Replacement Heifer Strategy for Suckler Herds

Tommy Cox, Education Officer, Teagasc Ballinrobe

With spring calving for 2021 almost complete on the majority of suckler herds, the saying a farmers work is never done springs to mind as focus must quickly turn to breeding. A key aspect to successful suckler breeding is the selection and management of replacement heifers to ensure they make the successful transition into the herd for next year’s calving season. An annual 15-20% replacement rate is recommended for suckler herds in order to maintain long term herd productivity. To improve your herd from year to year there should be a good replacement policy in place. In this article we look at some of the key areas a famer must look at in selection of his heifers.

Sourcing and Selection of Replacement Heifers

Replacement heifers represent the next generation of cows in a herd and therefore thorough selection is required to ensure they are going to be genetically superior to their predecessors. Farmers have two options when sourcing replacements; either breed from within the herd or source replacement stock from outside the farm. Both options come with advantages and disadvantages. Breeding replacements from within the herd reduces the risk of bringing in disease by keeping the herd closed.  It also has the added advantage that the farmer knows the breeding history of his replacements.  On the flip side, sourcing heifers from another farmer can make faster genetic progress in desired traits such as milk provided stock can be sourced from a reliable source.

Selection from within the herd

When selecting from within the herd the farmer knows exactly the breeding of the animal and can keep replacements from the top performing cows in the herd. Replacement heifers should be kept from cows that produce a quality calf with high weight gain to weaning, from cows that are fertile and have a tight calving interval, from cows that calve with little assistance and very importantly from docile cows that are quiet and easily handled.

Sourcing outside the herd

On some farms where a terminal stock bull is been used the only option might be to source replacements from outside the herd.  The ideal case scenario is where a relationship can be built up with a farmer with a good track record who is producing surplus replacement stock. Visually correct animals with sound feet, good pelvic width, and reasonably good conformation with a well formed udder are important physical aspects to look at when selecting heifers. The ICBF Replacement Index is a useful tool to aid in selection with research data showing high replacement 4 and 5 star females out performing lower index cows.  Try source genotyped heifers where parentage is verified, as it gives extra security on the breeding of the heifer, which helps reduce the risk of any inbreeding occurring. When sourcing from outside the farm increased biosecurity practices need to be put in place on farm to prevent a potential disease outbreak.

Hitting 24 month calving targets

Calving replacements at 24 months of age, has being shown to be the most profitable age to calve down heifers.  However, ICBF data shows that less than a quarter of heifers calve down at that age. Calving at 24 months increases the lifetime output of the cow, allows for faster genetic progress in the herd, reduces the proportion of non-productive females, while also reducing the carbon footprint of the herd.  Good management and performance is important to ensure the target weights of 60% of mature weight (approximately 400-420kg) at bulling and then 80% mature weight at calving (approximately 600kg) is achieved.

Sire selection

A critical aspect for making 2 year old calving work is Sire selection. Easy calving high reliable sires should be used with calving difficulty figures no greater than 6.5% for beef heifers. Heifers should be bred for an eight-week period which allows each heifer to be served at least twice, after this if there is an issue they should be culled as they are likely to have future fertility issues. 

Pre and Post calving Management

Once in-calf ensure a high level of performance up to housing. At housing heifers should be penned separately and maintained on good silage to continue growing. Pre-calving minerals should be offered 6-8 weeks before calving.  Post calving management is critically important to ensure resumption of oestrus and to get heifers back in calf. Ideally heifers should grouped separately and offered preferential treatment.