The association between body condition score, residual feed intake, and hyperketonemia

Abstract Text: The transition period in dairy cows is associated with the onset of negative energy balance and body fat mobilization. Mobilized lipids can lead to excessive ketone production. The objective of this trial was to characterize the relationship between hyperketonemia (HYK) and milk production, body condition score (BCS), and residual feed intake (RFI). Blood and milk samples were collected twice weekly from cows 5 to 18 days in milk (DIM) for a total of 4 samples. Hyperketonemia was diagnosed using the Precision Xtra Meter and defined as blood β-hydroxybutyrate (BHBA) ≥ 1.2 mmol/L. Cows were treated upon diagnosis. Dry period (-28 DBCS), calving, and final blood sampling BCS was recorded. Previous mid-lactation production and DMI were used to calculate RFI by subtracting predicted energy intake from the observed energy intake. Effect of milk composition, milk yield, lactation number, BCS, and previous RFI on the observed maximum BHBA concentration (MAXBHBA) was determined using PROC MIXED of SAS 9.4. Least square means ± standard error are reported. Of the 570 cows sampled, 19.7% were diagnosed with HYK. Mean DIM at the first positive HYK test were 9 ± 0.9 d and the average BHBA concentration at the first positive HYK test was 1.53 ± 0.14 mmol/L. MAXBHBA was greater (P≤0.05) for multiparous cows compared to primiparous cows. Milk fat content was increased (4.33 vs. 4.69 ± 0.05%, P<0.0001), milk protein content was decreased (3.60 vs. 3.40 ± 0.02%, P<0.0001), somatic cell count was decreased, and milk yield was increased (44.02 vs. 47.47 ± 1.46 kg/day, P<0.0001) in the first 30 DIM, for cows positive for HYK compared to negative cows. Cows with a DBCS ≥4.0 had greater MAXBHBA (0.88 vs. 1.28 ± 0.08 mmol/L, P≤0.05) than cows with lower BCS. Cows that lost >0.75 BCS units after calving had greater (P≤0.05) MAXBHBA than cows that lost ≤0.75 BCS units. MAXBHBA was not significantly correlated to RFI. Prompt diagnosis and treatment of HYK appears to prevent HYK associated decreases in milk production. Avoiding over conditioning of dry cows and excessive fat mobilization during the transition period may decrease HYK incidence; however previous lactation RFI does not appear to be correlated to developing HYK.

Keywords: hyperketonemia, body condition score, residual feed intake