Estrus Detection System Research Articles

Timing of Insemination for Dairy Cows Identified in Estrus by a Radiotelemetric Estrus Detection System

The optimal time of artificial insemination (AI) was determined from data for 2661 AI in 17 herds utilizing a radiotelemetric system for estrus detection that has the potential for continuous 24-h surveillance to monitor behavioral events associated with estrus. The system consisted of pressure-sensitive radio frequency transmitters affixed over the sacrum region of cows. The activation of the sensor sent a radiotelemetric signal to a microcomputer via a fixed antenna. Cow identification, date, time, and duration of each standing event were recorded in the software program provided with the system. Each farm selected a 3-h interval to AI for cows that were identified in estrus during the previous 24h. Pregnancy status was determined from data for return to estrus and palpation of the uterus 35 to 75 d following AI. Standing events during estrus averaged (± SD) 8.5±6.6 per cow, and the number of events per estrus across herds averaged from 6.2±5.1 to 12.8±9.9 per cow. The duration of estrus ranged from 5.1±3.8 to 10.6±6.8h across herds; the mean was 7.1±5.4h. The interval from the first standing event to AI affected the probability of pregnancy; the highest conception rates for AI occurred between 4 and 12h after the onset of standing activity. The probability of pregnancy was higher for cows >100 d in milk, exhibiting >2 standing events during estrus, and inseminated during March, April, or May.

Oestrus Detection in Dairy Cattle Using a Fuzzy Inference System

Because a well-controlled calving interval in dairy cattle improves the profits of the farmer, it is significant to develop an efficient oestrus detection system. Therefore, a fuzzy inference system has been developed as a management tool.It uses signals, correlated with physiological and behavioural effects like changes in activity, milk yield and milk temperature. A Controlled Random optimisation method is used to tune the membership function shapes. Using routinely collected data, the system proves to detect cows in heat with acceptable results.

Ultrasonic evaluation for the time of ovulation in ewes treated with norgestomet and norgestomet followed by pregnant mare's serum gonadotropin.

Progestogens and follicular stimulants have proved reasonably successful for estrus synchronization, but time of ovulation relative to removal of the progestogen is not clearly established. We monitored time of ovulation in ewes following synchronized estrus. Ovaries of 40 Dorset and Rambouillet x Dorset ewes were evaluated during the spring and fall (20/replicate). Ewes were randomly assigned to one of two treatment groups (n = 20/group): implant-only (I) ewes received a norgestomet implant for 10 d; and implant + PMSG (PI) ewes received a norgestomet implant for 10 d with an i.m. injection of 500 IU of PMSG at implant removal. Time of estrus onset was detected with the HeatWatch Estrus Detection System. Following the initiation of estrus, ovaries were monitored via rectal ultrasonography every 6 h to determine the interval from implant removal to ovulation (OVUL), and onset of estrus to ovulation (INT). Four I and PI ewes that lost implants before scheduled removal on d 10 were removed from the study. Estrus was detected in 13 of 16 (81%) I and 14 of 16 (88%) PI ewes within 108 h after implant removal. The interval from implant removal to estrus (EST), INT, and OVUL were not affected by replicate. The INT was not different in I (33.8 h) and PI (35.0 h) ewes. Mean OVUL was greater (P < .01) in I (79.8 h) than in PI ewes (68.6 h), and mean EST was also greater (P < .01) for I (46.0 h) than for PI ewes (32.6 h). The present data indicate that ovulation occurs on average 70 to 80 h after implant removal in ewes treated with norgestomet, and PMSG reduces the interval from implant removal to ovulation.

An Electronic System for studying the relationship between Behaviour and Body Temperature in Dairy Cows

With the widespread use of AI on many commercial dairy farms, the efficient detection of oestrus has become a subject of increasing importance. Of all the physiological variables that have been investigated as predictors of oestrus, body temperature monitoring either on its own or in conjunction with other physiological variables, has shown promise mainly because of the ease with which it can be adapted as a practical on-farm oestrus detection system. However, oestrus detection rates by body temperature monitoring rarely exceed 70-80%, and often 10-20% of non-oestrus cows are wrongly diagnosed as being in heat. If the percentage of false positives is to be minimised, then identifying those factors that affect body temperature is important. Equally important, is an understanding of the way and the extent to which each factor affects body temperature. The more complete these two pieces of information, the more confident can one be of diagnosing an oestrus cow correctly. The aim of the present study was to investigate whether the behaviour of a dairy cow affects her body temperature, and what light this information can throw on the use of body temperature as a predictor of oestrus.