Association between weight gain, blood parameters, and thyroid hormones and the development of ascites syndrome in broiler chickens

The effect of peroxisome proliferator-activated receptor gamma (PPARγ) as a mediator of dietary fatty acids and thiazolidinedione in pulmonary arterial hypertension induced by cold stress of broilers

The objective of this experiment was to evaluate the effects of dietary fish oil and pioglitazone as peroxisome proliferators-activated receptor gamma (PPARγ) activating ligands on the reduction of cold-induced ascites in broiler chickens. A total of 480 one-day-old (Ross 308) male chicks were randomly allocated to four treatment groups with eight replicates of 15 birds each. The following treatments were used: 1) ambient temperature (negative control), with basal diet; 2) cold-induced ascites (positive control), with basal diet; 3) cold-induced ascites, with basal diet +10 mg/kg/day pioglitazone and 4) cold-induced ascites, with basal diet +1% of fish oil. When compared with the positive control, body weight gain was higher (P ≤ 0.05) for broilers fed diets containing fish oil and pioglitazone at 28, 42, and 0-42 d. Broilers under cold-induced ascites had the highest blood pressure at 21 and 42 d, while fish oil and pioglitazone treatment reduced the blood pressure (P ≤ 0.05). Red blood cells, white blood cells, hematocrit, erythrocyte osmotic fragility, bursa of Fabricius and spleen weights were improved (P ≤ 0.05) for chickens fed fish oil diets and pioglitazone compared to the cold-induced ascites (positive control). Exposure to cold temperature resulted in an increase in plasma T3 and T3/T4 ratio and decline in plasma T4 (P ≤ 0.05). In conclusion, PPARγ agonist pioglitazone and fish oil as source of omega-3 polyunsaturated fatty acid could be used as a strategy to reduce the negative effects of pulmonary arterial hypertension and ascites in broiler chickens.

Sudden death syndrome in broiler chickens: a review on the etiology and prevention of the syndrome

Sudden death syndrome (SDS) is a condition in which apparently healthy broiler chickens die suddenly. There are short convulsions and frantic wing-beating prior to death, and the weight of internal organs is the same as in healthy chickens. The exact etiology of SDS is unknown. Heart problems have been implicated as a potential cause of the disease in broiler chickens. Despite considerable research, effective methods of prevention are still being sought. Furthermore, the prophylactic measures often make production less profitable (reduced body weight gain resulting from restricted feeding) and prolong the growth period. It is necessary to continue research on SDS, in particular on stimulation of the cardiovascular system to reduce the susceptibility of broilers to sudden death syndrome under intensive production systems.

Effects of low eggshell temperatures during incubation, in ovo feeding of L-arginine, and post-hatch dietary guanidinoacetic acid on hatching traits, performance, and physiological responses of broilers reared at low ambient temperature

This study aimed to investigate the effect of eggshell temperature (ET) manipulations during incubation, in ovo feeding (IOF) of arginine, and post-hatch dietary supplementation with guanidinoacetic acid (GAA) on hatching traits and subsequent growth and physiological performance of hatched broiler chicks reared under subnormal temperature. In experiment 1, from d 8 of incubation onward, a total of 2,160 hatching eggs were randomly arranged in a 2 × 3 factorial design, in which the eggs were exposed to 2 ET (37.8°C or periodically low ET), and 3 IOF treatments (noninjected, diluent-injected, and 1% arginine solution-injected). In experiment 2, a total of 576 one-day-old male broiler chicks from 2 temperature conditions and 2 IOF treatment groups (noninjected and Arg-injected) were reared for 42 d with or without GAA supplementation in a 2 × 2 × 2 factorial design. Each treatment had 6 replicates with 12 birds each. A subnormal ambient temperature (17°C) was applied from 15 d onward to induce ascites. Results from experiment 1 showed a 2-way interaction between ET and IOF for embryonic mortality rate during 19 to 21 d of incubation and residual yolk weight at hatch (P < 0.05). A periodically low ET significantly increased yolk free body mass, first-grade chicks, and relative heart weight than an ET of 37.8°C. In the second experiment, overall average daily gain (ADG) was increased, but feed conversion ratio (FCR), ascites mortality, and serum thyroid hormones and corticosterone were reduced in the low ET group (P < 0.05). There were also IOF × GAA interactions for ADG and FCR (P < 0.05). IOF of arginine or dietary GAA increased serum nitric oxide concentration and jejunal villus height, but decreased ascites mortality (P < 0.05). In conclusion, a periodically low ET accompanied by IOF of arginine during incubation and posthatch dietary supplementation with GAA could be a useful strategy for improving the chick quality at hatch and subsequent improvements in post-hatch performance and ascites indices in cold-stressed broilers.

