Preparation of “Shi Ying Zi” powder
“Shi Ying Zi” powder is consisted of Cnidium monnieri (L.) Cuss, Taraxacum mongolicum Hand-Mazz and salt with the proportion of 55: 40: 5 (g/g/g). The two herbals were procured from Baicaotang pharmaceutical chain Co. LTD (Chengdu, China). The samples of the two plant material (Cnidium monnieri (L.) Cuss and Taraxacum mongolicum Hand-Mazz) are deposited at the herbarium of Natural medicine research center, College of Veterinary medicine, Sichuan Agricultural University, with voucher number 2017-0168 and 2017-0205, respectively. The quality criteria of the two herbals were fit for the standards of the Pharmacopoeia of the People’s Republic of China (Version 2015, China pharmacopoeia committee).The content of osthole in Cnidium monnieri (L.) Cuss is not less than 1% and the content of caffeic acid is not less than 0.02% in Taraxacum mongolicum Hand-Mazz. The mixture of Cnidium monnieri (L.) Cuss, Taraxacum mongolicum Hand-Mazz and salt were smashed into powder, followed by sieving through 150μm ± 6.6μm screen cloth to give the “Shi Ying Zi” powder.
Experiment design
200 1-day-old broiler chicks free of coccidiosis were purchased from a local hatchery and equally divided into 10 groups which contained normal group, untreated group, 4 protective groups (positive control group and three “Shi Ying Zi” powder groups) and 4 therapeutical groups (positive control group and three “Shi Ying Zi” powder groups). Chicks were reared in poultry shed and maintained free from coccidian infection and anticoccidial drug
At 11th day of age, the chicks in the three “Shi Ying Zi” powder groups were prophylactically supplemented with “Shi Ying Zi” powder at the doses of 5g/kg (ShiYingZi-PL), 10g/kg (ShiYingZi-PM) and 15g/kg (ShiYingZi-PH), respectively. In the positive control group, monensin was added (100mg/kg). The normal group and untreated group were fed with normal diet. At 14th day of age, chicks except those in blank group were inoculated with 2×104 sporulated oocysts of E. tenella. When the first hemorrhagic fecal was found, therapeutical drugs started administration. The low (5g/kg, ShiYingZi-TL), medium (10g/kg, ShiYingZi-TM) and high doses (15g/kg, ShiYingZi-TH) of “Shi Ying Zi” powder were added into the diet, respectively. In the positive control group, sulfachloropyrazine sodium was added into water (1g/L).
Clinical symptoms
The chicks were examined daily for recording clinical signs, such as ruffled feathers, anorexia, huddling together, ruffled feathers, loose dropping, hemorrhagicy feces, and mortality.
Hemorrhagic fecal score
Hemorrhagic fecal score is a qualitative estimation of the deviation of fecal appearance from normal. They were obtained by scoring the fecal each morning from 4dpi to 8dpi. Hemorrhagic fecal score was made from 0 to 4: a score of 0 indicates normal fecal without hemorrhagic, a score of 1 indicated 1%-25% fecal with hemorrhagic; a score of 2 indicated 25%-50% fecal with hemorrhagic; a score of 3 indicated 51%- 75% fecal with hemorrhagic; a score of 4 indicated 76%-100% fecal with hemorrhagic.
Lesion score of caecum
The postmortem examination was conducted on 8dpi. The dead and slaughtered birds were incised, and gross lesions in caecum were recorded. The pathogenicity and severity of the disease was studied by recording lesion scoring, which was evaluated based on extent of lesions in a particular organ as described by Johnson and Reid [13]. The lesions included petechial hemorrhages, thickening of caecum wall, hemorrhagic fecal contents, and mucoid discharge. Lesion score was made from 0 to 4: a score of 0 indicated no lesion; a score of 1 indicated mild lesion; a score of 2 indicated moderate lesion; a score of 3 indicated severe lesion; a score of 4 indicated more severe lesion.
Oocysts index in caecum
Caecum contents were collected on 8dpi after postmortem examination. The counting of oocysts was made by McMaster method [14]. The score was made from 0 to 40: a score of 0 indicated the oocysts in feces were 0-0.1×106;a score of 5 indicated the oocysts in content were 0.11×106-1×106;a score of 10 indicated the oocysts in content were 1.1×106-1.9×106;a score of 20 indicated the oocysts in content were 2.0×106-5.9 ×106;a score of 30 indicated the oocysts in content were 6.0×106-10.9×106;a score of 40 indicated the oocysts in content were more than 1.1×107
Anti-coccidiosis index
Anti-coccidiosis index(ACI)=(Relative weight gain rate + Survival rate)-(Oocysts index in caecum + Gross lesions score)[15].
When ACI is larger than 180,it means the anti-coccidiosis drug is high efficiency; when ACI is 160-180, it means the anti-coccidiosis drug is medium efficiency; when ACI is 120-160, it means the anti-coccidiosis drug is low efficiency, and when ACI is lower than 120, it means the drug do not possess anti-coccidiosis efficiency.
Biochemical indexes
For biochemical studies, 3–4 ml blood was collected from randomly selected 5 chicks of each group into tubes without any anticoagulant at intervals 0, 4 and 8dpi. After clotting, serum was separated and various parameters were estimated, including total serum protein, albumin, aspartate aminotransferase and alanine aminotransferase, serum creatinine and serum triglyceride. The globulins were calculated by subtracting the values of albumin from total serum proteins.
Histopathology
After dissection, the caecum, liver, kidney tissue samples were excised, fixed with neutral buffered formalin (10%), and then embedded in paraffin. Approximately 4 μm thick cross sections were excised and stained with hematoxylin and eosin (HE) for histopathological examination.