87 - Beef Heifers Housed in Muddy Environmental Conditions Lose Body Weight and Body Condition but Meet Gestational Requirements for Fetal Growth

Beef heifers experience an exponential increase in energy requirements during late gestation. Heifers must simultaneously grow a fetus, reach mature body weight, and prepare for their first lactation. In spring calving herds, these energy demands coincide with environmental stressors. Future climate projections for the Midwest predict increased winter rainfall, creating muddy conditions. It is likely that muddy conditions increase heifer energy requirements. The increased energy requirements, if not met, may compromise growth of the heifer and fetus. The objectives of this experiment were to evaluate the effects of muddy conditions on heifer body weight (BW), body condition score (BCS), and calf birth weight. Eighteen Angus heifers (n = 9/treatment) were paired based on initial BW. One heifer from each pair was assigned to either the mud (MUD) or control (CON) treatment. Heifers in the CON treatment were housed in pens with sawdust, and heifers in the MUD treatment were housed in pens with mud (20.3 ± 7.6 cm). Heifers were housed individually, and each pair received the same dietary allowance based on the CON heifer’s BW for maintenance, growth, and gestation. From day 196 to 266 of gestation, heifers were weighed and assigned a BCS weekly. Data were analyzed as a randomized complete block design with repeated measurements (SAS 9.4). On day 196 of gestation, heifers were similar in BW and BCS (P > 0.05). By day 266, MUD heifers weighed 43.5 kg less than CON heifers (P < 0.01) and were assigned a BCS of 4.3 compared with CON heifers that were a BCS of 6.1 (P < 0.01). Calf birth weight was not different (P = 0.21). Heifers in both treatments were able to maintain fetal growth, however, MUD heifers did not meet their energy requirements and had decreased BW and BCS compared with the CON heifers.