Economics of Using GnRH on Day 5 After Timed Artificial Insemination in a Modified Double-Ovsynch Protocol at a Low-Fertility Dairy Farm.

This study evaluates the effectiveness and financial impact of treating anoestrus dairy cows using a modified DO protocol. Among the 350 cows included in the study, 142 (40.6%) were identified as anoestrus. The average daily milk production, days in milk at artificial insemination (AI), number of AIs, and parity were 33.8 ± 6.8 kg, 152.6 ± 24.4 days, 1.3 ± 0.2 AIs, and 1.9 ± 0.8 lactations, respectively. To assess embryo survival in anoestrus dairy cows undergoing the modified DO protocol, two groups were established. The experimental group (E group, n = 74) received the GnRH agonist gonadorelin five days after TAI as part of the DO protocol. The control group (C group, n = 68) received only the DO protocol. The pregnancy rates and cumulative pregnancy rates were significantly higher in the E group (35.1% and 56.8%) compared with the C group (26.5% and 45.6%, p < 0.05). A binary logistic regression analysis indicated that the interaction between treatment and anoestrus status considerably affected the pregnancy rate (p < 0.001) and the occurrence of accessory corpus luteum (aCL, p < 0.0001). The UW-DairyRepro$ decision support tool utilized in this study, indicated that implementing this approach could increase the net present value (NPV) by USD 54.2/anoestrus cow/year.