Canola meal as a sustainable protein source for indigenous Tswana lambs: Comprehensive evaluation of carcass, meat quality, physicochemical, and sensory responses

In the vast, semi-arid landscapes of Botswana, the supply of mutton is a matter of national food security, yet it remains fragile. For generations, local farmers have relied on sheep grazing on natural rangelands, but the rhythm of the seasons dictates the availability of grass. When the rains fail or the dry season stretches too long, the supply of meat shrinks, forcing the country to import expensive alternatives to feed its people. To solve this, farmers often turn to intensive feeding systems where sheep are kept in pens and fed high-quality grains and protein supplements to ensure they grow fast and yield good meat. For decades, the standard protein ingredient in these supplements has been soybean meal, a nutrient-dense crop that helps animals build muscle. However, soybean meal is costly to import and often out of reach for local producers. This economic reality has pushed researchers to look for a local, affordable alternative that can perform just as well without compromising the quality of the meat on the plate.

Enter canola meal, a byproduct of oilseed processing that is not suitable for human consumption but is rich in protein. The question facing scientists was whether this local resource could replace the expensive imported soy in the diets of indigenous Tswana lambs without hurting the final product. A team of researchers from the Botswana University of Agriculture and Natural Resources and North-West University set out to answer this by conducting a rigorous feeding trial. They took twenty six-month-old Tswana lambs, a hardy local breed, and divided them into groups. Each group received a diet where the soybean meal was gradually swapped out for canola meal. One group ate the standard diet with no canola, while the others ate diets where the soy was replaced by canola at levels of 25%, 50%, 75%, and finally 100%. The goal was to see if the lambs grew just as well, if their bodies yielded the same amount of meat, and if the meat itself tasted and felt the same to a human eater.

After ninety days of feeding, the lambs were processed to measure their growth and the quality of their carcasses. The researchers found that as the amount of canola meal in the diet increased, the total weight of the hot carcass—the animal's body weight immediately after slaughter—did decrease slightly. This suggests that the lambs on the highest canola diets were not quite as heavy as those on the pure soy diet. However, this difference did not translate into a loss of overall meat quality or a change in the proportion of meat to bone. The percentage of the live animal that became usable meat, known as the dressing percentage, remained stable across all groups. Similarly, the thickness of the fat layer and the size of the ribeye muscle, which are key indicators of a good cut of meat, showed no significant differences between the groups. The internal organs, such as the liver and lungs, also weighed about the same regardless of what the animals had eaten, indicating that the switch to canola did not cause any hidden stress or health issues for the animals.

When the scientists examined the specific cuts of meat that consumers value most, such as the rib chops and the chump, they noticed a small linear decline in weight as the canola levels rose. This likely stems from the fact that canola meal contains more fiber than soy, which can make the animals eat slightly less or digest their food a bit differently, leading to a modest reduction in muscle growth. Yet, despite this slight reduction in size, the fundamental characteristics of the meat remained intact. The meat's ability to hold onto water, its tenderness, and its cooking loss were all comparable across the different diets. Even the chemical makeup of the meat, including its protein and mineral content, showed only minor variations that did not alter the meat's fundamental nature. The most important test, however, was the human palate. A panel of seventy people tasted the cooked meat from all the groups. They rated the appearance, taste, flavor, tenderness, and juiciness on a scale. The results were clear: the panelists could not tell the difference. The meat from the lambs fed 100% canola meal was just as acceptable and enjoyable as the meat from the lambs fed the traditional soy diet.

The study concludes that canola meal is a viable, sustainable alternative to soybean meal for feeding indigenous Tswana lambs. While the highest levels of inclusion might result in a very slight reduction in the total weight of the carcass and specific cuts, the overall quality of the meat, its safety, and its appeal to consumers remain unaffected. This finding offers a practical solution for local farmers who wish to reduce their reliance on expensive imports. By using a locally available resource like canola meal, they can maintain the production of high-quality mutton, helping to secure the food supply for their communities without compromising the standard of the product. The research demonstrates that the local sheep can thrive on this alternative diet, turning a byproduct of the oil industry into a reliable source of protein for the next generation of meat production.