Effect of organic mineral supplementation in reducing oxidative stress in Holstein calves during short‑term heat stress and recovery conditions

Background This study investigated the effects of inorganic and organic minerals on physiological responses,oxidative stress reduction,and rumen microbiota in Holstein bull calves(123.81±9.76 kg;5 months old)during short-term heat stress(HS)and recovery periods.Eight Holstein calves were randomly assigned to four treatment groups:no mineral supplementation(Con),inorganic minerals(IM),organic minerals(OM),and high-concentration organic minerals(HOM)and two thermal environments(HS and recovery)using 4×2 factorial arrangement in a crossover design of four periods of 35 d.Calves were maintained in a temperature-controlled barn.The experimental period consisted of 14 d of HS,14 d of recovery condititon,and a 7-d washing period.Results Body temperature and respiration rate were higher in HS than in the recovery conditions(P<0.05).Selenium concentration in serum was high in the HOM-supplemented calves in both HS(90.38μg/dL)and recovery periods(102.00μg/dL)(P<0.05).During the HS period,the serum cortisol was 20.26 ng/mL in the HOM group,which was 5.60 ng/mL lower than in the control group(P<0.05).The total antioxidant status was the highest in the OM group(2.71 mmol Trolox equivalent/L),followed by the HOM group during HS,whereas it was highest in the HOM group(2.58 mmol Trolox equivalent/L)during the recovery period(P<0.05).Plasma malondialdehyde and HSP70 levels were decreased by HOM supplementation during the HS and recovery periods,whereas SOD and GPX levels were not significantly affected(P>0.05).The principal coordinate analysis represented that the overall rumen microbiota was not influenced by mineral supplementation;however,temperature-induced microbial structure shifts were indicated(PERMANOVA:P<0.05).At the phylum level,Firmicutes and Actinobacteria decreased,whereas Fibrobacteres,Spirochaetes,and Tenericutes increased(P<0.05),under HS conditions.The genus Treponema increased under HS conditions,while Christensenella was higher in recovery conditions(P<0.05).Conclusion HOM supplementation during HS reduced cortisol concentrations and increased total antioxidant status in Holstein bull calves,suggesting that high organic mineral supplementation may alleviate the adverse effects of HS.

Evaluation of Holstein cows with different tongue‑rolling frequencies:stress immunity,rumen environment and general behavioural activity

Background The tongue-rolling behaviour of cows is regarded as an outward sign of stressed animals in a low welfare status.The primary aim of this observational study was to evaluate the association between the frequency of tongue-rolling behaviour and its physiological function.The secondary aim was to explore the relationship between general activities and the frequency of tongue-rolling behaviour of cows.A total of 126 scan sampling behavioural observations were collected over 7 d on 348 Holstein cows with the same lactation stage in the same barn.The tongue-rolling frequency was defined as the number of tongue-rolling observations as a percentage to the total observations per individual cow.According to their tongue-rolling frequency,the cows were grouped into the CON(no tongue-rolling),LT(frequency 1%),MT(frequency 5%),and HT(frequency 10%)groups.Six cows from each group were randomly selected for sampling.Serum samples,rumen fluid,milk yield,and background infor-mation were collected.The general behaviour data during 72 continuous hours of dairy cows,including eating time,rumination time,food time(eating time+rumination time),and lying time,were recorded by the collar sensor.Results Cortisol(P=0.012),γ-hydroxybutyric acid(P=0.008),epinephrine(P=0.030),and dopamine(P=0.047)levels were significantly higher in tongue-rolling groups than in the CON group.Cortisol levels and tongue-rolling frequency had a moderate positive correlation(linearly r=0.363).With the increase in tongue-rolling frequency,the rumen pH decreased first and then increased(P=0.013),comparing to the CON group.HT cows had significantly less food time than CON cows(P=0.035).The frequency of tongue-rolling had a moderate negative relationship with rumination time(r=-0.384)and food time(r=-0.492).Conclusions The tongue-rolling behaviour is considered as a passive coping mechanism,as the stress response in cows with high tongue-rolling frequency increased.Food intake and rumination activities were all closely related to the occurrence of tongue-rolling behaviour.

