Rapid Detection of Somatic Cell Count Based on Hybrid Variable Selection Method

Somatic cell count detection is the daily work of dairy farms to monitor the health of cows.The feasibility of applying near-infrared spectroscopy to somatic cell count detection was researched in this paper.Milk samples with different somatic cell counts were collected and preprocessing methods were studied.Variable selection algorithm based on hybrid strategy and modelling method based on ensemble learning were explored for somatic cell count detection.Detection model was used to diagnose subclinical mastitis and the results showed that near-infrared spectroscopy could be a tool to realize rapid detection of somatic cell count in milk.

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.

Udder Health Status of First Parity Dairy Cows in Early-Lactation Based on Somatic Cell Count Categories

The main aim of this study was to investigate the prevalence of intramammary infection (IMI) in early-lactation of primiparous cows using milk recording cow composite somatic cell count (CSCC) categories (combining the first 2 milk recording results after calving). Another aim was to evaluate the milk urea (MU) content as a potential supplementary indicator to SCC or CSCC for the identification of IMI in primiparous cows after calving. This retrospective observational study was conducted on records of test-day of primiparous cows over a period of 6 years (January 2016 to December 2021. The SCC data for 158 Holstein Friesian primiparous cows, with their first milk recording 5 to 35 days after calving and their second milk recording 28 to 56 days in milk (DIM), were identified. Each primiparous cow was assigned a CSCC category (low-low, low-high, high-low or high-high) based on the CSCC at the first 2 milking recordings using the following cut-offs: ≤150,000 cells/ml (low), >150,000 cells/ml (high). The association between CSCC categories and MV content was analyzed using correlation models. At the first milk recording, a proportion of 63.29% was in the low SCC category, and the rest (36.71%) was in the high SCC category. At the second milk recording, a proportion of primiparous cows in CSCC categories was 59.49%, 3.80%, 27.85% and 8.86% in low-low, low-high, high-low and high-high, respectively. At the second milk recording, a proportion of 12.66% of primiparous cows was in the high CSCC category and a proportion of 87.34% of primiparous cows was in the low CSCC category, indicating a poor and a good udder health, respectively. The association of SCC with MU content in low and in high SCC categories at the first milk recording was positive and moderate (+0.49) and negative and strong (-0.97), respectively. The association of CSCC categories with MU contents at the second milk recording was inconclusive. We concluded that CSCC categories may be a useful tool for identifying success and problems regarding the udder health of primiparous cows in early lactation.

中国荷斯坦牛SCC变化规律及其与产奶性状之间的关系

本研究旨在分析北京地区中国荷斯坦牛测定日体细胞数的变化规律及其与产奶性状之间的关系,推断适于中国荷斯坦牛隐性乳房炎的判定标准。通过对北京地区76个荷斯坦牛牛场63510头母牛的DHI数据进行整理筛选,按每毫升奶中体细胞数(SCC)情况,用SAS8.2将其划分为12个子数据集及8个累积数据集。首先用Excel对12个子数据集的SCC和产奶性状作图,然后用Matlab的Spline函数对12个子数据集及8个累积数据集做泌乳期的SCC曲线。除乳脂率外,12个子数据集的SCC均值与各产奶性状均值的变化趋势相关显著,随着SCC的增长,产奶量、乳蛋白量和乳脂量逐渐下降,乳蛋白率逐渐上升(P<0.001)。累计数据集作图发现,SCC<20万与SCC<10万的差异较大,而SCC<50万与SCC<40万差异较小。结果表明,为有效降低隐性乳房炎发病率,北京地区中国荷斯坦牛牛群宜以10万～50万SCC作为隐性乳房炎划分标准。

采用SCC-100型体细胞计数仪研究不同保存条件对生鲜乳体细胞数的影响

为了研究不同保存条件下生鲜乳体细胞数(SCC)的变化规律,试验采用SCC-100型体细胞计数仪,探讨防腐剂、保存温度和保存时间对生鲜乳中体细胞数的影响。结果表明:添加防腐剂并在4℃保存的生鲜乳,6 d内体细胞数无显著差异(P>0.05),但无防腐剂乳样只能保存3 d。30℃高温条件对生鲜乳中体细胞数影响较大,即使添加防腐剂,从保存第3天开始体细胞数仍极显著降低(P<0.01);而无防腐剂只能保存不到1 d。生鲜乳体细胞数与保存温度和保存时间存在极显著负相关(P<0.01)。说明4℃添加防腐剂的乳样最适合使用SCC-100型体细胞计数仪进行体细胞测定,在该条件下可最大限度地保证乳样体细胞数的稳定性。

