Abstract #M188

# M188
Effects of rain exposure on environmental conditions and vaginal temperature of Criollo dairy cows in Dominican Republic.
H. L. Sánchez-Rodríguez*1, K. Domenech-Pérez1, R. C. Youngblood3, L. Björk-Magnúsdóttir2, P. Iglesias-Estévez2, I. I. Suero-Pérez2, G. Muñiz-Colón1, C. Cabrera-Cabrera2, 1University of Puerto Rico at Mayaguez, Mayaguez, Puerto Rico, 2ISA University, Santiago, Dominican Republic, 3Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Mississippi State, MS.

This study evaluated rain exposure effects on relative humidity (RH), air temperature (AT), and vaginal temperature (VT) of Criollo dairy cows in Dominican Republic (n = 22; 3.24 ± 1.43 lactations; 129.38 ± 62.13 d in milk). The dairy farm RH and AT were collected by 4 environmental data loggers and each cow had an implanted waterproof data logger for VT collection. Data were collected every 5 min for 3 consecutive days (and averaged by hour) as part of a larger trial affected by rain. A rainy day (RAIN; from 1115 to 1540 h) was compared with the day before (PRE-RAIN) and the day after (POST-RAIN), both without rain (PROC GLIMMIX, SAS). Day and hour interacted to affect RH (P < 0.0001), AT (P < 0.0001), and VT (P < 0.0001). During RAIN greater RH values were observed than in PRE-RAIN and POST-RAIN from 1300 to 2400 h (81.08 ± 1.23, 62.22 ± 0.50, and 63.14 ± 0.64%, respectively; P < 0.0001). However, from 0100 to 0600 h, RH was higher in POST-RAIN than in PRE-RAIN and RAIN (98.08 ± 0.12, 93.47 ± 0.28, and 93.68 ± 0.17%, respectively; P < 0.0001). The AT followed an opposite trend, from 1300 to 2300 h its values were lower during RAIN than in PRE-RAIN and POST-RAIN (28.07 ± 0.27, 32.10 ± 0.15, and 32.30 ± 0.16°C, respectively; P < 0.0001). Also from 2400 to 0800 h, the AT values were lower during RAIN than in PRE-RAIN (23.58 ± 0.05 and 24.74 ± 0.06°C, respectively; P < 0.0001). During RAIN the VT was lower than in PRE-RAIN from 1500 to 2400 h (38.77 ± 0.05 and 39.11 ± 0.06°C, respectively; P < 0.0001), and lower than in POST-RAIN during 1500 to 1900 h (39.15 ± 0.06 and 39.70 ± 0.06°C, respectively; P < 0.0001). However, during POST-RAIN the VT values were greater than in PRE-RAIN from 1500 to 1700 h (39.96 ± 0.05 and 39.63 ± 0.06°C, respectively; P < 0.0001). Then POST-RAIN VT values sharply decreased from 1600 to 2400 h (40.08 ± 0.05 to 38.21 ± 0.03°C, respectively; P < 0.0001), reaching lower values than in the PRE-RAIN from 1900 to 0100 h (38.46 ± 0.04 and 38.71 ± 0.05°C, respectively; P < 0.0001). Rain exposure facilitated immediate heat dissipation in grazing cattle. However, it also increased relative humidity (RH), which may have later limited body heat dissipation through evaporation.

Key Words: Criollo cows, rain exposure, heat dissipation