Time Before Cow Gets Inseminated Again

Detection of oestrus (heat) is often cited every bit the most costly component and undoubtedly, the major limiting gene to the success of A.I. programs on many dairy farms. Incorrect detection of estrus is related to loss of income due to extended calving intervals, milk loss, increased veterinary cost, increased heifer rearing cost, and slowed genetic progress. To achieve splendid estrus detection, many factors have to be taken into account. First, the moo-cow must limited behavior and physiological changes, and secondly, these changes must be detected to decide if and when insemination should occur. Information technology is clear that an excellent rate of heat detection is vitally important. Some herds have exceptional fertility while others struggle with conception rates, calving intervals, pregnancy rates and other parameters, which might be caused by inefficient heat detection. Numerous factors, environmental, managerial, and cow-related, play a function in estrus expression and detection. Many devices are commercially available to assistance with estrus detection and each producer must decide which works the best in their dairy. The time of ovulation and age of the egg at sperm penetration is critical for conception, so the goal of a oestrus detection program should non merely exist to achieve a high detection rate but to attain a high detection charge per unit with a corresponding loftier conception rate.

BEHAVIORAL CHANGES

The occurrence of estrus is due to specific influences of ovarian steroid hormones on behavioral centers in the brain. Equally a growing follicle matures under the stimulation of follicle-stimulating and luteinizing hormones (FSH and LH) during the last three to four days of the estrous cycle, information technology synthesizes and secretes increasing quantities of estradiol. A threshold level of estradiol is reached which triggers two closely linked events – the behavioral response known as oestrus and a surge of pituitary hormones, primarily LH.

Information technology is useful to point out that the maturity of the Graafian follicle that regulates the amount of estradiol synthesized regulates its ain time of ovulation and concurrent maturation of the oocyte. Traditionally, the cow that stands still and allows others to mount her is in "standing heat." Standing is the primary sign of heat. Ovulation usually occurs approximately 24 to 32 hours afterward the onset of standing rut in dairy cows. Later ovulation, there is only a curt period when ova can be fertilized (Effigy 1). Optimal fertility of ova is projected to be between 6 and 12 hours later ovulation. The feasible life span of sperm in the reproductive tract is estimated at 24 to 34 hours.

The average catamenia of "continuing heat" is usually less than 10 hours and consists of about ane continuing issue per hour. Secondary signs of heat may be an indication that the cow may presently display standing estrus, is currently in rut, or has already gone out of standing heat. Since the degree of these advanced signs vary in length and intensity, a combination or having multiple secondary signs increases the reliability of the determination to breed. It tin likewise aid to increase the corporeality of cows submitted to A.I. past allowing the insemination of cows that cannot be detected otherwise. Secondary signs are acquired by elevated levels of estrogen on the day the fauna is in heat. They are besides near likely acquired past oestrus-related activities and events. The primary sign of estrus is a cow standing to be mounted by another cow(due south) even though she could accept resisted the mounting activity. The reason why secondary signs of estrus get this name is they tin also be caused by events other than estrus and are secondary to standing to be mounted as the definitive sign. Therefore, a unmarried secondary sign of estrus should not be plenty to make the decision to inseminate; if a cow is not seen standing to be mounted and is suspected in estrus, it will be necessary to have a combination of secondary signs to confirm that the cow is really in estrus. Beneath are some of the near commonly recognized secondary signs of estrus.

• Rubbed marks – When a cow dismounts another, she slides down her tail head and rump. Therefore she puts considerable pressure on the pin basic and backbone, and this repeated abrasive action pulls out hair and may produce red, bloody or swollen sores. Size, appearance, and freshness of these marks along with the fact that few other events can cause like signs; these rubbed marks are one of the near reliable secondary indicators of estrus. Additionally, you may detect that the flanks of the cow in question accept dirt or manure marks from the hooves of other cows riding them and are another indication that riding events have recently happened.

• Mucus – Many technicians would state that fungus is the most liked secondary sign of estrus. Experienced inseminators put a profound credence on this sign when deciding to brood or not to breed a cow, and sometimes they even massage the cervix and anterior vagina to express a mucus discharge. Discharged mucus dries apace so finding stale mucus on the tail, flanks, or legs is but as skilful a secondary sign as seeing a string of clear viscid mucus coming from the vulva.

• Sweaty appearance – Some cows will develop a sweaty appearance when in heat. This "moisture" appearance, even though it is easily detected, is frequently disregarded and may be where the slang term "hot" cow originated.

• Swollen vulva – Rapidly growing follicles produce high circulating levels of the hormone estrogen that increase blood menses to the reproductive tract. The vulva increases in size and takes on a pink swollen appearance. Upon opening the labia an intense dark pink to carmine and highly moistened vagina is nowadays if the cow is in estrus. In contrast, the vagina will appear dry and pale to white in color when the cow is not in estrus.

