In this study the influence of back fat thickness (BFT) of cattle on fertility, metabolic problems and certain diseases post partum (p.p.) was investigated. Five dairy farms in Germany with 292 Holstein Friesian (HF) cows and two farms in Austria with 111 Simmental cows participated in this trial. In total 1062 lactation periods were considered in this project. The BFT was measured with ultrasound (3.5 to 5.0 MHz) between the tuber coxae and the tuber ischia at five different times beginning at the end of lactation to day 100 after parturition.
At the end of the lactation cows should have sufficient values of BFT in order to perform good fertility and high milk yield as well as good metabolic status.
The BFT should be 30 to 35 mm at the end of the lactation and at the day of parturition.
In this study cows with elevated BFT in the dry period had significant lower milk yield and significant more problems related to uterus. On the one hand HF cows with higher values of BFT at the day of calving showed significant shorter intervals between day of parturition and day of first insemination as well as shorter first service intervals. On the other hand Simmental cows with elevated values of BFT at the day of parturition suffered more often from problems related to cycling.
Cows with BFT lower than 30 mm at the day of parturition had significant shorter intervals between the day of calving and first insemination as well as shorter first service intervals.
At the end of lactation, when milk yield is declining, cows easily become overconditioned. To prevent that cows accelerate BFT over 35 mm during the dry period, measuring of BFT should be done continuously.
Correction of feeding should take place before the beginning of the dry period.
Higher milk yield was correlated to higher loss of BTF after parturition. As milk yield competes with fertility, HF cows had longer intervals between the day of calving and the day of insemination as well as longer first service intervals. In addition, higher numbers of inseminations and a higher conception rate were noticed. To reach good healthy status of the herds and satisfactory economic revenues, excellent feeding management is necessary.
Cows within 42 days p.p. and a BFT loss over 35 % had a significant higher risk to develop problems with cycling, mastitis or abomasal displacement. BFT loss of more than 40 % until day 42 p.p. was correlated with higher risk for orthopedic problems. A significant higher risk for ketosis and mastitis was found for cows which lost more than 35 % BFT within 100 days p.p.
Milk yields over 8.000 kg in a 305-day-period were associated with higher risk for orthopedic problems, problems related to uterus and cycling as well as for ketosis and mastitis.
The age of the cows had a negative influence on the body condition and the fertility in this study. Cows with more than one lactation period had higher BFT values at the end of the lactation and at the day of parturition as well as higher BFT loss after calving. For these cows the risk was significantly higher for ketosis, mastitis, abomasal displacement, locomotion disorders, uterus and cycling problems. The energy balance is represented by the BFT. In herd health management BFT measuring is an important tool to control the body condition of cows.
Based on the evaluation of the BFT the veterinarian is able to give advices to the herd manager in order to have positive influence on milk yield, fertility and general health status of the herds.
At the end of the lactation and at the day of parturition the BFT should be 30 to 35 mm. The maximum BFT loss within 100 days p.p. should not exceed 35 %.
back fat thickness / ultrasound / cattle / herd management / negative energy balance / diseases post partum / fertility / metabolism