Pregnancies and calvings drive production and profitability. Despite this well documented and well accepted primary principle of profitable milk production a lot of dairy farmers still struggle to achieve the minimum levels of performance to achieve a consistent flow of calvings on an AYR calving system.
In addition CI does not show where problems are occurring and is therefore of little use in monitoring reproductive performance. As an alternative we use heat detection rate, conception rate and pregnancy risk/rate. The main benefits of this approach are as follows
a) Defined as the percent of cows that are eligible to become pregnant that become pregnant during each 21 day period commencing at the VWP
b) Eligible animals are past VWP, not DNB, not recently bred and not pregnant
c) Combines the two major components of reproductive management – Conception Rate x Heat Detection Rate
d) Measures success – how many pregnancies against number of attempts
e) Monitors short term and long term trends every 21 days
f) Includes all cows – 1st lactation and animals not yet pregnant
If you have a calving interval of 425 as opposed to 385 days you are in all probability forfeiting a whole year’s milk cheque every 12 years. Although calving interval (CI) gives an indication of the
magnitude of the effect poor fertility has on profitability, it is in reality a very poor performance indicator for the following reasons.
a) A cow has to be pregnant to get a CI
b) Historic – suffers a 12 month to 2 year lag
c) Does not include 1st lactation animals
d) Projected CI assumes bred cows maybe pregnant
In an AYR calving system services, pregnancies, and calvings per week are the important targets that need to be achieved.
Figure 3, shows the effect of achieving these targets on farm profitability. In this example the herd needs to generate 34 pregnancies per week. When pregnancies per week are above this target the herd
will generate profit, fall below this line and profitability comes under pressure. This is known as the hardcount line, a figure easily calculated for any herd. Pregnancy rate or risk can be given a direct financial value. One percentage point is worth between £20 and £24 per cow. For a 100 cow herd a drop in preg rate/risk of 2% below the 17% level required to maintain a flat calving pattern is worth between £4000 and £4800 a year. There are potentially a large number of reasons why cows do not get in-calf (Figure 4). But by far the most significant reasons will be energy deficiency and extreme
negative energy balance and semen deficiency as a consequence of poor heat detection rate and a failure to intervene with controlled hormonal breeding programs.
Maintaining or improving reproductive efficiency in herds will be essential to maintain profitability through a period of lower milk prices this coming spring. However, because of the negative effect
that low energy intake has on fertility reducing feed quality and feeding levels is not a justifiable approach. Quite simply maintain or increase production and fertility to produce more milk and
reduce fixed costs per litre. In the next part of pregnancies for profit we will look at the options for improving heat detection rate, protocols to induce heat and synchronised breeding programs.
Written by Dr Huw McConochie – Head of Dairy Technical Services
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