Subclinical ketosis in the oocyte donors of Holstein × Gir cows

In Brazil, the prevalence of subclinical ketosis in F1 Holstein × Gir oocyte donors has never been assessed in published literature. The aim of this study was to evaluate the prevalence of subclinical ketosis (SK) in F1 Holstein x Gir embryo donors and the effects of this syndrome on reproductive and economic efficiency. Data was collected from several farms in Minas Gerais, Brazil, from May to August 2015. Twenty-eight lactating F1 Holstein x Gir cows were used as oocyte donors. The dosage of ketone bodies was performed using the handset Ketovet (Ketovet Brazil, TaiDoc technology, Taiwan). Cows with blood β-hydroxybutyrate (BHBA) above 1.2 mmol/dL in the blood were considered as with SK. Donor cows were aspirated for follicules, which were then taken to the laboratory and classified into viable, non-viable and irregular, according to the methodology recommended by the International Embryo Transfer Society (IETS, 2010). Economic analysis was performed considering the following: average price of one follicular aspiration ($75.00), in vitro production of one embryo ($17.75) and cost of each embryo transfer ($12.75). The experiment was analyzed as a complete randomized block design, and means were compared by the Tukey test with significance declared as P < 0.05. Results show that each cow produced an average of 20 oocytes, with only 6 oocytes converted into embryos with a final ratio of 3.5: 1 (oocytes:embryos). Two embryos were required to result in 1 pregnancy. Of the 28 donors evaluated, 17 were healthy and 11 had SK, resulting in a disease prevalence of 39.3%. Specifically, the prevalence of SK was higher in primiparous cows (71.4%) compared with multiparous cows (28.6%, P < 0.05). Cows with SK produced less total oocytes (11.5 vs. 26.1; P = 0.014); less non-viable oocytes (2.09 vs. 10.65; P = 0.004), less viable oocytes (6.45 vs. 15.41; P = 0.005) and fewer embryos (1.82 vs. 5.41; P = 0.038) when compared with healthy cows. The total cost of pregnancy in cows with SK was $142.41, whereas, for healthy cows, was $87.25. In summary, oocyte donors with SK were less efficient as embryo donors. High prevalence of SK observed in this study had a negative effect in the economic efficiency of embryo transfer, causing this technology to be 60% more costly when compared with the same technology used in healthy cows.