Comparative effects of supplementary different copper forms on performance, protein efficiency, digestibility of nutrients, immune function and architecture of liver and kidney in growing rabbits.

The various sources of supplemented copper had a different impact on the animal performance based on their bioavailability. The current study compared the effects of supplementary copper oxide (CuO), copper acetate (Cu-acetate) and copper nanoparticles (Cu-NP) on performance, immune function, nutrients digestibility and architecture of the liver and kidney of growing rabbits for eight weeks. Sixty rabbits (581 ± 6.56 g) were randomly allocated to four treatments as follows: basal diet, 100 mg copper/kg diet as CuO, 100 mg copper/kg diet as Cu-acetate and 50 mg copper/kg diet as Cu-NP. Cu-acetate and Cu-NP improved specific growth rate, final weight and daily weight gain. Cu-NP supplementation had higher feed intake, feed conversion, protein efficiency, hematocrit and hemoglobin values compared with other copper forms. All copper sources showed higher levels of serum complement component 3, Immunoglobulin M, lysozyme activity and the digestibility of nitrogen-free extract, dry matter and organic matter. As a result, increased nutritive values were detected when the rabbits were fed copper-supplemented diets. No liver and kidney architecture alterations were identified between the experimental groups. In conclusion, both dietary Cu-NP and Cu-acetate were more efficient than CuO in enhancing growth and seem promising in fattening rabbit nutrition.

Productive performance response of growing rabbits to dietary protein reduction and supplementation of pyridoxine, protease, and zinc.

An 8-week experiment was carried out to assess the impact of supplemental dietary pyridoxine (PY), protease (PR), zinc (Zn) and their mixture (MIX) with low protein diet (LP; 14.76% CP) or high protein diet (HP; 18.53% CP) on rabbit growth, feed utilization, and nutrients digestibility. Rabbits were divided into ten similar groups in a 2 (protein level) ×5 (treatments) factorial design. Treatments included a control group (without any additives), 5 mg PY/kg of diet, 100 mg Zn/kg of diet, 500 mg PR/kg of diet or a mixture of all tested feed additive with the same doses. Results indicated that growth performance, feed utilization, and nutrients digestibility indicators were retarded significantly with reduction of dietary crude protein. Growth performance and feed conversion were significantly enhanced as a result of PY, PR, Zn, and MIX supplementation. All feed supplements had significantly improved the digestibility of crude protein and digestible crude protein. No change in carcass traits was recorded in response to protein level and tested feed supplements. It is concluded that the growing rabbit responded positively to PY, Zn, PR, and MIX (particularly PY) supplemental of LP or HP diets, in terms of growth performance, feed conversion, and nutrient digestibility.