奶牛乳汁SCC分布及其与肝功酶的相关性研究

为了评估奶牛的健康状况,研究乳汁体细胞数(somatic cell count,SCC)量级分布、乳汁SCC与肝功酶的相关性,探索乳汁SCC变化对肝功酶活性的影响,试验随机选取101头荷斯坦奶牛,测定乳汁SCC和血浆肝功酶指标[丙氨酸氨基转移酶(ALT)、γ-谷氨酰基转移酶(GGT)和天门冬氨酸氨基转移酶(AST)],并分析其相关性。结果表明:被检奶牛中乳汁SCC≥50万个/m L的有24头,占被检总数的23.77%;乳汁SCC≤50万个/m L的有77头,占被检总数的76.24%;乳汁SCC与血浆ALT呈极显著负相关(r=-0.271,P<0.01),且存在一定的线性关系。说明根据奶牛乳汁SCC量级水平的分布情况,可以初步评价牛群的整体健康状况,乳汁SCC水平在一定程度上能够反映血浆ALT的水平,或许可作为评估奶牛肝脏健康状况的一个潜在指标。

牛乳样染色和处理方式对SCC镜检计数的影响

体细胞数(SCC)是诊断乳房炎和判定原乳质量和加工稳定性的关键指标。通过实验评价了SCC镜检计数的3种染色方法,以及乳样保藏温度和时间、防腐剂、热处理等对SCC的影响。结果表明,美兰染色计数效果最好,甲基绿-派洛宁次之,瑞士染色效果最不理想。乳样应在4℃保存,建议在48h内检测;室温存放12h内体细胞破裂溶解殆尽。体积分数为0.4%甲醛即可显著防止牛乳的酸败,但对SCC没有明显的稳定意义;戊二醛使乳样显著变色。冻融使SCC急剧下降,乳样切忌冷冻。短时间煮沸和巴氏杀菌对SCC计数均有显著的影响,巴氏杀菌损失的SCC比短时间煮沸的高。

奶牛乳SCC与产奶性能的相关性分析

为了探讨牛乳SCC与日产奶量和乳成分等生产性能指标间的相关性,为牧场乳品质量安全、奶牛乳房炎的综合防控和奶牛健康养殖提供参考,本试验随机选择焦作市某奶牛场80头泌乳期奶牛进行DHI测定。根据牛乳SCC水平的变化,分为正常组(SCC≤50万/mL)、低度组(50<SCC≤200万/mL)、中度组(200<SCC≤500万/mL)和高度组(SCC>500万/mL)。结果表明,不同SCC数值水平内,各组间日产奶水平差异极显著(P<0.01);高度组的乳脂率与正常组间差异极显著(P<0.01),与低度组间差异显著(P<0.05);正常组的乳蛋白率与中度组、高度组间差异极显著(P<0.01),与低度组间差异显著(P<0.05);高度组的乳糖率与正常组间差异极显著(P<0.01),与低度组间差异显著(P<0.05);各组间的总固体水平差异未见显著(P>0.05)。奶牛日产奶量与SCC水平、乳蛋白率存在极显著负相关(P<0.01),与乳脂率、乳糖率存在极显著正相关(P<0.01),与总固体无显著相关性(P>0.05)。这说明乳SCC的显著变化一定程度上影响牛奶的产量和质量。

Blood neutrophil extracellular traps:a novel target for the assessment of mammary health in transition dairy cows

