Winter Management of Replacement Heifers
Type Media Article
By Sinéad Devaney, Teagasc Adviser, Galway/Clare Regional Unit
By and large at this time of year suitable suckler replacements have been selected from within the herd. At the same time we see cows being culled for various reasons. These are appearing in the marts and factories of late. Perhaps there is an increase in the sale of cows due to those being scanned as not in calf or cutting back in the keeping of cows over the winter. Therefore the replacement heifer should be chosen based on the performance, conformation, weight gain, temperament and most of all the maternal traits of your best suckler cows. The BDGP data supplied by ICBF Eurostar report on replacement indexes was of major benefit as it identifies replacement heifers with a 4 or 5 star rating which are essential for the rules of the BDGP scheme. These reports are updated three times a year as more genotyped animals are added. Once weaned, these potential replacements should be grazed and fed on their own away from any male cattle.
Now having done everything right so far, you are facing into the winter housing period and keeping these heifer weanlings on target in terms of live weight gain over the winter period.
There are a couple of targets to bear in mind as you go along. The aim is to have these animals at 60% of their mature weight at breeding and 80% of their mature weight at first calving. Cows don't reach their mature body weight until they are five years old. So naturally these heifers calving at two years of age will be lighter as first and second calvers and will need preferential treatment. However by their third calving it will be difficult to see the difference.
Table 1. Necessary weights of replacement heifers at different stages compared to mature cow weight.
|Mature cow weight||Weaning weight||Bulling weight||Calving weight|
|600 kg||260-280 kg||360 kg||480 kg|
|700 kg||300-320 kg||420 kg||560 kg|
We are aiming to calf the replacement weanling heifers at 24 months. Looking at the table above a target weight for heifers next spring at breeding could be 400kgs. This means heifers at 320kgs now will need to put on 80kgs over the winter. Achieving at least 60% of their mature weight at bulling will ensure that there is a strong likelihood that heifers will be cycling at 15 months. Puberty in heifers is more related to weight than age so a good plane of nutrition is important. Traditional breeds and crossbred heifers reach puberty earlier than purebreds.
It is good practice to weigh the heifers at housing and once or twice during the winter to see that the weights are on track. This can be done by selecting a few from the group if you have your own weighing scales or weighing a group in a trailer on a weighbridge locally if available.
In order to achieve the targets outlined you will need to feed the best quality silage available supplemented with 1.5kg concentrates daily until early January when feeding rates will be reduced in advance of turnout. This concentrate feeding should be front-loaded at the start of the winter, offering up to 2kg per head. It is good practice to have silage tested to assess quality and feed value. This will give rise to more efficient meal supplementation with silage particularly where there may be fodder shortages on farm. The replacement heifer group is not the group that should be sacrificed when it comes to rationing of fodder.
Particular attention needs to be given to parasite control at housing. The heifer needs to be dosed for fluke and worms including a lice treatment. It is important to be able to accurately determine the weights of animals in order to administer the correct dose for weight.
Finally investing time into good management of replacement heifer weanlings is your investment in the future success of the suckler herd and is time well spent.