|Cruz, Ruben - OREGON STATE UNIVERSITY|
Submitted to: Applied Animal Behaviour Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 1998
Publication Date: N/A
Interpretive Summary: In the arid west, ranchers often move cattle among several pastures during the year, or animals are sold and shipped to completely new surroundings. When this occurs, cattle must adapt to new mixes of grasses that they are not familiar with before they can feed efficiently and start to gain weight. There was no information available describing how long it takes naive cattle to determine which grasses are most palatable and nutritious. We paired naive cattle, that had no knowledge of our forages, with local animals that had a full growing season of experience and compared their grazing behavior. Within 5 to 6 minutes naive cattle began to focus on the same 2 grasses that were favored by local cattle (giant wildrye and crested wheatgrass). After 4 days of grazing, however, experienced steers took 97 percent of their bites from the 2 favored grasses while naive steers used those plants only 88 percent of the time. Naive steers took a single bite from a plant and began searching for another 37 percent of the time. Experienced steers took a single bite only 20 percent of the time. In the same amount of time, naive steers harvested 21 percent fewer total bites than the experienced animals suggesting that naive cattle do not graze as efficiently as native cattle. Rapid moves among pastures may reduce weight gains in cattle.
Technical Abstract: Cattle are often required to adapt to new forages if they are moved among pastures or ownership changes before the animals attain market weight. The objectives of this research were: 1) to determine how rapidly naive cattle express clearly defined preferences when they encounter a new array of forages, and 2) to compare their evolving forage preferences and grazing gbehavior with those of experienced cattle. After only 5 to 6 minutes naive steers selected the same 2 grasses as the experienced steers at significantly (P=0.05) higher frequencies than expected. Across the 4-day trial, 97% of total bites by the experienced animals were from the 2 preferred grasses, while the naive animals took only 88% of their total bites from the same forages (P=0.000). Naive steers were more (P<0.000) likely (37%) to harvest a single bite at a feeding station than experienced steers (19.5%). In about the same amount of time, naive steers harvested 21% fewer total bites than experienced animals, implying that naive steers were less efficient grazers. Researchers should not assume that naive cattle will provide an accurate depiction of the dietary composition of native stock, because naive cattle may sample a broader array of forages than their experienced counterparts and harvest fewer bites than experienced cattle from the preferred grasses.