中国西门塔尔牛第6号染色体上部分微卫星的特征

利用微卫星技术对牛第6号染色体上9个微卫星位点进行了研究,检测其在中国西门塔尔牛育种核心群中152头母牛的多态性。本试验9个位点中,BM4528为单态,BM4203属于中度多态位点(0.5>PIC>0.25),而其它的7个位点均是高度多态位点(PIC>0.5)。     

Polymorphism in promoter region of growth hormone receptor is associated with potential production capacity of insulin‐like growth factor‐1 in pre‐pubertal Holstein heifers

Insulin‐like growth factor‐1 (IGF‐1) is one of the important factors for growth, milk production and reproductive functions and mainly released from the liver in response to growth hormone (GH) via GH receptor (GHR) in cattle. Recently, some single nucleotide polymorphisms (SNPs) were identified in the bovine GHR gene. Some GHR‐SNPs were shown to be related to plasma IGF‐1 concentration in cattle. Hence, the capacity to IGF‐1 production in the liver might be affected by GHR‐SNP and associated with performance in the future. This study examined whether GHR‐SNP is associated with IGF‐1 production in the liver of pre‐pubertal heifers. In 71 Holstein calves, blood samples for genomic DNA extraction were obtained immediately after birth. To genotype the GHR‐SNPs in the promoter region, polymerase chain reaction (PCR) products were digested with restriction enzyme NsiI (cutting sites: AA, AG and GG). All heifers at 4 months of age were intramuscularly injected with 0.4 mg oestradiol benzoate. Blood samples were obtained from the jugular vein just before (0 h) and 24 h after injection. The number of AA, AG and GG at the NsiI site was 0, 17 and 54 respectively. In AG and GG, plasma GH concentrations were higher pre‐injection than 24 h post‐injection (p < 0.01). Moreover, plasma GH concentrations in AG post‐injection were higher than in GG (p < 0.05). In contrast, the GG genotype exhibited higher plasma IGF‐1 concentrations in pre‐injection than post‐injection (p < 0.01), although oestradiol did not change IGF‐1 concentration in the AG genotype. We conclude that the GG polymorphism in the promoter region of GHR is associated with a higher potential capacity of IGF‐1 production in the liver of cattle.     

1—2月龄荷斯坦奶牛不同组织中FMDV受体亚基αv、β3、β6 mRNA转录水平的相对定量研究

【目的】建立检测牛口蹄疫病毒(FMDV)受体亚基αv、β3、β6 mRNA相对转录水平的实时定量PCR方法,分析受体αvβ3和αvβ6在不同器官组织中的转录水平。【方法】在对牛FMDV受体基因克隆和测序的基础上,设计实时定量PCR引物,以GAPDH为内参基因,采用△△Ct相对定量PCR方法检测分析FMDV受体亚基αv、β3、β6 mRNA在1—2月龄荷斯坦奶牛体内不同器官组织中的转录表达谱。【结果】αvβ3在荷斯坦奶牛24种组织中均有不同程度的转录表达;αvβ6在甲状腺、硬腭、鼻内皮、喉头、肺、食管、肾、后蹄冠状带等组织表达量较高,在唇、舌皮、软腭、气管、心脏、瘤胃、直肠、前蹄冠状带等组织转录表达量适中,在唾液腺、下颌淋巴结、肝、脾、肌肉等组织未检测到表达;αvβ6在牛体内的表达分布与FMDV组织嗜性基本一致,αvβ6受体可能是决定FMDV组织嗜性的主要功能受体,αvβ3的组织分布似乎与FMDV组织嗜性无关,但不能排除αvβ3在病毒感染过程中的作用。【结论】建立了检测FMDV受体亚基mRNA在不同器官组织中表达水平的相对实时定量PCR方法。     

红色荷斯坦牛与西改牛杂交一代产奶性能的研究

为提高西改牛产奶量，选用外表与其相似的红色荷斯坦牛精液对西改牛进行杂交改良，结果表明，杂一代牛一、二、三胎泌乳期平均产奶量达到4010.33 kg；乳脂、非脂、蛋白质、乳糖含量分别为3.54%、8.52%、2.72%、4.70%，说明，红杂牛完全可作为奶牛的后备资源，加以开发利用。     

Beef quality traits of heifer in comparison with steer,bull and cow at various feeding environments

The present review has been focused largely on the sex type differences in beef quality among heifers, cows, steers and bulls in various feeding environments. Genetic groups, feeding systems and gender are the major factors that change carcass characteristics and fatty acid profiles of cattle. Studies identified that heifer beef has super characteristics in eating quality and a better healthy composition in fatty acids than steer, cow and bull. Diet influences the variation of fatty acid profile; particularly the level of polyunsaturated fatty acids (PUFA) interacts with breed and sex. Animals finished in pasture systems were reported to show better ratios of PUFA/ saturated fatty acids and n‐6/n‐3. Carcasses of roughage‐fed beef are lighter and have less marbling and lower quality grades but have higher cutability than carcasses of grain‐fed bulls. Heifers and cows are reported to deposit more fat than steers and bulls. Among males, lower production of testosterone by steers favors more fat thickness compared with bulls. Marbling greatly varies among cattle belonging to different sexes, and particularly, females have genetic makeup that efficiently controls deposition. The current review identified that heifers can be a premium beef brand, while steer beef currently take a large part of market share across the world.     

