Assessing the impact of olive pomace and whey powder on growth performance and nutritional parameters in Wistar rats

The present study was conducted to evaluate the nutritional efficacy of olive pomace (OP) and whey powder (WP) as alternative feed ingredients in animal diets. A total of 18 male Wistar rats were randomly assigned to three experimental groups (n = 6 per group) and fed one of the following diets for 28 days: a standard control diet (S), an OP-based diet, and a WP-based diet. The OP diet resulted in body weight gain of 95.86 ± 2.48 g (78.33% increase), which was 92.6% of the S group’s performance (103.5 ± 0.80 g; 80.73% increase) despite significantly lower energy intake (1,250.00 ± 7.40 kcal/rat vs. 1,891.6 ± 7.14 kcal/rat). The WP diet led to moderate growth of 85.24 ± 3.92 g (66.03% increase) with an energy intake of 1560.6 ± 6.6 kcal/rat. Despite lower nitrogen balance and protein digestibility, the OP diet improved intestinal morphology, showing a higher villus height-to-crypt ratio than both S and WP groups. These changes may help mitigate the loss in digestibility. The WP diet showed numerically lower lipid levels without reaching statistical significance, while liver enzymes were significantly increased (aspar-tate transaminase: 253 ± 3.21 U/L, P < 0.001; alanine transaminase: 97 ± 4.93 U/L, P < 0.05), compared to control and OP groups. Both diets offer distinct benefits for sustainable animal nutrition.