Analysis Of Influencing Factors Of Boar Longevity And Semen Quality,and The Study On Feeding Regimen Of Young Boars

Boars,whose longevity?boar herd life month,BHLM?and semen quality can determine the economic benefit of the herds are the most basic and important portion of the swine production.The objectives of this research were to analyze the influencing factors of boar longevity and semen quality basing on scientific statistical methods,and to extend their life span through nutrition regulation in improving boar fertility,libido,and feet and leg heath.Firstly,the general linear model and multiple analysis model were used for the data of 1630 culling boars and 172408 ejaculates in nine artificial insemination?AI?centers from January 2013 to May 2016 to analyze influencing factors of boar longevity and semen quality,respectively.And then 1299 boars raised in nine AI centers were evaluated to study the occurrence regularity of their claw lesion and lameness in individual pen with solid concrete floor pattern and individual stall with slatted concrete floor pattern.Finally,sixty-one Duroc boars were allotted to a low,medium,and high feed intakes dietary treatments to study the appropriate energy requirement on semen quality,libido,and lameness of 170 kg – 250 kg boars.Therefore,there were 4 parts including in this study,and the main research contents and their results were as follows:The first part: Linear model analysis of the influencing factors of boar longevity.A total of 1630 records of culling boars from nine AI centers were collected from January 2013 to May 2016.Firstly,a logistic regression model was used to analyze the effects of boar breed,housing type,age at herd entry,and seed stock herd on boar removal reasons.And two linear models were then used to analyze the effects of breed,housing type,age at herd entry,seed stock herd,and removal reason on boar BHLM.The main results of this part are as follows:1.The propotion of lameness?36.3%?,poor semen quality?8.0%?,and disease?9.0%?were significant higher than that of other lesions?P < 0.001?.The results of logistic regression showed boar breed and age at herd entry both had significant impacts on boar removal reasons?P < 0.001?.Compared with Duroc boars,Yorkshire boars had higher odds ratios of lameness and other reasons than old age?P < 0.05?.Compared with boars aged 5 months at herd entry,those aged 10-12 months at herd entry had higher odds ratios of lameness,stress and dieth,and other reasons than old age?P< 0.05?.2.Results of linear model showed duroc boars exhibited shorter BHLM than Landrace boars?P < 0.01?,while no significant difference in BHLM was observed between Landrace and Yorkshire boars?P > 0.05?.Boars raised in individual stalls showed a shorter BHLM than those raised in individual pens?P < 0.001?.The BHLM increased with age at herd entry before 9 months,and then decreased with the age at herd entry increasing.Neither no significant difference in BHLM was observed among boars aged 5,6,and 7 months,nor between boars aged 8 and 9 months in both models?P > 0.05?.The second part: Analyzing the factors affecting boar semen characteristics from a Linear Growth Model.Data from the years Jan.2013 through Apr.2016 were collected from 9 AI centers.The 172,408 ejaculates originated from 2,688 boars of the Duroc,Landrace,and Yorkshire breeds.A two-level linear growth model was used to analyze the effects of housing pattern,boar breed,boar age,season,and boar age at herd entry on boar semen quality.The main results of this part are as follows:1.The intra-class correlation coefficient?ICC?of semen volume?Vol?,total sperm number(N_Total),functional sperm number(N_Func),sperm concentration?Con?,sperm motility?Mo?,and abnormal sperm?Ab?in the growth model were 0.38,0.62,0.61,0.60,0.54,and 0.70,respectively.Results of the type III tests showed that housing type?level 2?,breed,age,season,and boar age at herd entry?level 1?were all significant at two levels in the linear growth model.2.Boars reared in the ordinary house had lower Vol,N_Total,and N_Func than those reared in house with air filtration?P < 0.05?.Additionally,boars reared in the ordinary house also had higher Ab than those reared in house with air filtration?P < 0.05?.3.The Vol of Yorkshire boars was highest,followed by Landrace and Duroc boars,while the order of Con in three breeds was as Duroc > Landrace > Yorkshire boars?P < 0.001?.Moreover,Duroc boars also had lower N_Total and N_Func than Landrace and Yorkshire boars?P < 0.001?.4.The Vol,N_Total,and N_Func of boars were reached the most optimal level at at the age between 30.2 months and 38.5 months,while boar Mo was reached the most optimal level at the age of 18 months.In addition,boar Ab increased after the age of 47 months.5.Boar N_Total was decreased before June,and then increased after July.Boars ejaculated less semen between from May to