Hypothermia, hypoglycemia, and hypothyrosis associated with poult enteritis and mortality syndrome

Heat Stress Biomarker Amino Acids and Neuropeptide Afford Thermotolerance in Chicks

With global warming, heat stress is becoming a pressing concern worldwide. In chickens, heat stress reduces food intake and growth, and increases body temperature and stress responses. Although it is believed that young chicks do not experience heat stress as they need a higher ambient temperature to survive, our series of studies in young chicks showed that they are sensitive to heat stress. This review summarizes current knowledge on amino acid metabolisms during heat stress, with special emphasis on the hypothermic functions of l-citrulline (l-Cit) and l-leucine (l-Leu), and the functions of neuropeptide Y (NPY) in terms of body temperature and heat stress regulation in chicks. Amino acid metabolism is severely affected by heat stress. For example, prolonged heat stress reduces plasma l-Cit in chicks and l-Leu in the brain and liver of embryos. l-Cit and l-Leu supplementation affords thermotolerance in young chicks. NPY expression is increased in the brains of heat-exposed chicks. NPY has a hypothermic action under control thermoneutral temperature and heat stress in chicks. The NPY-sub-receptor Y5 is a partial mediator of the hypothermic action of NPY. Further, NPY stimulates brain dopamine concentrations and acts as an anti-stress agent in heat-exposed fasted, but not fed chicks. In conclusion, young chicks can serve as a model animal for the study of heat stress in chickens. l-Cit, l-Leu, and NPY were identified as biomarkers of heat stress, with the potential to afford thermotolerance in chicks.

Central NPY-Y5 sub-receptor partially functions as a mediator of NPY-induced hypothermia and affords thermotolerance in heat-exposed fasted chicks

Exposure of chicks to a high ambient temperature (HT) has previously been shown to increase neuropeptide Y (NPY) mRNA expression in the brain. Furthermore, it was found that NPY has anti‐stress functions in heat‐exposed fasted chicks. The aim of the study was to reveal the role of central administration of NPY on thermotolerance ability and the induction of heat‐shock protein (HSP) and NPY sub‐receptors (NPYSRs) in fasted chicks with the contribution of plasma metabolite changes. Six‐ or seven‐day‐old chicks were centrally injected with 0 or 375 pmol of NPY and exposed to either HT (35 ± 1°C) or control thermoneutral temperature (CT: 30 ± 1°C) for 60 min while fasted. NPY reduced body temperature under both CT and HT. NPY enhanced the brain mRNA expression of HSP‐70 and ‐90, as well as of NPYSRs‐Y5, ‐Y6, and ‐Y7, but not ‐Y1, ‐Y2, and ‐Y4, under CT and HT. A coinjection of an NPYSR‐Y5 antagonist (CGP71683) and NPY (375 pmol) attenuated the NPY‐induced hypothermia. Furthermore, central NPY decreased plasma glucose and triacylglycerol under CT and HT and kept plasma corticosterone and epinephrine lower under HT. NPY increased plasma taurine and anserine concentrations. In conclusion, brain NPYSR‐Y5 partially afforded protective thermotolerance in heat‐exposed fasted chicks. The NPY‐mediated reduction in plasma glucose and stress hormone levels and the increase in free amino acids in plasma further suggest that NPY might potentially play a role in minimizing heat stress in fasted chicks.

Heat Production and Energy Efficiency of Broilers Infected With Necrotic Enteritis

Necrotic enteritis (NE) in poultry is the most important bacterial disease in terms of economic losses. The present study was conducted to evaluate the effect of an experimental challenge with necrotic enteritis on respiration and heat production in birds pretreated with dietary acylated starch or antibiotics (AB) zinc bacitracin (50 mg/kg) plus salinomycin (60 mg/kg). In total, 48 1-day-old Ross 308 male broilers were assigned to floor pens until day 10. On day 11, birds were randomly placed into 16 calorimetric chambers with four replicates of three birds per treatment. Treatments were: control, AB, acetylated high-amylose maize starch (SA), or butyrylated high-amylose maize starch (SB). Birds were NE challenged by inoculation with 5000 sporulated oocysts each of Eimeria maxima and Eimeria acervulina and 2500 sporulated oocysts of Eimeria brunetti on day 9 and Clostridium perfringens (3.8 × 10(8) colony-forming units) on day 14. The results showed that heat production (HP), respiratory quotient (RQ), heat increment, weight gain (WG), feed intake (FI), and livability (LV) of birds fed control, SA, and SB diets were lower than birds fed AB at 19 and 42 hr postinoculation (P < 0.05). At 65 hr postchallenge, increased FI and WG of birds were observed, indicating recovery from NE. During the entire period, from day 14 to day 17, birds fed control, SA, and SB had lower WG, FI, HP, RQ, metabolizable energy intake (MEI), and metabolizable energy (P < 0.01) than those fed AB. The data demonstrate that Eimeria sp. and C. perfringens challenge reduces growth performance, HP, RQ, metabolizable energy, and MEI of birds fed control, SA, and SB but not AB diets.

