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Contents Oestrous detection is crucial for successful dairy cow reproduction. Bulls identify cows in oestrus by oestrous-specific odours especially in urine and vaginal fluid. These have been used to train dogs to detect cows in heat. To improve and simplify the dog training, a spray containing synthetic oestrous molecules was developed. The objective of this study was to test the spray on similarities to the natural substance thus to assess its suitability as a training substance for heat detection dogs. Ten privately owned dogs of various breeds were trained. Dogs should be trained either to differentiate natural vaginal fluid from cows in oestrus and dioestrus (n = 5), or spray with or without synthetic oestrous molecules (n = 5). Dogs trained on natural fluid and on spray could detect the oestrous odour they had been trained on with an overall accuracy of 69.0% and 82.4%, respectively (p = 0.019). To validate the synthetic molecules, dogs trained with synthetic molecules had to detect oestrous odour in natural fluid without further training (accuracy 37.6%). Dogs trained on natural fluid detected the synthetic molecules with an accuracy of 50.0% (50% vs 37.4%, p

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.

Estrous expressions in dairy cows have been shortened and weakened. Dairy heifers, on the other hand, may not have had such changes in estrous signs as observed in cows, since they have less stresses than cows. The aim of this study was to describe the duration of estrus in a herd of dairy heifers. A total of 56 Holstein Friesian heifers estrus was synchronized using two different hormonal protocols. They were checked for primary and secondary estrous signs with the help of heat detection devices for 48 h at an interval of 4 h starting at 16.00 hour, one day after PGF(2alpha) treatment. Onset and end of standing estrus during 48 h observation period was recorded in 35 of the 44 heifers coming into estrus within 5 days after PGF(2alpha) treatment during the observation period. The duration of standing estrus on the average (+/-SD) was 9.7 +/- 5.3 h. Percentage of heifers with standing estrus longer than 12 h was 40%, and 53% showed standing estrus only for 4-8 h. It is indicated that duration of estrus in dairy heifers has been shortened recently.

Studies using quantitative sensory testing (QST) often present incongruent results due to intra- and intersubject as well as interobserver variability which limit widespread use of the technique. Eliminating or reducing the factors responsible for this variability is of great interest, as it increases reliability and reproducibility of QST. Thermal sensory threshold determination is a crucial part of QST. It was previously suggested that the pressure of the thermode on the skin could influence measurements. To verify this, we developed a new thermode with a built-in pressure sensor. Thresholds obtained with this thermode were compared to those obtained with a commercially available thermotesting device (Medoc TSA-II). Heat detection and heat pain detection thresholds were higher, and cold detection thresholds were lower when measured with our thermode than they were with the Medoc thermode. Cold pain detection thresholds did not differ between the thermodes. Analysis of the heat transfer capacity of the thermodes indicated that the material of the skin contact surface of the thermode may play a role in these shifts in threshold values. Altering the thermode pressure on the skin did not affect the thermal thresholds. Furthermore, the intrasubject variability of the measurements (minimal-to-maximal range of measured threshold values in individual subjects) was also not influenced by the pressure with which the thermode was attached to the skin. Our results suggest that the pressure with which the thermode is attached to the skin does not significantly affect the intra- and intersubject reproducibility of the thermal sensory threshold measurements. Muscle Nerve, 2008

index is over 365 days has been estimated at £3-5 per day (Kingshay Trust 2008). Currently, the value of replacement heifers is high, so farmers often keep animals that fail to get in calf for many months rather than culling them. Poor dairy cow fertility is a major cost and national fertility figures are getting worse, with average heat detection rates at 35% and conception rates of 35-40% (Cook 2008). There are many reasons for this deterioration, particularly that many cows, particularly Holsteins, show few oestrus signs for only a short (average less than 8 hours) period, and that there is inadequate observation of cows (Fig. 1).

the last 20 years have steadily deteriorated to the current UK position of a national average conception rate estimated at around 35-40% (Fig. 1), heat detection rates of around 35% (Fig. 2) and an overall calving to conception interval of around 120 days (Fig. 3). Alongside this apparent fall in reproductive performance has been a steady increase in yield (Fig. 4), an increase in herd size to around 140 cows (Promar FBA Data 2007) and a reduction not only in the labour available on the modern dairy farm but also arguably a reduction in the quality of labour available to carry out certain key tasks.

UK Vet Vol 15 No 6 October 2010 38 INTRODUCTION The decline in dairy herd reproductive performance over the last 20-25 years or so has seen a fall in heat detection rates accompanied by a fall in conception rates (Lucy, 2001; Royal et al., 2000). This has led to the development of a variety of systems of heat detection, aimed at increasing the number of cows detected in heat thus increasing submission rates, in the simple belief that, providing egg and sperm are brought together in the right place at the right time, conception success is assured. However, if heat detection were the sole problem relating to the decline in performance then surely conception rates would have remained static? The question then arises that if the methods of heat detection that have been employed over the last 20-25 years are accurate, and the quality of purchased semen has been maintained, there must be other factors on the female side which have contributed to the decline.

OESTRUS synchronisation is a useful technique in cattle practice as it allows the use of fixed-time artificial insemination (Al) or improved heat detection efficiency. It can also be used to prepare donor and recipient cattle in embryo transfer programmes. As synchronisation techniques have improved, the number of beef cattle being served by Al has steadily increased. Not only does oestrus synchronisation with fixed-time Al eliminate the practical problems of heat detection in beef cattle, it also allows the use of superior, easy-calving sires. Until recently, oestrus synchronisation and fixed-time Al, while often used with replacement dairy heifers, was seldom used in lactating dairy cows in the UK as results tended to be poor compared to Al to observed heats. However, interest in synchronising oestrus in dairy cows has increased with the introduction of improved techniques utilising combinations of gonadotrophin releasing hormone and prostaglandin. The theory and current methods of oestrus synchronisation for fixed-time Al in cattle are briefly reviewed in this article.

