Effect of dietary zinc supplementation on nutrients digestibility and fermentation characteristics of caecal content in physiological experiment with young rabbits

Abstract

The effects of orally administered zinc from inorganic or organic sources on selected parameters of nutrient digestibility and caecal fermentation pattern in rabbits were the priority of this study. A total of 96 weaned rabbits (35th day of age, both male and female) were divided into 4 groups (control C and three experimental groups – 1EG, 2EG and 3EG) with 24 animals in each group. Maternal albinotic line (crossbreed New Zealand White, Buskat Rabbit, French Silver) and paternal acromelanic line (crossbreed Nitra Rabbit, Californian Rabbit, Big Light Silver) were used. The feed mixture was additionally administered as follows: in the 1st experimental group 1EG by a dose of 27.47 g ZnSO4 .H2 O (zinc sulphate monohydrate), in the 2nd group (2EG) by a dose of 38.46 g Glycinoplex-Zn and in the 3rd group (3EG) a dose of 66.67 g Bioplex-Zn, each per 100 kg. Rabbits were fed with complete pelleted mixtures ad libitum and had free access to water via a nipple drinker. Dietary supplementation of rabbits with zinc was carried out to determine its effects on growth of live weight and consumption of feed per unit of live weight growth. Between 77-81 days of age, four rabbits from each group were selected for digestibility tests using the balance method. On the 91st day of age (6 weeks after all experimental procedures), 6 animals from each group were slaughtered, caecum and appendix were separated, and the caecal samples were collected for analysis; pH, VFA, ammonia-N and lactic acid were determined. We did not find any differences among experimental groups in the digestibility coefficients of starch, N-Free Extract, organic matter and Ca, P, Mg, and Cu obtained through the balance method (P > 0.05), compared with the control group or those fed with 100 Zn mg.kg-1 supplemented diets. Increase in the supplemental Zn level to 100 mg.kg-1 diet resulted in significant increase in digestibility coefficients of Na, K, Fe, Mn (P < 0.05) and Zn (P < 0.01) compared to the control group. No significant effect of the diet was detected on caecum in relative weights of its content, as well as on dry matter content. Feeding of rabbits with inorganic or organic zinc sources did not influence selected biochemical parameters in caecal fermentation, as well as had no negative effect on the rabbit growth performance.