<正>对宁夏牧区陶赛特、得克赛尔、萨福克、滩羊、小尾寒羊、滩寒杂种羊6个绵羊群体间杂种优势进行预测,结果显示:在进行肉羊杂交羊生产中,母本品种以滩寒杂种的效果最好,滩羊次之,小尾寒羊最差;杂交父本的选择为得克赛尔、萨福克、陶赛特。

The genomes of six populations(Dorset,Texel,Black-Suffolk,Tan sheep,Small-tailed Han sheep,hybrid of Tan and Small-tailed Han sheep) were screened with 7 microsatellite loci,and genetic diversities and genetic distance were estimated in this study.The results showed that,108 alleles were detected in six populations,all the loci showed polymorphism in each population.The expected heterozygosity of all populations were much higher than the observed heterozygosity.The coefficient of phenotype differentiation(Fst) between populations was very low,the value was 5.8%,which was consistent with the coefficient of gene differentiation(Gst).The inbreeding coefficients for all populations(Fit) amounted to 56.90%.The inbreeding coefficients within breeds(Fis) was 54.36%.The heterosis between populations was also forecast according to DC distance and Nei's genetic distance(DA),hybrid with Tan and small-tailed Han sheep as female parent was the best,then was Tan sheep,and Small-tailed Han sheep was the worst.The selective order for male parent should be Texel,Black-Suffolk,and then Dorset concerned with hybrid effects.

The genetic polymorphisms of β-Lg exon Ⅳ and β-Lg 5′ flanking region in five populations of Chinese cattle,including Holstein,Luxi cattle,Minnan cattle,Bohai cattle and Yak,were detected using PCR-RFLP.The results indicated that mutations of β-Lg exon Ⅳ and β-Lg 5′ flanking region in the populations were found.Genetic analysis showed that,the frequencies of allele A and B in former four populations were 0.4125/0.5875,0.1419/0.8581,0.0333/0.9667 and 0.1857/0.8143 respectively.The allele frequencies of A and B on β-Lg 5′ flanking region were 0.4125/0.5875,0.7286/0.2714,0.7328/0.2672 and 0.8637/0.1364 respectively.Only alleles B and E were found in Yak,with allele frequencies of 0.0732/0.9269 and genotype EE and BE,no carriers of other genes or genotypes were found.A chi-square analysis suggested that Holstein,Luxi cattle,Minnan cattle,Bohai cattle populations had reached Hardy-Weinberg equilibrium in two loci,and Yak was unequilibrium in β-Lg exon Ⅳ.Only Minnan and Yak cattle population had low polymorphism information content in two loci,others had moderate values.Heterozygosity and expected heterozygosity were highest in Holstein cattle and lowest in Minnan cattle.Conclusions from this study lay scientific foundation to protection and utility of genetic resources.

The genomes of 6 populations were screened by using microsatellites as molecular markers,including Ujmuqin sheep,small-tailed Han sheep,Tan sheep,Hu sheep,Tong and Yangtse River Delta White Goat.A total of 7 microsatellite markers were used and genetic diversity and genetic distance were also determined.The results showed that there were 224 alleles in 6 populations,all 7 locus showed polymorphism in all populations.Average heterozygosity of all populations was 0.9499,and the mean polymorphism information content(PIC) of all 6 populations was 0.8425~0.9294.A UPGMA dendrogram was constructed based on Nei′s standard genetic distance and DA genetic distance respectively.Hu and Tong were grouped at first,Ujmuqin and small-tailed Han clusted and then clusted with Tan sheep,Finally Yangtse River Delta White Goat clusted with all above.From this study,Ujmuqin is belong to Mongolia sheep group,it correspond with the historical records exactly.Ujmuqin and small-tailed Han sheep,Tan sheep,Hu sheep,Tong sheep,vest in Mongolia sheep group.

PCR-SSCP was applied to detect single nucleotide polymorphism(SNP) of exon 10 of the follicle-stimulating hormone receptor(FSHR) gene for 254 sheep,including Hu sheep,Ujumqin sheep and Tan sheep.The results demonstrated monopolymorphism.After sequenced,sheep FSHR gene exon10 DNA sequence was acquired.DNA sequence analysis showed that the homology of nucleotide sequence of exon 10 of FSHR gene among sheep,small-tailed Han sheep,yak,water buffalo and mouse were 100%、98%、98% and 86%.The results implied that whether it provides evidence for the fact that the exon 10 of FSHR gene could be the candidate gene for high fecundity in sheep.

The Callipyge sheep produced some muscle hypertrophy,because of a single nucleotide mutation A-G at the end of the 18th chromosome.Callipyge gene is belonged to the imprinted gene family,performancing paternal polar dominance.The Callipyge gene may affect one cis-acting element LRCE(long range control element),activate one enhancer or inhibit one silencer.Callipyge sheeps have the higher rates of the lean and the slaughter than the average,but the longissimus have the higher shear strength and affect the taste.Callipyge gene can be used!in the breeding of the sheeps.