Inhalt Der Einflus der Milchleistung auf Fruchtbarkeitskriterien von Milchkuhen (n = 80) post partum (p.p.) wurde unter den standardisierten Bedingungen einer Versuchsherde anhand von Progesteronprofilen analysiert. Progesteron wurde dabei im Milchfett gemessen. Wie in fruheren Studien war das herausragende Fruchtbarkeitsproblem die reduzierte Auspragung von Brunstsymptomen und daraus resultierend Probleme bei der Brunsterkennung und bei der Wahl des optimalen Besamungstermins. Insgesamt verliefen 41,2% aller durch Progesteronmessung ermittelten Ovulationen ohne erkennbare Symptome. 94,8% aller Kuhe waren mindestens einmal von stiller Brunst betroffen. Resonders haufig verliefen die ersten Ovulationen nach dem Einsetzen der zyktischen Ovaraktivitat unerkannt. Bei stiller Brunst waren dabei die pheripheren Progesteronkonzentratwnen im Periostrus signifikant hoher als bei beobachteter Brunst. Dieses Phanomen war jedoch auf die ersten 5 Ovulationen p.p. begrenzt und weist auf hormonale, d.h. tierspezifische Ursachen der stillen Brunst in dieser Phase hin. Im weiteren Verlauf waren dagegen keine signifikanten Unterschiede in den Progesteronkonzentrationen zwischen stiller und beobachteter Brunst feststellbar. Damit mussen fur die spatere p.p.-Phase eher managementbedingte Ursachen fur die “stille” Brunst unterstellt werden. Wahrend mit steigender Laktationsleistung die Haufigkeit anderer Fruchtbarkeitsprobleme lediglich tendenziell und nicht signifikant mit der Leistung korreliert anstieg, nahm bei hoherer Milchleistung die Intensitat von Brunstsymptomen deutlich ab. Damit traten stille Brunsten und Besamungen zumfalschen Zeitpunkt signifikant haufiser auf. Entsprechend last sich die Verlangerung der Zwischenkalbezeit bei steigender Laktationsleistung nahezu vollstandig auf eine Zunahme stiller Brunsten und eine Haufung von Fehlbesamungen zuruckfuhren. Neben der Milchleistung waren eine Reihe weiterer signifikanter Einflusse auf die Fruchtbarkeit der Herde (z. B. Saison, Kalbenummer etc.) nachzuweisen. Der signifikant negative Einflus steigender Milchleistung auf Fruchtbarkeitsparameter, insbesondere auf die Brunstsymptomatik, bestatigt sich jedoch auch nach Berucksichtigung dieser Einflusfaktoren im statistischen Modell. Contents: Influence of milk yield on the fertility of dairy cows post partum: evaluation of progesterone profiles Progesterone profiles were evaluated to monitor the influence of milk yield on fertility traits of dairy cows. The cows (n = 80) were kept under standardizised experimental farm conditions and progesterone was measured in milk fat during the post partum (p.p.) period. Overall, the most frequent fertility problem was a reduced intensity of oestrus symptoms and resulting drfficulties in heat detection and timing of artificial insemination (A. I.). 41.2% of all ovulations were not accompanied by observed heat symptoms (silent heat). 94.8% of the cows investigated were affected at least once during the p.p.-period by this problem. Silent heat was most frequent afer resumption of cyclic ovarian activity pp., In case of silent heat progesterone concentrations during perioestrus were significantly elevated compared to observed oestrus. This phenomenon was obvious up to the 5th ovulation p.p. indicating endocrine determinants of silent heat during this part of the pp. period. Thereafter progesterone concentrations during perioestrus were similar in case of both, silent and observed heat, indicating that during the late p.p. period silent heat is mainly due to management failure. The frequency of fertility problems in general tended to increase slightly but not significant with increasing milk yield. A significant adverse influence of increasing milk yield however was obvious for the intensity of oestrous symptoms. Consequently the frequency of silent heat and number of unsuccessful inseminations increased with advanced yield representing the main reason for increasing interval between calvings. Additionally other injluences on herd fertility were obvious (e.g. season, number of calving). The significant negative influence of increasing milk yield, particularly concerning oestrus intensity, could be confirmed even if these influences were eliminated by the statistical model.

The use of a milk progesterone assay in determining the extent to which dairy cows are presented for insemination at the wrong time is reported. Milk samples were taken from cows at the time of insemination and were subjected to plasma progesterone assay. In a preliminary study samples were obtained from 96 cows in an experimental herd at insemination. The calving rate of these cows was compared with the milk progesterone level at insemination. Eight cows which had levels of progesterone much above the normal oestrus level 9 more than 0.3 ng per ml) failed to conceive. As the progesterone level at insemination rose, calving rate declined. A further 1177 milk samples taken from cows being inseminated in commercial dairy herds were also examined. Ninety-one animals (7.7%) had levels of milk progesterone in excess of those observed at normal oestrus. A negative correlation was confirmed between non-return rate and milk progesterone level at insemination. These investigations show that the proportion of cows from the national herd which have high progesterone levels when presented for insemination is similar to that found under experimental conditions and suggests that the problem of heat detection may be a relatively constant factor in reduced conception to artificial insemination.