Up-regulation of Endothelin-1 and Endothelin type A receptor genes expression in the heart of broiler chickens versus layer chickens

To compare Endothelin (ET) production and genes expression of ET-1 and ET_A receptor (ET_AR) between broiler and layer chickens during rearing, semi-quantitative RT-PCR and enzyme immunometric assay were performed in the heart ventricles and serum. There were gradual elevations of ET-1 and ET_AR mRNAs in the left ventricle of broiler and layer chicken groups that were mainly significant (P < 0.05) at 28, 35 and 42 days of age with compared to previous days whereas were not significant between two groups.These gradual elevations of ET-1 and ET_AR mRNAs were also observed in the right ventricle that were significant (P < 0.05) at 28, 35 and 42 days of age in broilers and 42 days of age in layers with compared to previous days. Increasing of these mRNAs in the right ventricle of broiler chickens were significantly (P < 0.05) more than layer chickens at 28, 35 and 42 days. Serum ET in broilers was significantly (P < 0.05) higher than layer chickens at 28 and 42 days of age. It is concluded that circulating ET and cardiac ET-1, ET_AR genes expression is higher in broiler chickens than in layer chickens particularly after 21 days of age. It is probably that these breed differences make broiler chickens to be more susceptible to Endothelin related-cardiomyopathies such as congestive heart failure and ascites.     

Reduced PKCalpha expression in pulmonary arterioles of broiler chickens is associated with early feed restriction

OBJECTIVE: The present study was conducted to investigate the effect of early feed restriction on protein kinase Calpha (PKCalpha) expression in pulmonary arterioles, which has been revealed to promote pulmonary vascular remodeling in pulmonary hypertensive broilers. METHODS: A total of 270day-old mixed sex commercial broilers were randomly distributed to a normal temperature control group (NT), a low temperature control group (LT) and a low temperature plus feed restriction group (LR). The PHS incidence, the right/total ventricular weight ratio (RV/TV), the vessel wall area/vessel total area ratio (WA/TA), the mean media thickness in pulmonary arterioles (mMTPA) and the expression of PKCalpha in the pulmonary arterioles were measured weekly. RESULTS: Low temperature treatment significantly increased the PHS mortality. The RV/TV, WA/TA and mMTPA values of group LT were significantly elevated compared with those of group NT on d 35 and 42. The LT chickens had increased PKCalpha expression compared with their NT counterparts on d 28 and afterwards. Feed restriction reduced the PHS mortality, RV/TV, WA/TA and mMTPA in cold-exposed broilers. The LR chickens had much lower PKCalpha expression in pulmonary arterioles than the LT chickens. CONCLUSION: Early time feed restriction inhibited pulmonary vascular remodeling in broilers, which might be partly attributed to reduced PKCalpha expression in pulmonary arterioles.     

肉鸡肺脏内皮素-1及其受体基因在高原低氧环境下的表达

为了研究高海拔缺氧环境对肉鸡肺部内皮素-1(ET-1)其受体ET-A和ET-B的影响,从低海拔地区引进1日龄AA肉仔鸡600羽,饲养在西藏大学农牧学院附属试验畜牧场。实验动物随机均分为2组,A组为对照组,饲喂于增氧房间内;B组暴露于高原低氧环境下。试验周期为28d,试验开始后每周随机扑杀20羽,测定心脏指数,统计腹水发病率。每个时间段每组肉仔鸡采集一部分肺组织制作石蜡切片,采用免疫组化的方法检测ET-1及其受体的表达,并应用image-pro plus图像分析系统对免疫组化切片进行半定量分析。试验结果显示:与对照组相比,高原低氧组肉鸡肺组织ET-1和ET-A基因在21,28d出现上调;ET-B表达水平在28d出现显著下降,其他时间段未见明显变化。此外,高原低氧环境对肉鸡增重和腹水发病率均有不利影响。本研究结果提示,ET-1、ET-A和ET-B表达于肉鸡肺脏;ET-1和ET-A表达水平上升和ET-B下调可能与肉鸡腹水发病紧密相关。     