Effect of a rumen-protected conjugated linoleic acid mixture on hepatic lipid metabolism in heifers

This study was performed to assess the effects of rumen-protected conjugated linoleic acid (CLA) on hepatic lipid metabolism in heifers. In particular, it was of interest whether feeding CLA causes development of fatty liver as observed recently in mice. Thirty-six growing heifers with an initial body weight of 185 kg were allotted to three treatment groups and fed daily 250 g of different rumen-protected fats for 16 weeks: The control group received 250 g of a CLA-free control fat, the CLA100 group received 100 g of a CLA fat containing 2.4% of cis-9, trans-11 CLA and 2.1% of trans-10, cis-12 CLA and 150 g control fat and the CLA250 group received 250 g of the CLA fat. CLA supplementation had no effect on animal performance parameters, liver weight and hepatic triglyceride concentration. Moreover, mRNA expression of hepatic genes involved in lipogenesis, β-oxidation and fatty acid transport was not influenced by dietary CLA. The fatty acid composition of hepatic total lipids, with particular consideration of ratios of fatty acids indicative of Δ9-, Δ6- and Δ5-desaturation, was also less influenced by dietary CLA. In conclusion, the study shows that dietary rumen-protected CLA has less effect on hepatic lipid metabolism in young heifers and does not induce the development of a fatty liver such as in mice.     

Association of a missense mutation in the luteinizing hormone/choriogonadotropin receptor gene （LHCGR） with superovulation traits in Chinese Holstein heifers

Background: Upon binding luteinizing hormone in the ovary, the luteinizing hormone/choriogonadotropin receptor (LHCGR) is necessary for follicular maturation and ovulation, as well as luteal function. We detected mutations in the LHCGR gene and evaluated their association with superovulation. Methods: Using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing, we examined polymorphisms in LHCGR and the genotypes associated with superovulation traits in 127 Chinese Holstein heifers. Results: A G/T polymorphism (ss52050737) in exon 11 was significantly associated with the total number of ova and the number of transferable embryos. Conclusions: LHCGR may be a new predictor for superovulation in Chinese Holstein heifers.     

Relation of reproductive performances and rectal palpation for luteum function of heifers 7 days after estrus

Diagnosis of corpus luteum (CL) function by rectal palpation (RP) has been widely used for recipient selection of embryo transfer (ET), a technology essential for genetic improvements in cattle. To examine the accuracy of RP diagnosis method, the relationship between RP‐based CL function and reproductive performance was compared in this study. In Experiment 1, CL of Holstein heifers on day 7 after estrus was classified into functional or hypoplastic by RP, and the results were compared with ultrasonographic (US) images and plasma progesterone (P4) levels. As a result, heifers with functional CL judged by RP had a mean maximum CL diameter of 20.1 ± 3.1 mm on US and a mean P4 concentration of 8.1 ± 2.3 ng/mL. These values were significantly greater than those of heifers with hypoplastic CL (12.4 ± 5.4 mm, 4.0 ± 2.8 ng/mL) (P < 0.001). In Experiment 2, the length of the estrus cycle was examined between functional CL and hypoplastic CL. The rate of heifers with a normal estrus cycle length with 18–25 days was significantly lower with hypoplastic CL than with functional CL (16/24 vs. 43/46, P < 0.01). In Experiment 3, 543 inseminated heifers were similarly classified by CL function by RP 7 days after estrus. The heifers with functional CL showed higher pregnancy rate compared with the heifers with hypoplastic CL (75.2 vs. 47.9%, P < 0.0001). Finally, the CL function of 66 heifers was examined by RP on day 7 post‐estrus, and ET was performed in 49 (74.2%) heifers with functional CL. As a result, 27 (55.1%) of them became pregnant. Taken together, these results reconfirm that RP on day 7 after estrus is useful for selection of heifers with functional CL.     

娟姗牛与西杂牛杂交后代生长发育观测

[目的]旨在繁育适于牦牛杂交改良的乳肉兼用父本.[方法]在海拔相对较低的半农半牧区,用娟姗牛与西杂牛杂交,观察杂交后代的生长发育和配种情况.[结果]娟姗牛与西杂牛的杂交后代在甘南州高海拔地区具有较好的适应性,表现出明显的杂交优势,能与甘南牦牛自然交配.