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.

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.

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.

Growth and Development Regularity of Holstein Cows

[ Objective ] The paper was to study growth and physical structure of Holstein cows at specific phase under intensive rearing conditions in the South China. [ Method] The body sizes of 279 Holstein cows including 49 calves, 35 young cows and 195 adult cows in the experimental farm of Yangzhou University were measured. The raw data were processed by computer to obtain body size index at various physiological stages. The body size indexes were analyzed by SPSS 15.0 software to reflect changes in different physiological stages and various parities of cows. Body size indexes such as body height, body length and heart girth of young cows and calves were fitted by scatter plot. [ Result] The eider the cows were, the longer their bodies were. Calves had a stable growth and development. The body size of young cow at different month-ages was imbalanced. The physical structure of adult cows showed no regularity at different parities, so the specific feeding for growth and development of bone should be strengthened in multiparous cows. [ Conclusion] The study provides reference for keeping management of calves, breeding and keeping management of young cows as well as selection and assortative mating of adult cows.

A comparative study of the intestinal digestive characteristics of diferent feeds for Holstein cows

This experiment was conducted with lactating Chinese Holstein cows to study the nutritional value of local protein feed resources.A three-step method(TSP)and a modifed three-step method(MTSP)were used to measure the in vitro digestibility of rumen undegraded protein(RUP)for 11 feedstufs and correlation.Eleven experimental feeds were chosen and air-dried to investigate the efects of diferent growth periods and varieties on nutrition value and RUP digestibility.The small intestinal digestibility of RUP by TSP in concentrated feed was determined to be higher than that of roughage,approximately 65%.The highest concentrate(79%)was SBM(soybean mean),while the lowest was corn(65%).The proportions of DDGS(with soluble wine lees)and SFM(sunfower meal)were 70.9 and 74.9%,respectively.ASS(alfalfa mowed at the squaring stage)had the highest small intestinal digestibility of RUP(55%)among roughages,and WCS(whole-plant corn silage)had the lowest digestibility(40.5%).When the small intestinal digestibility of RUP was determined using the MTSP method,it exhibited similar results to the TSP method.Nevertheless,the values were generally higher,and there was a strong signifcant correlation between them(R2=0.967,P<0.01).The comparative study of these two methods help us have a better understanding of small intestine digestibility of diferent feeds,make a reasonable feed formula to efectively prevent diseases.

Development of Microbial Fermented Feed and Its Effect on the Production Performance of Holstein Cows

[Objectives]This study was conducted to investigate the development method of microbial fermented feed and its effect on the production performance of Holstein cows.[Methods]Thirty Holstein cows were selected and randomly divided into 2 groups,15 cows in each group.The diet composition of the experimental group was:concentrate supplement added with 30% microbial fermented feed+silage+alfalfa hay,and the diet composition of the control group was:concentrate supplement added with 30% flax cake+silage+alfalfa hay.The experimental period was 60 d.[Results]Compared with the control group,the experimental group increased the average daily milk yield per cow by 2.25%(P>0.05)and the total increase in average milk yield per cow in the experimental period by 43.51%(P<0.01),and reduced the average feed-to-milk ratio by 9.20%(P<0.05).The average gross profit per cow of the experimental group was 40.34 yuan higher than that of the control group,showing an increase of 3.53% in the economic benefit.[Conclusions]Feeding a diet supplemented with the microbial fermented feed could improve the efficiency of Holstein cow farming and is recommended to be promoted.

The Resumption of Ovarian Activity in Postpartum of Chinese-Holstein Cows

Ovarian activitly in 10 postpartum Chinese-Holstein cows was monitored by ultrasonography every other day, stared from day 3 postpartum and finished by the end of a normal ovarian cycle. Meanwhile, the concentrations of progesterone and 17β-oestradiol in peripheral plasma of the cows were measured by radioimmunoassay (RIA). The resutis showed that the first postpartum ovulation was found in 67% of the cows on the ovary opposed to the gravid horn. The first dominant foillicles ovulated for the six of ten cows. The time intervals from calving to the first ovulation were significantly associated with the number of follicular waves (r=0.83, P<0.01). No difference between the diameters of the first and the second ovulated follicles was found in the study, however, the growth rates of the first and the second ovulated follicles were significantly different (P<0.05), and the concentrations of 17β-oestradiol prior to the first ovulation were significantly lower than that before the second ovulation.

