Effects of treatments with cyclooxygenase inhibitors on chickens infected with Eimeria acervulina

Differential immune response to Eimeria maxima infection in fast- and slow-growing broiler genotypes

Very little has been reported comparing resistance to coccidiosis in fast or slow growing broilers, the latter of which are becoming more prevalent in the broiler industry. We examined mRNA expression in the intestines of fast and slow growing broilers following Eimeria infection. We show that by day 13 post-infection (d pi) with 2500 or 7000 oocysts of Eimeria maxima, slower-growing (Ranger Classic) broilers significantly (P < 0.01) upregulated expression of proinflammatory cyclooxygenase genes (LTB4DH, PTSG1 and PTSG2) above that detected in fast growing (Ross 308) broilers. Expression of CD8α mRNA was downregulated in Ross 308 at day 6d pi with either 2500 or 7000 oocysts of E maxima (P < 0.05), compared to uninfected controls, but was not differentially expressed in Ranger Classic. CD4 genes were not differentially expressed in either chicken line infected with either infectious oocyst dose at d6 pi, compared to uninfected controls. However, at d13 pi, CD4 expression was significantly upregulated in both chicken lines infected with either infectious oocyst dose, compared to uninfected controls (P < 0.05) but this was significantly greater in Ranger Classic broilers compared to Ross 308 (P < 0.05). At d13 pi, expression of CD3 chains (required for T lymphocyte activation) was significantly increased in Ranger Classic compared to Ross 308, infected with either oocyst dose (P < 0.05-0.01). Expression of IL-2 and IL-15 mRNA, required for T lymphocyte proliferation was also significantly upregulated, or maintained longer, in Ranger Classic broilers compared to Ross 308. These differences in immune response to E maxima corresponded with a reduction in E maxima genome detected in the intestines of Ranger Classic compared to Ross 308.

Manipulating the immune system for pigs to optimise performance

Disease and enhanced microbial load are considered to be major factors limiting the performance and overall efficiency of feed use by pigs in Australian piggeries. It is recognised that pigs exposed to conventional housing systems with high microbial loads grow 10–20% more slowly than do gnotobiotic pigs or pigs kept in ‘clean’ environments. Consequently, a proportion of pigs in any production cycle are continuously being challenged by their immediate environment, which can cause an immune response to be mounted. Such a process is physiologically expensive in terms of energy and protein (comprised of amino acids), with, for example, the enhanced rate of protein turnover associated with the production of immune cells, antibodies and acute-phase proteins increasing energy expenditure by 10–15% of maintenance needs and protein requirements by 7–10%. The requirements for lysine, tryptophan, sulfur-containing amino acids and threonine can be increased by a further 10%. The over-stimulation of the immune response with excess production of pro-inflammatory cytokines causes excessive production primarily of the prostaglandin E2 (PGE2), which contributes to anorexia, fever and increased proteolysis, and a concomitant reduction in pig performance. Prostaglandin E2 is produced from dietary and cell-membrane phospholipids via secretory phospholipase A2 (sPLA2) to produce arachidonic acid, which is catalysed by the COX-2 enzyme. Negating the negative effects of PGE2 appears not to adversely affect the ability of the immune system to combat pathogens, but improves pig performance. There are negative outcomes for pig health and productivity through both under- and over-stimulation of the immune response. This review briefly outlines the impact of immune stimulation on pigs and discusses strategies to optimise the immune response for pig health and performance.

In vitro activity of the nonsteroidal anti-inflammatory drug indomethacin on a scuticociliate parasite of farmed turbot

The scuticociliatosis produced by the endoparasite Philasterides dicentarchi is a severe parasitic infection of farmed turbot (Scophthalmus maximus) characterized by several histopathological effects including extensive inflammation. Indomethacin is a nonsteroidal anti-inflammatory drug that specifically inhibits synthesis of the proinflammatory mediator prostaglandins. The effect of indomethacin on the in vitro growth of P. dicentrarchi was investigated. In vitro growth of the scuticociliate was significantly inhibited by treatment with 100 microM indomethacin for 48 h. Higher concentrations of indomethacin (mM levels) did not affect the gelatinolytic activity of the cysteine proteinases of P. dicentrarchi. In vitro treatment with 25, 50 or 100 microM indomethacin for 3 days did not significantly affect the enzymatic activity of cysteine proteinases, as assayed with p-nitroanilide as substrate. Immunoblot analysis with anti-cysteine proteinase antibodies revealed an increase in proteinase expression (molecular weights of 80, 32 and 40-45 kDa) in parasite lysates originating from in vitro cultures incubated with 25 microM indomethacin for 72 h. Degradation of genomic DNA of the ciliates was observed in cultures incubated with 100 microM indomethacin for 1, 3 and 7 days. The results suggest that indomethacin is capable of inhibiting in vitro growth of the scuticociliate P. dicentrarchi by a mechanism related to the induction of programmed cell death, without affecting the enzymatic activation of parasite proteinases, which demonstrates the potential therapeutic use of this drug in the control of turbot scuticociliatosis.

