| An important aim in animal breeding is the improvement of growth and meat quality traits. Previous studies have demonstrated that adipocytokines are bioactive factors that are closely related to lipid, glucose, and energy metabolism, which play key roles in regulation of growth and fat deposition. Therefore, five major adipocytokine members were selected as candidate genes, including Leptin, Adiponectin, Resistin, TNF-a and Angptl8. The genetic variations of five genes were detected by DNA sequencing and forced-PCR-RFLP technologies, and association analysis were carried out between 537 cattle from six breeds and SNPs to evaluate the effects of SNPs detected on growth traits. Tissues expression of Leptin, TNF-a and Angptl8 were subsequently detected by qRT-PCR in ten different Zaobei cattle tissues. The aim of this study was to provide a theoretical basis in cattle breeding programs.The results were as follows:1. SNPs detection of the bovine Leptin gene and their correlation with growth traits in Chinese cattleTwo SNPs were detected in bovine Leptin gene, named g.l2254(T/C) and g.14177(C/T). The g.12254(T/C) resulted in a substitution of arginine for cysteine at position 25, while the g.14177(C/T) led to a substitution of valine for alanine at position 80. In Jiaxian cattle population, individuals with genotype CT of g.14177(C/T) displayed larger hip width and height at hip cross than individuals with genotype CC (P< 0.05). In Nanyang cattle population, individuals with genotype CT of g.12254(T/C) had greater body weight at birth than those with genotype TT (P< 0.05), and body weight at 12 months of individuals with genotype CT were higher than those with genotype CC (P< 0.05). And individuals with genotype TT had greater heart girth at 24 months than those with genotype CC (P< 0.05). In all yellow cattle population, the heart girth, abdominal circumference, hipbone width, hip width, body weight, and beef performance index of animals with genotype CT of g.14177(C/T) were significantly higher than those with genotype CC(P< 0.05).2. SNPs detection of the bovine TNF-a gene and their correlation with growth traits in Chinese cattleOne SNP was detected in bovine TNF-a gene, named g.2130(A/G). It is a synonymous mutation in exon 2. In Jiaxian and yellow cattle, there were no significant differences between three genotypes and growth traits. In Nanyang cattle population, individuals with genotype GA of g.2130(A/G) had greater body weight at 6,18,24 months, heart girth at 6,18,24 months, average daily gain at 6,18 months and hip width at 12 months than individuals with genotype GG (P< 0.05).3. SNPs detection of the bovine Angptl8 gene and their correlation with growth traits in Chinese cattleTwo SNPs were detected in bovine Angptl8 gene, named g.629(G/A) and g.884(T/C), which were both in the 5’flanking region. In Jiaxian cattle population, animals with genotype GG of g.629(G/A) had significantly greater height at withers and abdominal circumference than those with genotype AA (P< 0.05). Animals with genotype TT of g.884(T/C) had significantly greater heart girth, abdominal circumference, hipbone width and height at hip cross than those with genotype TC (P< 0.05). In Nanyang cattle population, animals with genotype TT of g.884(T/C) had significantly greater body length at 18,24 months than those with genotype TC (P< 0.05). In yellow cattle population, the abdominal circumference of animals with genotypes GG and GA of g.629(G/A) had significantly greater than those with genotype AA (P< 0.05). And animals carrying genotype TT of g.884(T/C) had significantly greater heart girth, abdominal circumference, body weight, and beef performance index than those with genotype TC (P< 0.05).4. Association analysis between five combined sites of Leptin、TNF-α and Angptl8 gene and growth traits in Chinese yellow cattleIn yellow cattle population, the multiple effects of five sites showed that abdominal circumference of animals with combined genotype CCCCGAAATC had significantly greater than those with combined genotype CCCCGAGATC (P< 0.05). And animals carrying combined genotype CCCCGAGATC had significantly greater abdominal circumference than those with combined genotypes CTCCGAAATC and CTCCGGAATC (P< 0.05).5. Tissues expression of three bovine genes in Zaobei cattleTissues expression of bovine Leptin, TNF-a and Angptl8 genes were detected in Zaobei cattle by qRT-PCR. The results demonstrated that bovine Leptin gene was highly expressed in back fat and visceral fat, followed by longissimus dorsi muscle, with low levels in heart, rumen, spleen and almost no expression in other tissues. The bovine TNF-a gene was predominantly expressed in spleen, lung, intestine and liver, with minor expression in kidney, heart, rumen, and longissimus dorsi muscle. The bovine Angptl8 gene was predominantly expressed in back fat and liver, followed by visceral fat, lung and intestine, with low levels in heart, longissimus dorsi muscle, kidney, spleen and rumen. |
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