肉鸡血浆极低密度脂蛋白浓度与屠体肥度性状的相关研究

以白羽肉仔鸡为研究材料，４９日龄采血，用此法浊法测定血浆极低密度脂蛋白浓度。试验结果表明，血浆ＶＬＤＬ浓度的变异系数为５５％，其与腹脂重，腹脂率呈显著的正表型相关。体重和屠体重与腹膜重呈极显著的正表型相关，对血浆ＶＬＤＬ浓度的低向选择将间接低体重。为防止肉仔鸡上市体重的下降，应该同时考虑对血浆ＶＬＤＬ浓度和体重的选择。对血浆ＶＬＤＬ浓度的低向选择将降低腹膜重，腹脂率，肝脂含量和肝脂重而对胸肌脂肪含     

Lesions of the pericardium and their significance in the aetiology of heart failure in broiler chickens

The present study focuses on lesions of the pericardium commonly observed in fast growing broilers. These lesions are examined in the context of electrophysiological and functional changes associated with cardiac performance and patho-physiology in broilers succumbing to acute or chronic heart failure. Typical lesions involving the pericardium in fast growing broiler chickens included: (1) excessive pericardial effusion, (2) locally extensive or focal adhesions between parietal and visceral components of the pericardium, (3) fibrous deposits on visceral pericardium, and (4) thickened pericardium. Echocardiographic evidence indicated that severe pericardial effusion and/or adhesions may have a restrictive effect on heart pump function, where both diastolic and systolic function of the heart may be affected. Electrocardiographic data showed a strong trend indicating that pericardial adhesions may be associated with ventricular arrhythmia and increased risk of sudden death in fast growing broilers. Relatively high levels of matrix metalloproteinase MMP-2 activity have been found in pericardial effusions from affected chickens, suggesting a possible involvement of this enzyme in the aetiology of pericardial lesions. The present results indicate that pericardial lesions may be associated with biochemical, morphological, electrophysiological, and functional changes occurring in the hearts of broilers succumbing to acute or chronic heart failure and ascites.     

Serum and bronchoalveolar lavage fluid endothelin-1 concentrations as diagnostic biomarkers of canine idiopathic pulmonary fibrosis

Background: Diagnosis of canine idiopathic pulmonary fibrosis (IPF) is challenging. Endothelin‐1 (ET1) is a biomarker of IPF in humans, but whether ET1 can detect and differentiate IPF from other canine respiratory diseases is unknown. Objective: To evaluate whether measurement of the concentration of ET1 in serum and bronchoalveolar lavage fluid (BALF) can be used to distinguish canine IPF from chronic bronchitis (CB) and eosinophilic bronchopneumopathy (EBP). Animals: Twelve dogs with IPF, 10 dogs with CB, 6 dogs with EBP, 13 privately owned healthy West Highland White Terriers (WHWT), and 9 healthy Beagle dogs. Methods: Prospective, case control study. ET1 concentration was determined by ELISA in serum and in BALF. Results: No significant difference in serum ET1 concentration was detected between healthy Beagle dogs and WHWT. Serum ET1 concentration was higher in dogs with IPF (median interquartile range; 2.32 pg/mL, 2.05–3.38) than healthy Beagle dogs (1.28, 1.07–1.53; P < .001), healthy WHWT (1.56, 1.25–1.85; P < .001), dogs with EBP (0.94 0.68–1.01; P = .001), and dogs with CB (1.54 0.74–1.82; P = .005). BALF ET1 concentration was below the detection limit in healthy WHWT and in dogs with CB, whereas it was measurable in all dogs with IPF. A cut‐off serum concentration of 1.8 pg/mL had a sensitivity of 100% and a specificity of 81.2% for detection of IPF, with an area under the receiver operating characteristic curve of 0.818. Conclusions and Clinical Importance: Serum ET1 can differentiate dogs with IPF from dogs with EBP or CB. ET1 can be detected in BALF of dogs with IPF.     

