Replacement of soybean meal with varying inclusions of black soldier fly larvae in albino wistar rats as a model for monogastric animals

Regarding universal food and feed security, alternate feed resources are the leading market stance. Black Soldier Fly (BSF) is the most well-reputed because of its cost-effectiveness, ecological, sustainability, and less labor and land intensive. Subsequently, the payback of BSF larvae for health sustainability has become a great necessity. EU has legalized it to feed poultry, fish, pigs, cats, dogs, quails, ducks, reptiles, birds, and laboratory animals. BSF larvae farming helps to reduce organic waste removal and in return it provides animal feeding, organic fertilizer and biodiesel as end products. The objective of this study was to evaluate the effect of feeding varying inclusions of BSF larvae to Wistar albino rats as a replacement to soybean meal on blood chemistry, oxidative biomarkers and tissue histopathology parameters. The number of total rats was 80 in this study. Half of the rats were male, and half of them were female. All rats were divided into five groups; each group contained eight subgroups, of which the first four contained male rats and the following four included female rats. In this way, each group had 16 total rats, 8 male and 8 female, and each subgroup consisted of two rats in one cage. The rats were fed with 0, 5, 10, 15, and 20% inclusions of BSF larvae meal as replacement to soybean meal. The effect of BSF larvae on body weight gain, average feed intake, hematological and serum biochemical parameters, tissue and serum oxidative stress parameters, and histopathological findings were seen. At the end of the study, the blood and tissue samples were collected from all rats. The blood samples were immediately analysed for hematological and serum biochemical parameters. Some of the blood and tissue (liver, kidney, and heart) samples were stored at -18 °C for serum oxidative parameters analysis which was performed at the Biochemistry lab. Tissues including liver, kidney, heart, testis, ovaries, uterus and duodenum were collected in sterile jars containing formalin and were analysed for histopathalogical analaysis. The experimental feeds, soybean and BSF larvae samples were sent to the TUBITAK Marmara Research Centre for their nutritional profile analysis. The feed samples were analysed for dry matter, crude ash, crude protein, crude fat, crude fiber, fatty acid and amino acid composition. The statistical analysis showed weight gain and average feed intake to be non-significant (p > 0.05) for all experimental groups compared to control. For statistical analysis, first of all, the normality test of the data was performed by descriptive statistics. On the basis of the normality test, the data was further analysed by One way Analysis of Variance (ANOVA) or Kruskal Wallis test (KWH) which were performed by IBM SPSS (V. 24.0) to analyse the difference between experimental groups. For Correlational analysis Pearson's test was performed. The statistical analysis showed that MCHC, PDW, MPV, P-LCR, uric acid, ALT, ALP, LDL, HDL, cholesterol total, liver, and kidney MDA and GSH, and tissue TOS and TAS were significant (p < 0.05) compared to the control as the male and female combined effect. However, as a gender-specific effect, MCV, MCHC, PLT, RDW-CV, LDL, non-HDL, ALP and cholesterol total in male rats and lymphocytes, PDW, PCT, creatinine, protein total, ALT, calcium, phosphorous, OSI, GSH (heart) in female rats were statistically significant (p < 0.05) compared to the control. Moreover, uric acid, TOS and TAS in serum, MDA and GSH in kidney and liver, and villus length were significant in both male and female rats and there were not any considerable histopathological changes. Convincingly, up to 20% inclusion of BSF larvae as replacement to soybean meal is effective for feeding rats without causing any negative effect on health and nutrient absorption. An improvement in blood chemistry, intestinal histopathology and oxidative parameters in response to partial inclusion of BSFL up to 20% is recommend for use in lab animals. Key words: BSF larva, Rat, Health, Soybean meal