Body condition scores in dairy cows: associations with metabolic and endocrine changes in healthy dairy cows

Relationships between body condition scores (BCS), metabolic profiles and endocrine traits were investigated in 53 healthy Red Holstein cows. Cows were categorized into groups based on BCS ante-partum (a.p.: >3.25 or < 3.25) and on BCS losses during the first 8 weeks after calving (ABCS8 > 0.75 or < or = 0.75). Blood samples were collected 1 week before calving and every 2 weeks post-partum (p.p.). Cows with BCS a.p. >3.25 and deltaBCS < or = 0.75 were oldest and cows with BCS a.p. < or = 3.25 and deltaBCS < or = 0.75 were youngest. Cows with BCS > 3.25 a.p. and that lost > 0.75 BCS in the first 2 months of lactation exhibited signs of subclinical ketosis. If statistically adjusted for the effect of lactation number, average milk yield within the first 8 weeks p.p. and milk fat concentrations were similar between BCS groups, whereas milk protein concentrations differed significantly between BCS groups. Significant differences between groups were observed for blood plasma glucose, bilirubin, beta-hydroxybutyrate, non-esterified fatty acids and insulin concentrations. No differences were seen for albumin, urea, insulin-like growth factor-1, and 3.5.3'-triiodothyronine concentrations and for plasma activities of glutamate-oxalacetate transaminase, gamma-glutamyltransferase and glutamate dehydrogenase. There was a good agreement between BCS and profiles of metabolites and hormones related to energy metabolism in clinically healthy cows. Cows in good body condition a.p. had greater risks of metabolic problems because of excessive mobilization of body reserves. However, the metabolic status was best in cows with a BCS > 3.25 a.p.. if they did not lose much body condition p.p.