Effects of Chinese Herb Additive on Milk Yield and Anti-heat Stress Ability of Holstein Cows

[Objective] To explore the effects of Chinese herb additive on milk yield and anti-heat stress ability of Holstein diary cow. [Method] A total of 36 Holstein cows at same parity and with similar milk yield were randomly divided into three groups, namely, control group, Chinese medi- cine group I and Chinese medicine group I1. The cows in the Chinese medicine group I were fed basal diet containing 4% compound Chinese herb additive; those in the Chinese medicine group II were fed basal diet containing 3% compound Chinese herb additive; and those in the control group were fed common basal diet. All cows in the three groups were analyzed comparatively. [Result] Supplementing some compound Chinese herb ad- ditive into basal diet increased milk yield and anti-heat stress ability of Holstein cows, besides, it also decreased cow diseases like cow mastitis. The Chinese medicine group I generated the highest economic benefit of practical production. [ Conclusion] Supplementing Chinese herb additive in- to basal diet is an effective way to relieve heat stress and increase milk yield.

Use of Random Regression Test-Day Model to Estimate Genetic Parameters of Milk Yield in Holstein Cows

(Co) variance components and genetic parameters were estimated for milk yield of Iranian Holstein cows. A total number of 68,945 milk test-day records of first, second and third lactations of 8515 animals from 100 sires and 7743 dams originated from 34 herds collected during 2007 to 2009 by Iranian animal breeding center were used. The ASReml computer program was used to analyze the milk test-day records using the random regression procedure. Herd test date (HTD), milking times per day (milking frequency), number of lactations, year of birth, year of calving, age of animal at calving and days in milk (DIM) considered as fixed effects and additive genetic effects and animal permanent environmental effects were considered as the random effects. Additive genetic variance, animal permanent environment variance, residual variance, phenotypic variance, heritability and repeatability were estimated during different months of lactation between 5.7 - 19.6, 15.3 - 27.1, 31.4 - 17.2, 45.8 - 64.83, 0.1 - 0.32 and 0.4 - 0.6, respectively. Genetic correlation and phenotypic correlation were also estimated between months of lactation in range of -0.35 - 0.98 and 0.03 - 0.67, respectively. Genetic correlation and phenotypic correlation both showed the same changing pattern and they decreased as the interval between months of lactation increased.

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.

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.

红薯秧替代玉米青贮对奶牛生产性能、乳品质和养分表观消化率的影响

本研究旨在探究红薯秧替代玉米青贮对奶牛生产性能、乳品质和养分表观消化率的影响。试验将健康状况良好、产奶量相似、泌乳天数和胎次相近的80头荷斯坦奶牛随机分为4组,每组20头。对照组粗饲料为全株玉米青贮,试验组分别使用15%、30%和45%的红薯秧替代全株玉米青贮为试验饲料,试验共计130 d(其中预饲期10 d,正试期120 d)。试验结果表明,与对照组相比,使用45%的红薯秧替代全株玉米青贮可显著降低奶牛5.5%的干物质采食量(P<0.05);使用45%的红薯秧替代全株玉米青贮可显著提高奶牛5.6%的饲料转化率(P<0.05);此外,使用红薯秧替代玉米青贮对奶牛产奶量无显著影响(P>0.05)。使用30%和45%的红薯秧替代玉米青贮可显著提高奶牛的乳脂产量和乳蛋白产量(P<0.05);此外,使用红薯秧替代玉米青贮对奶牛乳脂率、乳蛋白率、乳糖率、固形物含量和乳糖含量均无显著影响(P>0.05)。使用15%~45%的红薯秧替代玉米青贮可显著提高奶牛的粗蛋白表观消化率(P<0.05);使用30%~45%的红薯秧替代玉米青贮可显著提高奶牛的酸性洗涤纤维表观消化率(P<0.05);此外,使用红薯秧替代玉米青贮对奶牛粗脂肪、中性洗涤纤维、钙和磷的表观消化率均无显著影响。总之,在本试验条件下,红薯秧最适替代量为45%。

