Effect of Partial Replacement of full Fat Soya with Soaked Sorrel (Hibiscus sabdariffa L.) Seed Meal in the Diet of Weanling Rabbit

In the world of animal farming, the cost of feeding livestock often hinges on a few expensive ingredients, particularly protein sources like soybeans. Farmers and scientists are constantly searching for local, affordable alternatives that can replace these costly staples without harming the animals' growth or health. One such alternative is the seed of the sorrel plant, a common crop in West Africa known for its tart, red flowers used in drinks and its leaves eaten as vegetables. While the seeds are nutritious, they naturally contain compounds that can interfere with digestion if eaten raw. To make them safe and useful as feed, researchers must process them, often by soaking them in water to wash away these unwanted elements. The question facing agricultural scientists is whether this simple, room-temperature soaking method can turn sorrel seeds into a reliable food source for rabbits, a species known for its ability to thrive on diverse plant materials.

A team of researchers at the University of Ibadan in Nigeria set out to test this idea with weanling rabbits, young animals just starting their independent lives. They designed a feeding trial to see if they could swap out full-fat soybeans, a standard protein source, with meal made from these soaked sorrel seeds. The study involved seventy-five young rabbits, all about six or seven weeks old and weighing roughly the same at the start. The animals were divided into five groups, each receiving a different diet. One group ate a control diet with no sorrel seeds, serving as a baseline. The other four groups ate diets where the soybeans were partially replaced by the soaked sorrel seed meal at increasing levels: ten percent, twenty percent, thirty percent, and forty percent. The rabbits were given unlimited access to their specific food and clean water for ten weeks, allowing the researchers to observe how their bodies responded to the changing ingredients.

The results revealed a clear pattern in how the rabbits handled the new ingredient. The animals fed the control diet, with no sorrel seeds, grew the fastest, gaining an average of 12.25 grams every day. While the study noted statistically significant differences in growth rates across all groups, the rabbits that received a diet with ten percent sorrel seed meal grew at a pace comparable to the control group, gaining about 9.01 grams daily. This similarity suggests that the rabbits handled the ten percent replacement effectively, despite the statistical variation. However, as the researchers increased the amount of sorrel seeds in the food, the rabbits' performance began to drop. Those eating diets with twenty, thirty, or forty percent sorrel seeds gained weight more slowly and had to eat more food to achieve the same amount of growth compared to the control group. The most efficient rabbits, those that converted their food into body weight with the least waste, were found in the control group and the ten percent group.

Beyond just how much the rabbits grew, the researchers also looked at how well the animals could digest the food they were eating. They collected waste samples to measure how much of the protein, fiber, and fat in the diet was actually absorbed by the rabbits' bodies. The data showed that the control diet and the ten percent sorrel diet were the easiest for the rabbits to digest. As the amount of sorrel seed meal increased, the rabbits' ability to break down protein and fiber declined. The group eating the highest level of sorrel seeds, forty percent, struggled the most, digesting the least amount of protein and fiber. Interestingly, the fat in the diet was also harder to digest when the sorrel seeds were either completely absent or present at the highest level, suggesting that a moderate amount of the ingredient might actually help the body process fats, but too much or too little causes issues.

From a financial perspective, the study offered a practical solution for farmers. While the control diet was the most expensive to produce, the cost of making the feed dropped steadily as more sorrel seeds were added, because the seeds are cheaper than soybeans. The most expensive feed cost 216.83 Nigerian Naira per kilogram, while the cheapest, containing forty percent sorrel seeds, cost only 200.39 Naira. However, because the rabbits on the cheaper, high-sorrel diets grew so slowly, the cost to produce a single kilogram of rabbit meat actually ended up being higher for those groups. The sweet spot was the ten percent replacement level. This diet cost less to make than the control, and because the rabbits grew almost as fast, the final cost to produce a kilogram of weight gain was nearly identical to the expensive control diet.

The study concludes that soaking sorrel seeds at room temperature is a viable method for preparing them as rabbit feed, but only up to a certain point. Replacing full-fat soybeans with up to ten percent of this processed seed meal allows young rabbits to grow just as well as they would on a standard diet, while saving money on feed costs. Pushing the replacement rate higher than ten percent, however, introduces too many anti-nutritional factors that the rabbits cannot fully overcome, leading to slower growth and poorer digestion. For farmers looking to reduce their reliance on expensive imported proteins, using soaked sorrel seeds at this specific low level offers a reliable, economical path forward without compromising the health or productivity of their animals.