September,and reached the lowest level at June.6.Boars with the 5,6,and 7 month of age at herd entry had significantly lower N_Total than those with the 8 and 9 month of age at herd entry,which had higher N_Total than boars with the 10,11,and 12 month of age at herd entry?P < 0.001?.The third part: Effects of flooring type on boar claw lesion and lameness.A total of 1299 boars,which included 788 boars on individual-pen pattern with solid concreted floor?IPS?and 511 boars on individual-stall pattern with slatted floor?ISS?,were examined for claw lesion and lameness to investigate the occurrence regularity of boar claw lesion and lameness on two flooring types.The main results of this part are as follows:1.The prevalence of claw lesion was 84.1%,and the average lesion score was 4.2 ± 4.4.Compared with ISS boars,IPS boars had significantly higher prevalence of claw lesion?88.7% vs.76.9%;P < 0.01?.In addition,IPS boars also had significantly higher lesion scores than ISS boars?5.2 ± 4.9 vs.2.6 ± 2.8;P < 0.01?.2.The prevalence of white line,heel sole crack,and heel overgrowth and erosion were significantly higher than other lesion types?P < 0.001?,while no significant difference in prevalence was observed among these three lesion types?P > 0.05?.Except for dew claw and toe overgrowth,the prevalence of white line,heel sole crack,heel overgrowth and erosion,cracked wall vertical,cracked wall horizontal,and swelling ankle for IPS boars was higher than that for ISS boars?P < 0.001?.3.The average lesion score of IPS boars with lameness was 11.7,which was higher than that of ISS boars with lameness by 6.8?P < 0.001?.In addition,the prevalence of IPS boars with lameness in hind limbs was significantly higher than that of ISS boars with lameness in hind limbs?83.7% vs.47.4%;P < 0.01?.4.There was a weak correlation between lameness and toe overgrowth and swelling ankle for ISS boars?? = 0.2151 and 0.3039,respectively?,while lameness was middling correlated with swelling ankle for IPS boars?? = 0.6153?.The last part: Effects of feeding regimen on weight gain,semen characteristics,libido and lameness in 170-to 250-kilogram Duroc boars.Sixty-one Duroc boars were allotted to one of three dietary treatments: 1)low energy intake group?L,n = 20,7.3 Mcal/d of ME?,2)medium energy intake group?M,n = 20,7.7 Mcal/d of ME?and 3)high energy intake group?H,n = 21,8.3 Mcal/d of ME?in period 1.Feed intake was then increased to 7.6,8.2 and 8.6 Mcal/d of ME for the three groups,respectively,in period 2.The main results of this part are as follows:1.The H boars had a greater ADG?P < 0.05?than L boars,but there was no difference between M and L or M and H boars in period 1?P > 0.05?.In period 2,as well as in the entire experimental period?from 170 to 250 kg BW?,the ADG significantly increased with the increase of energy intake?P < 0.01?.2.The semen volume,total sperm number and functional sperm number of the M and H boars were significantly greater than those of the L boars?P < 0.05?,and these parameters of the M boars did not differ from those of the H boars in either period?P > 0.05?.3.boars in the H group took more time to mount the collection dummy and produce an ejaculate than the L and M boars in period 1,period 2 and the entire experimental period?P < 0.05?.The M boars took less time to mount the collection dummy and produce an ejaculate than the L boars in period 1?P < 0.05?,but there was no difference between the M and L groups in period 2?P > 0.05?.During the entire experimental period,there was a slight tendency for M boars to take less time to mount and produce an ejaculate when compared with the L boars?P = 0.06,P = 0.10,respectively?.4.The H boars had a significantly greater percentage of lameness than the L and M boars at wk 27 and wk 29?23.8% vs.0% and 5%,respectively;P < 0.05?.In addition,two boars?9.5%,2/21?were culled due to lameness from the H group,but no boars were culled?0%,0/20?from the L and M groups.In conclusion,we can conclude that 1)the General Linear Model and Multilevel model can be used to analyze the culling boar and semen production data.Boar breed,age at herd entry,seed stock herd,housing type,removal reason,and season can impact boar longevity and/or semen quality.2)Claw lesions are common in boar breeding herd,and the prevalence and severity of each lesion are affected by the flooring type.Producers should pay more attention on the lesions of white line,heel sole crack,heel overgrowth and erosion,and swelling ankle for IPS boars and on the lesions of dew claw and toe overgrowth for ISS boars.3)The medium energy intake regimen?energy intakes of 7.7 and 8.2 Mcal/d of ME with ADG of 454.5 and 375.3 g/d in the two periods,respectively?improved the total sperm number and functional sperm number and meanwhile decreased the occurrence lameness by optimizing ADG in 170-to 250-kg Duroc boars,which may improve boar longevity.