| Sow maternal behavior after parturition performance as behaviors of lactating and nursing for piglets.Sows with bad maternity may attack or even kill their offspring.Therefore,it is necessary to improve requirements for sow maternity to ensure piglets’higher survival and growth rate.This present study investigated the sow milking ability and caring behavior for piglets during nursing period,and the piglets’ resilience to environmental change.This experiment included four parts:the first part analyzing the sow nursing behavior and piglet’ suckling behavior differences in different weaning litter weight groups,based on the hypothesis that suckling of piglets could stimulate sow milking ability,in order to reaveal the interaction between the sow and offsprings.The second part studied connection of sow placental efficiency and productive performance and the effects on piglets’ back-test score,aimed to find the effects of piglets’ embryonic development and sow nutrition metabolism on sow milking ability.The third and fourth parts evaluated the effects of sow behavior during nursing on weaning gregarious fighting and lonely test of piglets.1 Maternal behavior of lactating sows16 multiparous Large White sows with 2-5 parity inseminated by Landrace boars were used in the present study.Sows were divided into three groups low litter weight group,middle litter weight group and high litter weight group as 21d litter weight Mean±1/2SD for the upper and lower limits.Analyzed sow nursing behavior,lying behavior,sensitivity to piglets scream,salivary cortisol and piglets Backtest score differences within three groups.The results showed that lactation interval of low litter weight became longer as piglets grow,and was longer than the other two groups in the 2nd and 3rd week.Lactation interval of high litter weight group had small differences among different weeks.Duration of pre-massage in high litter weight group was shorter than that in other two group(P=0.018),and high litter group had higher proportions of nursing initiated by sows.Proportions of non-nutritional nursing of low litter weight group was highest in the first week(P<0.01),although duration of pre-massage was the longest(P<0.01).In low litter group,proportions of nursing initiated by piglets was the highest(P<0.01).With the growth of piglets,piglets more likely to initiate nursing(P=0.001),while proportions of nursing initiated by sows decreased(P=0.014),nursings more easier to success but counts decreased.Lactation interval of low litter weight group and MW longer as piglets 21 days litter weight increased in 1st week,lactation interval of low litter weight group was shorter than middle litter weight group and low litter weight group in the 2nd and 3rd week.Lactation interval of high litter weight group was stable during the lactation day.Duration of pre-massage in high litter weight group was shorter than that in low litter weight group.Percentage of nursing initiated by sows increased,while percentage of nursing initiated by piglets decreased as days gone by.Percentage of nursing initiated by high litter weight group sows was the highest,while percentage of non-nutritional nursing of low litter weight group was highest.Nursing initiated by piglets percentage of high litter weight group was lower than other two groups(P<0.05).Within the 3 days after parturition,duration of the lying down sequences significantly longer than other two groups(P<0.01),no difference was found the carefulness score during standing-to-lying in the observe period.Sows like lying when no piglets under them in order to decrease the piglets mortality.The score of sow sensitivity to piglets scream in low litter weight group(1.45)was lower than middle litter weight group(3.75)and high litter weight group(4.25)(P<0.01).Salivary cortisol of low litter weight group and high litter weight group significantly higher than that before weaning(P<0.05).The results showed that 21 day litter weight of piglets affected by sow milking ability.The results showed that sows in low litter weight group had longest duration of pre-massage in the 1 st week,their lactation interval increased with piglets growth and sows performed more likely to terminate nursing,which suggested that they had poor sow milking ability.Shorter duration of pre-massage indicated sows of high litter weight group were easier to milking and better communicating with offspring during nursing.Sows in high litter weight group were more likely to initiate nursing which meaned their milking capability better.Higher sensitivity of sows had higher piglets weaning weight.Sows in low litter group had highest massage stimulation threshold in the beginning,but the success rate was low.All the group had high success nusing rates in the later period meaned sow-piglets cooperate better.Sensitivity to piglets scream can reflect the sow maternal ability,which can be taken as an evaluation index of sow maternity.Sows of high litter group faced greater weaning stress.Above