The cost of poor reproductive performance in the dairy herd can be quite significant, arising from reduced milk production, increased costs for replacement of culled animals, and veterinary intervention and medicine costs.
In order to maximise the benefits of optimal fertility, the following areas are of great importance.
* Achieving a body condition score (BCS) target between 2.75 and 3.0 at the mating start date (MSD) for milking cows, is the most important factor in dairy fertility.
A shortage of good quality grass may lead to a critical negative energy balance, resulting in increased incidence of retained placenta, displaced abomasum and uterine infection, ultimately giving rise to reduced dairy cow fertility.
Post-calving control of energy balance can be achieved by prioritising energy feeding over protein feeding.
This strategy deliberately restricts milk yield response to the energy consumed with the cow storing this energy in BCS rather than “milking off her back”.
Ensuring a rising plane of nutrition is critical in producing good quality oocytes for breeding.
For heifers, body weight and body condition score are of greater importance at the mating start date than age.
A target weight at the MSD of 300kg-330kg (60% of mature adult weight) and BCS of 3.25 are desirable in order to achieve optimum fertility and subsequent economic performance.
* Pre-breeding heat detection should begin four weeks prior to the planned MSD, which is mid-April for most spring systems.
All heats should be recorded.
By MSD, you will be able to anticipate when cycling cows will next come on heat (that is, week 1, 2 or 3 of the breeding season) and you will have a list of all cows not yet been seen in heat.
Based on pre-breeding heat detection results, you will know if your herd is hitting the target of 70% cycling by MSD.
If it is below this figure, it is unlikely that the three-week submission rate target of 90% will be met.
During this period of heat detection, keep records of any problem cows.
Issues such as milk fever, retained placenta, metritis, low BCS, cystic cows, anoestrus, lameness, etc, can all be discussed with your vet, who will also offer the valuable service of the pre-breeding scan.
It is advisable to scan all cows that have not showed signs of heat within 35 days after calving.
Endometritis, luteal cysts, follicular cysts, anoestrus, and many other conditions can all be treated with good success, once diagnosed early, therefore reducing the cost of unnecessary culling.
Implement a simple but effective form of heat detection such as tail painting or pressure activated patches.
Vasectomised bulls with chin balls are widely used, but must be operated on at least eight weeks in advance of the breeding season. Always be safety aware; remember these animals are still bulls.
* Check stock bull fertility at the beginning of the breeding season.
A bull breeding soundness evaluation, provided by your vet, involves a full clinical examination of the bull (to ensure he is fit for the job ahead) and a microscopic evaluation of the semen quality.
Also, note that bulls may become intermittently infertile during the breeding season due to lameness or other illnesses.
Have enough of them; and always be aware of safety.
Vaccinations against infectious diseases such as bovine leptospirosis, BVD and IBR must be kept up to date; however in most spring calving systems, annual booster injections have been completed by now.
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