Study on the Effects of Chinese Herb Additive on Milk Yield and Anti-heat Stress Ability of Holstein Cow

[Objective] The research aimed to explore the effects of Chinese herb additive on milk yield and anti-heat stress ability of Holstein cow.[Method] 36 Holstein cows with similar birth order and milk yield were equally and randomly divided into 3 groups which were control group, Chinese medicine Ⅰ group and Chinese medicine Ⅱ group. In control group, cows were fed with basic feed, while in Chinese medicine Ⅰ group, cows were fed with basic feed containing 4% compound Chinese herb additive and in Chinese medicine Ⅱ group, cows were fed with basic feed containing 3% compound Chinese herb additive.All cows in the 3 groups were analyzed comparatively.[Result] Adding some compound Chinese herb additive into basic feed would increase milk yield and anti-heat stress ability of Holstein cow,besides,it also could decrease cow diseases such as cow mastitis.Chinese medicine Ⅰ would generate the highest economic benefit of practical production.[Conclusion] Adding Chinese herb additive into basic feed is an effective way for reliefing heat stress and increasing milk yield.

Holstein极化子能带和有效质量的温度依赖性

使用正则变换方法,考察了一维Holste in极化子能带和有效质量的温度依赖性。结果表明,对于一定的电子声子耦合强度,Holste in极化子能带宽度随温度升高而变窄,有效质量随温度升高而增大。特别是当电子声子耦合强度足够大时,极化子能带宽度在很小的温度范围内会迅速地变为零,我们认为这种情况实际上是极化子从能带状态向自陷局域态的迅速转变,这与通常的相变现象有点相类似。当电子声子耦合常数越大时,极化子有效质量随温度的升高而增加得越快。很显然,研究电子声子相互作用,对理解固体的光学和输运等性质将有重要的意义。

Cloning and Expression of IL-2 Gene from Holstein-Friesian Cow

[Objective] The aim of this study is to clone bovine interleukin-2 gene(IL-2)and observe its expression in prokaryotic cells.[Method]Bovine IL-2 gene was amplified from total RNA of peripheral blood lymphocytes of holstein-friesian cows by RT-PCR.Subsequently,the gene was cloned into pGEX-2T prokaryotic expression plasmid to construct recombinant,which was then transformed into Escherichia Coli BL21.After IPTG induction,SDS-PAGE analysis was conducted.[Result]A 500 bp target fragment corresponding with expectation was obtained by RT-PCR.The cloned gene successfully expressed fusion protein of about 43 kD in prokaryotic cells.[Conclusion]This study provided a theoretical and material basis for further researches on IL-2 gene.

前外侧入路双钢板固定治疗Holstein-Lewis骨折

目的:探讨前外侧入路双钢板内固定治疗Holstein-Lewis骨折的疗效。方法:2003年1月至2015年3月,复旦大学附属上海市第五人民医院收治45例Holstein-Lewis骨折患者。男32例,女13例,年龄21~52岁,平均36.8岁,均合并桡神经损伤。经臂部前外侧入路探查桡神经后,复位骨折端,植入3.5mm加压钢板,置于肱骨干前及外侧联合固定。桡神经根据损伤程度予以修补或松解。记录术后并发症,骨折愈合时间,桡神经功能恢复时间,肩、肘关节屈伸范围。采用UCLA肩关节和Mayo肘关节评分标准评价疗效。结果:本组患者切口均Ⅰ期愈合。随访8~36个月,平均15.3个月。骨折愈合时间3~6个月,平均3.9个月。41例桡神经嵌压水肿及不完全断裂患者于术后3~6个月恢复,平均4.8个月;4例桡神经完全断裂患者于2年后伸腕、伸指功能完全恢复。本组患者术后肩关节外展155°~165°,平均160°。肘关节活动范围125°~135°,平均128.5°。根据加州大学肩关节评分(UCLA)标准,肩关节功能优45例。根据Mayo评分标准,肘关节功能优42例,良3例。结论:前外侧入路双钢板固定治疗Holstein-Lewis骨折,具有内固定可靠,肌群损伤小,桡神经探查修补便利的特点,是一种安全可靠的治疗方式。

