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Parameters for the determination and evaluation of heat stress in dairy cattle in South Africa 总被引：2，自引：0，他引：2
Du Preez JH 《The Onderstepoort journal of veterinary research》2000,67(4):263-271
Not all parameters are trustworthy and practical to use as parameters to determine heat stress in dairy cattle. The temperature-humidity index (THI) is still the best, simplest and most practical index (parameter) for measurement of environmental warmth which cause heat stress in dairy cattle. It is practical, easy to determine and relatively trustworthy to use body temperature and respiratory rate as parameters to determine heat stress in dairy cattle. These physiological parameters must always be used together with THI values to determine and evaluate heat stress in dairy cattle. For practical purposes, plasma cortisol concentration and milk composition cannot be used as parameters to determine heat stress in dairy cattle although good indications of acute or chronic heat stress can be obtained. Vanillic acid is a break-down product of adrenalin found in milk, but before its concentration in milk can be used as an indicator/parameter of heat stress in dairy cows, more about the pharmacodynamics of adrenaline in the milk has to be known. Selection and breeding of dairy cows on the basis of their adaptibility to heat stress using the most practical heat stress parameters will ensure that their offspring will have superior performance in the prevailing environmental conditions. 相似文献
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Marcos G. Colazo Reuben J. Mapletoft 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(8):772-780
This is a review of the physiology and endocrinology of the estrous cycle and how ovarian physiology can be manipulated and controlled for timed artificial insemination (TAI) in beef and dairy cattle. Estrus detection is required for artificial insemination (AI), but it is done poorly in dairy cattle and it is difficult in beef cattle. Protocols that synchronize follicle growth, corpus luteum regression and ovulation, allowing for TAI, result in improved reproductive performance, because all animals are inseminated whether they show estrus or not. As result, TAI programs have become an integral part of reproductive management in many dairy herds and offer beef producers the opportunity to incorporate AI into their herds. Gonadotropin-releasing hormone-based protocols are commonly used in North America for estrus synchronization as part of a TAI program. Protocols that increase pregnancy rates in lactating dairy cows and suckling beef cows have been developed. Protocols that improve pregnancy rates in heifers, acyclic beef cows, and resynchronized lactating dairy cows are also discussed. 相似文献
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Oestrus detection error and conception rates after AI based only on secondary oestrus signs were evaluated in a high yielding, 24-h tie-stalled dairy herd with low fertility, using milk progesterone profiles. Oestrus detection was based on the secondary oestrus signs such as restlessness, swelling, congestion of vulva and clear mucus discharge. Sixty eight AI conducted after observing the secondary oestrus signs in 44 animals were included in the study. Of the 68 AI, 53 (77.9%) were conducted in the follicular phase, and 13 (19.1%) and 2 (2.9%) were carried out in the luteal phase and during pregnancy, respectively. The overall error in oestrus detection based on milk progesterone profiles was 22.1%. The oestrus detection error did not differ significantly among different secondary oestrus signs. None of the AI conducted in the luteal phase resulted in conception, whereas 20.8% of AI conducted in the follicular phase resulted in conception. No significant difference in the conception rates among the groups of cows with different secondary oestrus signs was shown. The high incidence of oestrus detection error in this study might have been caused by the detection of cows in oestrus based only on secondary oestrus signs due to the confinement of animals. In conclusion, there was a high incidence of heat detection error in the 24-h tie-stalled dairy herd and oestrus detection based only on secondary oestrus signs resulted in low conception rate. 相似文献
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D J Klingborg 《Veterinary Clinics of North America: Food Animal Practice》1987,3(3):483-499
Reproductive parameters are important in evaluating modern dairy management performance. Successful dairying results from constant attention to daily events, requiring more sensitive and immediate measurements of performance. Definitions of formulas, numerators, denominators, and population included or excluded are essential for proper interpretation and comparison of results. Veterinarians understanding these statistics and indexes, and using stratification of data to investigate production losses, will serve their clients well. My advice is to approach a herd with a perceived reproductive problem by evaluating these parameters; they are the means of determining if a problem exists and, if so, where it is. Find out how the various parameters are calculated so your interpretation will be correct. Herds with average days in milk of less than 165, culling rates below 25 per cent, and a milking rate of 85 per cent or more do not have long-term