Do Iodine and Colistin in broiler’s drinking water affect immune competence and performance ?

A total of 150 unsexed chicks (Ross 308) , one day old were used in a completely randomized design to study the immune responses against Newcastle disease vaccine (NDV), infectious bronchitis vaccine (IBD), and performance of broiler supplemented with iodine and colistin. The chicks were divided into 6 treated groups with five replicated pens (5 birds per pen). The treatments consisted of the: G1: received Iodine (1 ppm) in drinking water during all week days of experimental period (35 days). G2: received Iodine (1ppm) in drinking water, added 3 days a week. G3: received Colistin (Colistin sulphate) (0.5 mg/liter) in drinking water during all week days. G4: received Colistin sulphate (0.5 mg/liter) in drinking water, added 3 days a week. G5: vaccinated with NDV+IBD but did not receive iodine or colistin as consider positive control. G6: Neither vaccination nor iodine or antibiotic as consider Negative control. The oral administration of colistin enhanced (P≤0.05) the antibody titers against NDV and IBD, growth performance (body weight gain, feed intake feed conversion ratio), and reduced the intestinal bacterial counts (P≤0.05) during all the experimental periods (35 days). Also Iodine caused a marked increase (P≤0.05) in the antibodies titers (Ab) against NDV and IBD during the maternal, primary, and secondary response and showed a moderate effect in reducing the intestinal bacteria counts (P≤0.05). In the present study, both colistin and iodine could improve the immune response and health status of broiler at all the experimental period. We can use colistin and iodine during outbreak periods of NDV and IBD at neighboring farms. Key word: broiler, colistin, iodine, immune, vaccination. INTRODUCTION The improvement of the immune system and intestinal safety is associated with high production in a new strain of broilers (1), there for all methods that enhance these systems were studied deeply and we need to discover other strategies to create a balance between bird health and production. Although there are potential discussions about the use of some methods such as antibacterial substances due to public health concerns, but these substances continue to play an important role in animal production in developing countries so far (2). Colistin is an important antibiotic belonging to polymyxins group used widely in poultry production as growth promoter. Colistin is slowly absorbed by the gastrointestinal tract (2), so the body tissues are free of it under normal doses. Its effect on the cell membrane and make it useful against gram-negative bacteria (3). Additionally, the effect of disinfectants and sterilization on poultry production becomes a constant fact. Iodine is a common disinfectant used in the poultry industry. It has an effect on growth performance and immune response (4). The broiler chickens in tropical countries such as Iraq suffer from poor immune response to many vaccines especially IBV and NDV (5). Therefore, we need to give much more an attention on any substance that was shown the ability as an enhancer of immune responses and health status of broiler. The objective of this study was to assess the capacity of iodine and colistin on immune response against NDV, IBD, and also on health status with regard to intestinal bacteriology and growth performance. MATERIALS AND METHODS: Animal diet and Experimental Design The experiment period was 35 days (20 November to 26 December 2016 ) at the farm of Al-Qasim Green University, Babylon, Iraq , a hundred and fifty one-day-old unsexed Ross 308 broilers was conducted in floor litter, during 35 days with initial weight 43g ± 2 were purchased from commercial hatchery. This study was conducted at the Poultry Research Centre at the University of Baghdad . The chicks were divided into 6 treatment groups with five replicated pens (5 birds per pen). Each pen was equipped with a single,tube feeder and adjustable nipple-type drinkers. The treatments consisted of the: G1: supplemented with Iodine (1ppm) in drinking water during all week days of the experimental period (35 days). G2: supplemented with Iodine (1ppm) in drinking water, added 3 days a week. G3: supplemented with Colistine sulphate6 (0.5 mg/liter) in drinking water during all week days. G4: supplemented with Colistin sulphate (0.5 mg/liter) in drinking water, added 3 days a week. G5: vaccinated with NDV (Newcastle disease (La Sota) (intervet, Italy) + IBD (infectious bronchitis disease vaccine, intermediate plus strain, Genera company, Croatia), but did not receive iodine or colistin as consider control positive. G6: Neither vaccination nor iodine or antibiotic as consider control Negative. The birds were raised in two stages consisting of a starter diet up to 21d of age and a finisher diet up to 35 d of age. Diets were prepared to meet the nutrients of broilers of this age according to the recommended laws of (7) (Table1). An iodine-based sterilizer containing 1.75% of tritic iodine (Premis Aqua, West Benetton, Montreal and Quebec) was mixed with water at 1% concentration in a 20 liter container before obtaining final concentration of 1 ppm iodine. The animals were kept in controlled floor pens (50x50x50 cm) for 5 weeks and the access to water and feed was free through the entire experimental period. The lighting program was 23 hours lightness and 1 hour of darkness. The pen temperature was gradually reduced from 33 C° in the first days to 23 C° on day 21. Data collection: Body weight gain (BWG) of broilers were recorded weekly during the experimental period. The final body weight (BW) and feed intake (FI) and feed conversion ratio (FCR) were also recorded. On day 10 and, the birds were vaccinated against NDV (by oral administration) and then followed by booster dose at 20 days of the age except the negative control group. Also the IBD (by oral administration) was offered to the birds on day 12 of age except the negative control group. Blood samples were collected randomly from the jugular vein of 5 chicks in each treatment to evaluate antibodies against ND and IBD were seen in days 12, 20 and 35 of the age using Eliza. In order to determine the total number of bacteria in feace, exetra was collected from 10 birds per treatment from the rectal area by a sterile loop and then mixed together and 10 grams of blended exetra from each treatment taken. The bacteria count were determined by using plate count Yahya Sabah Abdulameer et al /J. Pharm. Sci. & Res. Vol. 10(2), 2018, 408-411