Glucose and electrolyte supplementation of drinking water improve the immune responses of poults with inanition

Enteric disorders predispose poultry to malnutrition. The objectives of this paper were 1) to simulate the inanition of poult enteritis mortality syndrome by restricting feed intake and 2) to develop a drinking water supplement that supports the immune functions of poults with inanition.

Poults were restricted to 14 g of feed/d for 7 d beginning at 14 d of age then fed ad libitum until 36 d (recovery). The control was fed ad libitum. During the feed-restriction period, duplicate groups of 6 poults received 1 of 5 drinking water treatments: 1) restricted feed, unsupplemented water; 2) restricted feed + electrolytes (RE); 3) RE + glucose + citric acid (REGC); 4) REGC + betaine (REGCB); or 5) REGCB + zinc-methionine (REGCBZ). Immunological functions were assessed by inoculating poults with SRBC and B. abortus (BA) antigen at 15, 22, and 29 d of age. Antibody (Ab) titers were determined 7 d later for primary, secondary, and recovery responses. The primary and secondary total Ab titers to SRBC for restricted feed were 4.71 and 6.16 log₃, which where lower (P < 0.05) than for controls (8.00 and 9.66 log₃) and the other treatments. The recovery Ab titer for controls was 10.7, significantly higher than restricted feed (8.71) and RE (8.10) groups but not different from other treatments. The primary total Ab responses to BA were significantly lower in the restricted feed and RE groups as compared with the control and other treatments. Although feed restriction of poults to maintenance reduces the humoral immune responses, these responses can be significantly improved by drinking water containing electrolytes and especially sources of energy such as glucose and citric acid.

Sequence analysis of the S3 gene from a turkey reovirus

The deduced sigma-2 protein sequence from the S3 gene segment of a novel turkey reovirus, designated NC98, isolated from the bursa of birds exhibiting poult enteritis and mortality syndrome was determined. The isolate, serologically distinct from other avian reoviruses, was isolated in turkey embryo kidney cells and RNA was purified for cDNA synthesis. Oligonucleotide primers were designed based on conserved avian S3 nucleotide sequence data. The NC98 S3 open reading frame comprised 1,101 base pairs and encoded 366 amino acids with a predicated molecular mass of 40.5 kDa. Although the S3 nucleotide sequence from several chicken isolates share at least 86% identity, they share only 64% with the NC98 turkey isolate. Interestingly, the S3 nucleotide sequence from a muscovy duck reovirus shares 55% identity with NC98 and 53% identity with chicken isolates. As observed in other avian reovirus sigma2 protein sequences, a zinc-binding motif and double-stranded RNA binding domain were found within the predicted amino acid sequence of NC98. Phylogenetic analysis of the deduced sigma2 sequence demonstrated that NC98 separated as a distinct virus relative to other avian strains. The results of this study indicate that NC98 is a novel turkey reovirus that shares limited genomic sequence identity to isolates of chicken and duck origin and should be considered a separate virus species within subgroup 2 of the Orthoreovirus genus.

