Mike Gamroth, Oregon State University
Often, convenience and bloat management dictate when groups are moved. However, there are inherent group behaviors that should be considered in the design and management of the grazing system. Individual animals differ in health and reproductive cycle, and will behave first as individuals in grazing selectivity. Practicality requires that we manage animals as a herd or flock to improve the efficiency of animal handling.
Herds and flocks often behave according to a leadership hierarchy. This is important to remember when moving animals. Each animal group has leaders, followers, and subordinates. Groups of animals appear to prefer to be able to see each other at all times. So when the lead animal begins to move to water or to a remote part of the pasture, many of the members of the herd move, too. This is an advantage when rotating to a different paddock in rotational systems.
Recent research in Missouri shows that if animals are within 700 to 800 feet of the water source, they can generally see each other and are more comfortable going to water individually in coordination with their own grazing and ruminating preferences. Providing water in each paddock or at several locations in large pastures will improve the efficiency of grazing, animal production, and manure nutrient distribution. In large pastures, grazing animals often prefer to graze near the water source and avoid grazing in distant corners. Some producers place salt and mineral supplements in locations away from the water source or shade to encourage better forage use over the entire pasture.
Cattle graze from 8 to 12 hours per day, and sheep from 6 to 8 hours per day. Cattle and sheep break this active grazing time into about 5 or 6 separate grazing periods, with time required for ruminating and resting between grazing periods. Cattle and sheep graze the first few hours after daybreak. In this early morning grazing, animals are less selective in their diet. A second large grazing period occurs in late afternoon until about sunset. This is normally the largest single meal of the day. There are minor grazing periods during other parts of the day and even at night. During hot weather, animals tend to graze more at night, while in winter, most grazing occurs from midmorning to mid-afternoon when temperatures are warmest.
Because the average nutritive quality of the forage declines the longer a group of animals is in a pasture, the early morning "quantity" grazing is a good time to get the animals to eat more of the lower-quality forage in the paddock. Under ideal conditions, when the nutritional requirements of the herd or flock are relatively low (dry, open, or gestating), moving the group after the morning grazing is a good use of the lower-quality forage on the last day of the grazing period. But if the animal group is one that requires a high-quality diet for lactation or gain (dairy cows, stocker calves, or lambs), then turning the group onto the next high-quality paddock before a big grazing (daybreak or mid-afternoon) is best. Sheep graze close to the soil while cattle prefer to graze more upright forage. Using more than one livestock species can help control weeds and reduce the need for pasture clipping. There are also data to show that sugar content of cool-season grasses is higher later in the day.
Altering grazing management to take advantage of inherent conditions and animal behaviors can improve the nutrient intake of your animals. A series of factsheets on Utah State's Behavioral Education for Human, Animal, Vegetation, and Ecosystem Management (BEHAVE) website further describe animal behavioral principles and practices.
- BEHAVE: Behavioral education for human, animal, vegetation, and ecosystem management [Online]. Utah State University Extension and Agriculture. Available at: http://www.behave.net/ (verified 17 March 2010).