Yield, Culling and Profitability Effects of Repeated Bacteria-Specific Bovine Clinical Mastitis Within and Between Lactations

Dr. Yrjö Gröhn

Abstract

NON-TECHNICAL SUMMARY: Mastitis limits dairy farm profitability in many ways, including consequences of the illness itself, and unfavorable treatment effects (e.g. antibiotic residues), leading to milk loss and culling. The goal of this project is to develop a comprehensive, farm-specific dairy management tool to assist farmers in determining how to handle cows with bacteria-specific clinical mastitis (CM). The objectives of this project include estimation of the effects of bacteria-specific CM episodes on milk yield and culling, both within one lactation, and for one complete lactation plus a portion of the subsequent lactation (to estimate the carryover effect of CM). We will then develop an economic model incorporating the above milk yield and culling results, to help farmers make optimal decisions (treat, not treat and keep, cull) concerning cows with bacteria-specific CM. The farm-specific management decision tool that results from this project will enhance the economic opportunities for dairy farmers, a goal of the USDA strategic planning process.

OBJECTIVES: Establish a data base containing information on daily milk weights, bacteria-specific clinical mastitis (CM) cases, and other information, from approximately 6070 cows in five herds, and merge this with existing data on approximately 2700 cows in two herds, from our previous USDA project (Award No. 98-5204-6489). Conduct a prospective study on the effects of repeated episodes (including single event cases) of bacteria-specific CM on milk yield, both within one lactation and over one complete lactation plus the first 120 days of the subsequent lactation (to estimate carryover effect). Conduct a prospective study on the effects of repeated episodes (including single event cases) of bacteria-specific CM on culling, both within one lactation and over one complete lactation plus the first 120 days of the subsequent lactation (to estimate carryover effect). Construct a comprehensive management decision tool for use on individual dairy farms, through economic modeling, based on the results from the above objectives.