Studies on the relationships between animal nutrition and immunity have sought reliable methodologies to measure responses. Cell-mediated immune response is similarly studied in humans. The cutaneous basophil hypersensitivity test (CBH) is one of the methods to measure that response and consists in the infiltration of inflammatory cells, particularly of lymphocytes and basophils, as result of the application of substances capable of inducing cell proliferation in determined sites, such as wings, wattle, and interdigital space in birds. CBH is considered a simple and fast method and can be applied in birds of different ages. In immunocompetence studies with poultry, phytohemagglutinin-P (PHA-P) is a commonly used substance, despite the variability of the response related to the method of application (intradermal injection) and the antigens used. In the present experiment, PHA-P was used to observe the cell-mediated immune response of 216 chicks fed three dietary levels of vitamin E from 1 to 36 days of age. All birds were immunologically challenged by vaccination against coccidiosis at three days of age and against Newcastle Disease (NCD) at 14 and 30 days of age. At 36 days of age, birds were submitted to the CBH test according to the methodology of Corrier & DeLoach (1990). Birds fed 65mg/kg of vitamin E presented lasting cell reaction (p<0.08), which indicates that this vitamin E level improved cell immune response of birds due to its antioxidant and immunomodulating properties. The use of this vitamin E level can be considered by nutritionists under practical conditions, aiming to improve broiler immunity.

One to 42-d-old (432) female broilers were fed different levels of inorganic selenium (ISe) and organic selenium (OSe), according to the following treatments: (1) 0.3 mg ISe; (2) 0.3 mg ISe + 0.2 mg OSe; (3) 0.5 mg ISe and (4) 0.3 mg OSe/ kg of feed. All birds were vaccinated against infectious bursal disease (IBD) at 19d of age and three birds/replicate (R) were inoculated with sheep red blood cells (SRBC) at 32d. Three other birds/R received Freund's adjuvant at 37d and avian tuberculin (AT) in the wattle at 47d of age. All birds were submitted to heat stress after 21d. Performance parameters, bursa and spleen weights, lymphocyte bursa depletion, antibody (Ab) production against IBD and SRBC, hematocrit, leukocytes, heterophil/lymphocyte ratio (H/L), and cellular reaction to AT were evaluated. The contrast analysis showed that OSe has improved feed intake (FI) between day 1 and 42 (p<0.10). Birds fed ISe presented worse H/L ratio (p<0.10), but higher Ab titers against IBD (p<0.04) and SRBC (p<0.05) than birds fed OSe, but OSe supplemented birds showed lower lymphocyte depletion scores in the bursa. The higher FI promoted by OSe may be beneficial when rearing broilers in hot weather. The use of ISe induced higher humoral immune response

The present study aimed at assessing the effects of methionine and arginine on the immune response of broiler chickens submitted to immunological stimuli. Three methionine concentrations (0.31, 0.51, and 0.66% from 1 to 21 days of age; 0.29, 0.49, and 0.64% from 22 to 42 days of age) and 2 arginine concentrations (1.33 and 1.83%; 1.14 and 1.64% for the same life periods) were tested. Birds were divided into two groups for immunological stimuli (3x2x2 arrangement). Vaccines against Marek's disease, fowl pox, infectious bronchitis, Freund's Complete Adjuvant, Sheep red blood cells (SRBC), and avian tuberculin were administered to one group as immunological stimuli; the other group did not receive any stimulus. The experiment was carried out with 432 one-day-old male Ross broilers, distributed into 12 treatments with 6 replicates of 6 birds each. Performance data were weekly collected. Anti-SRBC antibodies were collected by hemagglutination test and cell immune response (CIR) was measured by tubercularization reaction in one wattle 24 hours after administration of the second tuberculin injection at 42 days of age. The weight difference between the two wattles of each bird (one injected with tuberculin and the other not) was the measure of CIR. Arginine levels did not influence either bird performance or immune response. Methionine concentrations higher or lower than usually adopted in broiler production (0.51 and 0.49%) equally failed to influence the birds' immune humoral response, but the best CIR was observed at the intermediate methionine level. Vaccines administered on the first day of age impaired bird performance up to the 21st day of age.

The present study aimed at evaluating the effect of the prebiotic Bio Mos™ (2 kg/ton up to 10 days; 1 kg/ton from 10 to 21 days; and 0.5 kg/ton from 21 days to slaughter), of the probiotic Lac XCL 5x™ (by spray-mixing), of a combination of the two supplements (prebiotic + probiotic), and of one growth promoter antimicrobial agent (Avilamycin at 15 ppm). Birds were orally challenged with inoculated Salmonella Enteritidis (SE) 10(6) CFU at 3 days of age. Four hundred and eighty male Ross chicks were used. The experiment lasted 28 days, and the analyses were conducted at 15 and 28 days of age. Cecum and liver bacterial colonization of production of anti-SE antibiodies, intestinal micrometry and bird performance were assessed. Neither the prebiotic, nor the probiotic influenced performance or production of anti-SE antibodies in SE-challenged birds. Intestinal micrometry and bird mortality were not influenced by prebiotic or probiotic supplementation, or by the antimicrobial agent. The use of an antimicrobial agent produced higher SE CFUs in cecum bacterial counts, while prebiotic and probiotic yielded lower counts. The combination prebiotic+probiotic did not produce significantly different results from the individual use of the additives.

Several changes in amino acid levels occur during an infection. As a rule, glycine, taurine and serine levels diminish considerably, while cysteine levels increase. Such changes may be attributed to the intense consumption of sulfur amino acids (SAA- methionine+cysteine) during infectious challenge. Methionine plays an important role in humoral and cellular immune responses. It has been suggested that such effect is exerted by intracellular glutathione and cysteine levels. Four-hundred thirty-two day-old Ross male broiler chickens were fed (from 1 to 42 days of age) three SAA levels in the diet (0.72, 0.82, and 0.92% from 1 to 21 days of age; 0.65, 0.75, and 0.85% from 22 to 42 days of age) and submitted to two immunological stimulus series. Vaccines against Marek's disease, Fowlpox, Infectious Bronchitis and Infectious Bursal disease, Freund's Complete Adjuvant, and avian tuberculin were used as immunological stimuli. The experiment comprised 6 treatments, with 6 replications using 12 birds per replicate. Performance data were collected weekly. Gumboro antibodies were measured by ELISA, and the cellular immune response by the tuberculin test. SAA levels tested did not influence immune response. Nevertheless, the vaccines applied on the 1st day impaired chick performance up to the 21 days of age. The SAA levels generally adopted in poultry husbandry may not be enough to assure weight gain, especially when birds are raised if a low-challenge infectious environment.

Crop is a known source of Salmonella contamination during broiler carcass processing. The effect of drinking water acidification by lactic acid or citric acid or a combination of those with cupric sulfate and d-limonene in the reduction of Salmonella Enteritidis (SE) recovered from the crop of broilers was evaluated. Treatments were administered during 8 hours of preslaughter fasting period (Experiments I and II) and during the last 32 hours of preslaughter (Experiment III). It was observed that acidification reduced water intake when treatments began at preslaughter feed withdrawal, and affected the possible reducing effect of these acids on SE recovering (Experiments I and II). Water intake during preslaughter feed withdrawal was not affected when treatment began 32 hours before slaughter (Experiment III). Treatments reduced SE recovering from crop (p<0.05). In Experiment III, 0.470% of lactic acid reduced the number of recovered SE in 99%. This study suggested that the addition of organic acids in the drinking water 24 hours before beginning the preslaughter feed withdrawal might reduce crop SE colonization and might be an important strategy to reduce SE contamination of broiler products during processing.