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.

If global warming persists, new strategies will be necessary to keep high-yielding dairy cows’ reproduction at a thermo-neutral level. In this study, two years of data from around 2000 cooled cows from a dairy farm in northeastern Romania were analyzed. In both years, an automated cooling system was used to maintain the temperature–humidity index (THI) within the range of 65–75 when environmental conditions exceeded the upper limit of this range. The univariate analysis shows that there may be a potential association between parity and the heat detection rate (p < 0.25). Additionally, the analysis suggests possible associations between conception rate and season, parity, and 4 + AIs (p < 0.25). These findings warrant further investigation through multivariate analysis. Summer season had the biggest impact (p = 0.001) on poor conception rate, according to the multivariate logistic regression analysis. Notably, the effects on conception rates extended into autumn (p = 0.004) in cooled high-yielding dairy cows. As expected, repeat breeding (4 + AIs) and parity (3 + lact.) impacted reproduction (p = 0.05). However, there was no association between OvSynch and OvSynch + GnRH on day 5 after AI and conception rate (p > 0.05). According to data from the current study, we concluded that the current cooling systems need to be improved to maintain reproduction at a thermo-neutral level for high-yielding dairy cows.

In dairy cows, future advancements will require new strategies to minimize additional interventions and maintain reproduction at thermo-neutral level in high yielding dairy cows. Thus, this observational study used data from a high-yielding dairy farm in northeastern Romania over two consecutive years. In both years an automated cooling system was used, in order to maintain the temperature humidity index within the range of 65-75 when environmental conditions rise above this value. The study found that heat detection rates were high in both years and the values are similar (P > 0.05). However, the probability of conception/pregnancy was negatively affected by the cow's parity, season, and repeat breeding. As a result, pregnancy and conception rates showed a consistent trend over the two years and the values are similar. According to the observational data from the current study, we observed that current cooling systems are insufficient for maintaining reproduction at a thermo-neutral level for high-yielding dairy cows. Thus, conception and pregnancy rates were significantly affected during the summer (P < 0.05). Notably, the effects on conception rates extended into autumn (P < 0.05) across both years. As expected, multiparous and repeat-breeding dairy cows had the lowest reproductive performance (P < 0.05).