Changes in the expression of cardiac genes responsive to thyroid hormones in the chickens with cold-induced pulmonary hypertension

Cold stress is an environmental cause of pulmonary hypertension syndrome (PHS) in broiler chickens. This factor could increase the rate of metabolic activity via thyroid hormones (T3 and T4). To evaluate the effect of these hormones on the heart, the plasma concentration of T3, T4, and the gene expression of their receptors (THRα and THRβ) and many contractile proteins (ACTC1, MHCα, MHCβ, RYR2, SERCA2, THRα, THRβ, and troponin I) were measured in the right ventricle in 2 periods of age (21 and 35 d). Plasma T3 concentration was significantly higher in the PHS group of chickens than in the control one at 21 and 35 d while plasma T4 did not change. The relative expression of MHCα, RYR2, SERCA2, and THRα genes in the right ventricle tissues was only higher in PHS group of broilers than control group at 21 d (P < 0.05) whereas the expression of ACTC1, MHCβ, and troponin I did not differ at 2 periods of age. The positive correlations between MHCα, RYR2, SERCA2, and T3, THRα were confirmed. The expression of THRβ gene was only higher in PHS group of broilers than control at 35 d (P < 0.05). The data determined that cold stress could increase thyroid hormones and the gene expression of their receptor (THRα) in the pick of chicken growth (21 d) that they themselves elevates the expression of many genes related to contractile elements (MHCα, RYR2, and SERCA2), leading to adaptive right ventricle hypertrophy.

Effects of photoperiod on thyroid gland development and function in growing chicks: a biochemical and morphometric study

Context Light treatment has a regulatory role in some growth-related functions, including thyroid development in chicks. Aims This study aimed to investigate the effects of different photoperiod treatments on thyroid organ weight and serum thyroid hormone concentrations of broilers by use of biochemical and histological methods. Methods After the hatching, 120 broiler chicks (Ross) were divided into two main groups according to sex. Both groups were then split into two sub-groups based on photoperiod treatment: 16 h (i.e. 16 h light:8 h dark) and 24 h (24 h light:0 h dark). Thyroid gland and blood samples of six animals from each group were obtained after slaughtering at 7-day intervals from Day 14 after hatching to Day 42. Serum concentrations of free triiodothyronine (FT3), free thyroxin (FT4) and thyroid-stimulating hormone (TSH) were determined by the chemiluminescence method for all groups. Thyroid weight, bodyweight and thyroid follicle diameter were also measured. Key results Thyroid weight:bodyweight ratio generally started to increase from Day 14 to Day 42, with no significant (P &gt; 0.05) difference among the groups at the same age. For both male and female broiler chicks, morphometric measures increased as birds grew. Serum FT3 and TSH concentrations slightly decreased and serum FT4 concentrations increased in growing chicks of both sexes. Conclusions Extending the photoperiod from 16 to 24 h had no effects on thyroid gland development or functions in terms of both biochemical and morphometric parameters in broiler chicks. Implications Continuous light has minimal effects on thyroid functions of growing broiler chicks to Day 42.

Evaluation of cardiac status, ascites related factors and growth performance of five commercial strains of broiler chickens

The aim of the current study was to evaluate cardiac status, ascites susceptibility, thyroid hormones, some hematological parameters and performance of five commercial broiler strains. Chicks were selected from strains of Cobb, Hubbard, Ross 308, Arbor Acres, and Arian (Iranian commercial broiler strain). Management and nutritional conditions were the same for all strains. Ascites related factors, and growth performance were measured. The highest and lowest, RV weight/live weight at 21 day of age were related to Arian and Ross 308 strains, respectively (p < 0.05). The TV weight, TV weight/live weight and the RV weight/live weight were significantly different between various strains at 49 and 54 days of age (p < 0.05). Strain had no effect on RV/TV. Performance, T3 and T4 hormones, hematological parameters, and mortalities were not significantly different among the strains (p > 0.05). Ascites mortalities in the Ross 308 was zero; however, it had no significant difference with other strains (p > 0.05). It was concluded that, based on performance and physiological status, even though considered broiler strains did not differ significantly because of the same genetic programs probably, but according to the prices and market conditions each can be selected for breeding.

Effect of cyclic heat stress on thyroidal hormones, thyroid histology, and performance of two broiler strains

This study determined thyroid hormone (T₃ and T₄) serum levels and investigated thyroid gland histology, as well as two broiler strains performance kept at different periods of heat stress. Broilers (560 Cobb Slow™ and 560 Hubbard Flex™) were distributed in control environment (0) reared following the thermal recommendations, and environments 1, 2, and 3 exposed to high temperatures for 1 h, 2 h, and 3 h a day, respectively, from 14 to 42 days old. At 21, 28, 35, and 42 days old, blood samples were collected to determine T₃ and T₄ serum levels. At 42 days old, thyroid glands were removed for histological analyses. The performance was calculated weekly. T₃ levels decreased with age advance, while T₄ serum concentration was higher at 42 days old (23.27 nmol L^-1) and lower at 28 days old (15.69 nmol L^-1). The histological sections revealed that thyroid morphology was well preserved. Live weight was higher in Cobb Slow™ (2.97 kg) than Hubbard Flex™ (2.93 kg) broilers at 42 days old. It is possible to conclude that cyclic heat stress exposure for a 3-h period from 14 to 42 days old did not affect performance, thyroid histology, or T₃ and T₄ serum levels. Cobb Slow™ broilers had the best live weight values at slaughtering. With increasing age, T₃ levels decreased and T₄ levels increased for both strains.

