From drying off to calving is the critical period
The outcome of your spring breeding programme has already been predetermined by the transition management of your cows.
The importance of dry cow management has in the past not been prioritised. It must be remembered that 80pc of herd health problems arise in the transition period that stretches from around three weeks prior to calving and to three weeks post calving.
These health issues will slow the repair of the reproductive tract and result in a consequential increase in the incidence of metritis and endometritis.
In a recent study involving approximately 1,000 cows, 35pc had womb infections between 14 and 21 days post calving. Visually, 80pc of these cows appear perfectly normal. However, previous events associated with nutrition in the dry-cow period, housing environment, subclinical ketosis, fatty liver and milk fever will contribute to poor repair of the womb.
This environment facilitates the establishment of infection. Almost 40pc of these cows failed to go back in calf within six months of calving compared with 22pc for those cows in optimal health. In addition, the processability of milk from cows with womb infections was significantly decreased.
As the calving season progresses, there is a greater risk of poor management routines for late calvers. These cows cannot afford any setback, but usually they are more likely to be problem cases from last year.
Ensure your dry cows have access to fresh silage and water, balanced for minerals and vitamins. Do not feed mouldy silage to cows as the adverse health implications are immense. Mycotoxin binders are helpful, but do not give you a licence to feed mycotoxin contaminated silages. Egg quality for fertilisation and early embryo development are dictated by events six to eight weeks earlier. Therefore, it is essential that late calvers calving from now onwards come through transition successfully.
In addition, they cannot afford any setback in the shortened calving to first service interval. You will need to breed late calvers earlier to reduce empty rates at the end of the breeding season. Emphasis placed on the care of late calvers will pay major financial dividends.
Late calvers carry greater risk of metabolic diseases associated with longer calving intervals and a genetic predisposition to lower fertility. Higher replacement rates are a financial drain on the business and need to be avoided.
Cows experiencing setbacks in the transition period will also have impaired resumption of normal heat cycles. Over 90pc of first heats post calving are silent. They can occur between eight and 20 days post calving. Although these heats are not fertile, they are an excellent predictor of future health fertility.
In the North, farmers successfully use scanning 14 to 44 days post calving to identify their more fertile cows for the use of sexed semen. Pregnancy rates of 40-45pc have been repeatedly recorded using sexed semen in first and second lactation cows.
Successful transition management should not be undone by an emphasis on low-cost milk production from grazed grass. You cannot afford to induce either a non-cycling state or an abnormal environment in the womb of your cows because of excessive negative energy balance, lameness, mastitis, poor grazing conditions or quota management.
You must focus on keeping cows fit and selling cows which are surplus to your quota requirements. Although the current quota regime will end in 2015, many farmers have too many cows for the grazing platform available. Why strive and struggle to manage 100 cows when 80 well-managed cows will result in lower empty rates and greater business profitability?
The goal now is to maximize the use of sexed semen in both maiden heifers and dairy cows. In last year's experiment using sexed semen, there was a huge variation in the results achieved.
Transition and pre-breeding management have to be excellent to optimise the opportunities that sexed semen can deliver. There is a variation between sires used in terms of their fertility after semen sexing. Unfortunately, with the use of new genomic sires each year, there is little opportunity to evaluate their fertility prior to widespread use in spring breeding programmes.
Ensure that all vaccination programmes for IBR, BVD and Leptospirosis have been put in place one month before the breeding season begins.
In conclusion, remember that good transition management will always be the primary driver of a successful breeding programme in grass-based milk production systems.
Dr Dan Ryan is a cow fertility expert and can be contacted at www.cowsDNA.com
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