| In this study,500 small-tailed Han sheep ewes in different reproductive stages(nonpregnancy,estrus,pregnancy,and lactation)were used as the experimental population.By measuring the distribution level of various blood indexes(15 physiological indicators,9biochemical indicators,4 reproductive hormone indicators,5 immune indicators,and 4antioxidant indicators)during reproductive cycles,the differences in germplasm characteristics of small-tailed Han sheep ewes during their reproductive cycles were revealed.The polymorphism of the g.746 A > G locus in the FecB gene of small-tailed Han sheep was detected by PCR-Sanger sequencing technique,the genetic parameters of the FecB gene were calculated by pop Gen 32 software,and the association between the FecB gene mutations and37 indicators(physiological,biochemical,hormonal,immune,and antioxidant)in the above blood indexes,3 reproductive indicators,and 13 body size indicators were analyzed by SPSS26.0 software.with a view to exploring the blood physicochemical characteristics and phenotypic structural characteristics of small-tailed Han sheep ewes with high reproductive performance.The main results showed that:The measurement results of physiological indicators in the reproductive cycle of smalltailed Han sheep ewes showed that the eight indicators of lymphocyte rate(LYM%),lymphocyte(LYM),hemoglobin(HGB),mean corpuscular volume(MCV),mean corpuscular hemoglobin(MCH),mean corpuscular hemoglobin concentration(MCHC),red blood cell volume distribution width-SD(RDW-SD),and the red blood cell volume distribution widthCV(RDW-CV)in the oestrus periods were significantly higher than those in the other three reproductive periods(pregnancy,lactation,and nonpregnancy)(P < 0.01),while the granulocyte(GRAN)and granulocyte rate(GRAN%)were significantly lower than those in the other three reproductive periods(P < 0.01),but all were in the normal range.The red blood cells(RBC)and hematocrit(HCT)of estrus ewes were significantly lower than those of the other three reproductive periods(P < 0.01).The measurement results of biochemical indicators showed that the five indexes of triglyceride fatty acids(TG),glutamic-pyruvic transaminase(GPT),urea nitrogen(BUN),glucose(GLU),and lactate dehydrogenase(LDH)in lactating ewes were significantly lower than those in the other three reproductive periods(P< 0.01).The measurement results of reproductive hormones showed that the highest estradio(E)content occurs during oestrus,with a continuous decline in secretion during pregnancy and lactation and a rebound close to oestrus during nonpregnancy.Follicle-stimulating hormone(FSH)and luteinzing hormone(LH)secrete the highest levels during oestrus and continue to decline during pregnancy and lactation.The progesterone(P4)secretion level of ewes was the highest during pregnancy and showed a continuous decreasing trend until nonpregnancy.The measurement results of immune indicators showed that the five indexes of immunoglobulin A(lg A),immunoglobulin M(lg M),immunoglobulin G(lg G),interleukin-2(IL-2)and terferon-γ(IFN-γ)in lactating ewes were significantly lower than those in the other three reproductive periods(P < 0.01),while the opposite was true for ewes during estrus.The measurement results of antioxidant indicators showed that glutathione peroxidase(GSH-Px)and superoxide dismutase(SOD)in lactating ewes were significantly higher than in the other three reproductive periods(P < 0.01),but malondialdehyde(MDA)was the lowest in the lactating period,which was an extremely significant difference from pregnancy and nonpregnancy(P < 0.01).The results of mutation analysis of the FecB gene in small-tailed Han sheep ewes showed that the g.746 A > G locus of the FecB gene was in a Hardy-Weinberg equilibrium state and showed three genotypes(BB,B+,and ++),with B being the dominant allele and B+being the dominant genotype.The B allele had significant positive effects on litter size(LS),rump width(RW),chest width(CW),hip width(HW),and width of the ischiatic end(WE)(P< 0.05)and had extremely significant positive effects on chest depth(CD)and circumference of abdomen(CA)(P < 0.01).It had a significant negative effect on lymphocyte rate,body length(BL)and hip height(HH)(P < 0.05)and an extremely significant negative effect on chest girth(CG)and body weight(BW)(P < 0.01).The results of correlation analysis between reproductive traits and blood indexes and body size traits in small tailed Han sheep ewes showed that there was a significant positive correlation between litter size and total protein concentration(TP),shank circumference(SC),rump length(RL),hip width,and hip height(P < 0.05);there was a significant positive correlation with body height(BH),body length,chest girth,rump width,chest depth,chest width,circumference of the abdomen,and body weight(P < 0.01);and there was a significant negative correlation with total antioxidant capacity(T-AOC)(P < 0.05).The number of live lambs(NL)was significantly positively correlated with granulocyte rate,follicle stimulating hormone,body length,chest width,and hip width(P < 0.05);there was a significant positive correlation with body height,chest girth,rump width,chest depth,circumference of the abdomen,hip height,and body weight(P < 0.01);there was a significant negative correlation with lymphocytes and mean corpuscular hemoglobin content(P < 0.05).The lamb survival rate(LR)was significantly positively correlated with interleukin-2 and total antioxidant capacity(P < 0.05).It was negatively correlated with total protein concentration,chest girth,and shank circumference(P < 0.05).Based on the above results,this study revealed the differences in blood indicators of small-tailed Han sheep ewes during different reproductive stages,revealing the changing rules in different germplasm characteristics and physiological functions of small-tailed Han sheep ewes during reproductive cycles.Combined with analysis of the FecB gene in multiple births,it was found that there were significant correlation effects with blood physiology,reproductive traits,and phenotypic appearance,thereby achieving the unification of phenotypic selection and molecular selection.The correlation between reproductive performance and blood physiology,biochemistry,hormones,immunity,antioxidant indicators,and the phenotypic structure of small-tailed Han sheep ewes can be used as the data basis and theoretical support for screening ewes with high fertility.Finally,it provides an important scientific theoretical basis for accurate identification of the excellent germplasm resources of small-tailed Han sheep. |
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