挪威红牛改良荷斯坦奶牛的妊娠率分析

[目的]研究现存混养的条件下挪威红牛配种荷斯坦奶牛后的妊娠优势,以提高荷斯坦奶牛的繁殖力。[方法]以荷斯坦奶牛作为母本,进口挪威红牛冻精为父本,进行杂交改良(挪威红牛♂×荷斯坦奶牛♀),培育杂种牛,统计不同月份、不同年龄段的配种数、妊娠数、妊娠率。[结果]杂交种牛相比于荷斯坦牛,自然发情配种的妊娠率提高36.41百分点;同期处理配种,妊娠率提高30.24百分点;青年牛配种,妊娠率提高47.64百分点;群体年度配种,妊娠率提高了36.83百分点,杂交牛场配种妊娠率显著高于荷斯坦牛场。[结论]杂交牛场经过挪威红牛乳肉兼用型牛的品种改良,明显提高了牛场群体繁育率。

江苏地区荷斯坦成母牛长寿性状遗传参数估计

旨在估计荷斯坦成母牛长寿性状遗传参数及评估育种值,为提高生产性能及实施平衡育种提供参考。本研究共收集江苏地区9个规模化牧场2017—2023年间19 756头荷斯坦成母牛的离群记录,分析牛只的长寿性和淘汰情况。利用R软件的GLM程序对影响奶牛长寿性状的固定效应(包括牧场、出生年季、头胎产犊月龄)进行显著性检验;采用BLUPF90软件进行遗传参数估计以及育种值评估,并绘制遗传趋势图。结果表明:江苏地区规模化牧场成母牛平均在群寿命为1 640.87 d,生产寿命为917.15 d,平均利用胎次为2.60胎;长寿性状遗传力估计值变化范围为0.07~0.15,属低遗传力性状;7个长寿性状(在群天数、生产寿命、利用胎次和L1-L4)间均具有中等到较高的遗传和表型相关(0.27~0.99),其中在群寿命与生产寿命的相关性趋近于1;通过计算长寿性状的育种值,绘制遗传趋势图,发现近年来长寿性状遗传进展缓慢且整体呈下降趋势。本研究对江苏地区规模化牧场成母牛长寿性状进行了系统的遗传分析,可为制定南方地区奶牛长寿性状育种规划提供参考。

牛TARDBP基因核心启动子鉴定与转录调控分析

【目的】为了解牛TARDBP基因结构、功能及启动子活性区域,分析该基因的转录调控机制。【方法】通过PCR技术克隆牛TARDBP基因编码区全长序列。应用生物信息学软件对牛TARDBP蛋白性质和结构进行分析。通过实时荧光定量PCR(RT-qPCR)技术检测TARDBP基因在泌乳期荷斯坦奶牛不同组织中的表达情况。应用5'RACE技术确定牛TARDBP基因的转录起始位点,PCR技术克隆牛TARDBP基因启动子区和5'端系列缺失片段,并运用生物信息学软件对牛TARDBP基因启动子区域CpG岛和潜在转录因子结合位点进行预测,双荧光素酶报告系统确定该基因的核心启动子区域。【结果】牛TARDBP基因在包括乳腺在内的多个组织中均有表达。TARDBP蛋白是一种水溶性非分泌蛋白,存在RNA识别结构域和DNA结合位点。TARDBP基因启动子区存在2个CpG岛和大量转录因子结合位点包括SP1、PPARA、PPARD、PPARG、SREBF1等。双荧光素酶活性分析结果显示牛TARDBP的核心启动子区位于-476--149之间,该区域包含Sp1、PPARG、PPARD、SREBF1结合元件,但不存在TATA-box。【结论】牛TARDBP基因在奶牛多个组织中均有表达。-476--149片段为牛TARDBP基因的核心启动子区,且该区域中存在与乳脂合成和分泌相关的转录因子结合位点。