The long-term oral administration of thyroxine: effects on blood hematological and biochemical features in broiler breeder hens

Published data on the beneficial effect of short-term administration of thyroxine (T₄) in broiler breeder hens to reduce the ascites incidence in their progeny chicks raises the question as to what extent might the long-term maternal administration of T₄ affect the blood hematological and biochemical attributes in breeder hens. A total of 70 broiler breeder hens (47-wk-old) were randomly allotted to control or thyroxine treated (T₄) groups. Pure T₄ (0.3 mg/bird per day) was orally administered to T₄ birds for 14 successive weeks, whereas the control group received the drinking water only. Blood samples were obtained from the brachial vein prior to the initiation of the trial as well as weeks 50, 53, 55, 57, 59, and 61 of age. Body weight was decreased but egg production was not affected by T₄ treatment. Plasma concentration of T₄, but not triiodothyronine (T₃), was increased in T₄-treated hens (P < 0.05). The total number of leukocytes and erythrocytes were also higher in T₄ birds. A significant effect of time was observed for erythrocyte number and plasma cholesterol concentration (P < 0.05). The long-term administration of T₄ did not affect the concentrations of serum calcium and plasma total protein, albumin, globulin, cholesterol, triglyceride, high density lipoprotein, low density lipoprotein, very low density lipoprotein, alanine amino transferase, and aspartate amino transferase (P > 0.05). However, serum concentrations of phosphorus, glucose, and alkaline phosphatase were higher in T₄ hens as compared to their control counterparts. In spite of differences in circulatory concentrations of a number of traits between the experimental groups, the recorded values were within their reference ranges. Therefore, the administration of T₄ for an extended period of time had no apparent adverse effect on the clinical profile in subjected hens, which may practically support the implementation of this preventative treatment as an approach to decrease the ascites incidence; however, a lower incidence rate in the progeny chicks produced from hens receiving T₄ for long-term periods of time remains to be elucidated.

Effects of light-sources and photoperiod on hemato-physiological indices of broilers grown to heavy weights

We evaluated the influence of light sources and photoperiod on blood physiological variables in four trials. In each trial, 720 1-d-old Ross × Ross 708 chicks were randomly distributed into 12 environmentally controlled rooms (30 males/30 females/room). The experimental design was a 4 × 3 factorial treatments consisting of four light sources [incandescent (ICD, standard), compact fluorescent, neutral light emitting diode, and cool poultry-specific-filtered LED] and three photoperiods [long/continuous (23L:1D), regular/intermittent (2L:2D), and short/non-intermittent (8L:16D)] from d8-d56 at 50% relative humidity. Birds were fed the same diet, while feed and water were provided ad libitum. Blood samples were collected from the brachial wing vein on d 14, 28, 42, and 56 of age and analyzed immediately. Light sources had significant (P ≤ 0.05) effects on body weight (BW), and some of the selected blood physiological indices except Hb, Hct, Ca2+ angap, glucose, and corticosterone. Also, the photoperiods had significant (P ≤ 0.05) effects on BW and most of the selected blood physiological indices except HCO3-, angap, glucose, corticosterone, and T4. However, all these changes were still within the normal acid-base homeostasis and physiological ranges of this species. Acid-base regulation during the short photoperiod exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH, due to a respiratory acidosis. Plasma corticosterone and glucose concentrations were not affected by treatments, suggesting an absence of physiological stress. It was concluded that the three LED light bulbs evaluated could be suitable for replacement of ICD along with the regular/intermittent photoperiod. Commercial poultry facilities can thereby reduce energy costs and optimize production efficiency without compromising the welfare of broilers grown to heavy weights (>3 kg).

Securigera securidaca seed medicinal herb supplementation of diets improves pulmonary hypertensive response in broiler chickens reared at high altitude

This experiment was conducted to evaluate the effects of dietary Securigera securidaca seed powder on growth performance, haematological parameters, cardiac indices, electrocardiographic parameters and expression of catalase (CAT), endothelin 1 (ET-1) and inducible nitric oxide synthase (iNOS) genes in the lung in the broilers reared at high altitude (2,100 m above sea level). A total number of 200-day-old male broilers (Ross 308) were randomly assigned to five treatments including different levels of S. securidaca 0, 1, 2, 3 and 4 g/kg in a 42-day trial. The results of this experiment showed that the dietary inclusion of S. securidaca powder improvement in feed conversion ratio (p < 0.05). The dietary utilization of 2-4 g/kg S. securidaca significantly increased concentrations of nitric oxide (NO), although significantly lower serum concentrations of malondialdehyde (MDA) and significantly decrease T, R, S electrocardiogram waves compared with control group. Also, the dietary inclusion of 2-4 g/kg S. securidaca prevented right ventricular hypertrophy and increased the expression of iNOS and CAT genes in lung tissue of broilers. On the other hand, S. securidaca significantly suppressed the expression of ET-1 in lung tissue. Generally, the results of this study showed that the use of 3 g/kg of medicinal plant S. securidaca can be beneficial in prevention of pulmonary hypertension syndrome (PHS) in broiler chickens reared at high altitudes.