Background:Mammary health is important for transition dairy cows and has been well recognized to exert decisive effects on animal welfare.However,the factors influencing mammary health are still unclear.Differential somatic cell count(DSCC)could reflect the mastitis risk since it is the percentage of neutrophils plus lymphocytes in total somatic cells and could be reflective of mammary health of dairy cows.This work aimed to investigate the assessment and prognosis of the health of transition cows based on blood neutrophil extracellular traps(NETs).Results:Eighty-four transition Holstein dairy cows were selected.The serum was sampled in all the animals at week 1 pre-and postpartum,and milk was sampled at week 1 postpartum.Based on the DSCC in milk at week 1,cows with lower(7.4%±4.07%,n=15)and higher(83.3%±1.21%,n=15)DSCCs were selected.High DSCC cows had higher levels of red blood cell counts(P<0.05),hemoglobin(P=0.07),and hematocrit(P=0.05),higher concentrations of serum oxidative variables[reactive oxygen species(P<0.05),malondialdehyde(P<0.05),protein carbonyl(P<0.05),and 8-hydroxy-2-deoxyguanosine(P=0.07)],higher levels of serum and milk NETs(P<0.05)and blood-milk barrier indicators,including serumβ-casein(P=0.05)and milk immunoglobulin G2(P=0.09),than those of low DSCC cows.In addition,lower concentrations of serum nutrient metabolites(cholesterol and albumin)(P<0.05)and a lower level of serum deoxyribonuclease I(P=0.09)were observed in high DSCC cows than in low DSCC cows.Among the assessments performed using levels of the three prepartum serum parameters(NETs,deoxyribonuclease I andβ-casein),the area under the curve(0.973)of NETs was the highest.In addition,the sensitivity(1.00)and specificity(0.93)were observed for the discrimination of these cows using NETs levels with a critical value of 32.2 ng/mL(P<0.05).Conclusions:The formation of NETs in blood in transition dairy cows may damage the integrity of the blood-milk barrier and thereby increase the risk for mastitis in postpartum cows.

An Interconnection between Elevated SCC Levels in Milk around the First Artificial Insemination and Pregnancy Rate in Dairy Cows

The aim of this study was to evaluate the impact of the somatic cell count (SCC) levels measured at 28-test-day intervals or pregnancy rate at the first artificial insemination of Holstein Friesian cows. All necessary information was taken from test day and farm records. Levels of SCC in milk, 30 days before, and 30 days after the first artificial insemination (FAI) date were divided into 4 categories and their interconnection with pregnancy rate (PR) at FAI was evaluated by applying logistic models. A SCC threshold of 150.000 cells/ml of milk was used to differentiate uninfected udders and infected udders of Holstein Friesian cows. A level of SCC > 150.000 cells/ml in milk, and a level of SCC < 150.000 cells/ml before and after FAI respectively were considered udders with new infections. A level of SCC > 150.000 cells/ml in milk before FAI as well as after FAI, was considered chronically infected udders or subclinical intramammary infections (IMI). Data from 792 FAIs from farm and test day records over a 4-year period (2019-2022) were evaluated. The outcome of this study revealed that the risk for low PR at the first AI was increased in cows with infected udders (OR = 1.33, CI 0.99 - 1.78), compared with uninfected udders. Increased levels of SCC after FAI had a negative effect on PR, while before FAI was not affected. To achieve a good PR, mastitis control measures must be fully adopted to a large extent around the first AI.

Direct Differentiation of Plants from Small Cell Clusters of Indica Rice in Suspension Culture

The major factors affecting plant regeneration in suspension culture were investigated.The resultsshow that,in order for cell clusters to differentiate directly in liquid medium,it is essential toestablish an embryogenic callus line with high potential for plant regeneration.Embryogenic calliwere suspended in AA basic medium supplemented with 2,4-D 1 mg/L,6-benzylaminopurine 0.5mg/L,CH 300 mg/L,sucrose 3％ and mannitol 3％ and subcultured 7 days for each passage.Aftermore than 6 months of culturing,a fine suspension culture of small cell clusters(SCC)wasestablished.The SCC,80-270μin diameter,were then transferred to a liquid medium(MSsupplemented with NAA 0.01 mg/L and 4-pyridylurae(4-PU)0.5 mg/L)and allowed to grow instationary culture.Finally direct differentiation from SCC was observed.Several factors in suspension-subculture exerted strong after-effects on differentiation ofSCC.Basicmedia,kinds and concentration combinations of auxin and cytokinin in the subculture media,duration of shaking at each subculture passage,and amount of packed cell volume transferred to newmedium at each subculture passage and so on,all these affected the frequency of differentiation ofSCC.Higher concentrations of NAA and kinetin in the differentiation medium inhibited the directdifferentiation of SCC.Low concentrations(0.01-0.1 mg/L)of NAA with 4-PU in thedifferentiation medium were helpful for the direct differentiation of SCC.The differentiated clusterspossessed typical embryogenic structure from which normal plantlets could develop after transferringto agar medium.

