Experimentally Neem leaves extract were given in broilers as a growth promoters. Growth performances of treated group found better & side by side broilers were not affected any disease without any vaccinations at 30 days of my experimental schedule.
Your question is not clear to me. Please reformulate the exact question you want an answer to.
By the way, depending on the (hygienic) conditions, it is not uncommon to raise unprotected broilers without diseases.
The ratio of heterophils and lymphocytes (H/Ls) is used by ornithologists as a tool to monitor immune function in birds (Davis, 2005)
Difficult to give a specific answer as it depends what you mean by 'immunity'. That said the best way to look at the level of a functional response to mitogenic stimulation-but it is very difficult to isolate and culture sufficient cells from blood samples though not too difficult from splenocytes if you are killing the birds. Heterophil: lymphocyte ratio is a crude method but may have some value-it certainly changes in response to stress. There are older methods that rely on DTH-type reactions-such as skin tests following injection of sheep red blood cells. It is perfectly possible to rear unvaccinated broilers without infectious disease-provided you have a biosecure unit to rear animals. Sadly few people have these
Regarding H/L ratio, we use this measure as an indicator to exposure to stress, where with stress the H/L ratio will be high compared to unstressed birds and vice versa. Phytohemagglutinin (PHA-P) is considered a good in vivo measure of T lymphocyte
function (Qureshi et al.,1997). The phagocytic ability of chicks was determined by the carbon clearance assay (CCA) based on the method of Cheng and Lamont (1988). Sheep red blood cells (SRBC) were used as T-dependent antigens to quantify
the antibody response. Finally, we can use the previous methods to take an overview about the immunity of the bird.
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