1990 Annual Report for LNC90-027
Rotational Grazing Systems for Wisconsin and Minnesota Dairy Farmers - An Evaluation of Animal and Forage Performance and Whole-Farm Socio-Economic Analysis
Summary
Objectives:
1) Evaluate animal forage performance using rotational grazing methods of livestock feeding.
2) Conduct whole-farm socio-economic analysis of rotational grazing systems.
3) Explore research/demonstration and outreach approaches which involve new relationships
between farmers, university researchers, non-profit farm organizations and cooperative
extension.
Methods:
At the Experiment Station near Grand Rapids, Michigan, experiments were conducted to
compare dairy cow performance in rotational grazing and conventional stored feeding systems.
At the Experiment Station near Arlington, Wisconsin, the productivity of a rotational grazing
system with two pasture types (pure alfalfa and a mixture of alfalfa/red clover/smooth
bromegrass/orchardgrass) was compared to a conventional stored forage (alfalfa silage) animal
confinement dairy system. Productivity was assessed in terms of agronomic (forage yield, quality
and persistence) and animal production (milk yield and composition). On-farm research and
demonstration was used to evaluate alternative methods of pasture improvement and
establishment and to document and analyze existing rotational grazing practices.
Results:
From the Grand Rapids Experiment Station:
The rotational grazing system used in this experiment for two seasons resulted in an average 482
lb of 4 percent fat corrected milk less per cow during a pasture season (mid May to early
October) compared to confinement feeding of good quality forage. Grazing reduced milk fat
percent especially in 1991 when the RG cows averaged 4.42 vs 4.68 percent for the CS cows.
There was a lesser difference in 1992 when RG cows averaged 4.52 vs 4.60 percent for CS cows.
The treatments did not affect percent protein in the milk. Somatic cell count in the milk was
lower for RG cows in 1992, but similar to the CS group in 1991. RG cows consumed 2,993 lb
stored forage and 381 lb concentrates (dry matter basis) less per cow than CS cows.
Adequate amounts of good quality forage were maintained for grazing on the grass pasture most
of the time. Quality and amount of forage available is dependent on rainfall as evidenced by the
drought period of August 1991. A more abundant and uniform pattern of rainfall occurred in
1992 resulting in uniformly higher pasture quality in 1992 compared to 1991. Milk production
was very sensitive to change in the quality of pasture as seen in June 1991. Milk production
dropped when the pasture matured and increased again when better quality pasture became
available. On the other hand, milk production did not suffer in August of 1991 when
supplemental haylage was fed to cows on pasture when pasture quality deteriorated due to
drought. While cows on pasture produced less milk of lower fat content, savings resulted form
less feeding of stored feeds, less use of facilities and equipment, and less labor. Consequently,
net returns per cow were consistently greater for the pasture system.
From the Arlington Experiment Station:
Dry matter yields of the mixed pastures were higher than the pure alfalfa pastures in both years.
Alfalfa pastures were slightly higher in quality than mixed pastures in year one. Herbage dry
matter losses due to selective grazing and trampling averaged nearly 30 percent in both grazing
years. Milk yields were similar for all treatments for cows and heifers in years one and two. Milk
fat percent was higher for cows and heifers on alfalfa silage in year one. In year two heifers on
mixed pasture had higher milk fat percent than heifers on the alfalfa silage or alfalfa pasture
treatments.
From on-farm research and demonstration:
The addition of legumes to pastures is a low-cost way to increase pasture productivity. Farmers
found that several methods of introducing legumes into pastures were effective alternative to
using conventional tillage methods. The alternative methods were frost seeding, broadcast
seeding following minimum tillage (disking, cultimulching), and animal impact. Frost seeding
was found to be the most cost effective method. Red clover was the legume most easily
established, while alfalfa and birdsfoot trefoil were more difficult.
Checking forage quality and amount of forage available was found to be necessary on a daily
basis. Most of the 15 project farms rotated cows to a new paddock every 12 hours. Farmers
made decisions by experience gained through measuring and testing forage, watching how much
cows eat, and checking daily milk weights. Properly managed pastures consistently averaged
22-27 percent protein and 135 to 175 relative feed value over the grazing season. All farmers
utilize various combinations of species of legumes and grasses in their paddocks. On many of
the farms in the project, pasture yield (in pounds dry matter per acre) was similar to
conventional harvest. However, the quality was better and the cost of harvesting by cows was
much lower than by machinery.