Reproductive efficiency has a major impact on the profitability of dairy operations. Focusing on improving the reproductive performance of cows with expected reduced fertility is desired; however, further research is needed in this area. The objectives of this study were to identify a subpopulation of cows with suboptimal fertility and evaluate whether hormonal interventions would improve the reproductive efficiency of low-fertility cows. Cows in one herd were enrolled in the study at 50 days in milk (DIM) and classified as low or high fertility according to a proprietary Fertility Index. Weekly cohorts of cows were allocated to three treatments at 50 DIM: (1) high fertility and Presynch-Ovsynch (H-PO; n = 1036); (2) low fertility and Presynch-Ovsynch (L-PO; n = 665); (3) low fertility and Double-Ovsynch (L-DO; n = 645). The voluntary waiting period (VWP) was 65 and 50 DIM for first-lactation and second- and greater-lactation cows, respectively, regardless of the treatment group. For H-PO and L-PO treatments, Presynch-Ovsynch was initiated at 75 ± 3 DIM, and when cows were not inseminated early after detected estrus, timed artificial insemination (TAI) occurred at 113 ± 3 DIM. For cows assigned to the L-DO treatment, Double-Ovsynch was initiated at 53 ± 3 DIM, and when cows were not inseminated early after detected estrus, TAI occurred at 80 ± 3 DIM. All cows were eligible to be inseminated after the end of the VWP and during the entire presynchronization schemes. The Fertility Index successfully identified differences in pregnancy and culling outcomes regardless of the lactation number. Fewer cows (p < 0.01) predicted to have high compared with low fertility required a TAI for the first service, more (p < 0.01) were pregnant by 100 DIM, more (p < 0.01) were alive and pregnant by 250 DIM, fewer (p < 0.01) were culled by 250 DIM, and fewer tended (p = 0.08) to have pregnancy loss after first AI. Applying a fertility scheme (DO) to low-fertility cows failed to increase the proportion of cows pregnant by 250 DIM compared with low-fertility cows exposed to PO when cows were allowed to be inseminated at estrus during the entire presynchronization scheme. We conclude that submitting low-fertility cows to DO optimized the service rate for the first service; however, it did not increase pregnancy per AI compared with L-PO. Lastly, the Fertility Index successfully predicted differences in practical reproductive outcomes routinely monitored in dairy farms.

Adequate identification of estrus is crucial to achieve satisfactory reproductive performance in dairy farms. Even though several studies evaluated expression and identification of estrus at the cow level, limited data exist regarding estrus identification parameters at the herd level. The objectives of this study were to use data from large dairy farms located in Kansas to describe temporal patterns of insemination risk (IR), and to investigate associations between IR and various herd-level factors. Nine herds that housed lactating cows in dry-lots or free-stalls were used in the study. Data from 2012 to 2017 were extracted and categorized in 21-day intervals in a total of 85 cycles, which were classified by season of the year. Mean (SD) IR was 67.6% (4.0) and increased 0.067% (0.009) for each 21-day cycle during the period evaluated. Annual, semi-annual, and trimestral IR peaks were detected using autoregressive integrated moving average analysis. Most of these variations, however, were considered minimal and likely not of economic concern for commercial herds. Insemination risk was greatest during autumn, but did not differ among winter, spring, and summer. Insemination risk was not associated with herd milk yield per season, incidence risk of mastitis during first 21 days in milk, proportion of primiparous cows in the milking herd, or voluntary waiting period of multiparous cows. Herds that housed lactating dairy cows in dry-lots had IR 2.4 percentage points greater than free-stall herds. In addition, mortality during the first 60 days in milk, and category of voluntary waiting period for primiparous cows were associated with IR. In conclusion, seasonal variability in IR was minimal, with increased values observed during the autumn. Insemination risk was greater for dry-lot than free-stall herds. In addition, reduced mortality of lactating cows by 60 days in milk and longer voluntary waiting period for primiparous cows seem to favor greater IR.

The consequences of heat stress during the dry period can extend into the postpartum period, affecting health and productivity in the subsequent lactation. We hypothesized that cows with distinct core body temperatures (CBTs) would exhibit disparate behaviors associated with different degrees of heat generation or dissipation. The primary objective was to investigate behavioral differences of dry Holstein cows (n = 50) classified as high-temperature (HT) or low-temperature (LT), based on median CBT during the summer months using visual observations and accelerometer technology. A secondary objective was to investigate the transcriptome of white blood cells (WBCs) collected from a subgroup of HT and LT cows (n = 5; per group). Minor behavior differences were observed during the visual observations (performed for a total of 16h/cow). Based on automated monitoring system (AMS) data, collected 24/7 over a period of 42 days per cow, HT cows displayed higher periods of high activity and lower periods of inactivity prepartum and diminished rumination time postpartum than LT cows. There were 16 differently expressed genes (DEGs) in WBCs of HT compared to LT cows. Several of the identified DEGs have been previously associated with heat stress. The observed trends in the AMS data indicate that CBT and patterns of activity prepartum may serve as valuable predictors for identifying dairy cows with distinct tolerance to heat stress.