Immunostimulatory and Antibacterial Effects of Cannabis sativa L. Leaves on Broilers

Food safety, climate change, the emergence of infectious diseases, the ban on the use of antibiotics as growth promoters, and increasingly demanding intensive production are daily challenges for poultry production. A functional immune system is a prerequisite for animal health, and nutrition is one of the modulators of the immune system; therefore, the appropriate balance of nutrients is extremely important for the proper development and maintenance of the immune system of animals. The antimicrobial and immunomodulatory effects of phytobiotics are properties that make their use important as feed additives for poultry. Cannabis sativa L. contains many different compounds such as flavonoids, terpenes, and cannabinoids, each with different properties and effects. The effects of C. sativa seeds, essential oils, and cakes as feed additives for poultry have already been investigated, but the effect of C. sativa L. leaves as a feed additive on immunostimulatory and antibacterial activity has not. The results of this study show that C. sativa as a phytogenic additive to animal feed has a favourable antimicrobial and immunomodulatory effect in the production of broiler chickens. The aim of this study was to evaluate the effect of dried Cannabis sativa L. leaves as a phytogenic mixture added to broiler feed on CD4(+) and CD8(+) T lymphocyte subpopulations, Newcastle disease virus (NDV) antibody titres, and the presence of E. coli in faecal samples. The study was conducted on 100 male Ross 308 broilers, divided into four groups of 25 broilers, for a 42day research period. The groups were housed separately in boxes on a litter of softwood shavings and were fed starter mixture from day 1 to day 21 and finisher mixture from day 22 to day 42. Industrial hemp (C. sativa) was grown in the Crkvina area, Croatia (latitude: 45 degrees 18 ' 46.8 '' N; longitude: 15 degrees 31 ' 30 '' E). The hemp leaves were manually separated, sundried, and ground to a powder. The mixture offered to the control group did not contain cannabis leaves, whereas the three experimental groups received mixtures containing mixed cannabis leaves in a quantity of 10 g/kg, 20 g/kg, or 30 g/kg (E_10, E_20, and E_30, respectively). The mean NDV antibody level was uniform in all study groups until postvaccination day 14 and increased comparably with time. The percentage of CD4(+) and CD8(+) lymphocytes in the peripheral blood subpopulation showed statistically significant differences (p < 0.001) in the E_20 group as compared with the control group and both the E_10 and E_30 groups throughout the study period. As the broiler age increased, the CD4(+)toCD8(+) ratios also increased and were statistically significant (p < 0.0001) on day 42 in all experimental groups as compared to the control group. Comparing the control group with the experimental groups indicated that the bacterial count was lower in broiler groups having received feed with the addition of 20 g/kg and 30 g/kg C. sativa leaves. In conclusion, the C. sativa leaves were found to elicit a favourable immunomodulatory effect on cellmediated and humoral immune responses in broilers via increased CD4(+) and CD8(+) lymphocyte subpopulations and higher CD4(+):CD8(+) cell ratios, thus indicating enhanced immune function capacity. In addition, C. sativa leaves may have complementary effects on the broiler postvaccination immune response, increase broilers' resistance to infectious diseases, reduce the effect of stress associated with vaccination, and improve broiler health and welfare.