reproductive problems. If management techniques fail to achieve these levels, first look at those areas involving people. Conception rates measure all the components that, when multiplied, equal fertility: insemination technique, semen quality, heat detection accuracy, and the cow factors involved. Poor conception rates require investigation into these areas individually. Heat detection intensity leading to prolonged days in milk at first service is another common finding. Comparison of inseminators and sires may identify a problem area. Cow factors require more intense investigation to determine their cause. Use the information outlined in the periparturient period to assist you. In most cases, a combination of failures in many of the independent factors creates the problems in reproduction that we encounter. A large data base including all the information discussed and additional information is necessary to define, correct, and monitor reproductive management performance. Since performance ultimately is determined by the quality of the labor force, ongoing monitoring for accountability and education is necessary for success. 相似文献
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通过对全国2020年18 个省份201 个规模奶牛场月度繁殖和产奶量数据进行分析,旨在确定不同月份下奶牛繁殖和产奶性能表现。结果表明：（1）5—6月成母牛受胎率、怀孕率开始下降,7、8月明显下降,9月仍较低,其中7—9月,2胎、3胎及以上牛只受胎率明显低于1胎（平均低4.3~5.1 个百分点）;（2）1—12月后备牛怀孕率、受胎率相对稳定,6—8月未出现明显下降趋势;（3）泌乳牛单产在6月之后呈缓慢下降趋势,平均下降0.50~0.90 kg,泌乳牛峰值产量在6月之后呈较明显下降趋势,其中经产牛下降幅度较大,头胎牛下降幅度较小。因此,为减少奶牛受不同月份热应激影响而导致生产性能下降,建议不同地区奶牛场根据实际情况做好防暑降温工作,优化配种方案,改善营养与饲养管理。 相似文献
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E. G. Kebebe S. J. Oosting I. Baltenweck A. J. Duncan 《Tropical animal health and production》2017,49(4):681-690
While there is a general consensus that using dairy technologies, such as improved breeds of dairy cows, can substantially increase farm productivity and income, adoption of such technologies has been generally low in developing countries. The underlying reasons for non-adoption of beneficial technologies in the dairy sector are not fully understood. In this study, we characterised adopters and non-adopters of dairy technologies in Ethiopia and Kenya based on farmers’ resources ownership in order to identify why many farmers in Ethiopia and Kenya have not adopted improved dairy technologies. As compared to non-adopters, farmers who adopt dairy technology own relatively more farm resources. The result signals that differences in resource endowments could lead to divergent technology adoption scenarios. Results show that a higher proportion of sample smallholders in Kenya have adopted dairy technologies than those in Ethiopia. Except for the use of veterinary services, fewer than 10% of sample farmers in Ethiopia have adopted dairy technologies—less than half the number of adopters in Kenya. The higher level of dairy technology adoption in Kenya can be ascribed partly to the long history of dairy development, including improvements in the value chain for the delivery of inputs, services and fluid milk marketing. Interventions that deal with the constraints related to access to farm resources and input and output markets could facilitate uptake of dairy technology in developing countries. 相似文献
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Objectives To determine whether a multivariate model could be developed to describe farm factors affecting fertility of dairy herd and to examine the factors that determined better reproductive performance on dairy farms in New South Wales.
Procedure We examined the results of a survey of breeding practices, mating policies, recording systems, timing of mating, heat detection, treatment of metritis and manager demographics of dairy farms using Principal components analysis, logistic regression and the sign test.
Results Eight principal components for heat detection computed using Principal component analyses were included in the multivariate model to reflect primary and secondary heat detection signs used in the breeding decisions of managers. A final model identified three variables: optimum number of days to first service, number of people detecting heats, and age of manager which significantly influenced the risk of being in the high or low reproductive performance groups. A failure to breed at an appropriate time after calving and having more people responsible for heat detection was associated with herds with a prolonged intercalving interval. While the model provided a good fit for the data, it was not highly discriminatory. Examination of 83 management practices affecting fertility using the sign test (P = 0.01) indicated that managers of herds with good reproductive performance employed better management and breeding practices more often than managers of herds with poor reproductive performance.
Conclusions Mating cows sooner after calving and using fewer people to detect oestrus should reduce calving to conception intervals. Veterinarians investigating herd reproductive performance should consider the potential for a number of subtle failures of management to significantly impair fertility rather than limit investigations to a few factors. 相似文献
Procedure We examined the results of a survey of breeding practices, mating policies, recording systems, timing of mating, heat detection, treatment of metritis and manager demographics of dairy farms using Principal components analysis, logistic regression and the sign test.