• Chin resting – Chin resting is thought to be testing by herd mates to determine if an individual is receptive to beingness mounted. This testing is performed past offset resting a chin on the dorsum of the moo-cow. Considerable salivating and licking normally takes place during this testing process so you should inspect the loin and tail caput area for saliva.

• Bellowing and urination – There is a tendency for increased urination. The cow volition begin holding her ears erect, go restless and nervous. Cows coming into heat will become more than agile and will spend more fourth dimension walking around rather than lying downward chewing their cud. Exist enlightened that during motion, like to and from the milking parlor, is an ideal time for a cow to mount some other and therefore a great time to find mounting activity. Some cows may announced to be standing when in fact they just couldn't become away because of crowding. Extra care should be taken to avert false positives like this i.

• Encarmine belch – A streak of blood in the mucus ordinarily means that that cow had a high summit of estrogen i to three days ago. It is therefore recommended to record that heat and date it two days ago. This simply indicates that she has been in heat. It has no human relationship with timing of ovulation or whether or non she conceived.

• Grouping – Cows in heat tend to look for willing partners to go involved in estrus-related activities. These sexually agile groups are a clear indication that at least i cow within one of these groups is in rut.

FACTORS THAT INFLUENCE DETECTION

Moo-cow factors

• Heritability – The heritability of heat expression is very depression and varies between cows, fifty-fifty for the same moo-cow, from ane heat menses to another. Just considering a cow is very agile today does not mean she volition be at her next rut period during this lactation or in subsequent lactations. However, there are differences between breeds. In full general, Bailiwick of jersey cows and heifers have more intense and longer periods of estrus expression than Holstein cattle.

• Days in milk – Silent heat (more correctly, silent ovulation), is mutual at the get-go ovulation subsequently calving. Progesterone released from the corpus luteum (CL), formed after the silent ovulation, appears to favor estrus expression during the next cycle.

• Lactation number – A study from Kingdom of spain in 2006 revealed a 21 percentage decrease in walking activity with each boosted lactation. A study from the United kingdom in 2009 reported a pregnant increase in walking activity during estrus for heifers versus kickoff lactation cows, and a significant subtract betwixt first and afterward lactations, merely no difference in walking activity during heat for cows between 2nd and later lactations.

• Milk production – There is no correlation between rut expression and milk yield; withal, the metabolic clearance of steroid hormones related to high milk product probably reduces behavioral expression of estrus. In a study with 267 lactating dairy cows, cows with daily milk yield greater than 57 lbs. (39.5 kg) per mean solar day had lower blood estrogen levels and shorter elapsing of rut than herdmates producing less than 87 lbs. (39.v kg) of milk daily.

• Lameness – Lameness is classically associated with a reduction of heat intensity. Lame cows spent more time lying and less time standing and walking during rut. Ane report reported an overall reduction of approximately 37 percent in estrus intensity for lame cows.

• Hormonal treatments – Progesterone increases the sensitivity to estrogen and unremarkably results in increased heat expression, specifically mounts, chin resting, and sniffing (which may explain why after removing a CIDR® insert, increased estrus expression is common). In contrast, Gonadotropin-releasing hormone (GnRH) reduces or suppresses the expression of estrus past causing the early ovulation of the developing follicle prior to top estrogen levels that prompt the expression of estrus.

Environmental factors

• Season – Well-nigh studies accept reported a depression in rut expression during extreme temperatures, either hot or common cold. The inability to have a period of recovery from loftier temperatures during the 24-hour interval has also been reported to negatively affect estrus behavior. Heavy rain, strong wind, and high humidity also reduce or suppress estrus behavior.

• Nutrition – Loss of body reserves (negative energy residuum) can negatively touch estrus expression. The presence of mycotoxins, specially vomitoxin and zearalenone, reduce or suppress rut expression.

• Housing – The type of flooring surface affects estrus behavior. Duration of estrus and number of mounts were longer (xiii.viii versus 9.4 hours) and greater (7 versus 3.2 times) on dirt than on concrete surfaces. Covering a physical grooved floor with perforated safe mats improved the ability of cows to limited normal behavior activeness.

• Herd size and over-crowding – The number of social interactions between cows is greater when the herd size is larger. Nevertheless, over-crowding volition reduce expression of estrus by limiting the space available for socially active groups to form and interact. The degree of oestrus expression and therefore, the possibility of detection, tin be dramatically favored by the number of cows in estrus simultaneously. This is the reason PGF injections work to increase detection, especially prior to first insemination. Each additional cow in estrus at the same time has been associated with a 6 percent increase in walking activity.