蒲公英水提物对热应激条件下奶牛产奶性能、血清生化指标、乳中体细胞数及粪便微生物多样性的影响

本试验旨在研究蒲公英水提物(DWE)对热应激条件下奶牛产奶性能、血清生化指标、乳中体细胞数(SCC)及粪便微生物多样性的影响,探究奶牛饲粮中适宜的蒲公英水提物添加水平。试验选用120头泌乳日龄、体重、胎次、产奶量均相近的产奶期荷斯坦奶牛,采用完全随机试验设计原则分为3组,每组5个重复,每个重复8头牛。对照组(DZ组)饲喂基础饲粮,试验组分别在基础饲粮中添加50(DWE_(50)组)和70 g/(头·d)(DWE70组)的蒲公英水提物。预试期3 d,正试期28 d。结果表明:1)正试期内,牛舍日平均温湿度指数(THI)>72,表明试验奶牛均处于热应激状态。2)与DZ组相比,DWE_(50)组、DWE70组的第14、21、28天时产奶量显著增加(P<0.05);DWE_(50)组的第21、28天乳蛋白率显著增加(P<0.05),第28天乳脂率显著增加(P<0.05);DWE70组的第7、14、21、28天乳蛋白率显著增加(P<0.05),第14、21、28天乳脂率显著增加(P<0.05)。3)第28天,与DZ组相比,DWE_(50)组的血清谷胱甘肽过氧化物酶(GSH-Px)活性和总抗氧化能力(T-AOC)显著升高(P<0.05),DWE70组的血清超氧化物歧化酶(SOD)、GSH-Px活性及T-AOC显著升高(P<0.05),DWE_(50)组、DWE70组的血清丙二醛(MDA)含量显著降低(P<0.05)。4)第28天,与DZ组相比,DWE_(50)组的血清免疫球蛋白G(IgG)含量显著升高(P<0.05),DWE70组的血清球蛋白(GLB)含量著升高(P<0.05)。5)与DZ组相比,DWE_(50)组、DWE70组的乳中SCC均呈下降趋势,DWE70组的乳中SCC下降较为迅速,且第28天乳中SCC更低。6)在门水平上,各组粪便优势菌门均为拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes);在属水平上,各组粪便相对丰度最大菌属均为拟杆菌属(Bacteroides)。线性判别分析效应大小(LEfSe)分析结果显示,DWE70组较其他组具有显著差异的物种更多,主要为梭状芽孢杆菌纲(Clostridia)、梭状芽孢杆菌目(Clostridiales)、厚壁菌门等。综上所述,饲粮中添加蒲公英水提物可提高奶牛产奶量、乳蛋白率、乳脂率,降低乳中SCC,增加粪便微生物多样性及相对丰度,正向调节机体抗氧化能力和免疫功能。

生乳中体细胞数检测方法研究进展

优质生乳是保证乳制品质量安全的前提,而体细胞数是衡量奶牛乳房健康和生乳质量的一个重要指标。随着奶牛生产性能测定技术和优质乳工程的推广应用,越来越多的养殖场将控制体细胞数作为提高生乳质量的重要手段,乳制品企业也将体细胞数作为收购生乳时的必检指标。快速、准确地检测生乳中的体细胞数对预防奶牛疾病和保证生乳质量意义重大。文章对国内外生乳中体细胞数的限量要求进行了对比,对近年国内生乳体细胞数水平进行了分析,并对生乳中体细胞数检测方法的最新研究进展进行综述。生乳中体细胞数的检测方法主要包括仪器检测法和化学检测法,其中,可自动计数的仪器检测法已成为研究热点。文章对体细胞数的检测方法进行介绍,以期为乳制品企业和养殖场加强对体细胞数的监测和控制提供参考,推动我国奶业健康发展。