Tanshinone IIA protects against pulmonary arterial hypertension in broilers

This investigation was conducted to study the effects of tanshinone IIA (TIIA) on pulmonary arterial hypertension (PAH) in broilers. Two-hundred newly hatched Arbor Acre commercial broilers were randomly divided into 3 groups. All groups, with the exception of the control group (tap water), were given NaCl water (0.3%) starting on the d 15, and broilers in the protected group were fed a diet supplemented with TIIA (2.5 g/kg) starting on the d 15. On d 28, 35, 42, and 49, the ratio of the right ventricular weight to the total ventricular weight (RV: TV) and the values of other biochemical indicators for each group chickens were determined. The concentrations of interleukin-6 (IL-6), interleukin-1β (IL-1β), nuclear factor kappa (NF-κB), and P38 (a mitogen-activated protein kinase) were measured using enzyme-linked immune sorbent assays (ELISA). The results showed that the proportion of chickens in the diseased group with an RV:TV ratio in the range of 0.250 to 0.299 (10%) was significantly higher (25 to 30%) compared to that of the other groups (P < 0.05), and the proportion in all chickens was 28%. In addition, the IL-6, IL-1β, NF-κB, and P38 protein concentrations were higher in the diseased group, whereas there were no differences between the control group and the protected group. Moreover, the measurements of body weight, liver function, kidney function and electrolytes showed significant differences between the diseased group and the other groups. These findings suggest that tanshinone IIA may protect broilers from PAH, which is an important piece of information for the poultry industry.

Whole genome resequencing identifies the CPQ gene as a determinant of ascites syndrome in broilers

BACKGROUND

Ascites syndrome is the most severe manifestation of pulmonary hypertension in fast-growing broilers. The disease can be attributed to increased body weights of birds, where the higher metabolic load is not matched by sufficient oxygen supply to the cells and tissues. Although there are environmental components, the disease exhibits moderate to high heritability. The current study uses high throughput whole genome resequencing (WGR) to identify genes and chromosomal regions associated with ascites.

RESULTS

The WGR data identified the CPQ gene on chromosome 2. The association was confirmed by genotyping a large collection of DNAs from phenotyped birds from three distinct broiler lines using SNPs in intron 6 and exon 8 of the CPQ gene. By combining the genotype data for these two SNP loci, we identified three different alleles segregating in the three broiler lines. Particular genotypes could be associated with resistance to ascites. We further determined that particular genotypes most associated with resistance overexpress CPQ mRNA in three tissues which might explain the role of these alleles in contributing to resistance.

CONCLUSIONS

Our findings indicate CPQ is an important determinant of pulmonary hypertension syndrome leading to ascites in broilers. We identified particular SNPs that can be used for marker-assisted selection of broilers for resistance to the disease. Our findings validate WGR as a highly efficient approach to map determinants contributing to complex phenotypic or disease-related traits. The CPQ gene has been associated with pulmonary hypertension in genome-wide association studies in humans. Therefore, ascites investigations in broilers are likely to provide insights into some forms of hypertension in humans.

Effects of purslane (<i>Portulaca oleracea</i> L.) powder on growth performance, blood indices, and antioxidant status in broiler chickens with triiodothyronine-induced ascites

Abstract. This study was carried out to evaluate the effects of dietary supplementation of purslane powder (PP) on performance, blood indices, and antioxidant status in broilers with triiodothyronine (T3)-induced ascites. In total, 240 one-day-old male broiler chicks (Ross 308) were randomly assigned to four treatments, with four replicates per treatment and 15 birds per replicate. The experimental diets included (i) a control diet, (ii) a control diet plus 1.5 mg kg−1 of T3 (T3 diet), (iii) a T3 diet with the addition of 1.5 g kg−1 of PP, and (iv) a T3 diet with the addition of 3 g kg−1 of PP. Feed intake and body weight were measured at 10, 24, 39, and 49 days of experiment. Blood and liver samples were collected from two birds in each replicate at 24 and 49 days of experiment. The T3-treated birds had higher (P < 0. 05) right ventricle to total ventricle (RV ∕ TV) ratio and mortality due to ascites compared with the control. In addition, during the entire experimental period (0 to 49 days of experiment) the T3-treated birds had lower (P < 0. 05) feed intake, body weight gain, and production efficiency index and higher (P < 0. 05) feed conversion ratio compared with the control. Dietary supplementation of PP reduced (P < 0. 05) mortality due to ascites and RV ∕ TV ratio, while the production efficiency index was increased (P < 0. 05) by the addition of PP to the diet. The T3-treated birds had higher (P < 0. 05) red blood cell counts, hematocrit percentage, and hemoglobin concentration compared with the control at 24 and 49 days of experiment. Dietary supplementation of PP substantially alleviated (P < 0. 05) the negative effects of T3 on hematocrit and hemoglobin values at both 24 and 49 days of experiment and on red blood cells counts at 49 days of experiment. The T3 birds showed an increase (P < 0. 05) in activities of lactate dehydrogenase, alanine aminotransferase, and aspartate aminotransferase at 49 days of experiment. However, the detrimental effect of T3 on alanine aminotransferase activity was attenuated (P < 0. 05) by dietary supplementation of PP. The plasma and liver activities of superoxide dismutase, catalase, and glutathione peroxidase were lower (P < 0. 05) in T3-treated birds compared with the control at 24 and 49 days of experiment, whereas malondialdehyde concentrations were elevated (P < 0. 05) by dietary T3 administration. Dietary supplementation of PP, especially at 3 g kg−1, increased (P < 0. 05) the plasma and liver activities of antioxidant enzymes, and reduced (P < 0. 05) the plasma and liver concentrations of malondialdehyde near to the control levels. It is concluded that the supplementation of 3 g kg−1 of PP in diet improves oxidative status and reduces ascites incidence in broiler chickens without impairing their growth performance.

