Monitoring ovarian and mating activity in breeding herds using heat-detecting tags.

Abstract

The objective of this study was to validate the use of mounting detection patches (MDP) for monitoring (90 days) natural breeding in a herd of 205 cows and 9 Polled Hereford bulls. Ovarian activity was diagnosed by ultrasound (5 MHz) at the beginning (DAO-1) and at 48 days mating (DAO-2) as a control method. MDP were placed on all females at the beginning of mating, and their status was monitored every 15 days (activated, detached), replacing them with a second color if they were discolored and/or detached, and recording any changes that occurred. Forty-nine days after the bulls were removed, pregnancy was diagnosed (ultrasonography, 5 MHz). The results obtained were analyzed using the Bayes test, using the DAO-2 as the reference technique, then comparing the DAO-2 with the MDT as a reference, and finally with the final pregnancy. Sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) were calculated for each technique, with particular emphasis on MDP. When using DAO-2 as the reference technique, MDP obtained a SE of 94%, a SP of 9%, a PPV of 95%, and a NPV of 8%. When using MDP as the reference, MDP obtained a SE of 95%, a SP of 8%, a PPV of 94%, and a NPV of 9%. Finally, using final pregnancy as the reference, MDP obtained a SE of 95%, a SP of 10%, a PPV of 91%, and a NPV of 17%. We can conclude that MDP is a feasible method for herd breeding monitoring. Monitoring herd sexual activity with MDP yields similar information than DAO-2, and that two readings are required to obtain accurate data. Compared with the final pregnancy rate, we found a relationship between activated patches and pregnant cows.