腹水综合征对肉鸡肝脏、心肌和肠黏膜线粒体抗氧化能力的影响

采取分组对比的方法（对照组，肉鸡腹水征发病组，治疗组）分别检测肝组织、肠黏膜、心肌线粒体中的MDA含量，SOD、GSH—PX的活性。结果显示，发生腹水综合征的肉鸡，其肝脏、心肌和肠黏膜线粒体MDA活力呈现先显著降低（1、2周时）、后显著提高（3、4、5周时）的变化趋势（P〈0．05）而与发病组线粒体MDA活力先降后升的动态变化趋势相反，治疗组线粒体MDA的活力则呈现先升后降的趋势，最终显著阻止了自由基的产生。线粒体SOD和GSH—Px活力的变化趋势则与MDA相反。提示：肉鸡腹水综合征显著诱导了肉鸡组织细胞和线粒体的脂质过氧化作用，显著降低了肉鸡组织细胞和线粒体的抗氧化能力；药物能有效地改善这一过程。     

Impact of dietary chitosan oligosaccharide and its effects on coccidia challenge in broiler chickens

ABSTRACT

1. Two experiments were conducted, the first to determine the optimum inclusion of chitosan oligosaccharide (COS) in broiler diets to support growth performance, digestive functions, intestinal morphology, and immune organs. The second experiment evaluated the immune-protective properties of COS on broiler chickens during coccidia challenge (CC).

2. Experiment 1 investigated the effect of graded dietary concentration of COS in the diets of broiler chickens using eight cage replicates for each of the six diets. A corn-soybean meal-based diet was used as the basal diet and supplemented with 0.0, 0.5, 1.0, 1.5, 2.0, or 2.5 g of COS/kg feed to form the six treatments.

3. The diet supplemented with 1.0 g COS/kg of feed provided the optimal inclusion level for broiler chickens regarding body weight (BW) gain, jejunal villus height, villus height to crypt depth ratio, and ileal energy digestibility at d 22 of age.

4. Experiment 2 investigated the immune-protective properties of COS in broiler chickens during CC. A total of 224 male broiler chicks were randomly assigned to eight replicate cages in a 2 × 2 factorial arrangement of treatments with two COS concentrations (0 or 1 g of COS/kg of diet), with or without CC.

5. On d 18 of age, birds in the CC group received twice the recommended coccidia vaccine dose of 30 doses/kg BW.

6. Coccidia challenge reduced (P < 0.05) and dietary COS increased (P < 0.05) BW gain, and feed intake. Dietary COS mitigated (P < 0.05) the CC-induced effects on gain:feed. Dietary COS supplementation attenuated the CC-induced effects (P < 0.05) on the expression of occludin genes.

7. In conclusion, dietary COS improved performance, and the immune-related beneficial impact of COS supplementation was associated with reduced expression of pro-inflammatory cytokine genes.     

Necrotic enteritis challenge regulates peroxisome proliferator-1 activated receptors signaling and β-oxidation pathways in broiler chickens

Necrotic enteritis (NE) is an important enteric disease in poultry and has become a major concern in poultry production in the post-antibiotic era. The infection with NE can damage the intestinal mucosa of the birds leading to impaired health and, thus, productivity. To gain a better understanding of how NE impacts the gut function of infected broilers, global mRNA sequencing (RNA-seq) was performed in the jejunum tissue of NE challenged and non-challenged broilers to identify the pathways and genes affected by this disease. Briefly, to induce NE, birds in the challenge group were inoculated with 1 mL of Eimeria species on day 9 followed by 1 mL of approximately 10⁸ CFU/mL of a NetB producing Clostridium perfringens on days 14 and 15. On day 16, 2 birds in each treatment were randomly selected and euthanized and the whole intestinal tract was evaluated for lesion scores. Duodenum tissue samples from one of the euthanized birds of each replicate (n = 4) was used for histology, and the jejunum tissue for RNA extraction. RNA-seq analysis was performed with an Illumina RNA HiSeq 2000 sequencer. The differentially expressed genes (DEG) were identified and functional analysis was performed in DAVID to find protein–protein interactions (PPI). At a false discovery rate threshold <0.05, a total of 377 DEG (207 upregulated and 170 downregulated) DEG were identified. Pathway enrichment analysis revealed that DEG were considerably enriched in peroxisome proliferator-activated receptors (PPAR) signaling (P < 0.01) and β-oxidation pathways (P < 0.05). The DEG were mostly related to fatty acid metabolism and degradation (cluster of differentiation 36 [CD36], acyl-CoA synthetase bubblegum family member-1 [ACSBG1], fatty acid-binding protein-1 and -2 [FABP1] and [FABP2]; and acyl-coenzyme A synthetase-1 [ACSL1]), bile acid production and transportation (acyl-CoA oxidase-2 [ACOX2], apical sodium–bile acid transporter [ASBT]) and essential genes in the immune system (interferon-, [IFN-γ], LCK proto-oncogene, Src family tyrosine kinase [LCK], zeta chain of T cell receptor associated protein kinase 70 kDa [ZAP70], and aconitate decarboxylase 1 [ACOD1]). Our data revealed that pathways related to fatty acid digestion were significantly compromised which thereby could have affected metabolic and immune responses in NE infected birds.     