Effects of dietary glutamine and arginine supplementation on performance, intestinal morphology and ascites mortality in broiler chickens reared under cold environment

Objective

An experiment was conducted to evaluate the effects of dietary glutamine (Gln) and arginine (Arg) supplementation on performance, intestinal morphology and ascites mortality in broilers.

Methods

A total of 675 day old chicks were randomly allocated to 9 experimental groups in a 3×3 factorial arrangement based on a completely randomized design with 5 replicates of 15 chicks. Three levels of dietary Gln (0%, 0.5%, and 1%) and Arg (100%, 130%, and 160% of Ross recommendation) supplementation were used in ascites inducing condition (15°C ±1°C) from 7 to 42 days of age.

Results

Dietary supplementation of Gln increased body weight gain during grower, finisher and total periods (p<0.05) and increased feed intake during total period. Ascites mortality was decreased by Gln supplementation (p<0.05). Gln supplementation increased the villus height (VH) and crypt depth (CD) in duodenum and jejunum (p<0.05). Arg supplementation decreased CD in duodenum and jejunum, and increased ileum villus width (VW) and also VH/CD ratio in duodenum and jejunum (p<0.05). Both Gln and Arg increased the goblet cell number (GCN) in duodenum whereas Gln supplementation decreased GCN in jejunum and ileum (p<0.05). The Gln×Arg interaction were observed for right ventricle (RV)/total ventricular (TV) ratio, VH, VW, CD, VH/CD.

Conclusion

It was concluded that dietary 0.5% Gln alone or along with 130% Arg of Ross requirement, improve the intestinal morphology and performance and hence decrease the ascites mortality in broiler chickens with cold induced ascites.

Influence of dietary glutamine supplementation on performance, biochemical indices and enzyme activities in broilers with cold-induced ascites

This study was conducted to investigate the effects of dietary glutamine supplementation on performance and biochemical indices of broilers with cold-induced ascites. A total of 240 1-day-old male broiler chicks (Ross 308) were randomly allotted to three treatment groups, with four replicate pens per treatment and 20 birds per pen. The control birds were kept in a thermoneutral chamber and fed a basal diet, whereas the other two experimental groups were kept in a cold chamber to induce ascites and fed the basal diet supplemented with either 0 or 100 mg of glutamine/kg. The cold-treated birds consumed less (P < 0.05) feed and had lower (P < 0.05) weight gain compared with the control birds. Dietary glutamine supplementation had no effect (P > 0.05) on broiler performance. The cold-treated birds had higher (P < 0.05) right ventricle to total ventricle ratio and mortality due to ascites compared with the control birds. However, mortality due to ascites and right ventricle to total ventricle ratio was reduced (P < 0.05) by dietary glutamine supplementation. The cold-treated birds had higher (P < 0.05) red blood cell counts, haematocrit percentage and haemoglobin concentration compared with the control birds at 21 and 42 days of age. The activities of plasma lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were increased (P < 0.05) in cold-treated birds compared with the control birds at 42 days of age, but dietary glutamine supplementation reduced (P < 0.05) the activities of alanine aminotransferase and aspartate aminotransferase near to the control levels. The plasma and liver glutathione peroxidase activities were increased (P < 0.05) in cold-treated birds compared with the control birds at 21 and 42 days of age, whereas the reverse was true for malondialdehyde concentrations. The glutathione peroxidase activity was increased (P < 0.05), whereas the malondialdehyde concentration was decreased (P < 0.05) by dietary glutamine supplementation compared with the cold-treated birds at 42 days of age. The results indicated that the beneficial effect of glutamine is probably related to its ability to maintain near to normal free radical scavenging enzymes and the level of glutathione peroxidase bioactivity, thereby protecting cell membranes from oxidative damage via decreased lipid peroxidation.

Effects of low ambient temperatures and dietary vitamin C supplement on growth performance, blood parameters, and antioxidant capacity of 21-day-old broilers

The study was conducted to determine the effects of low ambient temperature (LAT) and a vitamin C (VC) dietary supplement on the growth performance, blood parameters, and antioxidant capacity of 21-d-old broilers. A total of 400 one-day-old male Cobb broilers were assigned to 1 of 4 treatments as follows: 1) LAT and a basal diet; 2) LAT and a basal diet supplemented with 1,000 mg of VC/kg (LAT + VC); 3) normal ambient temperature (NAT) and a basal diet; 4) NAT and a basal diet supplemented with 1,000 mg of VC/kg (NAT + VC). All birds were fed to 21 d of age. Broilers in groups 1 and 2 were raised at 24 to 26°C during 1 to 7 d, and at 9 to 11°C during 8 to 21 d, whereas groups 3 and 4 were raised at 29 to 31°C during 1 to 7 d and at 24 to 26°C during 8 to 21 d. The LAT increased the feed conversion ratio during the whole experimental period (P < 0.01), whereas it increased heart index at 21 d (P < 0.05) and hematocrit and hemoglobin level at 14 d (P < 0.05). Supplementing the diet with VC increased hematocrit, hemoglobin, and red blood cell count at 21 d (P < 0.05). At 21 d, LAT conditions decreased total antioxidant capacity in the serum, liver, and lungs (P < 0.05), and it also increased the levels of VC in the serum and liver, the amount of protein carbonylation in liver and lungs, and the malondialdehyde level in the lungs (P < 0.05). The addition of VC tended to increase the total antioxidant capacity level in serum (P < 0.1). Low ambient temperature resulted in oxidative stress for broilers that were fed from 1 to 21 d of age, whereas no significant effect was found on the antioxidant activity by dietary VC supplementation.