Results Eight principal components for heat detection computed using Principal component analyses were included in the multivariate model to reflect primary and secondary heat detection signs used in the breeding decisions of managers. A final model identified three variables: optimum number of days to first service, number of people detecting heats, and age of manager which significantly influenced the risk of being in the high or low reproductive performance groups. A failure to breed at an appropriate time after calving and having more people responsible for heat detection was associated with herds with a prolonged intercalving interval. While the model provided a good fit for the data, it was not highly discriminatory. Examination of 83 management practices affecting fertility using the sign test (P = 0.01) indicated that managers of herds with good reproductive performance employed better management and breeding practices more often than managers of herds with poor reproductive performance.
Conclusions Mating cows sooner after calving and using fewer people to detect oestrus should reduce calving to conception intervals. Veterinarians investigating herd reproductive performance should consider the potential for a number of subtle failures of management to significantly impair fertility rather than limit investigations to a few factors. 相似文献
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J H du Preez P J Hattingh W H Giesecke B E Eisenberg 《The Onderstepoort journal of veterinary research》1990,57(4):243-248
Temperature-humidity index (THI) values applicable to South Africa and Namibia have been established during this investigation for each month of the year by means of computerized modelling and mapping techniques. The data indicate that each year heat stress risk areas (HSRA's) expand from August to January and retract from February to July. The THI values classified according to the Livestock Weather Safety Index (LWSI) for lactating dairy cattle (LDC), suggest that, especially during November to March there is the risk of moderate to advanced heat stress in most South African dairy cows. This has important implications for their general health, udder health, production and reproduction. Careful planning of facilities and highly adaptable herd management are required to protect dairy cattle from heat stress. 相似文献
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辽宁地区奶牛乳房炎源大肠杆菌毒力基因及耐药基因检测分析 总被引：1，自引：0，他引：1
为了掌握辽宁地区规模奶牛场乳房炎源大肠杆菌携带的毒力基因和耐药基因,为奶牛养殖业提供更好的乳房炎防制方案,本研究采用PCR检测方法对辽宁地区多个规模奶牛场临床奶牛乳房炎奶样中分离的66株大肠杆菌进行了4种毒力基因和4种耐药基因的检测分析。结果发现,66株大肠杆菌中仅有1株未检出相关目的基因,其余65株中最少检出2种目的基因,最多检出7种目的基因。其中,毒力基因stx2e、eaeA、K99和astA的检出率分别为56.1%、47.0%、34.8%和31.8%,双重毒力基因的检出率达到43.9%,以eaeA/stx2e基因型的检出率最高;耐药基因sul3、sul1、cmlA及aacA4的检出率分别为87.9%、83.3%、40.9%和28.8%,双重耐药基因的检出率为36.4%,以sul1/sul3基因型检出率最高;三重耐药基因的检出率为37.9%,以cmlA/sul1/sul3检出率最高。本研究结果证实,辽宁地区奶牛乳房炎源大肠杆菌携带磺胺类耐药基因和氯霉素类耐药基因的比率较高,与大肠杆菌的耐药性有较直接的关系,该结果对于辽宁地区奶牛乳房炎的防制具有重要的指导意义,更具有重要的公共卫生意义。 相似文献
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YAO Wei GAO Feng CAO Ming-hui GU Gui-bo ZHAO Xiao-tong YU Xue-wu CHEN Yao SHEN Guan-nan WEI Yuan-yuan 《中国畜牧兽医》2017,44(6):1832-1839
In order to understand the virulence genes and drug resistance genes carried by E.coli strains from dairy cows with mastitis in large-scale dairy farms in Liaoning region, and also provide improved programs for control and treatment of mastitis to dairy farmers, 66 strains of E.coli isolated from milk of dairy cows with clinical mastitis in several large-scale farms in Liaoning region were examined to detect 4 virulence genes and 4 drug resistance genes using PCR methods. The results showed that none of the target genes was detected in only one strain, while at least 2 and up to 7 target genes were detected in the rest of 65 strains. The detection rates of the virulence genes stx2e, eaeA, K99 and astA were 56.1%, 47.0%, 34.8% and 31.8%, respectively. In addition, the detection rate of dual virulence gene reached 43.9%, in which the genotype with the highest detection rate was eaeA/stx2e. The detection rates of the drug resistance genes sul3, sul1, cmlA and aacA4 were 87.9%, 83.3%, 40.9% and 28.8%, respectively. And the dual resistance gene detection rate was 36.4%, in which the highest detection rate was sul1/sul3 genotype; Triple drug resistance gene detection rate was 37.9%, and cmlA/sul1/sul3 presented the highest detection rate. These results confirmed that the E.coli isolated from dairy cow mastitis in large-scale dairy farms in Liaoning region had high detecting rates of sulfonamide resistance genes and chloramphenicol resistance genes, which was directly related to the drug resistance of the E.coli. These results provided important guiding significance for the prevention and control of dairy cow mastitis in Liaoning region as well as the safety of public health. 相似文献
