Characterization of ketolactia in dairy cows during early lactation

摘要

Fourier transform infrared spectroscopy (FTIR) allowsfor the determination of milk acetone (mACE) andβ-hydroxybutyrate (mBHB) concentrations, providinga potential herd monitoring tool for hyperketolactia,defined as elevated milk ketone bodies. The study aimwas to characterize mACE and mBHB concentrationdynamics during early lactation in Polish Holstein-Friesian cows. Milk samples (n = 3,867,390) were collectedwithin 6 to 60 days in milk (DIM) over a 4-yrperiod (April 1, 2013 to March 31, 2017) from approximately21,300 dairy herds (average 38.7 cows/herd).Fixed effects of parity, DIM, and their interaction onmACE and mBHB concentrations were determinedusing a mixed model with a herd-year-season fixed effectand random cow effect. Published hyperketolacticmACE (≥0.15 mmol/L) and mBHB (≥0.10 mmol/L)threshold concentrations were used to classify studymilk samples into ketolactia groups of normal (mACE<0.15 mmol/L and mBHB <0.10 mmol/L) and hyperketolactic(HYKL; either mACE ≥0.15 mmol/L ormBHB ≥0.10 mmol/L). Additionally, HYKL sampleswere categorized into subpopulations as having elevatedmBHB and mACE (HYKL_(ACEBHB), mACE ≥0.15mmol/L and mBHB ≥0.10 mmol/L), only elevatedmBHB (HYKL_(BHB); mACE <0.15 mmol/L and mBHB≥0.10 mmol/L), or only elevated mACE (HYKL_(ACE);mACE ≥0.15 mmol/L and mBHB <0.10 mmol/L). Effectsof parity, DIM, ketolactia group or subpopulation,and their interactions on mACE and mBHB concentrationswere also determined using the mixed model thatincluded ketolactia group or subpopulation as an independentvariable. Across all data, mACE and mBHBconcentrations were influenced by effects of parity, DIM,and their interaction as well as parity, DIM, ketolactiagroup or subpopulation, and their interactions. For allsamples, mACE and mBHB concentrations decreasedwith increasing DIM, with mACE concentration decliningmore rapidly compared with mBHB. In the dataset, 68% and 32% of all samples were defined as normalor HYKL, respectively. Among HYKL samples, mACEwas elevated soon after calving and declined over time.In contrast, mBHB started lower after calving and increasedreaching peak concentrations around 30 DIM,and then decreased. Within HYKL samples, 50.8, 41.3,and 7.9% were categorized as HYKL_(ACEBHB), HYKL_(BHB),and HYKL_(ACE) respectively. Between 6 and 21 DIM,11.3% of HYKL were classified as HYKL_(ACE). Primiparous cows had greater (14.8%) HYKL_(ACE) samples inthis time period. In conclusion, this study has characterizedmACE and mBHB concentrations during earlylactation and determined effects of parity, DIM, andtheir interaction. Using published criteria interpretingmACE and mBHB concentrations, it was intriguing toidentify a unique population of samples having elevatedmACE without mBHB in early lactation, especially inprimiparous cows. Further research is needed to determineif this sample population represents an unhealthymetabolic status that adversely affects cow health andperformance.