all,sows of high litter weight group acted more likely to nurse their offspring and better caring ability,their maternal behavior perfomed well.2 Exploration the relationship among placental efficiency,sow reproductive performance and piglet Backtest scoreIn the present study,66 multiparous Large White sows with 2-5 parity inseminated by Landrace boars were selected as study subject.In the farm,the placental weight(P<0.01),the 20 day litter weight(P<0.01)and the weaning survival rate(P<0.05)of placental efficiency≥4 group were significantly lower.than placental efficiency<4 group.The total number born and number born alive,the placental weight,total birth weight,litter weight born alive(r= 0.736,P= 0.000)had strong positive correlation.Number born alive and placental weight,total birth weight,litter weight born alive a strong positive correlation.20 day litter weight,20 day individual weight,and average daily weight gained a strong positive correlation.Birth weight and total number born live litter size(r=-0.512,P= 0.000)was moderately significantly negatively correlated.20 days individual weight and average daily gain had significantly strong positive correlation.Placental efficiency>4 group showed stronger resistance in Backtest,Backtest score significantly higher than placental efficiency<4 group and had heavier 20 day litter weight.Sow of placental efficiency≥ 4 had better reproductive performance.Speculated that placental efficiency affected piglets weaning weight,and then affected the resistance of piglets.Piglets of placental efficiency>4 had higher Backtest values.Placental efficiency can be considered to predictive sow feeding ability and can be used as evaluation index of sow maternity.3 Effects of 20 day litter weight on piglets fighting after weaning gregariousBased on weaning weight,we selected 44 sows high litter weight group(66.64±9.53Kg,Mean±S.D.)and low litter weight group(48.97±8.97 Kg,Mean±S.D.),22 sows each group.Based on the principles of similar weight,3 male and 3 female piglets from each sow were selected,synthesized two litters of piglets into one litter,a total of 22 litters,12 piglets per litter,and a total of 284 piglets.Fighting behavior after weaning gregarious was observed and skin lesions of piglets were counted by fixed observer.High litter weight group sows were more prone to initiated fighting within shorter time(P<0.05),fought more vigorous and gained more skin lesions.Skin lesion score and total fighting time(in seconds)(r = 0.732,P= 0.000),and duration of each fighting time/(second)(r ＝0.716,P= 0.716)follow 3 h after weaning gregarious were strongly correlated.Skin lesions can be used to assess the piglet aggressive and fighting extent after gregarious.The generation of good maternal sows was more likely to fight after weaning gregarious.4 Effects of 20 day litter weight on lonely test and resident-intruder testLonely testing time was on piglet’s 33rd and 34th days old.Pen was divided into two,4 female piglets were selected randomly which would be put into the side without feed and water sequentially.Compared to low litter weight group,piglets of high litter weight group had higher values in all the Heart rate variability indexes for the whole 30 min test.Heart rate variability indices of every 5 min during the lonely test were analyzed.Piglets of high litter weight group performed more vigorous in the test.Both Beats per minute and RMSSD had decline trend during the test.As to SD and RMSSD,they had higher values in the first 5 min,then decrease sharply and increase gradually.Results showed heavier Activity,faster BMP,larger SD and RMSSD compared to low litter weight group.High litter weight group had higher values in all the Heart rate variability indexes except LF:HF.Resident-Intruder testing time was on piglets’ 36h days old,10 days after weaning.Pen was divided into two,3 female piglets and 3 castrated boars were selected randomly which would be put into the side without feed and water sequentially.Then piglets with the same sex with resident and smaller than resident was put into the testing side.Intruder must from no-adjacent pen and one intruder could be used only once.No differences were found in contact and attack latency,however,piglets from high litter weight group easier to initiate fighting with intruder.The results indicated that Autonomic nervous system of high litter weight group group had better regulate ability.Stress to piglets caused activation of both sympathetic and vagal branch.The stress caused by lonely test could get relief in some extent within 30 min,HRV appeared decreased Activity and Beats per minute,vagal activity elevated and uncomfortable feeling eased.Heart rate variability can be used to evaluate stress condition of pigs.Piglets of high litter group fear less and more likely to attack stranger,which indicated that offspring of good maternity sow were more aggressive and had better self-regulation ability. |
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