Impact of glutamine and Oasis hatchling supplement on growth performance, small intestinal morphology, and immune response of broilers vaccinated and challenged with Eimeria maxima

Seven hundred and twenty hatchling broilers were allotted to 12 treatment groups. Groups 1 and 2 were fasted for 48 h posthatch; groups 3 and 4 were fasted for 48 h followed by ad libitum access to a 1% glutamine (Gln) diet; groups 5 and 6 had ad libitum access to a common diet; groups 7 and 8 had access to a 1% Gln diet posthatch; groups 9 and 10 were fed regular Oasis hatchling supplement; and groups 11 and 12 were fed Oasis sprayed with 1% Gln for the first 48 h posthatch. The birds in treatment groups 2, 4, 6, 8, 10, 11, and 12 were vaccinated with Eimeria maxima posthatch, and all birds were orally challenged with high dose E. maxima on d 22. During the first 2 wk, birds in group 7 had the highest gain and feed efficiency among treatments (P < 0.01). Compared with birds in the nonGln groups, birds in the Gln group had higher gain, feed efficiency, and livability (P < 0.05). Among the Fast (groups 1 to 4), Feed (groups 5 to 8), and Oasis (groups 9 to 12) groups, birds in the Feed groups had the highest gain during d 0 to 21 (P < 0.01). During d 22 to 28, birds in the Fast groups had the lowest BW and livability (P < 0.01), and the nonvaccinated birds had lower gain and feed efficiency relative to vaccinated birds (P < 0.01). Birds in the Feed and Oasis groups had higher villus height (VH) of mid small intestine than Fast groups at d 2 and 7 (P < 0.05), and nonvaccinated birds had higher VH than vaccinated birds (P < 0.01) at d 7 after hatch. On d 14, there were differences in serum interferon-gamma (P < 0.05) levels among treatments. During d 22 to 28, vaccinated birds had lower lesion scores in the mid small intestine than nonvaccinated birds (P < 0.01), and birds in the Feed or Oasis groups had lower lesion scores compared with the Fast groups (P < 0.02). These results indicated the importance of immediate access to feed posthatch, the beneficial effects of feeding Oasis hatching supplement and Gln after hatch, as well as the necessity of the vaccination program against coccidiosis challenge.

Effect of Ibuprofen on Coccidiosis in Broiler Chickens

Ibuprofen (IBU)-a nonsteroidal anti-inflammatory drug-inhibits the biosynthesis of prostaglandins with pro-inflammatory and immunosuppressive properties and is therefore proposed as a candidate molecule for the treatment of coccidiosis in broiler chickens. In all experiments, IBU was administered via drinking water. In a first experiment, chickens were infected at 10 or 21 days of age with oocysts of Eimeria acervulina (5 X 10(4)), Eimeria maxima (3 X 10(4)), and Eimeria tenella (7.5 X 10(3)) and medicated with IBU at a dose of 15 mg/kg body weight (BW). In a second experiment, chickens were infected at 6 days of age with 10(4) oocysts of E. acervulina and medicated with IBU at a dose of 100 mg/kg BW. In the third experiment, an inoculum consisting of 5 x 10(4) or 10(5) E. acervulina oocysts was administered at 6 days of age to chickens medicated with IBU at a dose of 100 mg/kg BW. In a fourth experiment, the effect of IBU on sporulation and infectivity of E. acervulina oocysts was studied. Coccidial lesion scores (CLSs), oocyst shedding, and weight gain were used as evaluation parameters in all experiments except the fourth, where weight gain was not taken into account. In addition, the sporulation percentage was determined in the last experiment. No influence of IBU on the indicated parameters was observed after providing the drug at a dose of 15 mg/kg BW, whereas CLSs and oocyst shedding were reduced when IBU was provided at a dose of 100 mg/kg BW. However, IBU did not significantly show any effect on the degree of sporulation and infectivity of E. acervulina oocysts at a dose of 100 mg/kg BW.