There seems to be a genetically determined trade-off between home range and movement tortuosity that may be useful in beef cattle breeding programmes aiming to improve the grazing distribution and utilisation of steep and rugged rangelands.

Environmental and landscape influences on the spatial and temporal distribution of a cattle herd in a South Texas rangeland

The multiple spatial and temporal parameters affecting cattle herd distribution and activity dynamics can significantly affect resource utilization but are not fully understood.The aim of this study was to determine whether current animal tracking technology and spatio-temporal analysis tools can be used to integrate multi-scale information on herd distribution patterns as a function of seasonal forage production,periods of the day,animal activity,and landscape features.Positional and activity information of 11 free-ranging cows within a 31-member herd was obtained at 5-min intervals by using GPS collars for 1 year within a 457-ha ranch in the semi-arid rangelands of South Texas.Forage biomass was calculated with satellite imagery.Spatial analysis of cattle distribution and landscape features was conducted with GIS.Herd spread was greatest during the growing season.Throughout the year,during midday,the herd showed smaller spread and greater use of shade patches than any other time of day.Cattle also aggregated under trees in winter,particularly during the night.There was no statistically significant overall pattern of seasonal changes in the use of water and supplemental feeding areas,but a trend toward highest use during the winter.However,significantly different diurnal patterns in the use of supplemental feed and water were observed within each season.This study found a strong influence of shade patches relative to the influence of water and supplemental feeding areas on the diurnal and seasonal movement patterns of cattle in shrub-dominated rangeland.Although this study used only 11 tracked cows in a 31-member herd,the results indicated that techniques such as seasonal and diurnal GPS tracking,GIS,and remote sensing data enable evaluation of multiple spatial and temporal dynamics of cattle distribution and activity patterns.The smaller spread during the dry winter season associated with the observed aggregation of individuals in water and supplemental feeding areas,may aid in determining the most critical times for providing supplemental resources and guide the allocation of those resources to areas not frequently used by cattle,thus stimulating the animals to visit unused sites during the non-growing season.