Variance components and correlations of female fertility traits in Chinese Holstein population

Background: The objective of the present study was to estimate(co)variance components of female fertility traits in Chinese Holsteins, considering fertility traits in different parities as different traits. Data on 88,647 females with 215,632 records(parities) were collected during 2000 to 2014 from 32 herds in the Sanyuan Lvhe Dairy Cattle Center, Beijing, China. The analyzed female fertility traits included interval from calving to first insemination, interval from first to last insemination, days open, conception rate at first insemination, number of inseminations per conception and non-return rates within 56 days after first insemination.Results: The descriptive statistics showed that the average fertility of heifers was superior to that of cows. Moreover,the genetic correlations between the performances of a trait in heifers and in cows were all moderate to high but far from one, which suggested that the performances of a trait in heifers and cows should be considered as different but genetically correlated traits in genetic evaluations. On the other hand, genetic correlations between performances of a trait in different parities of cows were greater than 0.87, with only a few exceptions, but variances were not homogeneous across parities for some traits. The estimated heritabilities of female fertility traits were low; all were below 0.049(except for interval from calving to first insemination). Additionally, the heritabilities of the heifer interval traits were lower than those of the corresponding cow interval traits. Moreover, the heritabilities of the interval traits were higher than those of the threshold traits when measuring similar fertility functions. In general, estimated genetic correlations between traits were highly consistent with the biological categories of the female fertility traits.Conclusions: Interval from calving to first insemination, interval from first to last insemination and non-return rates within 56 days after first insemination are recommended to be included in the selection index of the Chinese Holstein population. The parameters estimated in the present study will facilitate the development of a genetic evaluation system for female fertility traits to improve the reproduction efficiency of Chinese Holsteins.

Holstein模型的非波矢确定态稳定传播解

论文通过引入含时相干态形式波函数 ,对Holstein模型的非波矢确定态的稳定行波解做了详细的研究 .首先在紧束缚近似下 ,通过数值计算 ,给出了具有普遍意义的稳定传播解 ,即一种有着复杂结构的准周期波 ;同时在低激发态条件下 ,得到系统的解析解 ,并可看到数值解与解析解相吻合 ;最后计算了系统能量的无损耗传播过程 ,即系统的能量密度随群速变化的情况 .这些结果对进一步用Holstein模型研究其他领域传能问题有一定的指导意义 .

Establishment of paternity testing system using microsatellite markers in Chinese Holstein

To estimate the efficiency of microsatellite markers in paternity testing among Chinese Holstein, 30 microsatellite loci were used to differentiate 330 Chinese Holstein genotypes, according to the calculation of the allele frequency, number of alleles, effective number of alleles, genetic heterozygosity, polymorphic information content （PIC）, and the exclusion probability in this cattle population. The results demonstrated that the exclusion probability ranged from 0.620 in locus BM1818 to 0.265 in locus INRA005 with the average of 0.472 and 11 microsatellite markers exceeding 0.5. The combined exclusion probability of nine microsatellite markers was over 0.99. The result showed that paternity testing of Chinese Holstein was basically resolved using the nine microsatellite markers selected.

Relationship of Somatic Cell Count with Milk Yield and Composition in Chinese Holstein Population

