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The objective of this prospective cohort study was to characterize the metabolic profile, health, milk production, and reproductive outcomes of cows diagnosed with hyperketonemia (HK; β-hydroxybutyrate ≥1.2 mmol/L), hypoglycemia (HG; glucose ≤2.2 mmol/L), or concurrent HK and HG (HKHG). Glucose and β-hydroxybutyrate concentrations in whole blood were assessed using a handheld device (Precision Xtra, Abbott Laboratories) in lactating dairy cows (n = 2,418) between 3 and 9 d postpartum. Cows were categorized into 4 groups: no HK or HG (healthy; Norm = 1,821), HK only (HK = 232), HG only (HG = 161), and concurrent HK and HG (HKHG = 204). Subsequent milk production, along with health and reproductive outcomes, as recorded by farm personnel, were analyzed according to metabolic category. Serum collected on the day of cow-side diagnosis of hyperketonemia and hypoglycemia was evaluated for total calcium (tCa), magnesium (Mg), nonesterified fatty acids (NEFA), triglycerides (TG), and urea using an automated chemistry analyzer (Randox Daytona; Randox Laboratories Ltd.). Statistical analysis was carried out using SAS version 9.4 (SAS Institute Inc.). Hyperketonemia in multiparous cows was associated with greater incidence of metabolic abnormalities (hypomagnesemia, hypocalcemia, and elevated NEFA and urea). Hyperketonemia in primiparous and multiparous cows led to increased adverse health events (culling rate, retained fetal membranes, puerperal metritis, clinical ketosis, left displaced abomasum) relative to Norm cows. Multiparous cows with HKHG had fewer metabolic disturbances (hypomagnesemia, hypocalcemia, elevated NEFA) than HK cows. Cows with HKHG had an increased incidence of clinical ketosis and left displaced abomasum relative to Norm cows. Cows with HG had similar metabolic profiles to Norm cows and had lower incidence of retained fetal membranes and puerperal metritis than cows with HK. Multiparous cows with HG produced more milk than Norm cows from wk 10 to 20, whereas multiparous cows with HK produced less milk than Norm cows. For primiparous cows, HK did not have a negative effect on milk production compared with Norm cows.

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The objective of this study was to assess the effects of treatment with propylene glycol (PG) and cyanocobalamin (B12) on health, milk production, and reproductive outcomes of cows diagnosed with hyperketonemia (HK), hypoglycemia (HG), or concurrent HKHG. Glucose and β-hydroxybutyric acid (BHBA) concentrations were assessed in whole blood using a handheld device in lactating dairy cows (n = 2,418) between 3 and 9 d postpartum. Cows categorized as HK (n = 232, BHBA ≥1.2 mmol/L), HG (n = 161, glucose ≤2.2 mmol/L), and concurrent HKHG (n = 204, BHBA ≥1.2 mmol/L, and glucose ≤2.2 mmol/L) were randomized to receive treatment or to remain untreated (control). Treatment consisted of a single dose of B12 (10 mg, intramuscularly) and 300 mL of PG orally for 5 d, starting on the day of cow-side testing. Milk production, health, and reproductive outcomes were analyzed according to groups. Statistical analysis was carried out using SAS version 9.4 (SAS/STAT, SAS Institute Inc.). Treatment in HG cows decreased clinical ketosis, increased milk production in the fifth week of lactation for multiparous cows, and tended to increase 305-d mature-equivalent milk yield (305ME) for primiparous cows compared with untreated cows with the same metabolic profile. For cows with HKHG, treatment increased 305ME in multiparous cows and tended to increase 305ME in primiparous cows. No differences were found for treatment among any of the metabolic groups regarding reproductive outcomes, nor were any treatment effects found among HK cows.Glycemic status may help identify metabolically challenged early postpartum dairy cows, which may have differential response to PG and B12 treatment.

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The present trial evaluated the effect of crossbred composition and Temperature and Humidity Index (THI) on vaginal temperature (VT) of Girolando dairy cows maintained under tropical pasture during warm seasons. The VT was monitored along 41 to 96 h in 615 Girolando cows with different Holstein (H) × Gir genetic composition (1/2 H = 284, 3/4 H = 248, and 7/8 H = 83) from six Brazilian farms in the summer of 2016 and 2017. VT of each cow at each hour of the day and the respective THI were averaged per hour across all monitoring days to generate an averaged value for VT and THI during 24 h. A linear mixed model with repeated measures using restricted maximum likelihood (REML) method for (co)variance components estimation procedure was employed. The final model adjusted the VT for the effects of cow, time, THI, farm, year, pregnancy status, body condition score (BCS), milk yield, genetic composition, and genetic composition*time interaction. Fixed effects were evaluated by ANOVA and tested with Tukey test in R software version 3.6.1 (R Core Team, 2019). Overall mean of VT, air temperature (AT), and THI were 39.06 ± 0.52 °C, 25.63 ± 0.40 °C, and 75.06 ± 3.96, respectively. VT had moderate positive correlation with THI (r² = 0.45, P < 0.001) and AT (r² = 0.46, P < 0.001). The VT had estimated linear increase of 0.05 °C for each THI unit increase (P < 0.001). Least square mean of VT varied among the farms (P < 0.001), pregnancy status (P < 0.001), and BCS (P < 0.05) but not for Milk yield (P > 0.05). The daily average VT was affected by genetic composition (P < 0.001) with highest temperature for 3/4 H (39.08 ± 0.06 °C a) and 7/8 H (39.09 ± 0.06 °C a) and lowest temperature for 1/2 H (38.95 ± 0.06 °C b). The difference of VT among the three crossbred groups varied in function of the time of the day, from 12:00 to 20:00 h (P < 0.001), with 3/4 Holstein and 7/8 Holstein cows reaching similar VT, above to the upper limit 39.1 °C and higher than 1/2 Holstein cows during all this period. In conclusion, Girolando cows are sensitive to heat stress in tropical condition during warm seasons. Moreover, Girolando cows with genetic composition higher than 3/4 Holstein display reduced thermoregulatory efficiency. Therefore, Girolando cows in tropical dairy farms require strategies to mitigate heat stress according to their genetic composition.