The antimicrobial activity of lavender essential oil (Lavandula angustifolia) and its influence on the production performance of broiler chickens

The aim of the study was the evaluation of the antimicrobial activity (in vitro) of lavender (Lavandula angustifolia) essential oil (LEO) and the effect of its addition to the drinking water of broiler chickens on their production performance. Antimicrobial activity was determined by establishing the minimum inhibitory concentration (MIC) using a series of microdilutions. Bird experiments were carried out on a commercial farm on 300 Ross 308 broilers. One‐day‐old chicks were randomly assigned to three experimental groups of 100 individuals (five replications of 20 individuals each). In the control group, chickens received drinking water without added essential oil throughout the rearing period. In the LEO_0.2 and LEO_0.4 groups, from 1 to 42 days of bird life, the LEO_0.2 group had 0.2 ml/L of essential lavender oil added to the drinking water, while LEO_0.4 had 0.4 ml/L added. The results of the experiment showed the antimicrobial activity of LEO and its positive effect on the production results of broiler chickens. Application of higher concentration of essential oil (0.4 ml/L) significantly affected production results (BW, FCR, WCR—p < .01). No differences were observed in FI, WI, F:W and mortality (p > .05). In vitro studies indicate a significant effect of LEO on the inhibition of microbial growth. These results encourage further studies on a larger scale that will confirm antimicrobial efficiency and define the mechanisms of action of Lavandula angustifolia essential oil and its individual components.     

Dietary synbiotic supplementation improves the growth performance,body antioxidant pool,serum biochemistry,meat quality,and lipid oxidative stability in broiler chickens

The present study investigated the effects of Lactobacillus acidophilus (LBA) and mannan-oligosaccharides (MOS) supplementation on the production performance, serum biochemistry, antioxidant profile, health indices, meat quality, and lipid oxidative stability of broiler chicken. A total of 252 commercial broiler chickens at 1 d old of uniform body weight were randomly allocated to 6 maize-soybean-based dietary treatments: T₁ (control diet), T₂ ( antibiotic bacitracin methylene di-salicylate [BMD] at 20 mg/kg diet), T₃ (MOS at 0.1% + LBA at 10⁶ CFU/g feed), T₄ (MOS at 0.1% + LBA at 10⁷ CFU/g feed), T₅ (MOS at 0.2% + LBA at 10⁶ CFU/g feed), and T₆ (MOS at 0.2% + LBA at 10⁷ CFU/g feed). Each treatment was assigned to 6 replicates of 7 birds. The samples for meat quality and serum biochemistry analysis were taken from 12 birds per treatment (2 birds/replicate). The results revealed better (P < 0.01) growth performance and production efficiency of birds fed either T₅ or T₆ diet compared to control or BMD supplemented diet and BMD-supplemented birds superseded the control birds. Higher (P < 0.01) serum and liver antioxidant enzyme activities, meat antioxidant capacity (2, 2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid [ABTS] and 1, 1-diphenyl-2-picrylhydrazyl [DPPH] assays], serum total protein, high-density lipoproteins (HDL) cholesterol (P < 0.05), and globulin levels (P < 0.01) were observed in birds fed either T₅ or T₆ diet compared to control or BMD supplemented birds, whereas, lower lipid oxidation (P < 0.01), cardiac risk ratio, atherogenic coefficient, atherogenic index of plasma, serum glucose, triglyceride, total cholesterol levels (P < 0.01), and serum albumin-to-globulin ratio (P < 0.05) were observed in the chickens. The pH of meat from birds fed T₄, T₅ or T₆ diet was lower (P < 0.01) compared to control and other treatments. The extract release volume (ERV), water holding capacity (WHC), and protein content of meat were higher (P < 0.05) in birds fed either T₅ or T₆ diet compared to control or BMD supplemented birds. Thus, it was concluded that the supplementation of 0.2% MOS along with LBA at 10⁶ CFU/g is optimum for better growth performance, serum biochemistry, antioxidant profile, health indices, meat quality, and lipid oxidative stability of broiler chickens.     