The objective of this study was to analyze the relationship of somatic cell count （SCC） with milk yield, fat and protein percentage, fat and protein yield using analysis of variance and correlation analysis in Chinese Holstein population. The 10 524 test-day records of 568 Chinese Holstein Cattle were obtained from 2 commercial herds in Xi＇an region of China during February 2002 to March 2009. Milk yield, fat percentage, fat and protein yield initially increased and then dropped down with parity, whereas protein percentage decreased and SCC increased. Analysis of variance showed highly significant effects of different subclasses SCC on milk yield and composition （P〈 0.01）. Compared with milk yield with SCC ≤ 200 000 cells mL-1, milk yield losses with SCC of 200 000-500 000 cells mL-1, 501000-1 000 000 cells mL-1, ≥ 1 000 000 cells mL-1 were 0.387, 0.961 and 2.351 kg, respectively. The highly significant negative correlation coefficient between somatic cell score （SCS） and milk and protein yield, milk yield and fat and protein percentage, protein percentage and fat yield were -0.084, -0.037, -0.061, -0.168, and -0.088, respectively （P〈 0.01）. The highly significant positive correlation coefficients between SCS and fat yield and fat and protein percentage, milk yield and fat and protein yield, fat percentage and protein percentage and fat yield, protein yield and protein percentage and fat yield were 0.041, 0.177, 0.105, 0.771, 0.865, 0.122, 0.568, 0.318, and 0.695, respectively （P〈 0.01）. There was no significant relationship between fat percentage and protein yield （P 〉 0.05）. The results of the present study first time provide the relevant base-line data for assessing milk production at Xi＇an region of China.

Extended Holstein polaron model for charge transfer in dry DNA

The variational method is applied to the study of charge transfer in dry DNA by using an extended Holstein small polaron model in two cases： the site-dependent flnite-chain discrete case and the site-independent continuous one. The treatments in the two cases are proven to be consistent in theory and calculation. Discrete and continuous treatments of Holstein model both can yield a nonlinear equation to describe the charge migration in an actual long-range DNA chain. Our theoretical results of binding energy Eb, probability amplitude of charge carrier Ф and the relation between energy and charge-lattice coupling strength are in accordance with the available experimental results and recent theoretical calculations.

Identification Effects of Pedometer on Estrus of Holstein Cows during Peak Lactation Period

[Objective]The paper was to discuss identification effects of pedometer on estrus of Holstein cows during peak lactation period. [Method]The estrus of Holstein cows during peak lactation period were identified by manual observation and pedometer monitoring. [Result]Compared with manual observation,the detection rate of estrus in Holstein cows using pedometer monitoring was increased by 24. 01%,which reduced the labor cost and enhanced accuracy rate. [Conclusion]The research could provide reliable basis for estrus identification of cows.

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 sequencing, we examined polymorphisms in LHCGR and Chinese Holstein heifers. conformation polymorphism （PCR-SSCP） and DNA the genotypes associated with superovulation traits in 127 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.

Characterization and mitigation option of greenhouse gas emissions from lactating Holstein dairy cows in East China

Background:This study investigated greenhouse gas(GHG)emission characteristics of lactating Holstein dairy cows in East China and provided a basis for formulating GHG emission reduction measures.GreenFeed system was used to measure the amount of methane(CH_(4))and carbon dioxide(CO_(2))emitted by the cows through respiration.Data from a commercial cow farm were used to observe the effects of parity,body weight,milk yield,and milk component yield on CH_(4) and CO_(2) emissions.Results:Mean herd responses throughout the study were as follows:111 cows completed all experimental processes,while 42 cows were rejected because they were sick or had not visited the GreenFeed system 20 times.On average,lactating days of cows was 138±19.04 d,metabolic weight was 136.5±9.5 kg,parity was 2.8±1.0,dry matter intake(DMI)was 23.1±2.6 kg/d,and milk yield was 38.1±6.9 kg/d.The GreenFeed system revealed that CH_(4) production(expressed in CO_(2) equivalent,CO_(2)-eq)was found to be 8304 g/d,CH_(4)_(CO_(2)−eq)/DMI was 359 g/kg,CH_(4)_(CO_(2)−eq)/energy-corrected milk(ECM)was 229.5 g/kg,total CO_(2) production(CH_(4) production plus CO_(2) production)was 19,201 g/d,total CO_(2)/DMI was 831 g/kg,and total CO_(2)/ECM was 531 g/kg.The parity and metabolic weight of cows had no significant effect on total CO_(2) emissions(P>0.05).Cows with high milk yield,milk fat yield,milk protein yield,and total milk solids yield produced more total CO_(2)(P<0.05),but their total CO_(2) production per kg of ECM was low(P<0.05).The total CO_(2)/ECM of the medium and high milk yield groups was 17%and 27%lower than that of the low milk yield group,respectively.Conclusions:The parity and body condition had no effect on total CO_(2) emissions,while the total CO_(2)/ECM was negatively correlated with milk yield,milk fat yield,milk protein yield,and total milk solids yield in lactating Holstein dairy cows.Measurement of total CO_(2) emissions of dairy cows in the Chinese production system will help establish regional or national GHG inventories and develop mitigation approaches to dairy production regimes.

