Growth Performance and Carcass Characteristics of Arsi-Bale Lambs Fed on Effective Microbes and Urea-Molasses-Treated Tef Straw

In the highlands of Ethiopia, where the soil is rich and the seasons bring both abundance and scarcity, sheep are more than just livestock; they are a vital source of income, meat, and security for farming families. For these animals to thrive, especially when natural grazing lands are dry or unavailable, farmers rely on what is left over from the harvest: the dry stalks and stems of crops like teff, a grain that is a staple of the local diet. However, this leftover straw is often tough and low in nutrition, much like eating dry, fibrous hay that fills the stomach but offers little fuel for growth. To solve this, scientists have long explored ways to "upgrade" this roughage, turning it into a more digestible meal. Two common methods involve soaking the straw in a mixture of urea and molasses to boost its protein content, or treating it with a solution of beneficial microbes intended to help the animal's stomach break down the fibers more easily. The question facing researchers is whether these treatments actually make the straw better than the natural grass hay that is often in short supply, or if the extra effort and cost of treating the straw are worth the result.

A team of researchers at the Debre Ziet Agricultural Research Center set out to answer this question by testing these methods on a group of thirty young male sheep, a breed known as Arsi-Bale. The scientists wanted to see if feeding these lambs a diet based on treated teff straw would help them grow as well as, or better than, those fed on natural grass hay. They divided the animals into five groups, each receiving a different daily menu. One group ate natural grass hay, which served as the standard for comparison. Another group ate untreated teff straw. A third group received teff straw that had been soaked in a urea and molasses solution for three weeks. The final two groups were fed teff straw treated with a solution of effective microbes, one group receiving a lower concentration and the other a higher concentration. To ensure all the animals had enough energy, every single lamb in the study received the same amount of a nutrient-rich concentrate supplement each day, while their main roughage diet was available to them as much as they wanted.

The experiment ran for ninety days, a period long enough to see how the different diets affected the animals' growth and the quality of the meat they would eventually produce. The researchers carefully measured how much food each lamb ate, tracked their weight gain every two weeks, and, at the end of the trial, examined the carcasses of twenty of the sheep to determine the amount of meat, fat, and bone they yielded. They also calculated the cost of feeding each group to see which method was the most economical for a farmer. The results were clear and somewhat surprising to those hoping for a miracle cure for poor-quality feed. The lambs that ate the natural grass hay grew the fastest, gaining an average of 72.2 grams per day, while those on the various straw diets grew more slowly, with daily gains ranging from about 48 to 59 grams. The animals on the hay diet also ate more total food overall, suggesting that the natural grass was simply more appealing and easier to digest than the straw, regardless of how it was treated.

When the researchers looked at the final meat yield, the differences between the groups disappeared. The weight of the animals when they were slaughtered, the weight of the meat after the internal organs were removed, and the percentage of the body that turned into meat were all statistically similar across all five groups. The amount of lean meat, fat, and bone did not change based on whether the straw had been treated with microbes or chemicals. This finding indicates that while the treatments did not harm the animals, they also did not improve the straw enough to match the performance of the natural grass. In fact, the study found that treating the straw with the microbial solution at the higher concentration was the most expensive way to produce a kilogram of weight gain, costing significantly more than simply feeding the animals untreated straw or natural hay. The urea and molasses treatment did not lower the cost either; it remained more expensive per kilogram of growth than the untreated straw.

The study concludes that for farmers in this region, the most practical and cost-effective strategy during times when grass is scarce is to feed their lambs untreated teff straw along with a daily supplement of concentrate. The complex and costly process of treating the straw with microbes or urea did not provide a return on investment in terms of faster growth or better meat quality. While the treated straw was safe for the animals to eat, it did not transform the low-quality crop residue into a high-performance feed. The researchers suggest that until further studies can prove that different treatment levels or longer fermentation times might work better, farmers should stick to the simpler, cheaper method of using untreated straw combined with a solid concentrate feed to keep their flocks healthy and productive.