Gliricidia sepium hay a potential replacement for cotton seed cake concentrate as a source of protein: Effects on serum, rumen metabolites and nutrient digestibility of young bunaji bulls

In the tropical regions where cattle are raised, farmers face a constant challenge: finding enough high-quality food to keep their herds healthy and growing. Protein is the essential building block for muscle and tissue, but the traditional sources used to provide it, such as cottonseed cake, can be expensive and difficult to obtain in large quantities. This scarcity drives researchers to look for alternatives that are locally available, affordable, and capable of supporting the same level of animal growth. One such candidate is a fast-growing tree known as Gliricidia sepium. This tree is not just a source of shade; its leaves are rich in nutrients and can be harvested and dried to make hay. However, simply feeding leaves to cattle is not always straightforward. Plants contain natural compounds that can sometimes interfere with digestion or nutrient absorption, and the balance between protein and fiber must be just right to keep the animal's stomach, or rumen, functioning correctly. The question for scientists is whether this tree can truly replace the standard protein supplements without harming the animal or slowing its growth.

To answer this, a team of researchers conducted a feeding trial with twenty young Bunaji bulls, a hardy indigenous breed found in Nigeria. The animals were divided into four groups, each receiving a different diet. All groups ate the same base of hay and grain, but the source of their protein concentrate varied. One group received the standard diet with cottonseed cake as the sole protein source. The other three groups had this cottonseed cake gradually replaced with dried leaves from the Gliricidia sepium tree. The replacement levels were set at 25 percent, 50 percent, and 75 percent. The study lasted for eight weeks, a period long enough to see how the animals adapted to the new food and how their bodies processed it. Throughout the trial, the researchers monitored the bulls closely, checking their blood, sampling the fluid from their stomachs, and measuring how much of the food they actually digested and how much nitrogen, a key component of protein, they retained in their bodies.

The results revealed that the tree leaves were not only a viable alternative but, in some ways, a superior one. The dried leaves contained more crude protein and minerals than the cottonseed cake they replaced, while having less of the tough, fibrous material that can be hard for animals to break down. When the researchers analyzed the blood of the bulls, they found that those eating the diets with the tree leaves showed signs of better health and metabolism. Specifically, the animals that received a diet where half of the cottonseed cake was replaced with the tree leaves showed the most positive changes. These bulls had higher levels of packed cell volume, which indicates a healthy blood supply, and their blood glucose and albumin levels were elevated, suggesting efficient energy use and strong protein status. The blood urea nitrogen levels, which reflect how well the body is using protein, also indicated that the animals were utilizing the nutrients effectively without wasting them.

The environment inside the bulls' stomachs remained healthy across all groups, but the fermentation process showed interesting shifts. The fluid in the rumen, where microbes break down food, maintained a stable acidity level, which is crucial for the survival of the beneficial bacteria. While the total amount of volatile fatty acids produced—a primary energy source for the animal—varied slightly depending on the diet, the overall fermentation remained robust. The study found that replacing up to half of the cottonseed cake with the tree leaves did not disrupt the digestive process. In fact, the animals retained more nitrogen when fed the 50 percent replacement diet, meaning they were holding onto more of the protein they ate to build muscle rather than excreting it. This is a significant finding because it suggests that the tree leaves provide a form of protein that the animal's body can use very efficiently.

However, the study also highlighted that there is a limit to how much of the tree leaves can be used. When the replacement level reached 75 percent, the digestibility of the crude fiber in the diet began to decline slightly. This suggests that while the tree is an excellent source of protein, feeding it in very large quantities might introduce too much of certain plant compounds that slow down the breakdown of fiber. The researchers concluded that the sweet spot lies at the 50 percent replacement level. At this point, the bulls thrived, showing improved metabolic health and efficient nutrient use without any negative effects on their digestion or overall well-being. The findings confirm that Gliricidia sepium is a sustainable and cost-effective solution for farmers looking to reduce their reliance on expensive commercial feed. By integrating this tree into their feeding strategies, producers can support the growth of their cattle while utilizing a resource that is readily available in their local environment.