Influence of BioChrome on the response of metabolic hormones in PEMS-infected poults

Poult enteritis and mortality syndrome (PEMS), a disease that affects turkeys between 7 and 28 d of age, causes a severe inflammation of the intestinal tract and is characterized in poults by severe diarrhea, high morbidity, mortality, and stunting. The PEMS-associated mortality and growth depression is related to malabsorption and decreased metabolic activity caused, in part, by a possible insulin deficiency or insensitivity. Insulin receptors are stimulated by the glucose tolerance factor (GTF) that incorporates Cr. Body Cr deficiency can be exacerbated by dietary deficiency and by increased excretion due to stress associated with a diarrheal disease such as PEMS. BioChrome (BC) contains natural, preformed GTF, the bioactive form of Cr. Experiments were conducted in which BC was blended into poult starter feed at 400 ppb during the first 21 d posthatch. Body weights were determined at 1, 7, 14, and 21 d of age, and weekly feed conversions were calculated for each treatment group (control, BC, PEMS, and BC+PEMS). At 6 d post-hatch, each PEMS-designated poult was given a 0.1-mL oral gavage of a 10% suspension of feces from PEMS-infected poults. Blood samples were taken via cardiac puncture from four birds per treatment group at 7, 10, 14, 17, and 21 d of age. Radioimmunoassays were conducted for plasma insulin, glucagon, thyroxine (T4), and triiodothyronine (T3). Plasma insulin levels were depressed in PEMS-infected poults from Days 10 through 17, but plasma glucagon levels in the PEMS-infected poults were significantly elevated at 14 and 17 d, after which they returned to control levels in both of the PEMS-infected groups. The T3 and T4 levels were depressed through Day 21 in PEMS-infected poults, but with BC treatment these blood hormone levels rebounded by Day 21. Body weights of PEMS-infected poults were increased significantly by the BC treatment but not to the level of noninfected controls.

D-xylose absorption as a measurement of malabsorption in poult enteritis and mortality syndrome

Severe wasting of body tissues, diarrhea, high morbidity and mortality, and stunting are all characteristics of poult enteritis and mortality syndrome (PEMS). The wasting of musculature and loss of nearly all adipose tissue suggested that even though the PEMS-infected poults were eating some feed, nutrient intake was not sufficient to meet body requirements for maintenance and growth. Because epithelial cells in the gastrointestinal tract appeared to be a target of the undefined etiological agent (or agents) that causes PEMS, a study was conducted in which PEMS-infected poults were evaluated for malabsorption through 3 wk of age. D-Xylose, a poorly metabolized pentose, was given per os as a bolus, and blood samples were obtained from the ulnar vein in the wing of control and PEMS-infected poults over a 3-h period to estimate intestinal absorption. D-Xylose absorption in control poults peaked 30 to 60 min after the oral treatment, similar to results reported earlier. The PEMS-infected poults did not show a peak in absorption. The PEMS-infected poults showed significant delays in D-xylose absorption at 4, 7, and 11 d after PEMS challenge. The severe malabsorption and metabolic deficiency problem associated with PEMS was postulated to be a direct effect of the undefined infectious agent or agents that cause the disease.

Tryptophan methylester modulation of poult responses to Bordetella avium

On the day of hatching, four groups of poults [Control, L-tryptophan methylester (LTME), Bordetella avium-infected, and B. avium-infected plus LTME] were established and placed into heated metal brooding batteries. Bordetella avium infection caused a significant depression in body temperature within 24 h after intranasal challenge with the W strain, and the hypothermia persisted through 21 d of age. L-Tryptophan methylester, a water-soluble form of tryptophan, was given by oral gavage daily in saline at a concentration of 50 mg per poult beginning 4 d after hatch. Within 2 d after initiation of LTME treatments, colonic temperature of B. avium-infected poults was elevated to the level of Controls and remained at that level throughout the experimental period. The BW of B. avium-infected poults were reduced significantly. The LTME treatment caused a significant BW increase in the B. avium-infected poults, but the increase was not to the level of Controls. The anti-sheep red blood cell antibody titers in B. avium-infected poults were not affected significantly. However, LTME treatment induced a significant increase in anti-sheep red blood cell antibody titers in both the infected and Control poults. Based upon data reported herein, it was concluded that feed intake depression associated with development of bordetellosis caused the poults to react more specifically to a mild tryptophan deficiency than to other nutrient deficiencies. The tryptophan deficiency caused a growth depression that was only partially alleviated by daily supplementation of LTME. The physiological responses to daily supplementation of LTME to B. avium-infected poults suggested that growth depression and poor performance was not limited to dietary deficiency of tryptophan.