Gains of Dairy Replacement Heifers in Rotational vs. Continuous Grazing Systems

David Trott,  Agricultural Science major
Truman State University Undergraduate Research Stipend, 2000
Dr. Michael Seipel and Dr. Thomas Marshall, Faculty Mentors
Abstract:

Livestock farmers are experimenting with rotational grazing systems as an alternative to conventional grazing systems.  The research project of raising replacement dairy heifers on two grazing systems attempts to answer the question:  Is rotational grazing able to provide a healthier, more cost-effective means of raising replacement dairy heifers than continuous grazing?  To set up the research, a 24-acre field was divided into 4 pastures consisting of 2 continuously grazed pastures and 2 rotationally grazed pastures.  The pastures were stocked with approximately the same weight per acre of one-year-old replacement dairy heifers.  The weight gain of the heifers was measured each month for the 3-month grazing period.  The forage production (ib. of dry matter /acre) was measured every 2-weeks with a Pasture Gauge.  After the first month, excess forage from the pastures with the rotational grazing system was harvested.  The average gain over the entire period was 176.49 lb, per heifer for the continuous grazing system and 157.23 lb. per heifer for the rotational grazing system (p<0.02).  The rotational grazing system utilized more forage because approximately 20,000 lb. per acre was harvested and more forage was left standing after the end of the grazing period.