PS-1 An Evaluation of Cow Age and Activity Traits During the Breeding Season to Assess the Effect on Pregnancy Status

Abstract

Abstract The objective of this study was to evaluate activity traits and its influence on pregnancy during the breeding season. In a 2-year study, crossbred Angus cows (n = 17) were randomly assigned to receive a Knight global positioning system (GPS) tracking collar. All cows were synchronized for fixed-timed artificial insemination (TAI) utilizing a 7-d CO-Synch + CIDR protocol. Then, bulls were turned out with the cowherd 14-d after TAI for a 65-d breeding season. Cows were retrospectively classified in the following groups: (1) conception to TAI (n = 8), (2) Pregnant (n = 6), or (3) Open (n = 3). Cow activity traits were measured as total daily distance traveled, distance to water, and percentage of time spent near water and grazing challenging topography (i.e., > 15% slope) were analyzed during the breeding season. Data were analyzed using the MIXED procedure in SAS 9.4. The model included the main effect of cow age and year was used as a fixed effect. When testing the effect of pregnancy status and cow age on activity traits, these effects did not influence (P = 0.30) total daily distance traveled during the breeding season. Cow age had a significant (P = 0.03) effect on distance to water, wherein, younger cows traveled further from the water source when compared with older cows. Older cows tended (P = 0.08) to spend more time near the water source. Pregnancy status had no influence (P ≥ 0.25) on time spent near the water source nor distance to the water source. Pregnancy status and age had no impact (P ≥ 0.39) on the amount of time cows spent on challenging slopes. In this study, cow age had a stronger effect on cow grazing behavior during the breeding season when compared with pregnancy status. More data will be collected to validate results from the current study.