The effects of turmeric supplementation on antioxidant status, blood gas indices and mortality in broiler chickens with T(3)-induced ascites

1. A total of 320 one-day-old Ross male broiler chickens were used to investigate the effects of 0·0, 2·5, 5·0 and 7·5 g/kg turmeric rhizome powder (TRP) in the diet, on antioxidant status, biochemical gas indices and mortality in broiler chickens with triiodothyronine (T(3)) induced ascites. 2. The TRP supplementation had no effect on blood pH, pO(2) or pCO(2) during the whole period of study. Moreover, supplementation of TRP did not influence the heart weight, right ventricle, left ventricle, or total ventricle weights, all relative to total live weight; RV/TV (right ventricle to total ventricle) ratio; or serum GPX (glutathione peroxidase) or SOD (superoxide dismutase) activities at week 6. 3. TRP supplementation influenced the blood [Formula: see text] and O(2) saturation during the whole period of study, total mortality due to ascites, and serum total tocopherol and malondialdehyde (MDA) contents. Blood [Formula: see text] and serum total tocopherol increased linearly as dietary TRP level increased. Blood O(2) saturation increased quadratically as dietary TRP increased. 4. Total ascites mortality and serum MDA content decreased linearly with increasing TRP level to 5 mg/kg and then reached a plateau. 5. The results of the study indicate that the addition of 5·0 g/kg TRP is sufficient to increase the blood O(2) saturation and bicarbonate ([Formula: see text]) concentration, and reduce the mortality due to ascites and serum MDA content.

Improvement of cold resistance and performance of broilers by acute cold exposure during late embryogenesis

The aim of this study was to fine-tune previous acute cold exposure treatments of broiler embryos during late embryogenesis to improve lifelong cold resistance and performance. Six hundred Cobb hatching eggs were incubated under standard conditions and then exposed to 3 treatments: control; cold treatment in which embryos were exposed to 15°C for 30 min on d 18 and 19 of incubation (30 × 2); and cold treatment similar to 30 × 2 but with 60-min exposures (60 × 2). Egg shell temperature (T(egg)) and heart rate (HR) were monitored pre- and posttreatment. Upon hatching, hatchability, body weight, and body temperature were recorded. From 14 to 35 d of age, three quarters of the chickens in each treatment were raised under ascites-inducing conditions (AIC) and the remaining birds were raised under standard brooding conditions (SBC). The T(egg) and HR decreased significantly in response to increased exposure time on d 18 of incubation. On d 19 of incubation, before the second cold exposure, the 30 × 2 group showed greater T(egg) and HR than the controls, and during the second exposure they maintained these parameters better than the 60 × 2 embryos. No treatment effect on hatchability was observed. At 35 d of age ascites incidence among 30 × 2 chickens under AIC was significantly less than that among the controls (P < 0.01), and body weight of these chickens under either SBC or AIC was significantly higher than that of the controls. Under SBC relative breast muscle weight was significantly higher in 60 × 2 chickens, whereas the relative heart weight was higher in both cold-treated groups than in the controls. It can be concluded that repeated short acute cold exposures during late embryogenesis significantly reduced ascites incidence and improved growth rate under either SBC or AIC. These results may be related to a prenatal epigenetic adaptation of the thermoregulatory and cardiovascular systems to low ambient temperature.

Mapping of quantitative trait loci affecting organ weights and blood variables in a broiler layer cross

1. A genome scan was performed to locate genomic regions associated with traits that are known to vary in birds (most commonly broilers) suffering from heart, lung or muscular dysfunction and for weight of the dressed carcass and some internal organs. 2. The F2 population studied was derived from a cross between a broiler and a layer line and consisted of over 460 birds that were genotyped for 101 markers. 3. There was strong support for segregation of quantitative trait loci (QTL) for carcass and organ weights and blood variables. We identified 11 genome-wide significant QTL (most of them for dressed carcass weight) and several genome-wide suggestive QTL. 4. The results point to some genome regions that may be associated with health-related traits and merit further study, with the final aim of identifying linked genetic markers that could be used in commercial breeding programmes to decrease the incidence of muscular and metabolic disorders in broiler populations.

