PSIII-6 - Pre- and Postpartum Locomotor Activity in Nutrient Restricted Primiparous Beef Females

Abstract: To determine the effects of late gestational nutrient restriction (NR) on pre- and postpartum locomotion, fall-calving Hereford-SimAngus heifers were individually-fed 100% (control; CON; n=11) or 70% (NR; n=13) of energy and protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to calving. Heifers were housed in 3.7 x 15.8 m pens, and IceQube accelerometers were placed on a hind fetlock on d 265 of gestation to record motion index (MI), standing time (ST), lying time (LT), step count, and lying bout number (LB). Prepartum data were analyzed by day (72 h prepartum), 6-h periods (24 h prepartum), and hour (6 h prepartum). Post-calving data were analyzed by day (7 d postpartum). All analyses had fixed effects of nutritional plane, time period, their interaction, and calving date. In both 72- and 24-h analyses, ST was greater (P ≤ 0.02) in NR compared with CON. Nutritional plane x day affected (P = 0.008) LB within 72 h prepartum, where NR females had an altered pattern across days. In the 6 h prepartum, MI was affected (P = 0.005) by nutritional plane x hour where NR were more variable than CON. Post-calving, standing time tended to be greater (P = 0.06) in NR compared with CON. In the 72-h prepartum analysis, ST increased (P = 0.005) on the final day pre-calving. Step count, MI, and LB increased (P ≤ 0.008) during the last 6 h prepartum. Standing time decreased (P = 0.04) at -1 h prepartum, while LB increased (P < 0.001) at -2 h and again at -1 h prepartum. Step count and MI decreased (P < 0.001) for the first 4 d postpartum, and LB were greatest on d 1 postpartum (P < 0.001). These data suggest late gestational nutrient restriction increases peripartum standing time in beef females.