Dairy cow mortality. A review

We reviewed the literature to give an overview over the mortality among dairy cows in countries with a relatively intensive dairy production. A total of 19 studies focussing on dairy cow mortality were identified. Information about objectives, measures of mortality, sample sizes, study designs, causes of death and risk factors from these studies is presented and discussed. Additionally, recommendations for future recordings of mortality that will enable better possibilities for comparison of study results, generalization of results from a study population to a larger population and meta-analysis are given.     

Dairy cow mortality. A review

Summary

We reviewed the literature to give an overview over the mortality among dairy cows in countries with a relatively intensive dairy production. A total of 19 studies focussing on dairy cow mortality were identified. Information about objectives, measures of mortality, sample sizes, study designs, causes of death and risk factors from these studies is presented and discussed. Additionally, recommendations for future recordings of mortality that will enable better possibilities for comparison of study results, generalization of results from a study population to a larger population and meta‐analysis are given.     

奶牛福利及其安全性生产

在奶牛的饲养管理过程中，人们很少注意奶牛自身的健康和福利，这就导致在发展奶牛饲养业的同时也带来了许多奶牛福利和奶制品安全生产问题。为此，本文从我国奶业持续发展和奶制品安全生产的角度出发，介绍有关奶牛福利及其产品安全性生产，以期引起有关部门的注意和研究。     

Dairy cow preference for a soft track surface

Abstract

Extract

As dairy herds get larger cows have to walk further, and foot care becomes more important. Lameness from bruising of the soles of the feet is a particular hazard (Tranter and Morris 1991 Tranter, W P and Morris, RS. 1991. A case study of lameness in three dairy herds. New Zealand Veterinary Journal, 39: 88–96. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar], especially on hard tracks with loose angular stones or grit (Clackson and Ward 1991 Clackson, DA and Ward, WR. 1991. Farm tracks, stockman's herding and lameness in dairy cattle. Veterinary Record, 129: 511–512.  [Google Scholar]. One way of reducing this problem might be to provide an overlay of woodchips on top of the normal hard track. This would provide a softer grit-free surface, which could be more comfortable for the cows.     

Dairy cow reproduction under the influence of heat stress

Dairy farming is vulnerable to global warming and climate change. Improving and maintaining conception rates (CRs) have a paramount importance for the profitability of any dairy enterprise. There is an antagonistic relationship between fertility and milk yield, and intensive selection for milk yield has severely deteriorated reproductive efficiency. Irrespective of geography and husbandry, modern dairy cows experience heat stress (HS) effects leading to fertility declines, but it worsens in tropical climates. The threshold of HS experience among modern dairy cow has lowered, leading to decreased thermal comfort zone. Studies show that this threshold is lower for fertility than for lactation. HS abatement and robustness response to lactation yield lead to negative energy balance, and cow's reproductive requirements remain unfulfilled. The adverse effects of HS commence from developing oocyte throughout later stages and its fertilization competence; the oestrus cycle and oestrus behaviour; the embryo development and implantation; on uterine environment; and even extend towards foetal calf. Even cows can become acyclic under the influence of HS. These harmful effects of HS arise due to hyperthermia, oxidative stress and physiological modifications in the body of dairy cows. Proper assessment of HS and efficient cooling of dairy animals irrespective of their stage of life at farm is the immediate strategy to reduce fertility declines. Other long- and short-term mitigation strategies to reduce fertility declines during HS include feeding care, reducing disease and mastitis rates, using semen from cooled bulls, timed artificial inseminations (AI), allied hormonal interventions and use of embryo transfer technology. Ultimate long-term solution should be well-planned breeding for fertility improvement and HS tolerance.     

超排对供体奶牛生产性能和繁殖力的影响

本文探讨了超数排卵对供体奶牛生产性能和繁殖的影响。26头供体牛组成2个处理组,青年母牛做供体处理组,采卵后至首次发情时间为19.8±3.6天,首次发情配种妊娠率为53.8％(7/13),超排处理到末次配种间隔情期为3.7±0.5个;经产母牛做供体处理组,泌乳曲线不正常,超排当月产奶量比超排前后月均有所下降(下降分别为:98.8±19.10和8.50±11.56kg),采卵后至首次发情时间为23.2±4.1天,与青年母牛组比指标差异显著(P<0.05),首次发情配种妊娠率为38.5(5/13),超排处理到末次配种间隔情期为 3.9±0.7个。结果表明,超排影响产奶量,对其繁殖力也有些影响。     

