| Africa ostrich(Struthio Camelus) has a very high economic and scientific value, ostrich farming is a rapidly growing industry throughout the world. But a lot of problems encountered in ostrich farming, one of which is ostriches in brooding period are prone to osteoporosis, resulting in tibial deformation or fracture, the chicks will become defective birds and even death, thus reducing the bred rate, which cause great economic losses to the ostrich farming enterprises and farmers, this problem have a strong impact on the normal development of ostrich industry. Bone health is maintained by the dynamic balance between osteoblasts and osteoclasts, The fundamental reason of tibial fracture of ostrich chicks is the activated osteoclasts number increased relatively, which is responsible for bone resorption strengthened, thus resulting in the destruction of bone tissue structure and osteoporosis, ultimately cause fractures. Previous studies showed that boron can inhibit the differentiation of osteoclasts to reduce bone resorption, promote bone growth and development. This experiment adopts the method of adding borate in the daily drinking water of African ostrich chicks, with 45 days of ostrich tibias as research materials. Study on the effect of boron on tibial growth and RANKL/RANK/OPG signaling pathway of Africa ostrich chicks by using HE stain, cell specific stain, immunohistochemistry, ELISA, etc., aiming to provide theoretical basis for prevention and treatment of leg disease in ostrich chicks. The research content and results are as follows:1. The effect of boron on growth performance of African ostrich chicksTo evaluate the growth performance of different groups of ostrich chicks through statistical measurement of the ostrich chicks’ weight and feed intake in before and after the test. In the present study, final BW, ADFI and ADG of birds increased by supplementation of boron at 40, 80 and 160 mg/L level, and the maximum value of this three indicators all appear in the 160 mg/L level, feed conversion of birds decreased by supplementation of boron at 40, 80 and 160 mg/L level, and the minimum value of this indicator appear in the 160 mg/L level. Final BW, ADFI and ADG of birds decreased and feed conversion of birds increased by supplementation of boron at 320 and 640 mg/L level. Overall, additional 40, 80 and 160 mg/L boron could improve growth performance of ostrich chicks, and 160 mg/L supplemental boron seemed to be the most beneficial.320 and 640 mg/L boron could inhibit growth of ostrich chicks, and the two doses can not be used in the practical breeding production.2. The effect of boron on development of African ostrich chick tibia0-45 d is the critical period of Africa ostrich’s brood-stage; bone remodeling and resorption activities are very active in the 45 days of ostrich tibias. After adding different doses of boron, the anatomic indexes of ostrich chicks’ tibia have different changes. In the present study, the tibia length of birds significantly increased(P<0.05) by supplementation of boron at 40, 80 and 160 mg/L level, tibia weight significantly increased(P<0.05) by supplementation of boron at 80, 160 and 320 mg/L, tibia perimeter significantly increased(P<0.05) by supplementation of boron at 80, 160, 320 and 640 mg/L. In summary, 80 and 160 mg/L boron could improve the tibial anatomic indexes. In the present study, trabecular perimeter, area and volume increased with increasing dosage of the boron supplement, and these three indicators of group 160 and 320 mg/L are higher than other groups. There were no significant differences between boron and trabecular thickness of ostrich chicks’ tibia(P>0.05). The trabecular separation decreased with increasing dosage of the boron supplement, and the minimum value of this indicator appear in the 160 mg/L level(P<0.05). In summary, 160 mg/L boron could improve the tibial histological indexes.The results showed that boron can effectively improve tibial anatomical and histological structure, promote growth and development of ostrich chicks’ tibia, and 160 mg/L boron seemed to be the most beneficial. High doses of boron(320 and 640 mg/L) will inhibit the normal development of tibia.3. The effect of boron on differentiation of osteoblast and osteoclast of ostrich chicksStudy on the effect of boron on activating osteoblast number of Africa ostrich chicks by using ALP stain. The results showed that the number of osteoblast per unit area of ostrich chicks’ tibia increased with increasing dosage of the boron supplement from group 1 to 5, but no significant difference(P>0.05) was observed between groups. Thus, boron has no significant effects on the differentiation of osteoblast.Study on the effect of boron on activating osteoclast number of Africa ostrich chicks by using TRAP stain. The results showed that appropriate doses of boron can inhibit the growth of osteoclast. In the present study, the number of osteoclast per unit area of ostrich chicks’ tibia decreased with increasing dosage of the boron supplement from group 1 to 4, and the number of osteoclast of group 3, 4 and 5 have significant lower than group 1(P<0.05), the number of osteoclast of group 4 is lowest in all. Thus it can be seen 160 mg/L is the best dose of inhibiting osteoclast differentiation.4. The effect of boron on the expression of OPG and RANKL in ostrich chicksIn order to observe the distribution of OPG and RANKL expression in chick’s tibia is used the immunohistochemical staining. The results show that the addition of boron is conducive to the expression of OPG in osteoblasts and bone marrow stromal cells, there are a large number of positive signal appear in primary marrow cavity and its edge and the surface of bridging trabecular bone, and group 4(160 mg/L) shows the strongest positive signal. On the contrary, the addition of boron decreased the expression of RANKL in osteoblasts and bone marrow stromal cells, and the minimum expression quantity of RANKL appears in the 160 mg/L. This experiment has confirmed that boron addition can increase the ratio of OPG/RANKL, inhibit osteoclast differentiation and bone resorption, and have a positive effect on prevention and treatment of bone resorption diseases.Determination of the content of OPG and RANKL in serum by used ELISA, The results show that compared with 0 mg/L boron application, the OPG in serum were significantly increased by supplemental 80, 160 and 320 mg/L(P<0.05); the RANKL in serum were significantly decreased by supplemental 40, 80, 160 and 320 mg/L(P<0.05). And the maximum of the ratio of OPG/RANKL appears in the 160 mg/L. Serological test also confirmed that 160 mg/L boron is the best dose of inhibiting osteoclast differentiation. |
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