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. 2019 Nov 12;9(11):958.
doi: 10.3390/ani9110958.

Association of Polymorphisms in Candidate Genes with the Litter Size in Two Sheep Breeds

Zehu Yuan  1 , Junxia Zhang  2   3 , Wanhong Li  1 , Weimin Wang  2 , Fadi Li  1   4 , Xiangpeng Yue  1
Affiliations

Association of Polymorphisms in Candidate Genes with the Litter Size in Two Sheep Breeds

Zehu Yuan et al. Animals (Basel). .

Abstract

Hu sheep and Small-tailed Han sheep are the most widely raised and most famous maternal sheep breeds in China, which are known for precocious puberty, perennial oestrus and high fecundity (1-6 lambs each parity). Therefore, it is crucial to increase litter size of these two breeds for intensive sheep industry. The objective of this study was to identify potential genetic markers linked with sheep litter size located at ten genes. This study collected blood sample of 537 Hu sheep and 420 Small-tailed Han sheep with litter size of first parity. The average litter sizes in Hu sheep and Small-tailed Han sheep were 2.21 and 1.93. DNA-pooling sequencing method was used for detecting the potential single nucleotide polymorphisms (SNPs) in ten genes related to follicle development and female reproduction. SNPscan® was used for individually genotyping. As a result, a total of 78 putative SNPs in nine out of ten candidate genes (except NOG) were identified. In total, 50 SNPs were successfully genotyped in Hu sheep and Small-tailed Han sheep. After quality control, a total of 42 SNPs in Hu sheep and 44 SNPs in Small-tailed Han sheep were finally used for further analysis. Association analysis revealed that nine SNPs within six genes (KIT: g.70199073A>G, KITLG: g.124520653G>C, ADAMTS1: g.127753565T>C, ADAMTS1: g.127754640G>T, NCOA1: g.31928165C>T, NCOA1: g.32140565G>A, LIFR: g.35862868C>T, LIFR: g.35862947G>T and NGF: g.91795933T>C) were significantly associated with litter size in Hu sheep or Small-tailed Han sheep. A combined haplotypes analysis of the two loci (LIFR: g.35862868C>T and LIFR: g.35862947G>T) revealed that H2H3 (CTTT) combined haplotypes had the largest litter size than the rest combined haplotypes and more than those with either mutation alone in Small-tailed Han sheep. Taken together, our study suggests that nine significant SNPs in six genes can be served as useful genetic markers for MAS in sheep.

Keywords: MAS; SNP; SNPscan; litter size; sheep.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Reproductive physiology functions of the ten candidate genes.
Figure 2
Figure 2
Schematic diagram of the experimental protocol across times.
Figure 3
Figure 3
Frequency distribution of litter size in Hu sheep and Small-tailed Han sheep.
Figure 4
Figure 4
Linkage disequilibrium pattern for the significant single nucleotide polymorphisms (SNPs) in ADAMTS1 (A), NCOA1 (B), and LIFR gene (C). Scale of red color indicating the extend linkage disequilibrium (D′ value).
Figure 5
Figure 5
Frequency of haplotypes inferred form two loci (LIFR: g.35862868C>T and LIFR: g.35862947G>T) in Small-tailed Han sheep.
See this image and copyright information in PMC

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