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Getting her pregnant!

In the past 10 yrs. the dairy industry has made significant strides in efforts to get cows pregnant, we’ve seen reproduction improve from various factors whether it has come from improved cow transition, nutrition approach, management practices, or environment it certainly has been a focus in our herds.  I am all too aware of the focus of pregnancy rate of the lactating herd with my former career in the AI Industry, until the advent and commercial acceptance of sexed semen there was little pressure put on heifer breeding. The metric that I saw used the most was, “What % was pregnant at vet check?” If this number was quite high ~90%+ then little was done to look into how we were doing in terms of heifer reproduction.

Now this is not to say that there were not producers, consultants, etc. paying attention in more detail to heifer reproduction but I’d say the focus changed almost instantly when sexed semen was commercially adopted by a couple major studs in 2005.  Heifer conception rate became a metric in the cross-hairs as the costs of the heifer breeding program increased with the cost of sexed semen and the fertility drag resulting in more services and days-on-feed to get heifers pregnant. The graph below shows how a small increase in conception rate can impact a population of heifers/cows getting pregnant efficiently.

Group A                                                         Group B

Starting Head Count: 1000                           Starting Head Count:1000

Conception Rate: 55%                                 Conception Rate: 65%

# Preg/Service   Animals still open  # Preg/Service      Animals still open

Service #

  1.      550.0                450.0                     650.0                     350.0
  2.      247.5                202.5                     192.5                     157.5
  3.      111.4                91.1                        86.6                        70.9
  4.       50.1                 41.0                       39.0                        31.9

While conception rate is a very good metric in looking at reproductive results in both heifers and cows we need to focus on more metrics in our heifer breeding program.  Heat detection cannot be overlooked in our heifer program, we also need to have properly trained AI Technicians, quality facilities to be able to heat detect, highly fertile service sires and proper immunization. (Chebel et al. 2010)  With the above being mentioned, I’d like to focus on the “how to” in having a successful heifer AI program.  Once determining the age or weight that you want your heifers to be bred at we need to focus on how we can get the heifer bred in a timely matter.

At this time I believe there are three solid options to begin with (these protocols can also be used in conjunction with one another):

  1. Chalking/Observation protocol
  2. PGF-2a induced protocol
  3. 100% Timed AI protocol.

The chalking/observation protocol is a common practice in the western US and involves locking the breeding age heifers daily and placing a strip of chalk on the tailhead to utilize for estrous detection. Advantages: Easy to implement if have facilities to lock heifers & low cost. Disadvantages: Does not submit heifers to insemination that do not show heat.

The PGF-2a protocol is simply determining the heifers you want bred and administering a dose of PGF-2a and observing for heat utilizing observation, chalk, or some other heat detection device such as a Kamar® patch. The animals not showing heat and thus not being inseminated can be given another shot 1 or 2 weeks (to be determined with your veterinarian) later to induce a heat on those remaining animals. Advantages: Easy to set up, get inseminations in tight window which can allow for quicker flow through breeding pen if short on space. Outcome can yield tight distribution of average age at 1st calving. Disadvantages: Requires giving shots, additional record keeping, and some additional cost.

The final protocol mentioned is a 100% Timed-AI program.  In the past ovsynch protocols have not performed well on virgin heifers because heifers have 3 follicular waves vs. lactating dairy cows having 2 and the program not being set up to work with 3 follicular waves.  The 5 day program with the CIDR has addressed the follicular wave pattern of heifers and is the program of choice if you want to time AI your heifers.Advantages: Heifers get bred in a tight window, faster flow through breeding pens, great option if you do not have facilities to lock heifers daily or have heifers on pasture.  Disadvantages: Shot compliance is mandatory; need accurate record keeping, and additional cost.

The chart below shows a comparison of conception rate between two groups and the outcome on age fresh just due to conception rate differences. Keep in mind this is assuming 100% heat detection, if we factored in heat detection rate and open heifers at vet check this distribution would be even wider.

Group A Starting Age: 13.00

Starting Head Count: 1000

Conception Rate: 50%

Serv#  #Preg/serv   #Anim open  % open   % calv at age    Age @ 1st calf

  1.        500.0          500.0           50%          50%           22.0
  2.        150.0          350.0           35%          15%           22.7
  3.        105.0          245.0           25%          11%           23.4
  4.         73.5           171.5           17%           7%            24.1
  5.         51.5           120.1           12%           5%            24.8
  6.         36.0            84.0             8%            4%            25.5
  7.         25.2            58.8             6%            3%            26.2
  8.         17.6            41.2             4%            2%            26.9

Group B Starting Age: 13.00

Starting Head Count: 1000

Conception Rate: 60%

Serv#  #Preg/serv   #Anim open  % open   % calv at age    Age @ 1st calf

  1.         600.0           400.0         40%           60%           22.0
  2.         120.0           280.0         28%           12%           22.7
  3.          84.0            196.0         20%            8%            23.4
  4.          58.8            137.2         14%            6%            24.1
  5.          41.2              96.0         10%            4%            24.8
  6.          28.8              67.2          7%             3%            25.5
  7.          20.2              47.1          5%             2%            26.2
  8.          14.1              32.9          3%             1%            26.9

All these programs need the following to maximize their efficiency:

  • Heifers moved in a timely manner, preferably once a week or every other week move in heifers qualified by age/weight for breeding and move out pregnant animals.
  • Consistent pregnancy checks, if checking cow herd weekly check heifers as well. Don’t go more than two weeks without pregnancy check.
  • High level of accurate heat detection.
  • High fertility service sires.

Heifer breeding protocol suggestions (s):Please visit with your veterinarian on which alternative or variation of protocol would work best for your herd.

  1. Chalk heifers and heat detect. Vet check weekly or every other week. Administer PGF-2a to open heifers and missed heats/heifers not showing heat since last vet check.
  2. Chalk heifers and heat detect. After 2-3 days (allow technician adequate time to get chalk on heifers) in breeding pen administer PGF-2a to all heifers not bred.  Continue daily chalking and insemination of heifers showing heat. 2 weeks after 1st PGF-2a shot give another shot to all heifers not bred. Vet checks same as above and PGF-2a open heifers.
  3. Follow protocol of Option#2 except on open heifers utilize 5d CIDR Cosynch to insure open heifers are being bred.
  4. Set up all heifers qualified to be bred on 5d CIDR Cosynch protocol, chalk & heat detect daily and inseminate those heifers coming into heat. Re-enroll open heifers at vet check onto 5d CIDR program.

The group at Progressive Dairy Solutions wants you to use whatever program you find best for your operation that results in getting your virgin heifers pregnant is a very efficient manner allowing you to keep rearing costs low and produce a constant flow of fresh 1st lactation animals into your milking herd.

Literature Cited

Ricardo Chebel 2010. New Strategies for Synchronization of Dairy Heifers and Economic Considerations.

by Tony Timmons

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