Partial pressure of carbon dioxide in the venous blood of young birds as a predictor of ascites susceptibility in broiler chickens

In order to investigate the relationship between carbon dioxide tensions in the venous blood of young chickens and ascites susceptibility, one hundred day-old chickens from two pure broiler breeder lines differing in susceptibility to ascites syndrome were obtained and reared at low environmental temperature. Weekly, blood samples were taken for the determination of blood gas parameters and plasma thyroid hormone levels. Dead birds were examined for lesions of ascites daily and all survived birds were autopsied at the end of the trials. In cold conditioning, the cumulative incidence of right ventricular hypertrophy (RVH) and ascites was 78% (39/50) in fast-growing (line A) and 50% (25/50) in slow-growing (line B) chickens, confirming that line A chickens had higher susceptibility to ascites than line B chickens. At 12 days of age, the mean pCO(2) tension was significantly (P < 0.01) higher in the venous blood of line A than line B chickens. During the experiment, the majority of line A and line B chickens showing RVH and ascites exhibited pCO(2) tensions equal to, or exceeding 50 mmHg at 12 days of age. Additionally, fast-growing chickens showed significantly lower plasma T3 and T4 concentrations than slow-growing chickens. In conclusion, our data indicate that carbon dioxide pressure in the venous blood of early postnatal broiler chickens could be used as a valuable predictor in the selection of birds susceptible to pulmonary hypertension and ascites. The function of thyroid hormones should also be taken into consideration in further selection procedures for meat-type chickens.

Comparative study of myocardial high energy phosphate substrate content in slow and fast growing chicken and in chickens with heart failure and ascites

In order to explain the biochemical mechanisms associated with deteriorating heart function in broiler chickens, this study compared myocardial high energy phosphate substrates in leghorns, feed restricted (Broilers-Res) broilers, ad libitum fed broilers (Broilers-AL), and in broilers that developed heart failure and ascites. The profile of adenine nucleotide content in the heart tissue did not differ between leghorns and Broilers-Res, but there were significant differences among Broilers-Res, Broilers-AL, and broilers with ascites. During intensive growth periods, leghorns and Broilers-Res showed increasing trends in heart ATP levels, whereas in fast growing broilers the heart ATP declined (p<0.021). ATP:ADP and ATP:CrP ratios increased with age in both leghorn and Broilers-Res, declined in fast growing broilers, and were the lowest in broilers that developed heart failure. The changes in heart high energy phosphate profile in broilers suggest that the energy demand of the heart during a rapid growth phase may exceed the bird's metabolic capacity to supply adequate levels of high energy phosphate substrate. The insufficiency of energy substrate likely contributes to the declining heart rate. In some individuals this may lead to impaired heart pump function, and in more severe cases may progress to heart pump failure.

Electrolyte diets, stress, and acid-base balance in broiler chickens

We compared the acid-base balance in broiler chickens provided diets containing 2 dietary electrolyte balances (DEB), and administered with either adrenocorticotropic hormone (ACTH) or saline solution. Diets were moderate (174 mEq/kg) or high (241 mEq/kg) DEB formulated by altering Na-K-Cl based on actual analysis. The experiment was designed as a split plot, with the main unit consisting of 4 treatments and the factorial treatment structure arranged in a completely randomized design. Osmotic pumps delivered 8 IU of ACTH in saline/kg of BW per d for 7 d, or the same saline volume as used in ACTH at 1 microL/h for 7 d was implanted on d 35. Venous blood samples were collected on d 35 before the pumps were implanted and on d 42 and 49. Birds fed the high DEB diet exhibited significantly higher Na(+) and Ca(2+) levels than birds provided the moderate DEB diet on d 35. Infusion of ACTH significantly increased (P < or = 0.05) hematocrit, hemoglobin, partial pressure of CO(2) (pCO(2)), corticosterone, osmolality, and HCO(3)(-) and reduced pH, BW, partial pressure of O(2) (pO(2)), and plasma concentrations of Na(+) and Cl(-) in both diets compared with the control group on d 42. Similarly, the ACTH treatment significantly increased hematocrit, hemoglobin, Ca(2+), corticosterone, and osmolality and reduced (P < or = 0.05) pO(2), glucose, and BW on d 49. The diet formulated for high DEB partially lowered pCO(2) on d 42. Significant DEB x ACTH interactions were observed for pCO(2) and pO(2) on d 49. However, there was a reduction in pO(2) along with a concomitant increase in erythropoiesis under the ACTH treatment for both diets, compared with the saline control, because of the increased need for O(2) to support gluconeogenic energy production. This adaptive response provided greater numbers of erythrocytes and thus a higher amount of circulating hemoglobin to deliver O(2) for metabolism. The diet formulated for high DEB partially attenuated the adaptive stress condition in broiler chickens.

Possible role of nitric oxide in the pathogenesis of pulmonary hypertension in broilers: a synopsis

Nitric oxide (NO) produced by vascular endothelial cells is an important determinant of the basal tone of small arteries and arterioles. Impaired endothelial NO production has been implicated in the pathophysiology of pulmonary hypertension in humans. Available data suggest that reduction of endothelial NO synthesis, with evidence of reduced endothelial NO synthase expression in pulmonary arterioles, is associated with increased pulmonary vasomotor tone and vascular remodelling in hypertensive broilers. Supplemental l-arginine, a precursor of NO, has been shown to induce flow-dependent pulmonary vasodilation, to prevent reduced endothelial NO synthase expression and to inhibit vascular remodelling in broilers with pulmonary hypertension. Nevertheless, its effect on pulmonary hypertension syndrome incidence is limited. It appears that impaired production of NO is a secondary rather than a causative factor in the pathogenesis of pulmonary hypertension in broilers.