羊奶体细胞数与奶山羊瘤胃微生物区系的相关性

选择120只(2.5±0.2)胎次、体质量(54.84±4.21)kg、泌乳日龄(72.0±3.5)d的健康西农萨能奶山羊,饲养42 d后收集奶样,测定羊奶中体细胞数(SCC),按照SCC将奶山羊分为3组,L–SCC组(SCC<5.0×10^(5)个/mL),M–SCC组(5.0×10^(5)个/mL≤SCC<1.0×10^(6)个/mL),H–SCC组(SCC≥1.0×10^(6)个/mL),从每组随机选取15只奶山羊,收集瘤胃液,测定瘤胃的微生物多样性,分析羊奶体细胞数与瘤胃微生物的相关性。结果表明:1)不同SCC水平奶山羊瘤胃微生物的α多样性、β多样性和优势菌群的差异不显著;L–SCC组放线菌门(Actinobacteriota)相对丰度显著高于M–SCC组和H–SCC组的,主要的差异菌属有解琥珀酸菌属(Succiniclasticum)、普氏菌UCG–003属(Prevotellaceae_UCG–003)、厌氧弧菌属(Anaerovibrio)、Gastranaerophilales_unclassified、双歧杆菌属(Bifidobacterium)、p–251–o5_unclassified、大肠杆菌–志贺菌属(Escherichia–Shigella)、夏普氏菌属(Sharpea)、乳杆菌属(Lactobacillus)、肠球菌属(Enterococcus);2)羊奶SCC与瘤胃解琥珀酸菌属的相对丰度呈显著正相关(P<0.05),与普氏菌UCG–003属的相对丰度呈极显著正相关(P<0.01)。

DHI技术在浙江省某规模化奶牛场的应用分析

为提升奶牛生产性能测定(Dairy Herd Improvement,DHI)在浙江省某规模化奶牛场的应用效果,本研究整理了该场2022年、2023年的DHI参测牛数据,应用Excel 2016进行预处理,SPSS 22.0进行方差分析,对奶牛产奶量、乳脂率、乳蛋白率、305d产奶量、体细胞数和尿素氮等量化指标进行统计和比较分析。结果表明,该场泌乳牛的平均日单产为25.56kg/d,乳脂率为4.51%,乳蛋白率为3.58%,305d产奶量为7900kg,体细胞数为24.06万个/mL,尿素氮为15.62mg/dL,泌乳持续力较高。建议该牧场借此科学指导牧场日粮配方组成、饲养管理方案制定、更新牛群及配套设施改进以增加效益。

对甘肃河西地区某大型牧场DHI报告分析解读及建议

本研究旨在分析甘肃河西地区规模化牛场2023年1-12月份DHI报告中泌乳曲线、牛群结构、乳成分、脂蛋比、尿素氮水平、体细胞数等指标,通过限定指标分析反映该牧场在产量、牛群结构、营养水平和疾病管控、治疗等方面的情况。结果表明,整体单产水平仍有上升空间,牛群高峰奶亟待提高,泌乳持续力不足;全年平均胎次小于2.5胎,头胎占比39.0%,三胎及以上占比37.8%,应调整牛群结构向合理方向发展;牧场最低乳脂率4.10%、最低乳蛋白率3.31%,处于较高水平,但尿素氮水平超过18mg/dL的月份为5个月,应实时调整日粮水平,减少饲草料浪费;奶牛产后酮病发病率较高;牛群体细胞数过高,9月份奶损失0.592kg/头,乳房炎管控、舒适度管理和奶厅管理仍需加强。通过对规模化牧场的DHI报告分析,为牧场提高运营水平、经济效益和持续化发展提出了指导建议。

奶山羊生乳中体细胞数与乳成分的相关性分析

[目的]探索奶山羊乳中体细胞数与乳成分含量的变化,分析其相关性。[方法]选择山东省内6家奶山羊场的120只奶山羊为试验对象,取其乳汁检测体细胞数、乳脂肪、乳蛋白、乳糖、总固形物含量和酸度,同时记录其产乳量。[结果]不同奶山羊场的羊乳体细胞数、乳脂肪、乳蛋白、乳糖、总固形物含量和酸度存在较大差异。体细胞数与乳蛋白含量具有显著性正相关(P<0.05),相关系数为0.9173;与酸度具有显著性正相关(P<0.05),相关系数为0.8627;与乳糖含量具有显著性负相关(P<0.05),相关系数为0.7263。[结论]羊乳体细胞数和乳脂肪、乳蛋白、总固形物含量和酸度等为正相关,与乳糖含量呈现负相关。

