Does Artificial Insemination Pay? – Part TwoWritten by Scott Lake
Editor’s Note: In last week’s Extension column, Scott Lake looked at the advantages and disadvantages of utilizing artificial insemination (AI). In this column, he explores several AI protocols and options that producers have.
Though artificial insemination (AI) is one of the fastest and most economical ways to improve the genetics of the cowherd, there are advantages and disadvantages to the process.
Some of the largest disadvantages of AI involve increased labor and the necessity for accurate heat detection. Various protocols can help alleviate these challenges.
To reduce labor and eliminate the need to heat detect, timed AI protocols have been developed.
The theory behind a timed AI protocol is that the majority of females will be synchronized to ovulate within a short window of time that will allow for a mass breed without the hassle of watching heats. Recent advancements in synchronization protocols have improved so much that timed AI can be nearly as effective as breeding off of heat.
There are a lot of options for synchronizing estrus in heifers or mature cows. This article is not meant to be a comprehensive list of protocols, so we are going to just briefly discuss what type of options you have.
For beef heifers, there are several options that can deliver acceptable results. For very well developed heifers that are cycling, a two-shot prostaglandin protocol is inexpensive and requires relatively low labor.
However, we highly recommend that a progestin – melengesterol acetate or MGA, progesterone releasing intravaginal device or CIDR-based protocol are used with heifers. The exogenous progesterone supplied by these protocols can help jumpstart heifers that may not have started cycling yet.
The most common progestin used in heifers is MGA. One fall back with the MGA protocol is that it usually requires planning for a 33-day period. MGA will be fed for two weeks, followed by a shot of prostaglandin 19 days later, with three days of heat detection and breeding.
Acceptable conception rates can be achieved using MGA protocols. However, a concern with MGA is that because it is mixed in the feed, it is impossible to be sure that each heifer is consuming the required amount.
Other progestin-based protocols utilize a progesterone releasing intravaginal device (CIDR).
The advantages of CIDRs are that each animal is inserted with a CIDR, and therefore, each heifer/cow gets its full dose of progesterone. Protocols that utilize CIDRs vary from five to seven days with three days of heat detect and AI. Therefore the entire protocol can be completed within eight to 10 days.
Both MGA and CIDR protocols use GnRH and prostaglandin to help synchronize estrus. The biggest differences between an MGA protocol and a CIDR based protocol are time and money. It takes much longer and more planning to feed MGA. However, it is more expensive to use a CIDR, with a cost of about $10 per head.
For producers interested in breeding heifers or cows off of heat, good results can be obtained with any number of protocols, including MGA, a seven-day Co-Synch and CIDR, a five-day CIDR or a 14-day CIDR.
It probably makes the most economical sense to synchronize with MGA if you plan on breeding off of heat.
However, if you are going to breed cows or heifers off of a strict, timed AI protocol and no heat detection, using protocols that more tightly synchronize estrus response will yield greater results.
Synchronization without AI
Some producers would like the advantage of synchronizing cows to tighten calving intervals and jumpstart their cows without the hassle of AI. There are certainly advantages to simply having a more uniform calf crop regardless of genetics, as discussed above.
We would recommend an MGA-based protocol to minimize expense, while still gaining the advantage of utilizing a progestin based protocol. A simple and inexpensive approach is to give one shot of prostaglandin and turn out bulls.
Because of the nature of the estrus cycle and prostaglandin, roughly 33 percent of the heifers and cows will not respond to one shot. Much better results will come from a two-shot prostaglandin protocol, given 10 to 14 days apart, with bulls turned in following the second shot.
One final note
Success in any of these protocols is going to depend to a large degree with how strictly the protocols are followed. Make sure and administer the proper doses of prostaglandin, MGA or GnRH. Make sure schedules are followed, and if breeding off of heats, make sure plenty of time is allotted to watch for signs of estrus.
No matter how well you follow protocols, which type of protocol you use or how good an AI technician you are or hire, nothing will make up for undernutrition. Cows should be fed to have a body condition score between a five and six at breeding. Lower than a five or greater than a seven will result in reduced conception rates.