High dietary levels of zinc for young rabbits

Abstract

The effects of orally administered zinc from inorganic or organic sources on selected parameters of meat quality 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 3 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 acromalictic line (crossbreed Nitra‘ Rabbit, Californian Rabbit, Big Light Silver) were used. The feed mixture was additionally administered as follows: in 1st experimental group 1EG by a dose of 27.47 g ZnSO4 .H2 O (zinc sulphate monohydrate), in 2nd group (2EG) by a dose of 38.46 g Glycinoplex-Zn and in 3rd group (3EG) dose of 66.67 g Bioplex-Zn, per 100 kg each. They were fed with complete granulated mixtures ad libitum and had free access to water via a nipple drinker. Dietary supplementation of rabbit with zinc was carried out to determine its effects on growth of live weight and consumption of feed per unit of live weight growth. On 91st day of age (6 weeks after all experimental procedures), 6 animals from each group were slaughtered and sampled for testing in the morning hours. Meat quality was analyzed from each sample of Musculus longissimus dorsi (MLD) (50 g) for parameters characterizing the content of nutrients (content of water, proteins, fat, amino acids and fatty acids composition) and processing technology parameters (electric conductivity, pH, colour). The amino acids and fatty acids contents noted in this study indicate statistically insignificant changes (p ≤ 0.05). This study suggests that lean rabbit meat could be a high quality protein source due to its well-balanced essential amino acid composition. The growth rate in all groups was independent on zinc treatment. A weak influence of Glycinoplex-Zn on animal health was also noted. Zinc supplementation raises levels of cholesterol, water holding capacity and energy value, and lowers the value of pH in longissimus dorsi muscle compared to rabbits fed the control diet. Supplementation with Glycinoplex-Zn (100 mg of zinc) evoked a 25 % mortality rate respectively in comparison to 8.3 % of the Bioplex-Zn supplemented with frequent Pasteurella infections. These effects were not observed in rabbits fed with other diets.