Secondary compounds attenuation in Acacia macracantha leaves and its effect on intake, digestibility, plasma and productive variables by incorporating them in rations for rabbits

Abstract

A trial was conducted to evaluate the attenuation of secondary compounds in Uveda (Acacia macracantha) leaves at Animal Production Research Unit, Lisandro Alvarado University, Lara, Venezuela. A factorial design was used involving three water temperatures (25°C, 45°C and 65°C) × five water immersion times (0, 6, 12, 24 and 48 h). The best treatment was selected to prepare a balanced diet for rabbits with 30% inclusion of this material, to determine its effect on food intake and digestibility, plasma and productive variables compared with a basal diet especially for rabbits. Twelve New Zealand × Californian rabbits (969 ± 48 g liveweight) housed in individual cages were used for a total of 24 experimental units on a completely randomised experiment. Treatment to remove most secondary compounds involved soaking the foliage for 6 h at 25°C with led to reductions of initial total content: 70.9% total polyphenols, 77.8% simple phenols, 67.6% in total tannins, 90.4% tannins and 68.8% condensable tannins that precipitate proteins. The differences were significant for all variables (P < 0.05). Food intake was higher than the basal diet (134.9 ± 3.2 vs 107.4 ± 3.7 g/rabbit/day, P < 0.01), cell wall and hemicellulose digestibility was higher in the basal diet, whereas the apparent digestibility of dry matter, protein and energy was higher in the basal than in the Uveda diet (P < 0.01). Total cholesterol, LDL, glucose, urea and triglycerides were similar between diets, and HDL and transaminases were lower in the rabbits that consumed Uveda. The weight gain was similar between treatments (32.0 ± 1.5 g/day baseline vs 30.2 ± 1.0 g/day Uveda diet) although feed conversion was higher in the basal diet compared to the Uveda diet (3.1 ± 0.1 vs 4.1 ± 0.2, P < 0.01), with similar hot carcass weights (1294 ± 46 g vs 1206 ± 35 g). The results showed that it is feasible to include 30% of attenuated Uveda leaf in rabbit diets, resulting in weight gain and yields similar to those obtained from commercial diets and maintenance of animal health.