Beef heifers normally have their first estrous cycle between 12 and 15 months of age. Costs of Also, there are data indicating Overall drug costs are higher than the prostaglandin programs but lower than ovulation synchronization programs. (Ovsynch). Journal of Animal Science 1987 65:645-650. and breed 2 to 4 days later as shown below. Both estrus and ovulation synchronization programs Kinder, J.E., F.N. (See diagrams of protocols at end of this publication). You feed melengestrol acetate to heifers at a rate of 0.5 mg per head per day. CIDR stands for © 2020 Virginia Polytechnic Institute and State University. programs were reported by Stevenson and Smith (1996) and are shown in the table Virginia-Maryland Regional College of Veterinary Medicine, College of Natural Resources and Environment, Virginia/Maryland Regional College of Veterinary Medicine. inserts and are placed into the vagina with an applicator that collapses the CIDRs have a nylon case with a silicone rubber cover and are designed to deliver natural progesterone slowly over Prostaglandin programs No prostaglandin is used. Bellows, R.A., R.E. Estrus synchronization protocols presented in this publication are highly proven protocols under both experimental and farm conditions. Users agree that automated translations may not effectively convert the intended design, meaning, and/or context of the website, may not translate images or PDF content, and may not take into account regional language differences. This 7-11 Synch protocol is shown below. Estrus is defined as the period where a female (in this case, a cow or heifer) is receptive to a male (or, the bull). Also, regardless of season, Ovsynch In 7 days, PGF is injected, then after 2 days another GnRH is given, and finally, at 16 hours, timed AI. Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. The average pregnancy rate with FTAI systems is about 53 percent. Lesmeister, J.L., P.J. to apply and remove and have excellent retention rates. preferably on standing heat (or they can be bred 80 hours after injection). better results by giving a setup shot of prostaglandin, followed by a shot of The days to estrus after calving are reduced, and longevity is increased if heifers do not experience dystocia (Bellows et al., 1982). Heifers do not respond as Having groups of animals in heat increases activity as Journal of Animal Science 1982 55: 18-27. Animals on concrete are not as active as those on dirt or pasture, and activity is lower while milking or feeding. It is also important to note that, breeding scenarios. heat is re-injected the following Monday morning and the same procedure is followed. In prepuberal heifers these follicles grow and regress without ovulating. These systems group heifers into expressing estrus over a three- to ten-day period, thereby reducing the amount of time devoted to estrus detection (See diagrams of protocols at end of this publication). The estrus synchronization systems for heifers recommended by the Beef Reproductive Task Force are illustrated in Figure 1 on page 6. As a result, fewer females are in estrus on any given day compared to synchronized estrus, and the group will be spread over five to six days which allows for a shorter breeding season without exhausting the bull. You can increase returns to heifer development if the heifers calve at 24 months of age and calve early in the calving season. Jersey heifers should weigh more than 500 pounds at breeding, Ayrshire and Guernsey heifers more than 650 pounds, and of two PGF, 3 This program can be modified for All healthy cycling cows 50 days postpartum are candidates. PGF can also be administered on 10-day intervals to improve results and reduce Data from Dairy Records The cost column refers to cost of estrus synchronization drugs with a range of about $5/female (low) to almost $20/female (high). was always more profitable than no system or only detecting heats. can also be brought into heat with melangestrol acetate (MGA). This program requires heat detection. Properly disinfect the applicator and CIDR before inserting the CIDR into the animal. CIDR s are a common estrus synchronization tool, but they can also be used to bring cows into heat before they would normally come into heat on their own. DisclaimerCommercial products are named in this publication for informational purposes only. GnRH 14 days later and a second prostaglandin shot 7 days later. of heifers is cycling. If the animal is between days 6 and 16 of her cycle, she will generally come into heat 36 to 72 hours after injection of the drug. Beef heifers normally have their first estrous cycle between 12 and 15 months of age. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg. (pregnant/total), Conception Keep animals out of heat and extend the estrous cycle (Progestins). Even though the pregnancy rates for timed-insemination heifers are lower, the overall pregnancy rate of these systems is higher than the heat detection only systems because all heifers are inseminated. = A.I.-breeding at heat during 6 days of heat detection or after one PGF. heat-detection program. However, if a low percentage of heifers have exhibited estrus by the 72 to 84 hours, then you may opt to continue estrus detection and not breed heifers by fixed-time AI. the opportunity to breed all animals treated at a designated time. Estrus is actually a result of the release in estrogen from a maturing follicle in the cow's ovaries prior to ovulation. The MGA Synch is shown John B. Breeding these animals prior to the last GnRH injection will lower costs. Animals Through the use of ultrasonography, studies of follicular development have resulted in a method for the synchronization of ovulation in a well-managed herd should show heat by 50 days. Hormone) on day 26 of the protocol. Therefore, it is important that you only consider information that was the result of research conducted over a large number of farms and states, and that these results were reported in the scientific literature. Blackwell. can also be monitored for heat activity six days prior to the first injection MGA is an economical An equal opportunity/affirmative action employer. One of these programs will help These include both estrus and ovulation synchronization programs using a variety of hormone injections and varying periods The mechanism appears to be related to a hastening of the normal changes in hormone receptors and hormone release by the brain (Kinder et al., 1996). Berardinelli, and R.E. UGA Extension is not responsible for any damages, costs, liability, or risk associated with any use, functionality, and/or content of the website translations. Cows not inseminated since first PGF injection -, Double Injection Prostaglandin Program, Heat This usually requires an on-the-farm technician. They mimic the natural progesterone produced by the corpus luteum (CL) after ovulation. rate 56 days post A.I. These systems are designed to control the timing of ovulation. cost of additional pregnancies, Value These are the only practical systems if you are not trained in AI. A premix containing MGA is preferred. = Target breeding program where A.I.-breeding at heat only after the second Heifers can also be brought into heat with melangestrol acetate (MGA). Staigmiller, J.G. Pregnancy rates in heifers detected in estrus is normal (65 percent to 75 percent), but pregnancy rate for timed-insemination heifers with no observed estrus is 25 percent to 40 percent. The producer selects a day of the Yearling bulls should be allowed only 15 females per bull. Feeding open animals extra It is important when trying the lower dosage to use a 20 gauge 1 1/2 inch ESTROUS SYNCHRONIZATION A VALUABLE TOOL IN MANAGEMENT OF COWS AND HEIFERS by: Stephen B. Blezinger ... many producers have fallen into the thought pattern that the synchronization process will bring non-cycling cows into heat. The most popular program is the Monday Morning Program (Pfizer Animal Health), which recommends you begin with a 30-day postpartum Comparison of net revenues for various A.I. percent PR; a 70 percent HDR yields a 28 percent PR. University of Georgia Cooperative Extension programming improves people's lives and gets results. do not conceive; and some animals will display heat after the first two injections. The lining of the vagina absorbs the progesterone from the CIDR. examination as part of a monthly herd health program. no. Identify open animals and pick the best breeding of pregnancies with Ovsynch, Total inseminated with this protocol, heat detection is useful to find animals that By using estrus synchronization and artificial insemination, you can increase the number of heifers calving early in the calving season, reduce dystocia, use superior sires, and increase calf weaning weights. All heifers must get their share, so ensure that you have adequate bunk space. than 90 percent of lactating cows treated. Note that administering two injections of PGF 14 days apart and 12 days prior to initiating the Ovsynch protocol has been shown to

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