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The purpose of this study was to determine the effect of reproductive performance on profitability and optimal breeding decisions for Finnish dairy herds. We used a dynamic programming model to optimize dairy cow insemination and replacement decisions. This optimization model maximizes the expected net revenues from a given cow and her replacements over a decision horizon. Input values and prices reflecting the situation in 1998 in Finland were used in the study. Reproductive performance was reflected in the model by overall pregnancy rate, which was a function of heat detection and conception rate. Seasonality was included in conception rate. The base run had a pregnancy rate of 0.49 (both heat detection and conception rate of 0.7). Different scenarios were modeled by changing levels of conception rate, heat detection, and seasonality in fertility. Reproductive performance had a considerable impact on profitability of a herd; good heat detection and conception rates provided an opportunity for management control. When heat detection rate decreased from 0.7 to 0.5, and everything else was held constant, net revenues decreased approximately 2.6%. If the conception rate also decreased to 0.5 (resulting in a pregnancy rate of 0.25), net revenues were approximately 5% lower than with a pregnancy rate of 0.49. With lower fertility, replacement percentage was higher and the financial losses were mainly from higher replacement costs. Under Finnish conditions, it is not optimal to start breeding cows calving in spring and early summer immediately after the voluntary waiting period. Instead, it is preferable to allow the calving interval to lengthen for these cows so that their next calving is in the fall. However, cows calving in the fall should be bred immediately after the voluntary waiting period. Across all scenarios, optimal solutions predicted most calvings should occur in fall and the most profitable time to bring a replacement heifer into a herd was in the fall. It was economically justifiable to keep breeding high producing cows longer than low producing cows. 相似文献
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《Preventive veterinary medicine》1988,5(3):197-211
Six characteristics of innovations described as influencing their rates of adoption by farmers are their relative advantage, complexity, ability to be tried, visibility of outcome personal contact between the advocate and the farmer, and compatibility with existing values. In this study, these are related to the adoption of mastitis prevention and control procedures.An educational diagnostic method described by Green et al. was adapted from human health education and applied to mastitis prevention and control with a group of farmers form nine Minnesota dairy farms. The method included six phases. A social diagnosis determined farmers' perceived rewards from dairying to be profit-making, enjoyment of working with animals, a desire to see cows achieve their production potential and a desire to raise a family in a farm setting. An epidemiological diagnosis from the literature determined the reduction of new infection rate and increase in the infection elimination rate to be the principal means of reducing mastitis prevalence. Teat dipping, dry period therapy, detection of clinical mastitis, segregating infected cows at milking, correct udder preparation and correct function and use of the milking machine were the main behavioral factors involved in mastitis control. An educational diagnosis identified pre-disposing, enabling and reinforcing factors associated with mastitis control. Their use in a mastitis control education program is illustrated using the teat dipping behavior as an example. Planning implementation was the fifth phase of the method. It involved rating the importance to mastitis control of various possible control behaviors and the likelihood of changing them. A priority order for employing resources was established from these. Planning also involved defining the behavior changes desired of farmers in mastitis control. The final phase was evaluation.Information from a survey of 222 Minnesota dairy farms was also incorporated in the process. The diagnostic method proved valuable in helping the educators view mastitis from the farmers point of view. A practical educational program was produced. 相似文献
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奶牛热应激综合征是指奶牛受到超过本身体温调节能力的高温刺激而产生的非特异性防御反应。奶牛发生热应激后会激活体内的下丘脑-垂体-肾上腺轴,改变机体的神经内分泌调节网络,引起奶牛体内皮质醇激素和多种激素水平变化,协同作用于机体以抵抗热应激对自身的影响;此外,热应激奶牛采食量和消化率普遍降低,营养物质摄入不足,机体处于能量负平衡状态。在这种状态下,奶牛会通过增加体内糖、脂肪和蛋白质的代谢来为机体提供能量从而缓解热应激。然而,严重热应激会导致奶牛代谢功能紊乱及免疫系统损伤,最终导致奶牛消化率、产奶量、繁殖率下降,而疾病易感风险性增加,从而影响奶牛生产的经济效益,给畜牧业带来巨大的经济损失。目前,关于奶牛热应激的研究较多,且多集中于产奶性能和繁殖性能等方面,而有关生理和免疫机能的研究报道较少。作者阐述了奶牛发生热应激时皮质醇激素的变化和调节、三大代谢过程的改变及免疫细胞和相关细胞因子的表达分泌等过程,旨在更加深入地了解热应激对奶牛生理状态及免疫功能的影响,从而为奶牛热应激综合征的防控、诊断和治疗提供理论依据。 相似文献
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Haemophilus somnus: a comparison among three serological tests and a serological survey in beef and dairy cattle. 
