The Effects Of Transportation Stress On Ovary Injury And Production Performance In Laying Hens

Transportation stress is one of the stressors that cannot be ignored in the process of animal production.Transportation stress as a compound stressor has great influence on animal organism.The superposition of various stress stimulations affects the growth and development of animals,reduces immune function and production performance,seriously can lead tissues and organs to be injured or even individual deaths,which will cause huge economic losses to animal husbandry.In order to improve breeding scale and production efficiency of laying hens,the stage breeding mode of laying hens has been put forward in domestic in recent years,namely purchasing and raising the specific stage of chicks,growing hens or laying hens,unlike previous all-in and all-out breeding mode which feeding hens from brooding,growing,laying and finally be eliminated.This breeding mode has achieved good breeding results in developed countries,and the industry of laying hens in China is expected to develop rapidly with this breeding mode in the future.Therefore,laying hens will inevitably be affected by transportation stress during the transportation from purchasing laying hens to laying houses.However,there are few studies on the effects of transportation stress in laying hens at present.In order to study on the effects of transportation stress on ovary injury and production performance in laying hens,120 18-week-old poor stress-resistant Hy-Line Brown as research objects of this experiment were randomly divided into two groups:Control group and Experimental group,each group of 60.The road transportation stress was applied to Experimental group with the speed of 80 km/h for 6 h to simulate the road transportation process of purchasing age-appropriate laying hens in actual production practice.The body weight of Experimental group was weighed before and after the experiment.20 hens were randomly selected from Control group and Experimental group and then killed after the end of the transportation.Ovarian tissues and oviducal tissues were collected to be observed the changes of pathology,antioxidant function?T-SOD,CAT and MDA?,inflammatory factors?NF-?B,TNF-?,COX-2,PTGEs,iNOS and IL-6?and sex hormone receptors?FSHR,LHR,PRLR,E₂R,PR and AR?.The remaining 40 laying hens were kept feeding,and performance indexes?laying rate,day-feed intakes,egg weight and feed conversion ratio?were observed for 100 days.The results showed that:?1?Compared with Control group,the body weight changes of Experimental group were not significant?p>0.05?;Compared with Control group,there were many atretic follicles,the number of follicles at all levels was reduced and the follicles were surrounded by hemorrhage and infiltrated by a large number of inflammatory cells on the ovaries of Experimental group;Compared with Control group,the tube walls were thinner,the gaps between the tube and the cavity were smaller and adhered together,the arrangement of epithelium single-layer columnar cells was irregular,and the villous shedding was obvious on the oviducts of Experimental group which indicated that transportation stress induced laying hens follicle development to be inhibited and oviduct tolerance to be reducted,and then affected reproductive function of laying hens.?2?Compared with Control group,the activity of T-SOD in ovarian tissues of Experimental group was significantly decreased?p<0.05?,the activity of CAT was significantly decreased?p<0.01?,the content of MDA was significantly increased?p<0.01?which indicated that transportation stress induced laying hens ovaries to produce oxidative stress and caused oxidative injury.?3?Compared with Control group,the mRNA expression levels of NF-?B,TNF-?,iNOS and IL-6 in ovarian tissues of Experimental group were significantly increased?p<0.05?,the mRNA expression levels of COX-2 and PTGEs were significantly increased?p<0.001?which indicated that transportation stress induced laying hens ovaries to produce inflammation reaction and caused inflammatory injury.?4?Compared with Control group,the mRNA expression levels of FSHR,PRLR,E₂R and PR in ovarian tissues of Experimental group were significantly decreased?p<0.001?,the mRNA expression level of LHR was significantly decreased?p<0.05?,the mRNA expression level of AR was significantly increased?p<0.001?which indicated that transportation stress induced laying hens ovarian sex hormone secretion to be disordered,and then affected reproductive function of laying hens.?5?Compared with Control group,egg production rate of Experimental group were decreased significantly?p<0.05?.Although datas of day-feed intakes and egg weight both showed a downward trend,data of feed conversion ratio showed an upward trend,they were both not significant?p>0.05?which indicated that transportation stress affected production performance of laying hens.In summary,transportation stress can lead ovarian tissues and oviducal tissues to be injured,the development and ovulation of follicles are restrained,oxidative damage and inflammation damage are occurred in ovaries,which interfer ovarian sex hormones expression and then affect production performance of laying hens.The study laid a theoretical foundation and experimental evidence for prevention and treatment of transportation stress in veterinary clinic,which can also help laying hens farm or households to realize the importance of transportation stress.