The Analysis Of Emotion, Physicochemical Indicators And MiRNA Expression During The Formation Of Confined Sow’s Stereotypic Behaviors Base On The Pupil Light Reflex

With the developing of intensive swine production,the abnormal psychological state of sows has gradually been the research focus of animal welfare in recent years.The evaluation of animal welfare is mainly based on animal behaviors,while animal welfare research has been further developed combining with environmental physiology and comparative psychology.Although the group-housing system with straw could meet the welfare of sows,the stall-housing system have been widely used in modern swine industry.Sows suffer from chronic stress in confinement environment,which could lead to the weaker physiological function,the lower reproductive performance,the higher of elimination rate.That causes serious damage to the sow’s welfare.Social isolation,confinement,barren environment and other adverse factors might lead to psychological frustration,stereotypic behaviors and depression.As a non-destructive observation index,stereotypic behaviors have its unique advantages in the research of depression.Therefore,studying on depression psychology of sows could provide reference for improving the housing environment and welfare on sows.This study has great scientific significance for the improving the theory of sows depression and high application value for promoting sows welfare.Twenty gilts with same condition were selected,and transferred into gestation stalls from they had been confirmed pregnancy until the end of pregnancy.The behavior expression,and physicochemical indicators and miRNA expression in blood during confinement（early,middle,and late gestation）had been compared,to explore physiological mechanism for the formation of stereotypic behaviors on confined sows.Ninety-six confined gestation sows of 1^st,3^rd,or 6^th parity were selected to test their pupil light reflex（PLR）,and then classified according to principal component scores（negative or positive PLR）.And behaviors,Novel Object Test（NOT）,emotion evaluation,and blood physicochemical indicators and miRNA expression had been measured in sows with different principal component score,aiming to explore the psycho physiological changes with the development of stereotypic behaviors of confined sows with different pupil light reflex.Results showed that:（1）Gilts performed more ventral lying,sitting and vacuum chewing in late gestation than that of early gestation（P<0.05）,while lateral lying and rooting in early or middle gestation were significantly higher than late gestation（P<0.05）.The content of IL-6 in group-housed gilts were significantly higher than confined gilts（P<0.05）,and the content of TNF-α were significantly higher in late gestation than that of gilts in early gestation（P<0.05）.The relative expression of miR-335、miR-16、miR-134、miR-1202 in group-housed gilts were significantly higher than that of confined gilts in late gestation（P<0.05）,while the relative expression of miR-132、miR-504、miR-30e、miR-34 a in group-housed gilts and confined gilts in early gestation were significantly lower than that of gilts in late gestation（P<0.05）.（2）Sows of 6^th parity performed significantly less standing and lateral lying in negative PLR（P<0.05）,while they performed significantly more ventral lying,bar-biting and trough-biting behaviors（P<0.05）.Sitting and vacuum chewing in sows of each parity were significantly more in negative than positive PLR group（P<0.05）.The sucrose and quinine score were not significantly between two group（P>0.05）.In sows of negative PLR,the frequency and the duration of contact in NOT were significantly lower（P<0.05）,and the delay time in NOT was significantly higher（P<0.05）.Comparing to sows of 1^st parity,ventral lying,sitting,bar-biting,trough-biting,vacuum chewing in sows of 6^th parity were significantly more（P<0.05）,while standing,lateral lying,rooting were significantly less（P<0.05）.And sows of 6^th parity had the significantly lower sucrose score,frequency and duration of contact in NOT（P<0.05）,and significantly higher quinine score and delay time in NOT（P<0.05）than sows of 1^st parity.（3）Comparing to positive PLR sows,the content of 5-HT of negative PLR sows in each parity is significantly lower（P<0.05）,and the content of cortisol,IL-6 and β-EP were significantly higher（P<0.05）.The content of cortisol,IL-6,TNF-α and β-EP in sows of 6^th parity were significantly higher than that of 1^st parity（P<0.05）,while the contents of 5-HT and DA were significantly lower in sows of 6^th parity（P<0.05）.Comparing to positive PLR sows,miR-335、miR-16、miR-134 and miR-1202 of negative PLR sows were expressed less in 6^th parity（P<0.01）,while miR-132、miR-504、miR30 e were expressed significantly more（P<0.01）.Comparing to sows of 1^st parity,sows in 6^th parity expressed significantly less miR-335、miR-16、miR-134 and miR-1202（P<0.05）and more miR-504 and miR-34a（P<0.05）in each PLR group.Conclusion:（1）Short-term confinement would result in stereotypic behaviors and blood physicochemical indicators change in pregnancy gilts from group-housing system.（2）There are significant differences on behavior expression,emotional state,novel objective response,physiological status and miRNA expression between confined sows with different pupil light reflex,which indicate that the negative PLR sows performed more serious psychological frustration and are more similar to depression.（3）In both positive and negative PLR sows,there are significant differences on behavior expression,emotional state,novel objective response,physiological status and miRNA expression between confined sows of 1^st and 6^th parity.The difference between positive and negative PLR sows might be increasing along with the parity.