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下载免费PDF全文 D Sanfa?on R Higgins K R Mittal G L'Archevêque 《Canadian journal of veterinary research》1983,47(3):304-308
Serological tests for the detection of antibodies against Haemophilus somnus were carried out in herds of beef and dairy cattle using three different techniques: agglutination, complement fixation and counterimmunoelectrophoresis. The agglutination test appeared to detect more seroreactors than the complement fixation and counterimmunoelectrophoresis tests. Results of the three tests indicated that there were more positive reactors in beef cattle and dairy cattle from infected herds than in dairy cattle from clinically normal herds. 相似文献
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Khan Sharun Kuldeep Dhama Ruchi Tiwari Mudasir Bashir Gugjoo Mohd. Iqbal Yatoo Shailesh Kumar Patel Mamta Pathak Kumaragurubaran Karthik Sandip Kumar Khurana Rahul Singh Bhavani Puvvala Amarpal Rajendra Singh Karam Pal Singh Wanpen Chaicumpa 《The Veterinary quarterly》2021,41(1):107
Mastitis (intramammary inflammation) caused by infectious pathogens is still considered a devastating condition of dairy animals affecting animal welfare as well as economically incurring huge losses to the dairy industry by means of decreased production performance and increased culling rates. Bovine mastitis is the inflammation of the mammary glands/udder of bovines, caused by bacterial pathogens, in most cases. Routine diagnosis is based on clinical and subclinical forms of the disease. This underlines the significance of early and rapid identification/detection of etiological agents at the farm level, for which several diagnostic techniques have been developed. Therapeutic regimens such as antibiotics, immunotherapy, bacteriocins, bacteriophages, antimicrobial peptides, probiotics, stem cell therapy, native secretory factors, nutritional, dry cow and lactation therapy, genetic selection, herbs, and nanoparticle technology-based therapy have been evaluated for their efficacy in the treatment of mastitis. Even though several strategies have been developed over the years for the purpose of managing both clinical and subclinical forms of mastitis, all of them lacked the efficacy to eliminate the associated etiological agent when used as a monotherapy. Further, research has to be directed towards the development of new therapeutic agents/techniques that can both replace conventional techniques and also solve the problem of emerging antibiotic resistance. The objective of the present review is to describe the etiological agents, pathogenesis, and diagnosis in brief along with an extensive discussion on the advances in the treatment and management of mastitis, which would help safeguard the health of dairy animals. 相似文献
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Heat detection is a key factor in the profitability of dairy herds. However, this detection demands a significant part of the breeder’s working time and is made difficult by the short duration and the discrete behavioural changes associated with oestrus in modern dairy cows. Progress has been made in monitoring cow with electronics, biosensors and computer. As a result, automated heat detection systems have been developed. Currently available tools are automated detectors of standing heat, activity‐metres and automated in‐line systems measuring milk progesterone. Camera‐software systems and monitoring of body temperature are being developed and may also be used as heat detection tools. The heat detection rate of most systems is above 80% with a specificity of detection generally higher than 90%. The accuracy, however, may vary considerably depending on the tool and model developed. The initial investment of several thousands of euros required for these automated systems becomes a source of profit in large herds, provided the recorded data are properly managed. 相似文献