Characterization of Holstein Cull Cows using Morphometric Measurements: Towards Cattle Grading System in Tunisia

A total of 55 Holstein cull cows between 6 and 13 years old were characterized morphometrically in the objective to develop a live cattle grading standard. The withers and pelvis height, the chest width and girth, the pelvis width, and the chest depth along with, the weight and age at slaughter were recorded. High correlations were obtained for weight versus width of the pelvis (r = 0.66) and chest depth (r = 0.68). A high negative correlation was shown between weight and age (r = -0.51). Age was, in fact, negatively correlated with all of the live animal parameters. Principal components analysis suggested that two main components could be used to characterize the animals; the first component was related to the animal conformation and the second one to the frame size. Cluster analysis based on the two main components reported that cull cows could be divided into three groups defined as following: (1) cull cows with a low conformation and a small frame size, (2) cull cows with a fairly good conformation and a large frame size, and (3) cull cows with a fairly good conformation and a small frame size. In conclusion, this study provides valuable information about the characteristics of cull cows marketed through livestock auctions in Tunisia. It also permitted an initial classification scheme which can be a first initiative to determine the balance between price and quality of live cull cows.