Body condition score en de echografische bepaling van de hoeveelheid lichaamsreserves bij melkkoeien:

Abstract

The present study contains 3 experiments. In the first experiment were 74 dairy cows of which the body condition scores (BCS), determined with a tactile and visual method, were compared with the ultrasound fat thickness on both de back and the hip, and the thickness of the m. longissimus dorsi (back) and the m. gluteus (hip). There was a clear relationship between the BCS and the body reserves, measured with ultrasound. A coefficient of determination made clear that the fat thickness was more correlated with the BCS than the muscle thickness. The graphic relationship between the BCS and the ultrasound body reserves is shown with a linear mixed model. The second experiment contains 46 cows and is basically the same as experiment 1, except the BCS which is here determined with a tactile method. In this experiment the BCS showed also a clear relationship with the body reserves, determined by ultrasound. In this experiment we also determined the relationship in BCS between two observers, a weighted kappa showed us that there was a moderate relationship between the observers (weighted kappa 0,48). In the third experiment there were 10 cows which were followed in the period of 4 weeks before calving and 6 weeks after calving. During this period the BCS (tactile method) and the ultrasound measured body reserves were determined weekly. In the experiment it became obvious that the course of the BCS gave us a good impression of the course of the body reserves. Ultrasound is more labour-intensive but also more accurate and precise than the BCS method. We found that cows start mobilizing body reserves 2 tot 3 weeks before calving (especially muscle protein). After calving the cows mobilized al lot of fat. During the first 4 to 5 weeks of lactation the cows mobilized the largest amounts of body reserves.