Development and validation of a visual image analysis for monitoring the body size of sheep

Abstract

In china, there is a great variety of sheep production systems, from the most traditional grazing types, mixed (grazing/stabling) to the most technologically advanced facility sheep. Body size parameters can reflect its growth development, production performance and genetic characteristics. So, monitoring body size is very important. In view of the problems or limitations of the present manual measurement, using the tools of measuring stick, tape measure, etc., the sheep having to stand on a flat place with correct posture, a non-contact method for measuring body dimensions of small-tailed Han sheep based on machine vision has been proposed and discussed. This approach is based on a position limit apparatus, computer-assisted visual capture, an automatic foreground extraction algorithm and a measuring point detection algorithm. The measured body sizes include withers height, back height, rump height, body length, chest depth, chest width, abdominal width and rump width. This approach has been examined in a specific farm for a case study. The errors of more than 90% measurements for sheep body size are within 3%. The results indicate that the method based on visual image analysis is effective, and it is especially suitable for the sheep feeding in an intensive and large-scale way.

Keywords

• Vision image analysis
• automatic foreground extraction
• measuring point detection
• body dimensions measurement
• small-tailed Han sheep livestock