Genetic Polymorphism of TLR4 Gene and Correlation with Mastitis in Cattle

Toll-like receptor 4 （TLR4） recognizes pathogen ligands and mediates signaling to initiate innate and adaptive immune responses. In this experiment, a 316 bp and 382 bp fragments of TLR4 gene named T4CRBR1 and T4CRBR2, of Chinese Holstein, Sanhe cattle, and Chinese Simmental was amplified by polymerase chain reaction （PCR）, respectively. The genetic polymorphisms in the three populations were detected by Single-Strand Conformational Polymorphism （SSCP） in the first locus and by digesting the fragments with restriction endonuclease Alu I in the second one. Results showed that both alleles （A and B） of two loci were found in all the three populations and the value of polymorphism information content （PIC） indicated that these were a moderate polymorphism. Statistical results of X^2 test indicated that two polymorphism sites in the three populations fitted with Hardy-Weinberg equilibrium （P 〉 0.05）. After sequencing, A-G single nucleotide polymorphism （SNP） was identified at nucleotide 4,525 in intron 1 of TLR4 gene and C-T SNP was identified at nucleotide 1,397 in exon 3 of TLR4 gene. Meanwhile, the effect of polymorphism of TLR4 gene on somatic cell score （SCS） was analyzed, the results indicated that the cattle with allele A in T4CRBR1 showed lower somatic cell score than that of allele B （P 〈 0.05）. In short, the allele A might play an important role in mastiffs resistance in bovine.

新疆褐牛乳中体细胞数与产奶性状的影响因素分析

【目的】分析影响新疆褐牛乳中体细胞数(SCC)与产奶性状的非遗传因素,为有效指导并提高新疆褐牛的生产性能提供科学依据。【方法】构建协方差分析模型,利用SAS 9.2软件分析不同场、胎次、泌乳月及两两间互作效应等非遗传因素对262头新疆褐牛SCC与产奶性状的影响,并阐述各性状间的相互影响关系;采用Excel2 013对新疆褐牛1 510条DHI数据进行整理,利用相邻两月SCC差值等级划分方法,绘制了不同牛场SCC变化趋势及其与产奶性状间的变化规律。【结果】场和胎次对新疆褐牛SCC及产奶性状均有极显著影响(P<0.01);泌乳月效应对产奶量和乳中SCC影响极显著(P<0.01),对乳糖率有显著影响(P<0.05),对其它乳成分无显著影响(P>0.05);不同场、胎次、泌乳月两两间互作效应对新疆褐牛SCC均无显著影响(P>0.05),而场和胎次互作效应对产奶量和乳成分有极显著影响(P<0.01),场和泌乳月互作对乳脂率和乳中干物质有极显著影响(P<0.01),对乳糖率有显著影响(P<0.05),对其它性状无显著影响(P>0.05);胎次和泌乳月互作效应对新疆褐牛各产奶性状均无显著影响(P>0.05)。随着新疆褐牛乳中SCC增加,乳中干物质含量增加,而产奶量、乳脂率、乳蛋白率和乳糖率下降;绘制泌乳期SCC差值与产奶量和乳糖率变化曲线发现,随着SCC差值升高,产奶量及乳糖率均降低,表明使用SCC差值等级法能够有效评价奶牛产奶量变化并及时判定奶牛乳房炎的发病趋势。通过比较新疆褐牛两个牛场的产奶量、乳成分以及SCC控制情况,发现二号牛场各性状均优于一号牛场,其产奶量较高、SCC较低,且不同胎次水平的乳脂率、乳糖率及乳中干物质均较高,体现较好的生产管理水平。【结论】针对新疆褐牛非遗传因素的研究表明,为有效提高和改善该乳肉兼用牛品种的产奶性能和奶品质,应着力改善牛场管理水平、优化环境卫生及规范挤奶设备等;一号牛场应加强生产管理水平和DHI监测记录,通过控制新疆褐牛SCC来降低和避免泌乳牛的乳房炎隐患。

牛TLR4基因的遗传多态性与乳房炎的关联分析

TLR4通过识别病原体而激活免疫细胞,在先天免疫和适应性免疫防御中起着重要作用。以中国荷斯坦奶牛、三河牛和中国西门塔尔牛共397头为研究对象,利用创造酶切位点PCR法扩增243 bp的目的片段,通过限制性内切酶HinfⅠ酶切来检测TLR4第3外显子的多态性,结果发现扩增产物的27 bp处C到T的突变使得多态位点产生,编码的氨基酸由苏氨酸变为异亮氨酸。A、B 2个等位基因在3个群体中均有分布,A等位基因占优势(大于78%),经χ2适合性检验,三河牛在该位点未达到Hardy-Weinberg平衡状态(P<0.05)。运用SAS 8.2软件采用最小二乘法拟合线性模型,将该基因座不同基因型与奶牛乳房炎进行了关联分析,结果表明:AA基因型为乳房炎抗性基因型(P<0.05),A等位基因为乳房炎抗性的有利基因。