Sheep flock to new flavors, increase intake

Sheep given a variety of feed flavors will stop gorging and start eating more small meals over the course of the day. These findings, published August in the Journal of Animal Science, could help livestock producers maximize feed intake and nutrient efficiency at the same time.

Juan J. Villalba, study co-author and associate professor in foraging behavior at Utah State University, said that current sheep feeding practices usually provide animals will only one flavor of feed.

“This is like humans eating only hamburger every day,” Villalba said in an interview. “They get tired of eating that same flavor over and over.”

In one part of Villalba’s experiment, young sheep were given a choice of plain feed, sweet-flavored feed, bitter-flavored feed, and umami-flavored (savory) feed. Though all the feed types had the same nutritional value, the flavors were meant to indicate the presence of certain elements. Bitterness tastes like plant toxins, sweetness indicates a high-calorie feed, and umami indicates high protein content.

The growing sheep disliked the bitter feed and favored the umami feed. Previous studies that only compared plain feed and sweetened feed had shown that young sheep favor sweeter feed, but sweet feed wasn’t the favorite in Villalba’s study. He said it is probably not that sheep dislike sweet feed, they probably just like umami feed more.

“That reference for protein is more relevant to growing animals,” he said.

By measuring feed intake, the researchers discovered that offering a variety of food helps animals continue eating throughout the day. Instead of gorging on one type of food at the very beginning of the feeding period, the animals switched between flavors and came back for more meals throughout the day. Not only did this behavior increase feed intake, it kept ruminal pH from fluctuating. Stable pH is important because a increase in acid from eating too much starchy feed can lead to damage of rumen and abscesses in the liver.

“You won’t find those peaks and valleys in pH that you typically see in animals fed in feedlots,” said Villalba.

According to Villalba, pacing feed intake could also help animals process the nutrients more efficiently. He said that producers could apply these findings in their own flocks. He suggested mixing umami flavor into feed at different ratios.

“Producers do not need to increase feed rations,” Villalba said. “Flavors can also satiate the animal, not just nutrition.”

The desire to eat a variety of flavors is actually an evolutionary advantage. In the wild, and in some pastures today, sheep encounter many kinds of plants. By eating different plants, sheep can get a variety of nutrients as well as minimize exposure to any plant-specific toxins.

“Ruminants didn’t evolve in an environment where they had just one food to eat all the time,” Villalba said.

Interestingly, Villalba and his colleagues found that sheep given a variety of flavors at an early age were more willingly to accept changes in feed later in life. This is good news for producers who want to switch feed types without reducing intake.

The paper is titled “Feed behavior and performance of lambs are influenced by flavor diversity.” It can be read in full at http://journalofanimalscience.org/

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Madeline McCurry-Schmidt
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