Changes in skeletal muscle thickness and echogenicity and plasma creatinine concentration as indicators of protein and intramuscular fat mobilization in periparturient dairy cows

摘要

High-producing dairy cows experience a state ofnegative energy balance in the periparturient periodthat is partially addressed by increasing the rate of fatand protein mobilization. Previous studies have focusedon the rate of fat mobilization, and consequently therate of protein mobilization has not been well characterized.The objective of this study was therefore todetermine the change in indicators of muscle mass duringearly lactation using ultrasonographic measurementof muscle thickness and changes in plasma creatinineconcentration. The maximum thickness of the gluteusmedius and longissimus dorsi muscles of 106 Holsteincows (34 primiparous, 72 multiparous) was determinedultrasonographically on d −3, 0, 3, 7, 14, 21, and 28relative to the day of parturition. Plasma creatinineconcentration was measured periodically during thesame period. Mixed models analysis and Passing-Bablok regression were used to analyze the data.Gluteus medius thickness, longissimus dorsi loin thickness(LDLT), and longissimus dorsi thoracic thickness(LDTT) were decreased at 28 d postpartum comparedwith d 3 antepartum. Plasma creatinine concentrationwas weakly associated with gluteus medius thickness,LDLT, and LDTT (Spearman’s rho = 0.31, 0.39, and0.32, respectively). Plasma creatinine concentration inprimiparous and multiparous cows at 28 d postpartumdecreased by 0.24 and 0.30 mg/dL, respectively, comparedwith values 3 d antepartum. We concluded thatultrasonographic measurement of LDLT and LDTT andchange in plasma creatinine concentration may providepractical methods for monitoring the rate of proteinmobilization in periparturient dairy cows. Ultrasonographicexamination of LDLT and LDTT thereforecomplements ultrasonographic measurement of backfatthickness and may be useful in the evaluation of energyreserve mobilization in periparturient dairy cows.