N-carbamylglutamate restores nitric oxide synthesis and attenuates high altitudeinduced pulmonary hypertension in Holstein heifers ascended to high altitude

Background: High-altitude pulmonary hypertension(HAPH) is a life-threating condition for animals in high altitude,and disturbance of endothelial nitric oxide(NO) synthesis contributes to its pathogenesis. N-carbamylglutamate(NCG), which enhances arginine synthesis, promotes endogenous synthesis of NO. In this study, we determined the effects of NCG on alleviating HAPH in Holstein heifers that ascended to Tibet(Lhasa, 3,658 m).Methods: Exp. 1, 2,000 Holstein heifers were transported from low elevation(1,027 m) to Lhasa. After being exposed to hypoxia for 1 yr, Holstein heifers were assigned to a healthy group(Control, n = 6) with mean pulmonary hypertension(mPAP) < 41 mmHg, and an HAPH affected group(HAPH, n = 6) with mPAP > 49 mmHg.Lung tissues were collected to evaluate histopathological changes and the expression of endothelial nitric oxide synthase(eNOS). Exp. 2, ten healthy heifers and 10 HAPH affected heifers were supplemented with NCG(20 g/d per heifer) for 4 wk. Physiological parameters were determined and blood samples were collected on d-1 and d 28 of the feeding trial.Results: Expression of e NOS in small pulmonary arteriole intima was higher in the healthy than HAPH group(P = 0.006), whereas HAPH group had significantly thicker media and adventitia than healthy group(all P < 0.05). The mRNA of eNOS and protein level of eNOS were higher in the lungs of heifers in the healthy group than in the HAPH group(both P < 0.001), whereas endothelin-1 protein levels were higher in HAPH group than in the healthy group(P = 0.025). NCG supplementation decreased mPAP and ammonia(both P = 0.001), whereas it increased the expression of eNOS, arginine, and plasma NO(all P < 0.05).Conclusions: The expression of eNOS was decreased in Holstein heifers with HAPH. NCG supplementation decreased m PAP through the restoration of eNOS and endogenous NO synthesis.

Evaluation of Breeding Programs Combining Genomic Information in Chinese Holstein

Current study adopted gene flow theory and selection index method to compare the breeding efficiency of three breeding plans in the Chinese Holstein cattle using ZPLAN software. Simulated conventional progeny-testing program （PT） and young sire program （YS） were compared with breeding program using genomic selection （GS） taking parameters derived from Chinese Holstein breeding system. The results showed that, GS shortened generation interval by 1.5-2.2 years, and increased the genetic progress by 30-50%, comparing to PT and YS, respectively. Economic analysis showed that GS could obtain a higher breeding efficiency, being 119 and 97% higher than that of PT and YS, respectively; and GS was also powerful in improving functional traits with a low heritability. Main factors affecting breeding efficiency in GS were further discussed, including selection intensity, accuracy and the cost of SNP genotyping. Our finding provided references for future designing and implementing GS in Chinese dairy population.

