Effects of graded levels of black soldier fly (Hermetia illucens) larvae meal in diet on performance, carcass characteristics, serum biochemical parameters and gut morphology in broiler chickens

Poultry farmers face a constant challenge: finding enough affordable, high-quality food to raise healthy chickens. Traditional ingredients like soybean and fish meal are becoming expensive and sometimes hard to source, pushing scientists to look for alternatives that are both nutritious and sustainable. One promising solution lies in the insect world, specifically the larvae of the black soldier fly. These insects are natural recyclers, capable of turning organic waste into a protein-rich meal that can feed other animals. They are packed with nutrients, including essential fats and amino acids, which are the building blocks of growth. The question for researchers is not just whether these larvae can be eaten by chickens, but how much of them a chicken can safely consume before it stops helping or starts causing harm. Finding the right balance is crucial for turning a waste product into a reliable food source for the global food supply.

In a recent trial conducted in India, a team of scientists set out to test exactly how different amounts of black soldier fly larvae meal affect broiler chickens from the day they hatch until they are ready for market. They gathered 160 day-old chicks and divided them into four groups. Each group received a slightly different diet. The first group ate a standard feed with no insect meal, serving as a baseline. The other three groups ate the same base feed, but with the black soldier fly larvae meal added at increasing levels: 2.5 percent, 5 percent, and 7.5 percent. The researchers ensured that all the diets provided the same amount of energy and protein, so any differences in the chickens' growth would be due to the insect meal itself, not a lack of nutrition. The birds were raised under identical conditions for six weeks, eating as much as they wanted, while the scientists carefully tracked their weight, how much they ate, and how efficiently they converted food into body mass.

The results showed that adding the insect meal made a real difference in how the chickens grew. By the end of the six-week period, the chickens fed with 5 percent and 7.5 percent larvae meal were significantly heavier than those on the standard diet or the group with only 2.5 percent. Interestingly, the amount of food the chickens ate did not change much between the groups, but the efficiency of their growth improved early on. During the first three weeks, the chickens eating the insect meal converted their food into body weight more effectively than the control group. This suggests that the larvae meal helped the birds utilize their food better, at least during the early stages of their lives. The study found that even at the highest level tested, 7.5 percent, the diet remained safe and effective, with no negative impact on the overall growth rate over the full six weeks.

When the researchers examined the chickens after the trial, they looked at the meat yield and the health of the internal organs. The most notable change was in the breast meat. Chickens in all the groups that received the insect meal produced more breast meat than the control group, with the 5 percent group showing the highest yield. This is a significant finding because breast meat is often the most valuable part of the chicken for consumers. Other parts of the carcass, such as the liver, heart, and abdominal fat, remained unchanged regardless of how much insect meal the birds ate. This indicates that the insect meal specifically boosted muscle development without causing unwanted fat accumulation or stressing the internal organs.

Beyond physical growth, the scientists also checked the blood chemistry of the birds to understand how their bodies were processing the new diet. The chickens eating the insect meal had higher levels of protein in their blood, which is a sign of good health and active muscle building. However, there was a limit to how much was beneficial. While the 5 percent level kept blood chemistry stable, the 7.5 percent level caused a slight rise in uric acid, a waste product that the kidneys filter out. This suggests that while 7.5 percent is safe, it pushes the birds' systems a bit harder. On the positive side, the birds eating the insect meal had lower levels of cholesterol and triglycerides in their blood compared to the control group. This is a surprising and beneficial side effect, as it points to a diet that might produce leaner meat and healthier birds overall.

The most detailed look at the birds' health came from examining their intestines. The researchers took small samples of tissue from the duodenum, ileum, and caecum to see how the gut was structured. They found that the more insect meal the birds ate, the better their intestines looked. The tiny finger-like projections inside the gut, which are responsible for absorbing nutrients, became longer and wider in the groups fed with the insect meal. The groups with 7.5 percent larvae meal showed the most developed gut structure, with deeper folds and more immune cells present in the tissue. A healthier gut structure means the bird can absorb nutrients more efficiently and has a stronger defense against disease. This physical change in the gut likely explains why the birds grew faster and produced more meat; their bodies were simply better equipped to process the food they were eating.

The study concludes that black soldier fly larvae meal is a viable and effective ingredient for chicken feed, capable of replacing a portion of traditional protein sources without harming the birds. The researchers found that including the meal at levels up to 7.5 percent improved growth and meat yield while also enhancing gut health. While the highest level tested did cause a minor increase in blood waste products, it did not negatively impact the birds' overall performance. This work provides a practical path forward for the poultry industry, showing how an organic waste stream can be converted into a high-quality feed ingredient that supports both animal health and sustainable farming practices.