Impacts of supplementing growing rabbit diets with whey powder and citric acid on growth performance, nutrient digestibility, meat and bone analysis, and gut health

Abstract

The present study evaluated the impact of supplementing the rabbit diet with graded levels of whey powder and citric acid. The dietary treatments were as follows: T1, control diet (basal diet); T2, basal diet + 10 g/kg citric acid; T3, T2 + whey powder (7.5 g/kg); T4, T2 + whey powder (15 g/kg); and T5, T2 + whey powder (22.5 g/kg). Results, the T5 diet resulted in the best (P < 0.05) final body weight, body weight gain, feed conversion ratio, protein efficiency, relative growth rate, and dressed weight. The best (P < 0.05) digestion coefficients were associated with the T4 and T5 diets. Rabbits fed diets supplemented with citric acid alone or with addition of graded levels of whey powder showed significantly lower (P < 0.05) intestinal pH than those fed the T1 diet. The T4 and T5 diets resulted in greater CP and ash in the thigh muscle compared with the T1 and T2 diets. Calcium content in the femur bone was higher (P < 0.05) in the T5 group followed by T4 and T3. The wall of different parts of the small intestine improved in the T4 and T5 groups, showing the greatest increase in the small intestinal villi, intestinal glands, and amount of goblet cells. In conclusion, addition of whey powder (1.5, and 2.25%) increased the growth performance, nutrient digestibility and crude protein content of the thigh muscle, and improved the gut health of growing rabbits and the best level was 2.25% whey powder. Citric acid addition had no positive effect on growth performance, nutrient digestibility, crude protein content of the thigh muscle, and the gut health.

Keywords: Citric acid; Digestibility; Growth performance; Intestinal histology; Rabbit; Whey.

Fig. 1

Group T3: a, b showing normal duodenum mucosa and submucosa with brunners gland (B). c–e Normal jejunum mucosa and submucosa with normal covering epithelium of columnar absorptive and goblet cells (arrow)

Fig. 2

Group T4: a showing normal duodenum wall. b Normal covering epithelium of columnar absorptive (arrow) and goblet cells (arrow head). c, d Normal brunners gland (B)

Fig. 3

Group T5: a, b showing normal, intact jejunum mucosa. c, d Well-developed intestinal gland in the mucosa with increasing number of goblet cells (arrow)

Fig. 4

Group T5: a showing significant development in duodenum wall. b Showing massive layer of mixed brunners gland filling almost of the submucosa. c–e normal, regular and intact lymphatic nodules; peyers patches within the ileum submucosa (arrow head), intact villi (arrow) with increase in goblet lining cells (double arrows)