The restriction polymorphisms of MHC-DRB3.2 in 4 population of bovine were investigated by Semi-Nest PCR with enzyme of HaeⅢ and BstYⅠ.The results revealed that there were extensive polymorphisms in the site of HaeⅢ in 4 populations,but Xuyi buffalo had fewest alleles in 4 populations.Extensive mutations also existed in the site of BstYⅠ in Luxi cattle,Bohai cattle and Holstein cow,with homomorphism in Xuyi buffalo.Statistical analysis showed that polymorphisms in the site of HaeⅢ did not fit with Hardy-Weinberg equilibrium in Luxi cattle,Xuyi buffalo.Polymorphisms in the site of BstYⅠ also did not fit with Hardy-Weinberg equilibrium in Holstein cow.Polymorphisms in the site of BstYⅠ in Luxi cattle and Bohai cattle fitted with or almost reached Hardy-Weinberg equilibrium.NJ and UPGMA dendrograms were constructed based on DA and Roger genetic distance respectively.Luxi cattle and Bohai cattle were grouped at first,then Holstein cow,finally Buffalo clusted with all above.This study indicated the PCR-RFLP system of cattle can be applied in the research of Buffalo.The polymorphism of MHC-DRB3.2 in Buffalo is less abundant than cattle.

The level of genetic differentiation, gene flow and the relationship between geographical distance and genetic differentiation among six sheep populations of Mongolian group in China (Tong sheep, small-tailed Han sheep, Hu sheep, Tan sheep, Ujumuqin sheep and Bayinbuluk sheep) were analyzed using seven microsatellites. The trees were constructed from diversity coefficient (DC) distances among the six sheep populations. The overall heterozygote deficit across all the populations (F it) was between 0.167 (OarAE101) and 0.044 (MAF33). The over-all significant deficit of heterozygote, because of inbreeding within breeds, (F is) was between 0.089 (OarFCB304) and 0.005 (MAF33). The coefficient of genetic differentiation (F st) was between 0.100 (OarAE101) and 0.022 (OarFCB48). It indicated that 3.9% of the total genetic variation could be explained by breed differences and the remaining 96.1% by differences among individuals for each population. This illustrated that most variations existed within breeds and genetic differentiation level were very low among sheep breeds of the Mongolian Group in China. The average number of effective migrants exchanged per generation (Nem) ranged from 2.7369 (Tan sheep and Bayinbuluk sheep) to 44.3928 (Tong sheep and Hu sheep), and the mean value was 11.25213. Significantly positive relationships between the level of genetic differentiation and geographical distance and genetic distances were detected. It is concluded that genetic differentiation of sheep breeds of Mongolian group in China is mainly the result of natural selection (different living conditions).

This experiment was conducted with 1 120 Xueshan chickens(84 days old) to analysis the effect of different protein/energy ratio on growth and slaughter performance. Chickens were floor raised and divided randomly into seven groups, each group had two replicates(80 chickens each replicate),and different group were fed with different protein/energy ratio feed. The chicken′s body weight(BW) was measured every week,the ratio of feed and gain(F/G) was calculated,and the slaughter performance was observed at 19 weeks old. The results showed that weekly BW gain between different groups was significant difference at 13,14,16,18,19 weeks old(P<0.05),and BW and accumulative F/G ratio had not significant difference at different weeks old(P>0.05). There was significant difference in F/G ratio among some groups at 15,17,19 weeks old(P<0.05). Energy level had no effect on the slaughter percentage,half-eviscerated,eviscerated and leg muscle ratios at 19 weeks old(P>0.05). The breast and the thigh muscle percentages were significantly different between the second and fourth group(P<0.05).

The genomes of six populations were screened using microsatellites as molecular markers, including Ujmuqin sheep, small-tailed Han sheep, Tan sheep, Hu sheep, Tong sheep and Yangtse River Delta (YRD) white goat. A total of seven microsatellite markers were used and genetic diversity and genetic distance were also determined. The results showed that there were 224 alleles in six populations, all seven loci showed polymorphism in all populations. The average heterozygosity of all populations was 0.949 9, and the mean polymorphism information content (PIC) of all six populations was 0.842 5–0.929 4. The six sheep (goat) popualtions were lowly differentiated with all loci, and the coefficient of phaenotype differentiation (Fst) was 2.6%, which was consistent with the coefficient of gene differentiation (Gst). The global heterozygote deficit across of all populations (Fit) amounted to 0.5%. The overall significant deficit of heterozygotes because of inbreeding within breeds (Fis) amounted to −2.2%. Two Unweighted Pair-group Method using Arithmetic Averages (UPGMA) dendrograms were constructed on the basis of Nei’s standard genetic distance (DS) and Nei’s genetic distance (DA) respectively. Hu sheep and Tong sheep were grouped at first, Ujmuqin sheep and small-tailed Han sheep clustered and then clustered with Tan sheep. Finally, Yangtse River Delta white goat joined in with all above. From this study, Ujmuqin sheep belongs to “Mongolia sheep” group, which corresponds with the historical records exactly. Ujmuqin sheep and small-tailed Han sheep, Tan sheep, Hu sheep and Tong sheep all vest in the “Mongolia sheep” group.