β-酪蛋白不同基因型荷斯坦奶牛瘤胃微生物群落特征和功能分析

β-酪蛋白是乳汁中最重要的蛋白质之一,在荷斯坦奶牛中存在A1和A2这2种主要基因型。为探究β-酪蛋白不同基因型荷斯坦奶牛瘤胃微生物群落的差异,试验选取体况良好、第1胎次的A1A1、A1A2和A2A2基因型荷斯坦奶牛各15头(各基因型奶牛乳脂率和乳蛋白率相近),采集瘤胃液后通过Illumina HiSeq 2000平台进行宏基因组测序,并利用Diamond 0.9.7软件进行分类和功能注释,分析3种基因型奶牛瘤胃微生物群落的组成和功能。结果表明:1)A1A1基因型奶牛瘤胃中特征微生物有Intestinibaculum、戴阿利斯特杆菌属(Dialister)、克雷伯氏菌属(Klebsiella)和不动杆菌属(Acinetobacter)等;A1A2基因型奶牛瘤胃中特征微生物有普雷沃氏菌科(Prevotellaceae)的帕拉普雷沃氏菌属(Paraprevotella)和Paraprevotella xylaniphila;A2A2基因型奶牛瘤胃中特征微生物包括醋杆菌属(Acetobacter)和黄单胞菌属(Xanthomonas)等。2)A1A2和A2A2基因型奶牛瘤胃中富含与木质纤维素和纤维素降解相关的酶;A1A2基因型奶牛瘤胃参与淀粉和蔗糖代谢、脂肪酸生物合成、蛋白质消化与吸收、精氨酸和脯氨酸代谢以及RNA降解通路的基因数量更多;A2A2基因型奶牛瘤胃参与炎症介质调节通路的基因数量更多。由此可知,A1A1基因型荷斯坦奶牛的瘤胃标志物微生物是Intestinibaculum和戴阿利斯特杆菌属,可能与减少甲烷排放和A1型β-酪蛋白以及部分疾病存在潜在关联;A1A2基因型奶牛的瘤胃标志微生物是普雷沃氏菌科,可能对饲粮消化有促进作用;A2A2基因型奶牛的瘤胃标志微生物是醋杆菌属,其相对丰度对乳脂含量有调节作用。

新疆驴驴乳与荷斯坦牛乳营养成分的差异比较研究

分析比较新疆驴驴乳和荷斯坦牛乳营养成分的差异,为驴乳产品研发利用提供科学依据。使用乳成分分析仪、电感耦合等离子体光度发射光谱法、酶联免疫吸附法和气相色谱仪测定乳的理化特性、营养成分、主要生物活性物质和37种乳脂肪酸的含量,并分析比较差异。结果显示新疆驴驴乳水分、乳酸碱度、附子脂酸、花生四烯酸极显著高于荷斯坦牛乳(P<0.01),乳密度、钙磷比、亚油酸、α-亚麻酸显著高于荷斯坦牛乳(P<0.05)。电导率、乳脂、总干物质、丁酸、己酸、十三碳酸、肉蔻酸、十五碳酸、棕榈酸、珍珠酸、硬脂酸、花生酸、肉蔻油酸、γ-亚麻酸、顺-8,11,14-二十碳三烯酸、长链脂肪酸、极长链脂肪酸、奇数碳脂肪酸极显著低于荷斯坦牛乳(P<0.01),辛酸、癸酸、十一碳酸、月桂酸、油酸、芥酸、短链脂肪酸含量显著低于荷斯坦牛乳(P<0.05)。两组乳所检生物活性物质无显著差异(P>0.05)。新疆驴驴乳具有低乳脂、高钙磷比、高多不饱和脂肪酸的特点,本研究可提高公众对驴乳产品的科学认识以及为新疆驴驴乳产品的开发利用提供科学基础。

