Background: Control and eradication of intestinal infections caused by protozoa are important biomedical challenges worldwide. Prophylactic control of coccidiosis has been achieved with the use of anticoccidial drugs; however, the increase in anticoccidial resistance has raised concerns about the need for new alternatives for the control of coccidial infections. In fact, new strategies are needed to induce potent protective immune responses in neonatal individuals.

Lameness or leg weakness is becoming an important problem in broilers selected for rapid growth, and although the causes are not known, sedentary behavior could be a cause. Two experiments were conducted to study the effects of distance and the presence of ramps between resources (feed and water) on bone and tendon strength, ability to stand, and productive performance. In experiment 1, straight run Ross 708 chicks (n = 1,260) were randomly assigned to 1 of 3 treatments: 1.0, 3.3, or 6.6 m between resources (6 pen replicates/treatment). In experiment 2, Cobb 500 male chicks (n = 864) were randomly assigned to 1 of 4 treatments (2 × 2 factorial, 4 pen replications/treatment) consisting of 2 distances (3 or 8 m) with (WR) or without (NR) a ramp (a triangular prism 31 cm high and 132 cm wide at the base). At d 21, 45, and 56 (experiment 1), or at d 28, 35, 42, and 49 (experiment 2), birds were weighed, killed, and tibias collected to measure breaking strength (BBS), and abdominal fat (AbF) content. At d 49 (experiment 2), calcaneus tendons were also collected to measure breaking strength (TBS). Foot pad lesions and latency to lie (LTL) were determined before killing the birds. In experiment 1, distance did not affect BBS, LTL, foot pad lesions, or BW, but at d 49, birds in the 6.6 m treatment had lower AbF than birds in the other treatments. In experiment 2 at d 49, birds in the 8 m treatment tended to have a higher BBS than birds in the 3 m treatment (P = 0.09), whereas WR birds had lower tendon breaking strength than NR birds (P < 0.01); however, LTL was highest in 8-m NR birds. Final BW was not affected by distance, but birds in the NR group were heavier than birds in the WR group. Furthermore, AbF was lower in 8 m than in 3 m birds. Our results suggest that longer distances between resources have limited effects on bone strength, but increase the LTL, and may change feeding patterns and carcass characteristics, as evidenced by the lower AbF content. Ramps or inclination affected tendon breaking strength.

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The effects of l-Arg, vitamin C (VC), and vitamin E (VE) on xanthine- (XO) and NAD(P)H-oxidase (NOX) activities, and nitric oxide (NO) availability of hypoxic broilers were evaluated. Chickens were kept in wire cages with free access to feed and water. One-day-old chicks were assigned to 1 of 3 diets: control (CTL; ME 3,200 kcal/kg, CP 23%), high Arg (HA; CTL + Arg 0.8%), or high Arg plus VE and VC (AEC; HA + 200 IU of VE/kg of feed + 500 mg of VC/L of water), and grown under hypobaric hypoxia (HYP) from d 7 to 30. A fourth group of birds was fed the CTL diet and grown under normoxia (CTL-NOR). At d 30, chickens were euthanized, their lungs fixed in vivo, excised, and processed for cyto- and histochemistry. The enzymes XO and NOX were localized and activities assessed histochemically and in lung homogenates. The NO depletion was assessed through nitrotyrosine immunocytochemistry colloidal gold particles (NTY). The XO and NOX localized in cell membranes and within vesicles of pulmonary vessel endothelial cells. The XO activity was higher in CTL-NOR birds (586 ± 43 reflectance units) than in both AEC-HYP (456 ± 39) and HA-HYP birds (394 ± 31), whereas CTL-HYP birds had the lowest XO activity (313 ± 27). The NO depletion was not affected by dietary or hypoxia conditions in clinically healthy birds; nevertheless, hypoxic birds that developed pulmonary hypertension had higher NTY levels (less NO, 145 ± 19) than hypoxic but clinically healthy birds (56 ± 11). Thus, the concurrent supplementation of Arg, VE, and VC restored XO activity without affecting NOX activity or NO availability. The dual role of XO, which produces superoxide and uric acid, may have buffered the effects of superoxide in broiler chickens grown under hypobaric hypoxia.

1. Because tylosin is a time-dependent antibacterial agent, and because feeding and drinking of broilers decreases in late afternoon and ceases in the dark, it was hypothesised that serum concentrations of this drug are greatly reduced during the dark period. 2. The trial was carried out in a commercial poultry house, under standard broiler husbandry conditions, with food and water withdrawn from 22:00 until 07:00 h next morning and exposed to a natural light cycle of 13L:11D. 3. Broilers were given tylosin tartrate, in either feed or water, for 5 d as follows: 100, 200 and 300 ppm in feed, equivalent to 12.6, 25.2 and 37.8 mg/kg/d, respectively; and 200 and 400 mg/l in drinking water, equivalent to 51 to 102 mg/kg/d, respectively. 4. At 07:00 h on d 4, and for the next 40 h, hourly serum samples were obtained and analysed for tylosin by means of a microbiological assay. 5. Day vs night concentrations of tylosin expressed as area under the curve (AUC) in all groups revealed greater values during the day. The highest AUC and AUC(24)/minimal inhibitory concentration (MIC) ratio were obtained in the group medicated with 400 mg/l and the corresponding lowest values were found in the group medicated with 100 ppm in feed. 6. In conclusion, tylosin did not reach therapeutic serum concentrations during the dark period, at all dose rates tested when administered in feed or water. A sustained release form of this drug is needed to solve this inadequacy of tylosin medication in broilers.