Pathophysiology of heart failure in broiler chickens: structural, biochemical, and molecular characteristics

Modern strains of fast-growing meat type poultry are highly susceptible to heart failure. Heart-related mortalities are observed predominantly in fast-growing broiler chickens, with ascites and sudden death syndrome being the most common heart-related conditions in modern broiler flocks. This paper examines the role of structural, molecular, and biochemical factors pertinent to the pathophysiology of heart failure in fast-growing broilers. Evidence explaining the pathogenesis of acute and chronic heart failure, in the context of the underlying molecular and biochemical changes in the cardiomyocytes, contractile apparatus, and extracellular matrix in the ventricular myocardium are critically evaluated and discussed with reference to the clinical signs associated with deterioration of heart pump function. The secondary pathophysiological effects on the cardiovascular system, resulting from hemodynamic changes associated with the failing heart pump, are also reviewed and critically discussed.

Evaluation of Growth Rate, Body Weight, Heart Rate, and Blood Parameters as Potential Indicators for Selection Against Susceptibility to the Ascites Syndrome in Young Broilers

The continuous selection for rapid growth has been accompanied by an increasing occurrence of ascites syndrome (AS), which develops in broilers failing to supply the increasing demand for O(2) in their bodies. Moderate heritability has been reported for AS in broiler populations, suggesting that selection against AS is feasible. However, direct selection based on AS mortality requires exposure of candidate birds to AS-inducing conditions (AIC), which hinder selection for performance traits. Noninvasive indicators of AS, expressed under standard husbandry, may facilitate the integration of selection against AS into breeding programs. This study was designed to look for differences in heart rate, hematocrit, O(2) saturation of hemoglobin in arterial blood (SaO(2)), BW, and weight gain, all measured at early ages under standard brooding conditions, between birds that later developed AS and those that remained healthy under AIC, and to estimate the heritability of these AS-related parameters and their genetic correlation with the tendency of broilers to develop AS. The experimental population was derived from a broiler dam line. Male progeny of 34 half-sib sire families were reared under standard brooding conditions to 19 d of age, then under an AIC protocol consisting of housing in individual cages, cool air high-speed ventilation, and growth enhancement using high-energy pelleted feed and 23 h/d of light. Birds were necropsied upon mortality or at the end of the trials and were recorded as being susceptible, with manifestations of AS (SUS), or resistant and healthy (RES). About 44% developed AS, confirming the efficacy of the novel AIC protocol. The SUS and RES chicks did not differ in BW and weight gain up to 19 d of age, suggesting that there was no association between AS susceptibility and rapid early growth. The SUS chicks exhibited lower SaO(2) and heart rate than the RES chicks. Moderate heritability was estimated for all traits, but only SaO(2) exhibited consistently significant genetic correlation (-0.5) with AS, suggesting that it may serve as an early indicator for selection against AS, albeit with a limited efficacy.

Activation of PKCalpha and pulmonary vascular remodelling in broilers

OBJECTIVE

The present study was conducted to examine the presence of protein kinase Calpha (PKCalpha) in the pulmonary arterioles of broilers during the development of pulmonary hypertension and pulmonary vascular remodelling.

METHOD

One hundred and sixty day-old Avian-2000 broilers were divided equally into a control group and a cold temperature group. All the birds were reared in normal temperatures up to day 14, with the lighting schedule at 24 h per day. Thereafter, birds in the cold temperature group were subjected to low temperature by lowering 1-2 degrees C per day to 12-14 degrees C, and then kept constant until day 49, while birds in the control group were still brooded at normal temperatures. All the birds were fed a diet of pellets throughout the study. Samples of blood were taken from the wing vein, and of heart and lung collected after the birds were killed with an overdose of sodium pentobarbitial, at days 24, 32, 39 and 45 of age, respectively. Right ventricle to total ventricle ratio (RV/TV) and packed cell volume (PCV) were measured. Vessel wall area to vessel total area ratio (WA/TA) and mean media thickness in pulmonary arterioles (mMTPA) was examined using computer-image analytic software. Expression of PKC in pulmonary muscular arterioles was assessed by immunohistochemistry and quantified by measuring optical density (OD) using computer-image analytic software.

RESULTS

The incidence of pulmonary hypertension syndrome (PHS) was 12.5% in birds exposed to cold, and 3.75% in the control group (P<0.05). PCV in the cold temperature group was elevated after day 32 (P<0.05), and RV/TV ratio increased on day 45 (P<0.05). Both the WA/TA and mMTPA of birds subjected to cold were significantly elevated (P<0.05). The OD values were not significantly increased before day 32 (P>0.05), however, one week later (at day 39 of age), the difference between the two groups was significant (P<0.05). The increased PKCalpha expression was positively correlated with the values of mMTPA and WA/TA.

CONCLUSION

PKCalpha expression was up-regulated during the development of pulmonary hypertension. The activation of PKCalpha might be involved in the development of pulmonary vascular remodelling.