Dairy farmers' attitudes and intentions towards improving dairy cow foot health

Dairy cow foot health is a subject of concern because it is considered to be the most important welfare problem in dairy farming and causes economic losses for the farmer. In order to improve dairy cow foot health it is important to take into account the attitude and intention of dairy farmers. In our study the objective was to gain insight into the attitude and intention of dairy farmers to take action to improve dairy cow foot health and determine drivers and barriers to take action, using the Theory of Planned Behavior. Five hundred Dutch dairy farmers were selected randomly and were invited by email to fill in an online questionnaire. The questionnaire included questions about respondents' intentions, attitudes, subjective norms and perceived behavioral control and was extended with questions about personal normative beliefs. With information from such a framework, solution strategies for the improvement of dairy cow foot health can be proposed. The results showed that almost 70% of the dairy farmers had an intention to take action to improve dairy cow foot health. Most important drivers seem to be the achievement of better foot health with cost-effective measures. Possible barriers to taking action were labor efficiency and a long interval between taking action and seeing an improvement in dairy cow foot health. The feed advisor and foot trimmer seemed to have most influence on intentions to take action to improve dairy cow foot health. Most farmers seemed to be satisfied with the foot health status at their farm, which probably weakens the intention for foot health improvement, especially compared to other issues which farmers experience as more urgent. Subclinical foot disorders (where cows are not visibly lame) were not valued as important with respect to animal welfare. Furthermore, 25% of the respondents did not believe cows could suffer pain. Animal welfare, especially the provision of good care for the cows, was valued as important but was not related to intention to improve dairy cow foot health. The cost-effectiveness of measures seemed to be more important. Providing more information on the effects of taking intervention measures might stimulate farmers to take action to achieve improvement in dairy cow foot health.     

应用两厢情提高奶牛受胎率的试验

对11头发情不明显或不发情(卵泡发育不正常)的奶牛分两组注射两厢情注射液,第一组6头注射两厢情(Estradiol Benzorte)Ⅰ型20ml,Ⅱ型20ml,第二组5头注射两厢情Ⅰ型20ml,Ⅱ型30ml,观察发情情况,直检有卵泡成熟时配种。其结果表明:第一组两个情期的受胎率为100%;第二组两个情期的受胎率为80%;总受胎率为90.9%。经t检验两组奶牛总受胎率差异不显著(P>0.05)。     

Dairy cow defecation and urination frequency and spatial distribution in relation to time-limited grazing

The objective of this paper was to investigate the effect of limited grazing time on urination and defecation frequency, spatial distribution of excrement in the paddock, and the resulting nitrogen balance at animal and field level. During a 6-week period in early summer, 60 Holstein Frisian dairy cows (31.0 ± 5.4 kg ECM) were randomly allocated to three different treatments, with grazing at clover-grass pasture during daytime for 4, 6.5 or 9 h daily. Indoor feeding, with a mixture of roughage and concentrates (13% crude protein), was restricted for treatment 4 and 6.5 h to the amount the 9-h treatment could eat. Cows allowed grazing at pasture for 4 h moved more rapidly during pasture, moved longer distance per active hour and used a higher proportion of the time eating, both at pasture and indoor, than the cows allowed longer time at pasture. Limiting the grazing time had no influence on the urination (mean = 0.26) and defecation (mean = 0.37) frequency per cow per hour during pasture. Even though the proportion of time active (eating, drinking, standing or walking), and the actual time active during pasture was different for the treatments, the frequency of urination and defecation per active hour was also unaffected by the treatments. Urine and faeces were distributed in the pasture, without specific hot-spots. The estimated daily N-balance at animal level showed increased N excretion with time at pasture. Assuming that excretion follows the active periods during the day and 7000 kg DM foliage is available on yearly basis, this would result in total excretion at field level of 58, 86 and 108 kg N per ha respectively for treatment 4, 6.5 and 9 h. The results of this experiment show that it is possible to reduce the nitrogen excretion in a grazing system by restricting the grazing time of dairy cows together with restricted indoor feeding while maintaining high foliage intake.     

Assessing whether dairy cow welfare is “better” in pasture-based than in confinement-based management systems

ABSTRACT

Consumers perceive pasture-based systems of milk production as natural and therefore better for cow welfare than confinement systems. However both systems are heterogeneous and continually evolving, varying from total confinement to total pasture with many hybrid intermediaries. To compare the welfare of dairy cows in these various systems, we use the three spheres framework, comprising biological functioning, natural behaviour and affective states. Considering biological functioning, pasture-based cows are less at risk of subclinical and clinical mastitis, claw lesions, lameness, metritis, early embryonic mortality, culling and mortality, but at more risk of internal parasitism, malnutrition and delayed onset of oestrous activity postpartum than confined cows. Regarding natural behaviours, pasture-based cows exhibit less agonistic behaviour, better lying behaviour, more normal oestrous behaviours and better synchronicity of behaviours than confined cows. They also have the opportunity to graze, which is one of the main features of the behavioural repertoire of dairy cows, but, they may also experience long periods away from pasture in larger herds, and severe climatic stresses which will become increasingly important as the climate changes. Our current ability to assess the affective state of dairy cows is poor. For example, hunger is an important subjective state that cannot be measured directly. The growing focus on ensuring that animals have lives worth living, means that dairy cows should garner some positive emotions from their lives, and it seems clear that pasture access is essential for this. Clearly measurement of affective state is an important challenge for future dairy cow welfare research. At the extremes of management systems, there can be major differences in animal welfare but in hybrid systems, dairy cows experience elements of both confinement and pasture which may ameliorate the negative effects of each on cow welfare. Ultimately, the optimal system gives cows an element of choice between both environments. Moreover management of the system, whether it is confinement or pastured-based, may be as important as the system of management in ensuring good dairy cow welfare and addressing societal concerns.

Abbreviations: BCS: Body condition score; TMR: Total mixed ration