Impact of Dietary Zinc Sources and Levels on Growth Performance and Immune Response in Fattening Rabbits

This study aimed to assess how different levels and sources of dietary zinc affect the growth performance, carcass characteristics, certain blood parameters, and gene expression in New Zealand White rabbits. Sixty weaned rabbits were randomly assigned to five groups. The first group served as a control (C), while the second and third groups received a basal diet enriched with 10 and 20 mg of Nano-zinc per kg, referred to as 10 NZn and 20 NZn, respectively. The fourth and fifth groups were fed a basal diet supplemented with 20 and 40 mg of organic zinc per kg, labeled as 20 OZn and 40 OZn, respectively. The trial continued until the rabbits reached 14 weeks of age. The findings showed that:The 20 NZn and 40 OZn groups experienced significant improvements in weight gain and feed conversion ratio (FCR) compared to the control group. No significant differences were observed in the percentages of carcass, head, liver, and heart across the treatments.The rabbits on the 20 NZn diet had the lowest triglyceride levels, while those on the 10 NZn diet showed a reduction in total cholesterol compared to the control group.The 10 NZn group exhibited an over-expression of the IGF-1 gene.In summary, adding either the nano form (20 mg/kg NZn) or the organic form (40 mg/kg OZn) of zinc to the diets of growing rabbits led to enhanced growth performance, as evidenced by increased weight gain and improved FCR. However, these dietary levels did not significantly impact the expression of the IGF-1, GPX1, and MyD88 genes, highlighting the need for additional research to establish the safe levels of nano zinc in livestock feed.