Effects of dietary forage to concentrate ratio and wildrye length on nutrient intake, digestibility, plasma metabolites, ruminal fermentation and fecal microflora of male Chinese Holstein calves

Twenty-eight male, weaned Chinese Holstein calves（（156.8±33.4） kg） were used to investigate the effects of dietary forage to concentrate ratio（F：C） and forage length on nutrient digestibility, plasma metabolites, ruminal fermentation, and fecal microflora. Animals were randomly allocated to four treatments in a 2×2 factorial arrangement： whole-length forage（WL） with low F：C（50：50）; WL with high F：C（65：35）; short-length forage（SL） with high F：C（65：35）; and SL with low F：C（50：50）. Chinese wildrye was used as the only forage source in this trial. The grass in the SL treatments was chopped using a chaff cutter to achieve small particle size（-50% particles 〉19 mm）. Dry matter intake（DMI） and organic matter（OM） intake was increased by increasing both F：C（P〈0.01） and forage length（FL）（P〈0.05）, while acid detergent fiber（ADF） and neutral detergent fiber（NDF） intakes were only increased by increasing the F：C（P〈0.01）. The digestibility of NDF was increased as the FL increased（P〈0.01）, and it was also affected by interaction between F：C and FL（P〈0.05）. Cholesterol（CHO）（P〈0.01）, leptin（LP）（P〈0.05）, and growth hormone（GH）（P〈0.01） concentrations in plasma were increased as dietary F：C increased. A significant increase in plasma triglyceride（TG）（P〈0.01）, insulin（INS）（P〈0.05）, and GH（P〈0.01） levels was observed with decreasing dietary FL. Ruminal p H values of calves fed with low F：C diets were significantly lower than those in high F：C treatment（P〈0.05）. Increasing the F：C enhanced ruminal acetic acid（P〈0.05） and acetic acid/propionic acid（P〈0.01）. Fecal Lactobacillus content was significantly higher, while Escherichia coli and Salmonella contents were significantly lower in WL and high F：C groups（P〈0.05）. Lower fecal scores（higher diarrhea rate） were observed in calves fed with SL hay compared to WL hay（P〈0.05）. Denatured gradient gel electrophoresis（DGGE） bands and richness index（S） were significantly affected by the interaction between F：C and FL（P〈0.05）, under high F：C, band numbers and richness index from WL group were higher than that from SL group（P〈0.05）, whereas there were no differences between WL andSL groups under low F：C（P〉0.05）. Microflora similarity was 50–73% among the different treatments. It is concluded that the WL with high F：C（65：35） diet is suitable for weaned calves.

Milk Yield of Holstein Cows Induced into Lactation Twice Consecutively and Lactation Curve Models Fitted to Artificial Lactations

Nineteen multiparous barren Holstein cows were subjected to an induction of lactation protocol for 21 d administering estradiol cypionate （2 mg kg-1 of body weight （BW） d-1, on day 1 to 14）, progesterone （0.10 mg kg-1 of BW, on day 1 to 7）, lfumethasone （0.03 mg kg-1 of BW, on day 18 to 20） and recombinant bovine somatotropin （rbST;500 mg per cow, on day 1, 6, 16 and 21）. At the end of lactation and with a minimum of a 2-mon dry period, the same cows were again hormonally induced into lactation. Cows in both lactations were not artiifcially inseminated, they were milked 3 times daily and received rbST throughout lactation. Mean accumulated milk yield at 305 d in milk （DIM） did not differ between the ifrst and second induced lactations （（9 710 ＆#177;1 728） vs. （9 309＆#177;2 150） kg;mean＆#177;SD）. Total milk yield （（12 707＆#177;3 406） vs. （12 306＆#177;4 218） kg;mean＆#177;SD） and lactation length （（405＆#177;100） vs. （410＆#177;91） d;mean＆#177;SD） were not different between the ifrst and second induced lactations. In a second study, 15 empirical models including exponential, power law, yield-density, sigmoidal and miscellaneous models were compared for their suitability by modeling 12-mon （n=334）, 18-mon （n=164） and 29-mon （n=22） lactation cycles of Holsteins cows induced into lactation and treated with rbST throughout the lactation. Hoerl （Y=ab1/xxc）, Wood （Y=axb exp（cx）） and Dhanoa （Y=ax（bc）exp（cx）） models were equally suitable to describe 12-mon lactations. An exponential model with ifve parameters （Y=exp（a＋bx＋cd2＋e/x）） showed the best ift for milk yield for 18-mon lactations. The rational model （Y=a＋bx/1＋cx＋dx2） was found to produce the closest ift for 29-mon lactations. It was concluded that, with the protocol used in the present study, multiparous cows respond favorably to a second cycle of induced lactation, with milk yield similar to that experienced during the ifrst cycle. Thus, dairy producers might be able to lengthen the productive life of infertile high producing cows with a renewal of artiifcial lactation, which would imply an overall reduction in voluntary culling of cows. Also, various equations used to describe the lactation curves demonstrated the potential for iftting monthly milk records of Holstein cows with prolonged lactations and induced hormonally into lactation.

