A Deviation chart for evaluating heifer growth

Abstract

Optimal growth rate for dairy heifers has been defined as the rate that will allow heifers to develop to their lactation potential at the desired age and with minimum expense. Animals that follow a normal growth curve are likely to be more healthy, and grown at lower cost, than animals whose growth deviated from the normal curve. This paper describes a computer program, (readily available to veterinarians as shareware) that can be used to compare animals in a herd to growth standards. The program plots the deviation of each animals measured height and weight from standards for an animal of the same bred and age. A representative sample (25% or more) of heifers from a farm should be measured and charted. The chart produced is an efficient screen for problems in youngstock management. Frequently problems in youngstock management. Frequently particular husbandry problems will be suggested by characteristic patterns of abnormal growth. Heifer growth charts have been used in various ways for many years. Computerization saves a great deal of time and effort in plotting points on paper as well as greatly decreasing the chances for errors in plotting points. The deviation chart format emphasizes problems while minimizing clutter. The program will run on IBM-compatible microcomputers running MS-DOS or PC-DOS without additional software and is configurable to use either Metric English units.