Late Mating Management

Late Mating Management

 

The number of empty and late cows is also closely linked to farm profitability, and even to the balance sheet. As AI finishes and bulls are turned out many will turn attention to the finer details of how the fishing gear has handled the winter lay off rather than making sure that a job well started is finished properly.

  

The graph above shows a national median result of about 10-11% empty rates in herds last year based on their final preg tests. This is considered to be quite a bit worse than other years, although we don’t have a similar survey from previous years to compare it with.

The typical herd is one thing, but of more interest is the spread of results. For every farm above average, there is another one below! In all provinces surveyed and overall, there was a big spread between good and bad herds, the haves and the have nots. The results were pretty much consistent across provinces

 

So, what steps need taking for the final phase of the 2002 year Mating?

Cow Management

It may seem obvious but empty cows come from cows that are not mated, failed to conceive or have lost pregnancies. With your cows the following steps should be taken:

1. Get your Vet to Investigate cows which have missed AI - getting these cows to cycle earlier will reduce empty rates – the more matings a group of animals have the lower the empty rate will be.
2. While you are at it get the repeat breeders checked as well – there are options for treating these cows as well.

Bull Management

There is usually a great sigh of relief that day when you finish the drudgery of AI and finally let the bull(s) run loose. For six weeks or more you have been focusing on tailpaint, drafting cows, CIDRs and so on, and now it’s a welcome break to leave the rest of it to mother nature. Your responsibility is over…..

Or is it??????????

Bulls running with your herd (or heifers) do a remarkable job. They deliver up to 10 doses of semen per day to your cows, and may produce 10 billion sperm per day. That’s one for every human on the planet! They generally deliver it to the right cows at the right time, often repeatedly. They keep their heat detection vigil around the clock, seven days a week and willingly lose up to 20% of their bodyweight for the cause.

They are the true sexual athletes!

They are looking for a good team manager – YOU!

Mother nature has also been extremely lavish with sperm supply. While it takes only 10-20 million sperm near the cervix to result in fertilisation, the first three ejaculates of the day contain on average 3 billion sperm! That’s 100 fold surplus!

But danger lurks later in the day, as the bulls’ “love tank” (the epididymis, which drains the testicles, and stores semen ready for the next time) begins to empty. Ninety percent of the days’ sperm has gone by the third ejaculate. The diluted semen subsequently produced may be insufficient.

LIC expert, Vish Vishwanath estimates the likelihood of fertilisation drops 5% per ejaculate beyond the third mating for the day.

What does this mean for bull management?

1. Safety in numbers

Ensuring top bull performance in most herds starts by matching resources with required workload. A conservative estimate of 30-40 cycling cows per bull ensures that the bull’s capacity is not outstripped on a big day, where 10% of the cows may come on at once. This also means there is a little bit of healthy male competition in most herds!

The number of bulls required depends on the number of cycling, non-pregnant cows.

For example:

In a 400 cow herd, the number of cows requiring bull service	Open cows	No.  Bulls
§          6 weeks AI, First round Sub Rate 90%, Con Rate 60%	85   cows	3
§          6 weeks AI, First round Sub Rate 80%, Con Rate 60%	125 cows	4
§          4 weeks AI, First round Sub Rate 90%, Con Rate 55%	117 cows	4
§          4 weeks AI, First round Sub Rate 80%, Con Rate 55%	191 cows	6-7
§          shorter AI, lower Sub and Con Rates	more cows!	?

At a bull ratio of one to 30, it may surprise you how many are required! Recheck your numbers too if you have embarked on a synchrony, anoestrus or resynchrony program, either basing your requirements on a bull per 4 returning cows per day or using strategic AI at times of greatest demand.

2. Managing the team

The policy of buying or leasing yearling bulls minimises (or should minimise) the nutritional and disease risks. Pay attention to buying or leasing healthy, well grown, disease free bulls. A vet check of the bulls is a good investment. EBL and BVD status should be checked.

Be quick to spot disease and lameness. Treat promptly, to minimise downtime and maximise sperm quality.

Lameness can be obvious and vets see many nasty cases; however it can have a severe impact on bull performance as the bull is not keen to mount. A lame bull in the herd is as much use as a frisky steer. Avoid bull hoof wear by excluding him from the yard or farm dairy. Rotate bulls frequently, to avoid lameness and speed recovery.

The huge value of records

Last, but by no means least, don’t give up on recording heats for at least a couple of rounds. Barring early preg testing, this is the only way to get a handle on how well your AI (and your bulls) worked. Without natural mating data, it is impossible to analyse herd reproductive performance for troubleshooting. Even remembering to record when you left the bull in until is important information for later on.

Your heat detection efforts won’t have to be quite as intense as at AI time as there will be fewer cows and the bulls will help you a great deal!

If you get bull management right, it not only provides a strong finish to the mating season, it is a great safety net if AI did not go quite right. If on the other hand you neglect our hard working boys, the team may not be as relia-bull as you had hoped!

Clyff Harrington
Intelact