A Screening test for production evaluation in dairy herds

Abstract

Collecting data on production problems can be time-consuming and readily available data difficult to interpret. In day-to-day practice it is too easy to ask occasionally “How are the cows milking?” and leave it at that. This paper describes a computer-generated graph to show how the cows are milking, and help identify the source of production problems. Although as a screening test it is rarely by itself sufficient to diagnose the source of a problem, it can easily alert us to a problem before it becomes a disaster. The graph can be computed and printed automatically using data downloaded via modem from the Northeast Dairy Herd Improvement Association mainframe computer.

Looking at the dipstick in the bulk tank is an extremely crude measure of whether a herd is producing up to its potential. A herd is made up of individuals, and a herd is not producting at its potential until every individual is producing at hers. Since “normal” production for each individual varies with her age and lactation stage, normal production of a herd will vary as cows freshen, progress through their lactations, and are dried off. Each cow’s production is expected to follow a curve that will have a shape fiddering with the age of the animal. When we add together curves for a hundred different animals of different ages, breed, and parity only a computer can reasonably analyze and express the results.