Effect of combinative dietary zinc supplementation and plant thyme extract on growth performance and nutrient digestibility in the diet for growing rabbits

Abstract

The aim of this study was to evaluate the effect of combinative orally administered zinc from organic source (Bioplex-Zn) and 0.1 % of Thymus vulgaris L. plant extract to feed mixtures for rabbits, applied into water during the growing period, on the selected parameters of nutrient digestibility. Feeding trial was conducted on 96 post-weaned rabbits, meat line P91 and M91 (aged 35 days, both sexes). They were randomly divided into 4 experimental groups (EG) with 24 animals in each group. The rabbits in the EG1 and EG3 were fed the same commercially available diet with no zinc additive. The feed mixture in the EG2 and EG4 was additionally administered at a dose of 33.3 g Bioplex-Zn per 100 kg each (this is addition of 50 mg Zn.kg-1 feed mixture). The rabbits in the group EG3 and EG4 received 0.1 % of Thymus vulgaris L. plant extract applied into the water. Supplementation of the rabbit diets with zinc was done in order to determine its effects on live weight and consumption of feed per unit of live weight growth. Higher proportion of Zn in the mixture increased digestibility coefficients of fat, NDF, starch, organic matter, Mg, Na, K, Fe, Zn, Cu, Mn (P < 0.05) compared to EG1 with no zinc additive. Natural product of Thymus vulgaris L. extract consisted of flavonoids (54 %), diterpene (27 %) and phenolic acids (19 %), which are known to have an antimicrobial and antioxidant activity. The beneficial effect of combination of the Thymus vulgaris L. plant extract and zinc additive administration was manifested by the anti-coccidian action in rabbits. These results indicate that the addition of 50 mg Zn.kg-1 of a mixture is sufficient to achieve optimal health, performance, increased feed conversion rate (p < 0.05) and average daily weight gain in broiler rabbits.