This study analyzed skeletal development, body condition, and total body fat
development of growing heifers. A total of 144 female primiparous Holstein cattle from
four commercial dairy farms with different degrees of stillbirth rates were examined during
the rearing period. This included measurements in body condition, fat tissue, metabolic,
and endocrine factors. Pelvic measurements and the sacrum height were analyzed to
assess skeletal development. The body condition was classified via body condition
scoring, bioelectrical impedance analysis (BIA), back fat thickness measurements, and
the body mass. For the first time, BIA was used as an appropriate method to evaluate
the fat tissue content of cattle throughout the rearing period. This analysis technique can
be performed on heifers aged 8–15 months. Throughout that period, the fat content
decreased while the skeletal development increased. In addition, high free fatty acid
concentrations in serum of the animals with high frame development were found,
supporting our hypothesis that stored energy of body fat deposits is used for skeletal
growth. Furthermore, we were able to demonstrate complex endocrine relationships
between fat metabolism and skeletal growth by using specific markers, such as leptin,
insulin growth factor-1 (IGF-1), and estradiol (E2). Food analysis showed high crude
protein (CP) levels in the total mixed ration above recommendation for daily protein intake
of all farms. However, there was a positive correlation between CP and the body frame
measurements in our study. In summary, we established a novel regression formula for
BIA analysis (“BIA-Heine”) in heifers to evaluate the body composition throughout different
ages and physiological stages in the development of heifers. This special formula allows
the evaluation of fat tissue without a whole-body analysis and therefore provides an
innovative technique for animal welfare support