Reproductive performance of timed artificial insemination and activity-based estrus detection
A study comparing reproductive management programs without visual estrus detection was conducted using 268 cows from 2 commercial dairy herds in Kentucky between October 2012 and November 2013. Before enrollment, resumption of ovarian activity was confirmed and BCS was evaluated. Eligible cows (BCS ≥ 2.5) were balanced for parity and predicted milk yield then randomly assigned to 1 of 2 treatments: TAI or activity. Ovulation synchronization using G7G/Ovsynch and Resynch occurred up to 3 times for all cows assigned to the TAI treatment. Cows assigned to the activity treatment received a leg-mounted accelerometer (AfiTag Pedometer Plus, S.A.E. afimilk, Kibbutz Afikim, Israel) and were bred according to estrus alerts created by the system algorithm for up to 90 days after the voluntary waiting period (VWP). Pregnancy diagnosis via ultrasound occurred 33 to 46 days after insemination and pregnancy loss was determined between 60 and 74 days bred. The GLM procedure of SAS (SAS Institute, Inc., Cary, NC) was used to evaluate the effects of treatment (TAI or activity), herd (1 or 2), temperature humidity index (THI), parity (primiparous or multiparous), BCS ( ≤ 2.75 or ≥ 3.00), summit milk, and their interactions on days to first service, first service conception rate (CR1), repeat service conception rate (≥ 2CR), days open (DO), pregnancy loss (PL), and percent pregnant at the end of the 90 day study period (%P90). Stepwise backward elimination removed all non-significant interactions (P ≥ 0.05). Main effects remained in each model regardless of significance. Days to first service was lower (P < 0.01) for the TAI group than for the activity group (6.21 ± 0.98 vs. 18.30 ± 0.99 days after the VWP, respectively). Treatment was not a predictor of CR1 (TAI: 46.89 ± 4.43% vs. activity: 43.78 ± 4.47%, P = 0.61), ≥ 2CR (TAI: 41.15 ± 4.88% vs. activity: 39.92 ± 4.95%, P = 0.86 ), DO (TAI: 33.16 ± 3.09 vs. activity: 33.08 ± 3.02 days after the VWP, P = 0.98), PL (TAI: 16.97 ± 3.33% vs. activity: 10.77 ± 3.43%, P = 0.14), and %P90 (TAI: 65.54 ± 4.57% vs. activity: 66.11 ± 4.43%, P = 0.92). These results indicate that continuous activity monitoring can produce similar reproductive performance to TAI.
activity monitoring, timed artificial insemination, estrus detection