Antioxidant supplementation of low‐protein diets reduced susceptibility to pulmonary hypertension in broiler chickens raised at high altitude

A reduced‐protein diet (designated as RPD) was prepared and its effects on growth performance and the development of pulmonary hypertension syndrome (PHS) were evaluated in broiler chickens compared to a normal‐protein diet (designated as NPD) or to the RPD supplemented with CoQ₁₀ alone (30 mg/kg) or in combination with vitamin E (30 mg/kg CoQ₁₀ + 100 mg/kg vitamin E). The RPD had 30 g/kg less crude protein compared to the NPD. A total of 208 1‐day‐old male broilers (Ross 308 strain) were used in a 42‐day trial. Serum concentrations of uric acid (UA) and nitric oxide (NO) significantly (p < 0.05) declined when chickens fed on the RPD. However, supplementing RPD with the antioxidants significantly (p < 0.05) increased the serum NO concentration. Although serum malondialdehyde (MDA) concentration was significantly (p < 0.05) higher in the RPD than the NDP, supplementing RPD with CoQ₁₀ and CoQ₁₀ + VE decreased serum MDA concentration to similar levels found in the NPD. Significant overexpression in GPX1 gene observed in the heart and lungs of broilers fed on the RPD, which was effectively restored by supplementation of CoQ₁₀. The right to total ventricular weight ratio (RV:TV) was significantly (p < 0.05) increased in birds fed the RPD, which concurred with an increase in mortality from pulmonary hypertension syndrome (PHS). However, a significant decline in mortality from PHS was observed when birds on RPD received CoQ₁₀ or CoQ₁₀ + VE. In conclusion, antioxidant supplementation effectively improves pulmonary hypertensive response in broiler chicken fed of reduced‐protein diets.     

Dietary supplementation with acidifiers improves the growth performance,meat quality and intestinal health of broiler chickens

This experiment was conducted to study the effects of dietary supplementation with acidifiers on the growth performance, meat quality, and intestinal health of broiler chickens. A total of 648 male Arbor Acres broiler chickens at 1 d old were randomly divided into 6 groups, and each group consisted of 6 replicates with 18 broilers per replicate. The dietary treatments were as follows: negative control (NC, the basal diet), NC + antibiotic (enramycin, 8 mg/kg, positive control [PC]), NC + phosphoric acid (PA, 0.1, 0.2, and 0.3 g/kg), and NC + lactic acid (LA, 0.3 g/kg). The feeding trial lasted for 42 d. The results showed that the feed-to-gain ratio of the NC + acidifier groups was lower than that of the NC and PC groups from 1 to 42 d (P < 0.05). Compared with the values in the NC group, the pH of breast muscle was significantly higher in the NC + PA (0.2 g/kg) and LA (0.3 g/kg) groups (P < 0.05), and the cooking loss was lower in the breast muscle of the NC + PA (0.1 g/kg) and LA (0.3 g/kg) groups (P < 0.05). In addition, the shear force of the breast muscle and thigh muscle and the pH value in the crop, gizzard and duodenum of the antibiotic and acidifier groups were significantly decreased (P < 0.05). Moreover, the trypsin, chymotrypsin, and lipase activities of the duodenum in the NC + PA (0.2 and 0.3 g/kg) groups, as well as the villus height-to-crypt depth (VH:CD) ratio of the duodenum in the NC + PA (0.1 g/kg) group was significantly greater (P < 0.05) compared with those in the NC group. Meanwhile, the number of total aerobic bacteria, Escherichia coli and Salmonella in the cecum of the NC + PA (0.1 g/kg) and LA (0.3 g/kg) groups were decreased (P < 0.05). Collectively, diet supplementation with acidifiers could improve the growth performance, meat quality, and intestinal health of broilers, in which the effects of PA (0.1 g/kg and 0.2 g/kg) are better than the other supplementations.     

