Comparative nutritional characterization of three steppe Chenopodiaceae species from Algeria: implications for sheep feeding

In the vast, sun-scorched steppes of Algeria, where the soil is often salty and the rain scarce, a unique ecosystem supports the livelihood of thousands of sheep farmers. Here, the landscape is dominated by hardy, salt-tolerant plants known as halophytes, which thrive where most other crops would wither. Among these survivors are three specific types of shrubs from the goosefoot family: Salsola vermiculata, a native sub-shrub, and two species of saltbush, Atriplex halimus and Atriplex canescens, the latter of which was introduced to help restore degraded land. For generations, these plants have served as a critical food source for flocks, particularly during the dry season when fresh grass disappears. However, not all forage is created equal. Just as a human diet requires a balance of nutrients, sheep need specific amounts of energy and protein to grow, produce milk, and maintain their health. The challenge for scientists and farmers alike is to understand which of these wild shrubs offers the most nourishment, how easily the animals can digest them, and whether they can sustain a flock through the harsh months without the need for expensive supplements.

A researcher from an Algerian agricultural institution set out to answer these questions by putting these three plants to the test. They collected samples in the spring, a time when the plants are young and flowering, which is generally when they are at their most nutritious. The study focused on the central steppe region, an area characterized by hot, dry summers and cold winters, where the soil is often poor and salty. The researcher gathered samples from three different locations for each plant species to ensure they captured the natural variation found across the landscape. Once in the lab, they dried the plants, ground them into a fine powder, and analyzed their chemical makeup. They measured everything from the amount of water and minerals to the levels of fiber and protein. Crucially, they did not stop at chemical analysis; they wanted to know how the sheep's own bodies would handle this food. To find out, they conducted a living experiment using nine young lambs of the local Ouled Djellal breed, a hardy sheep famous in the region. The lambs were divided into three groups, with each group fed exclusively on one of the three plant species. Over several weeks, the researcher carefully measured how much food the animals ate and how much waste they produced, allowing them to calculate exactly how much of the plant the sheep could actually digest and turn into energy.

The results painted a clear picture of which plant reigns supreme in the steppe. The native Salsola vermiculata emerged as the superior forage option. The researcher found that this plant contained significantly less tough, woody fiber than the two saltbush species. In the sheep's stomach, this difference translated directly into better performance: the lambs eating Salsola vermiculata were able to digest nearly 77.5 percent of the dry matter they consumed, compared to roughly 68 percent for those eating the saltbushes. This higher digestibility meant that the native shrub provided more usable energy, with a value that the researcher calculated to be comparable to high-quality cultivated alfalfa, a gold standard for animal feed. In contrast, the two Atriplex species, while still useful, offered energy levels similar to average grass hay. The study also looked at the protein content, which is vital for the animals' growth and milk production. Here, the three plants were surprisingly similar; all contained enough protein to keep adult sheep healthy, but none provided enough for rapidly growing lambs or nursing mothers without additional food. This suggests that while the native shrub is the better choice for energy, farmers will still need to supplement the diet with extra protein during critical times like lambing.

Beyond the basic numbers, the study revealed interesting details about how these plants interact with the sheep's digestive system. The researcher discovered that the saltbushes, particularly Atriplex halimus, contained compounds that slowed down the breakdown of protein in the rumen, the first stomach compartment of the sheep. This meant that a larger portion of the protein from the saltbushes escaped the rumen intact and traveled further down the digestive tract. While this might sound like a benefit, the study found that the amount of protein actually absorbed by the sheep's intestines was not significantly different between the plants. In other words, the saltbushes did not offer a hidden advantage in protein delivery; they simply processed the protein differently. The native Salsola vermiculata, with its softer tissues and lower fiber, allowed for a more efficient and complete digestion overall. The researcher also noted that all three plants were extremely rich in calcium, far exceeding what a sheep needs, which could potentially upset the mineral balance if the animals ate nothing else. This high mineral content is a common trait among salt-tolerant plants, but it serves as a reminder that these shrubs should be part of a balanced diet rather than the sole source of food.

The study concludes that for the sheep farmers of the Algerian steppe, the native Salsola vermiculata is the most valuable resource among the three tested. Its ability to provide high energy and easy digestion makes it a standout choice for sustaining flocks during the dry season. However, the research also highlights that the introduced saltbushes are not without merit; they remain a viable option, especially in areas where they have been planted to rehabilitate damaged land. The findings suggest that a sustainable approach to managing these rangelands involves recognizing the unique strengths of each species. Farmers might benefit from prioritizing the native shrub for its nutritional quality while using the saltbushes to stabilize the soil and provide backup forage. The researcher emphasizes that these results are specific to the spring season, when the plants are at their peak. As the year progresses and the plants mature, their nutritional value will likely decline, requiring farmers to adjust their feeding strategies. Ultimately, this work provides a scientific foundation for making better decisions about how to feed sheep in one of the world's most challenging agricultural environments, ensuring that both the animals and the fragile steppe ecosystem can thrive together.