Records

A good record keeping system is one of the nigh valuable tools in any detection programme, mostly because information technology volition increase the accuracy of your decisions. All heats must exist recorded even if the cow is non bred at that rut. The pivotal question is when the concluding insemination occurred. Having an interval of eighteen to 24 days makes the determination to inseminate easier. Breedings that occur with an estrus interval of four to 16 days usually outcome in less than desired conception rates and should be avoided unless the secondary signs strongly sway the decision to inseminate. As well knowing if the previous breeding was a upshot of timed A.I. or from a standing result may alter the decision. These off-cycle cows could be palpated for the presence of a clear stringy mucous as the final and definitive secondary sign to confirm the decision to inseminate.

TIMING OF INSEMINATION RELATIVE TO ESTRUS

For the past 65 years, researchers have investigated the optimal time at which to inseminate cows relative to the phase of estrus. Trimberger (1948) found that formulation rates were highest when cows were inseminated between half-dozen and 24 hours before ovulation. This early on work led to the institution of the a.m./p.m. recommendation. This guideline suggests that cows in estrus during a.m. hours should be inseminated during the pm hours, and cows in estrus in the p.thousand. should be bred the following a.thou. Notwithstanding, inquiry with big numbers of cows indicates that maximum conception rates may not be achieved using the a.m./p.m. recommendation.  A large field trial (44,707 cows) constitute no difference in the percentage of not-return rates at 150 and 180 days (which would point pregnancy) between cows bred either the same morning as observed rut, between noon and 6 p.m. on the solar day of observed estrus, or cows bred the post-obit morning after observed estrus the previous evening. This indicates that a single mid-morning time insemination for all cows observed in estrus the night before or the same morning should yield acceptable conception. Also, cows bred once daily (between 8 a.one thousand. and xi a.1000.) had similar not-return rates as cows bred according to the am/pm guideline. When knowing the onset of standing beliefs, enquiry suggests that cows exist bred earlier than the a.m./p.m. guidelines. Highest conception rates for A.I. occurred betwixt iv and 12 hours after the onset of rut (Table one).  Cows inseminated 16 hours later the onset of heat had lower formulation rates than cows bred between four and 12 hours after the onset of estrus. The effects of interval to A.I. on conception rates of dairy cows (4,126 breedings) having high activity using the SelectDetect™ activity system were consistent with like studies based on observed mounting activity (Effigy 2).  he hateful duration of high activity was x.5 hours with a median of 10 hours. Amid starting time lactation cows (Figure 2), optimum conception occurred at A.I. intervals of eight to 16 hours subsequently the onset of high activity and trended lower for both earlier and later A.I. intervals. Amongst second lactation and older cows, conception rates were similar until 16 hours after the onset of high action. Optimum conception rates were obtained at A.I. intervals proximal to 12 hours after detected estrus with shorter intervals actualization to be less compromising to conception rates that are of longer intervals.

WHEN SHOULD DAIRY COWS Be INSEMINATED?

The traditional a.yard./p.m. recommendation works best with twice daily observations simply may not provide the all-time conception rates because several cows will exist bred too long after the onset of estrus, so the chance for successful fertilization may be missed. The exact onset of estrus is ordinarily unknown. For instance, according to the a.m./p.m. guideline, a cow beginning oestrus at 1 a.1000. and observed in estrus at 6 a.yard. would be bred approximately eighteen hours after the onset of estrus. Breeding cows at this time would reduce the number of cows that become pregnant (Table 1). Cows should be inseminated within 4 to 16 hours of observed heat when the precise onset of estrus is known (Figures ane and 2). If estrous detection is conducted twice daily, nigh cows should exist inside this time period. However, a single mid-morning insemination of cows that have been observed in rut the aforementioned morn or the previous evening should provide acceptable conception rates.

SUMMARY

Traditionally, the cow that stands still and allows others to mountain is in "standing oestrus." Continuing is the chief sign of estrus and determines the time of insemination since ovulation occurs 25 to 30 hours later on the onset of continuing activity. Secondary signs of heat may be an indication that the cow may before long display standing heat, is standing now, or has already gone out of continuing oestrus. Since the degree of these avant-garde signs vary in length and intensity, a combination or having multiple secondary signs increases the reliability of the decision to breed. Making the decision to inseminate ofttimes will require the employ of secondary signs of heat. There is a fine line that will only come up with experience when using secondary signs to make the conclusion to breed or not to breed. Considering of biological variation in the time of ovulation in respect to the onset of heat, sperm transport time in the female reproductive tract to the site of fertilization, and life bridge of both gametes (sperm and ova) there is a broad window for the optimum time of A.I., of approximately 12 hours. The key component to timing of A.I. is frequent and accurate ascertainment periods to make up one's mind the onset of rut.

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Time Before Cow Gets Inseminated Again

Source: https://www.selectsires.com/article/ss-blog/2020/11/03/heat-detection-and-timing-of-artificial-insemination

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