Effects of dietary 1 alpha-hydroxycholecalciferol in calcium and phosphorous-deficient diets on growth performance,tibia related indices and immune responses in broiler chickens

This experiment was conducted to investigate the effect of dietary 1α-hydroxycholecalciferol (1α-OH-D₃) in calcium (Ca)- and phosphorous (P)-deficient diets on growth performance, carcass characteristics, tibia related parameters, and immune responses of broiler chickens. A total of 280 one-day-old broiler chickens (Ross 308) were assigned to 20 floor pens and 4 dietary treatments with 5 replicates. Dietary treatments consisted of starter diets (starter diet of treatment A: 1% Ca, 0.73% total phosphorus [tP]; starter diet of treatment B: 0.85% Ca, 0.64% tP + 5 μg/kg of 1α-OH-D₃; starter diet of treatment C: 0.85% Ca, 0.59% tP + 5 μg/kg of 1α-OH-D₃; starter diet of treatment D: 0.85% Ca, 0.54% tP + 5 μg/kg of 1α-OH-D₃), grower diets (grower diet of treatment A: 0.86% Ca, 0.68% tP; grower diet of treatment B: 0.73% Ca, 0.59% tP + 5 μg/kg of 1α-OH-D₃; grower diet of treatment C: 0.73% Ca, 0.55% tP + 5 μg/kg of 1α-OH-D₃; grower diet of treatment D: 0.73% Ca, 0.50% tP + 5 μg/kg of 1α-OH-D₃) and finisher diets (finisher diet of treatment A: 0.81% Ca, 0.64% tP; finisher diet of treatment B: 0.68% Ca, 0.56% tP + 5 μg/kg of 1α-OH-D₃; finisher diet of treatment C: 0.68% Ca, 0.52% tP + 5 μg/kg of 1α-OH-D₃; finisher diet of treatment D: 0.68% Ca, 0.48% tP + 5 μg/kg of 1α-OH-D₃). Results showed that body weight gain (BWG) and feed intake (FI) of broilers in treatment B were similar to those of broilers in treatment A at the end of the trial (P < 0.05). Broilers in treatments C and D had lower BWG and FI than those in treatment A during the whole trial (P < 0.05). Feed conversion ratio, carcass traits and relative weight of lymphoid organs were not affected by dietary treatments (P > 0.05). Dietary treatments had no significant effect on antibody titers against Newcastle and Influenza disease viruses as well as sheep red blood cells. Dietary treatments had no significant effects on tibia ash and tibial dyschondroplasia score. Broilers fed Ca-P deficient diets had lower tibia Ca and P than those in treatment A (P < 0.05). In conclusion, results indicated that broilers fed Ca-P deficient diets supplemented with 5 μg/kg 1α-OH-D₃ failed to achieve the same tibia Ca and P values as broilers fed nonphytate phosphorus adequate diets.     

Microstructure of the small intestine in broiler chickens fed a diet with probiotic or synbiotic supplementation

The aim of the study was to determine the effect of dietary supplementation of a probiotic and a synbiotic on the morphometric parameters of the small intestine of broiler chickens. The experiment was conducted on three hundred sixty, one‐day‐old female Ross 308 chicks, which were randomly selected from 20,000 birds and divided into three treatment groups (n = 120) with ten replicates per treatment. The control group (C) was fed a commercial diet, the probiotic group (PRO) was fed the same diet with an added 1% of the probiotic Lavipan® (Lactococcus lactis, Carnobacterium divergens, Lactobacillus casei, Lactobacillus plantarum and Saccharomyces cerevisiae), and the synbiotic group (SYN) was fed the commercial diet with an added synbiotic: 0.8% of the prebiotic RFO (extracted from lupin seeds) and 1% Lavipan®. According to the manufacturer's data, apart from the typical probiotic action,microorganisms contained in the preparation release anti‐bacterial substances (hydrogen peroxide and bacteriocins) and, therefore, are antagonistic towards pathogenic bacteria present in the gut of animals. Supplementation took place in the first seven days of rearing, and all birds had ad libitum access to water and feed during the 42 days of the experiment. On the last day, all birds were slaughtered and samples from three segments of the small intestine were taken. Villi area, height, width and crypt depth ratios were read using Multiscan software. Synbiotic supplementation increased the BWG of broilers from first to tenth day of rearing, compared to the control group. The PRO group had improved villi morphometric parameters of the duodenum. In the jejunum and ileum, both bioactive substances improved villus width and villus surface area. Crypts were deeper in the small intestine of birds supplemented with bioactive substances, which allows greater renewal of the villi. As expected, the intestinal morphometric parameters of broiler chickens benefited from bioactive substance supplementation.