同期发情处理后荷斯坦奶牛外周血生殖激素水平变化

为了提高奶牛同期发情-定时输精技术的受胎率,试验研究同期发情处理后荷斯坦奶牛外周血中生殖激素含量的变化,探讨荷斯坦奶牛的人工授精最佳时间。选择24头空怀青年荷斯坦奶牛,使用抑制素(INH)结合同期发情-定时输精(TAI)程序处理,分别在第一次肌肉注射抑制素抗原和布舍瑞林前(记作第0天)、第一次肌肉注射PG前(记作第7天)、第二次注射布舍瑞林前(记作第9天),以及第一次人工输精前(记作第10天)采集外周血,采用ELISA法检测外周血中抗缪氏管激素(AMH)、INH(以抑制素B即INHB为代表)、促卵泡素(FSH)和促黄体素(LH)的浓度,分析母牛在同期发情处理前后外周血中生殖激素水平的变化、生殖激素浓度的相关性和各个阶段的差异性。结果表明:第7天试验牛外周血中LH含量极显著高于第0天、第9天以及第10天(P<0.01),并且第9天试验牛外周血中LH含量显著高于第10天(P<0.05);第9天试验牛外周血中FSH含量极显著高于第0天和第10天(P<0.01),并且第7天试验牛外周血中FSH含量极显著高于第10天(P<0.01);而AMH、INHB含量没有显著变化(P>0.05),且不同个体之间不同激素含量的变化波动明显减小,达到相对一致水平。说明INHB、AMH在调控卵泡期FSH的分泌过程中发挥了重要的作用,促进了卵泡的发育;在奶牛同期发情-定时输精过程中,可以通过监测奶牛体内的INHB、AMH、FSH、LH等生殖激素水平,精确判断排卵和人工授精时间,从而提高奶牛同期发情-定时输精效果。

2010-2020年江苏省牛乳中SCC变化模式对奶牛场隐性乳房炎发病规律的影响

奶牛隐性乳房炎(subclinical mastitis,SCM)是一种无症状表现的乳房炎,通常表现为体细胞数(somatic cell count,SCC)升高、乳脂率下降等。为探究SCC变化模式影响下江苏地区奶牛场SCM发病规律的因素,本研究收集了江苏地区14个牧场2010-2020年荷斯坦牛群体改良(dairy herd improvement,DHI)记录853936条,在划分4种SCC变化模式(持续健康、新感染、治愈和持续感染)基础上,利用卡方检验探究不同牧场规模、胎次、产犊季节、产犊间隔和305 d产奶量对荷斯坦牛4种SCC变化模式的影响。结果表明:所有DHI记录中4种SCC变化模式百分比分别为83.52%(持续健康)、6.02%(新感染)、5.89%(持续感染)和4.57%(治愈),牧场规模、胎次、产犊季节、产犊间隔和305 d产奶量对荷斯坦牛SCC变化模式分布均有极显著影响(P<0.01)。其中,中小型牧场、较高胎次、春季产犊、产犊间隔大于441 d和305 d产奶量为13001~15000 kg的奶牛下一泌乳月SCC升高的概率较大,增加了奶牛患SCM风险;规模在5000头以上的牧场、1胎牛、秋季产犊和305 d产奶量为9001~11000 kg的奶牛持续健康的比例均最高。综上所述,牧场规模、胎次、产犊季节、产犊间隔和305 d产奶量对SCC变化模式的分布均有极显著影响,该结果为江苏地区规模化牧场SCM防控提供了参考。