Characterizing body temperature and movement differences at the onset of estrus in replacement gilts

Abstract Text:

Accurate estrus detection can improve sow conception rates and increase the efficiency of swine production.  Unfortunately, current estrus detection practices may be inefficient due to large sow populations at commercial farms and the associated labor required.  Therefore, the study objective was to characterize body temperature and movement changes in replacement gilts at the onset of estrus in order to develop a remote estrus detection system for commercial swine operations.  Twelve replacement gilts (130.2 ± 1.9 kg BW) were fed Matrix® to synchronize estrus and data loggers (TemPlant; Data Sciences International) that detect vaginal temperature (T_V) and total movement (i.e., standing, lying, sitting, shifting position, etc) in 5 min intervals were attached to blank CIDR’s and inserted intravaginally for 7 d prior to expected estrus.  Movement was quantified as counts per minute (cnt/min) using an internal accelerometer.  During the 7 d of monitoring, gilts were checked for estrus twice daily (0800 and 1500 h) by two trained individuals.  To standardize data, only the day of estrus detection (d_E) and the three days prior (d_-3, d_-2, d_-1, n = 4 total days) were used in the final analysis since gilts came into estrus on different days.  Data were analyzed using the PROC MIXED procedure in SAS 9.4.  Overall, T_V was reduced (P < 0.01; 0.26°C) on d_E compared to the previous three days; however, no differences were detected between d_-3, d_-2, and d_-1.  Movement was increased (P < 0.01; 37.8%) on d_E compared to d_-3 and d_-2, but no differences were detected between d_E and d_-1. Vaginal temperature decreased linearly (P = 0.02; 0.08°C/d) from d_-3 to d_E and movement increased linearly (P < 0.01; 0.34 cnt/min/d) from d_-3 to d_E.  In summary, T_V was reduced and movement was increased at the onset of estrus, which has obvious implications for development of automated estrus detection system for use in a production setting.  

Keywords: pigs, estrus detection, temperature, movement