Mapping QTLs Affecting Economic Traits on BTA3 in Chinese Holstein with Microsatellite Markers

It had been demonstrated that the strong and highly significant quantitative trait locus（QTL） can affect protein percentage on Bos Taurus Autosome 3（BTA3） at the position 52 cM, near the microsatellite DIK4353, with the 95% confidence interval spanning from 25 to 57 cM in Chinese Holstein population using QTL-express, MQREML, and GRIDQTL softwares. This study herein focused on such region of fine mapping QTLs for milk production and functional traits with 16 microsatellite markers with coverage of 33 cM between the markers BMS2904 and MB099 on BTA3 in a daughter-designed Chinese Holstein population. A total of 1 298 Holstein cows and 7 sires were genotyped for 16 microsatellites with ABI 3700 DNA sequencer. The variance components QTL linkage analysis（LA） and linkage-disequilibrium（LD） analysis（LA/LD） was performed to map QTLs for 7 traits, i.e., 305-d milk yield, fat yield, protein yield, fat percentage, protein percentage, somatic cell score and persistency of milk yield. Four strong and highly significant QTLs were detected for fat yield, fat percentage, protein percentage and somatic cell score at the position 40, 30, 27 and 26 cM, respectively. Two minor QTLs for milk yield and persistency of milk yield were identified at 42 and 46 cM, respectively. These findings provided a general idea for the fine mapping of the causal mutation for milk production and functional traits on BTA3 in the future.

Fine Mapping QTLs Affecting Milk Production Traits on BTA6 in Chinese Holstein with SNP Markers

Our previous studies demonstrated that the region around markers BMS470 and BMS1242 on BTA6 showed a linkage to 305-d milk yield and composition traits in the Chinese Holstein population. We herein focused on such narrow region to fine map milk production QTLs with 15 SNPs across 25 Mb with each SNP in 1 Mb within most regions in a Chinese Holstein population with daughter design. 1 449 Holstein cows and 11 sires were genotyped for such SNPs by using TaqMan probe and RFLP assays. Multipoint linkage analysis across family revealed a QTL affecting milk yield between PPARGC1A C4075T and SLC34A2 T1713C. Meanwhile, within family analysis found three milk yield QTLs （two in CR T60984131G-CEP135 C501T and one in PDLIM5 A106C-OPN T3907, a fat yield QTLin UGDH T1670C-CR T60984131G region, and two protein yield QTLs in TBC1D1 G501C-UGDH T1670C and PPARGC1A C4075T-SLC34A2 T1713C, respectively. Associations between aforementioned significant SNP markers and milk production traits were further implemented. We found significant associations of PPARGC1A C4075T, SLC34A2 T1713C with milk yield （P0.05, P0.01, P0.01）, UGDH T1670C, and CR T60984131G with fat yield （P0.01, P0.01）, and PPARGC1A C4075T, SLC34A2 T1713C, UGDH T1670C and OPN T3907 with protein yield （P0.01, P0.01, P0.01, P0.01）. Our findings implied that QTLs affecting milk production traits on BTA6 were pleictropism or multigenic effect and PPARGC1A and OPN may be the causal mutations behind milk production QTLs on BTA6 in the Chinese Holstein population.