Lactating Holstein cows (located in 4 dairy herds) that had failed to display estrus as defined by increased pedometer activity by 63 +/- 3 d in milk, were enrolled to investigate the effect of a progesterone-releasing intravaginal device (PRID, n = 268) relative to a placebo intravaginal device (PID, control, n = 266) on days from device removal to artificial insemination (AI), the probability of pregnancy at first AI, and days from device removal to pregnancy. Cows were assigned randomly to receive a PRID or PID for 7 d and an injection of PGF2alpha at device removal. Upon device removal, a vaginitis score was assigned and AI occurred at observed estrus. Cows failing to display estrus within 14 d of device removal were subjected to a subsequent reproductive exam and were treated with PGF2alpha. Two percent of PRID-treated cows and 11% of control cows displayed estrus during the 7-d exposure period. Among the remaining cows, 93% of the devices were present at the scheduled removal. Cows treated with the PRID were 60% less likely to have purulent debris on the device than control cows. Vaginal reaction, however, was not associated with any of the reproductive outcomes. Investigation of the reproductive outcomes revealed a treatment x parity interaction. Progesterone-treated primiparous cows were inseminated 17 d earlier, with no significant change in the probability of pregnancy at first AI (30.3 vs. 42.0%), and no difference in median time from device removal to pregnancy (52 vs. 53 d) relative to control primiparous cows. Conversely, PRID-treated multiparous cows were inseminated 8 d earlier, with no change in probability of pregnancy at first AI (24.6 vs. 18.8%); however, median time from device removal to pregnancy was reduced by 20 d (67 vs. 87 d). These results support the efficacy of a PRID to induce estrus in previously anestrous cows. The reason, however, for the variable response between primiparous and multiparous cows was not clear.

Fistulated cows are becoming a popular resource for transfaunating sick animals, particularly in larger freestall dairies. The traditional method of creating a rumen fistula using a purse string suture approach can be a difficult and time consuming technique. A speedier alternative and somewhat easier approach has been developed.

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The objective of this study was to investigate genetic markers associated with different responses to ketosis treatment when compared to ketosis-free Holstein cows. Holstein cows (N=964) from four commercial farms, located in New York State/USA, were included in a randomized controlled trial for ketosis treatment for a period of 2 months (5/19/2019 to 7/20/2019). The cows were screened for BHB (β-hydroxybutyrate ≥1.2 mmol/L) in the first two weeks postpartum (0-14 DIM). Cows with negative results (BHB < 1.2 mmol/L) in the first week (0-7 DIM) were retested in the second week of lactation (8-14 DIM), if negative at both screening tests, cows were categorized as ketosis-free (control group). The cows with positive results in the screening period (0-14 DIM) were treated as detailed in Capel et al. (2020) and reassessed in the following two weeks. According to the cow`s response to the treatment, they were classified as CURED, RECURRENT, SEVERE, and CHRONIC. Out of the 964 cows, 489 were genotyped using the 50k Illumina Bead Chip array. A mixed linear model-based genome-wide association study (GWAS) was carried out in GCTA software. The GWAS was performed for each ketosis outcome compared to the control group. Several potential genomic regions were identified on chromosomes 1, 3, 4, 7, 8, 14, and 17. Overall, the highlighted genes included COL1A1, NEDD4l, DIP2A, CARD6, ITGA7, and MMP19, which have shared functions with genes previously associated with ketosis (e.g., CASP9, ACACA, and Interleukins) in pathways such as the transport of glucose and other sugars, bile salts and organic acids, metal ions and amine compounds, Cell adhesion_ECM remodeling Pathway, TGF-beta signaling, Nucleotide-binding Oligomerization Domain (NOD), and Mesodermal commitment. These findings contribute to a better understanding of the mechanisms that trigger response to ketosis treatment and warrant further investigation.