THE CHALLENGES OF INTENSIVE BREEDING
The emphasis on compact calving for cost efficient milk production from grazed grass in Ireland has placed an onus on dairy farmers to prepare for a breeding programme starting anywhere between the 10th of April and the 10th of May.
Many farmers find the transition from the current calving season to an intensive breeding programme difficult. Late calvers still pertain on most farms when the breeding programme begins. In reality most breeding programmes will extend between 10 and 14 weeks.
The original mantra for a grass-based breeding programme dating back 25 years was a 90pc submission rate with a 60pc pregnancy rate to give a 90pc calving rate over a 10 week period. However, very few dairy farms achieve these targets.
In my opinion, a 90pc calving rate with a 15pc replacement rate for a 12 week calving period should first be achieved as a meaningful target. Our farm visits for prebreed scanning currently reveal that between 10 and 20pc of cows remain to calve on farms. These late calvers will in reality face the greatest risk of survival because of poor dry cow transition management and a restricted window of opportunity to establish pregnancy in the current breeding programme. There is a significant opportunity cost associated with managing to establish pregnancy in these late calvers.
Farmers find it difficult to keep fresh feed in front of these late calvers on a daily basis. There is a greater risk of moulded and heated silage being fed to these cows without the required mineral supplementation. Over conditioned cows associated with long calving intervals will also fall into this group. The easy solution tends to be one of selling these late calvers. Good routine management will ensure a very profitable late calver portfolio.
In tandem with our late calvers which are generally housed indoors, our breeding groups are now grazing outdoors day and night. The primary focus in our breeding programme has to be ensuring our cows are fit for breeding. Too much emphasis has been placed on minimal or zero input of concentrates when cows are full-time on grass.
This may pertain under ideal grazing conditions for herds with 305 day yields averaging 6,000 litres and 20pc first lactation cows. In reality, increasing numbers of cows on a restricted land base and the vagaries of pasture, quality and quantity require concentrate supplementation prior to and during a breeding programme.
You need to be cogniscent of the fact that egg quality depends on its experience for the previous 8 week period and the first 2 weeks after fertilization will dictate the ability of the cow to recognise that there is an embryo present. The latter chain of events will primarily dictate the number of cows repeating to either AI or the stock bull.
A diet balanced for energy, protein, fibre and minerals is essential to ensure your cows are gaining body condition going into a breeding programme. Environmental stressors have to be minimised to ensure you achieve in excess of a 90pc submission rate in the first 3 weeks of the breeding programme.
Unfortunately, stressors such as lameness, poor BCS, mastitis, milk fever and calving difficulty will leave up to 30pc of cows unfit for breeding. Hormonal treatments may induce heats in these cows but outcomes are poor relative to a fit cow showing a natural heat. The primary focus has to be preventative health management which pertains not alone in dry and early lactation transition but also during the breeding programme.
Many farmers will focus on the use of AI for 4 to 8 weeks before introducing a beef sire as mop up bull. Various technologies have been introduced over the past 10 years to maximise heat detection considering a €250 opportunity cost for every heat missed.
Heat detection aids include tail paint, teaser bulls with chin-ball markers, activity monitoring devices attached to the legs or neck of cows and scratch cards. Fit cows will express signs of heat. You will need to spend three observation periods of 20 minute duration in association with any heat detection aid to maximise submission rate.
Various ov-synch programmes have been promoted which do increase submission rate over a concentrated period when compared the figures achieved by most farmers detecting natural heats. However, there is a risk according to Dr. Donagh Berry from Teagasc Moorepark that we will breed more cows in the future with poor ability to express heat naturally.
In conclusion, focus on keeping your cows fit for the breeding season to maximise the opportunity for heat detection.
Dr. Dan Ryan is a bovine reproductive physiologist and can be contacted at www.cowsdna.com