Ongoing Agri-Food and Biosciences Institute (AFBI) research is highlighting the opportunity for calf rearing practices within Northern Ireland’s dairy sector to be improved dramatically.

A survey carried out as part of the institute’s OptiHouse project, is pointing to an average mortality rate – up to weaning - of around 6%.

“In some cases it’s been reported to be as high as 14%,” explained AFBI research scientist, Dr. Gillian Scoley.

“In reality, the figure should be around 2-3%. But the alarming mortality figures must also be considered in tandem with a number of other concerning trends, where the rearing of dairy young stock is concerned.

“Morbidity levels within calf units are alarmingly high. We’ve also seen previous work from the UK indicating that up to 15% of all replacement heifers do not live long enough to complete their first lactation.

“All of these challenges must be actively addressed," she said.

Calf rearing research

Scoley went on to confirm that research to identify optimal calf rearing practices continues to be an important area of focus for AFBI.

She said:

“The over-arching aim for dairy farmers is to calve down heifers successfully at 24 months and, thereafter, to ensure that these animals enjoy a long and productive life within their respective milking groups.

“There have been tremendous strides made over recent years to improve the genetic potential of the dairy stock bred here in Northern Ireland.

"But this potential is not being fully realised if calf ill-health and weanling mortality rates remain high. In addition, this worrying set of circumstances is adding significantly to the carbon footprint of the dairy sector.”

Factors to consider in calf rearing

According to the AFBI scientist, three factors kick in when to comes to considering the best way to rear a dairy calf. These are housing, health and nutrition.

“All three factors are interlinked. However, the over-arching requirement is to ensure that the young calves receive the proper care and attention they need up to weaning and beyond," Dr. Scoley explained.

OptiHouse is a research project funded by the Department of Agriculture and Rural affairs (DAERA).

It incorporates research teams from AFBI Hillsborough and Queen’s University Belfast (QUB), the CAFRE dairy advisory team and a group of international veterinary, academic and industry experts.

The overall objective of OptiHouse is to improve the sustainability of calf rearing enterprises by optimising the rearing environment and calf management. In order to achieve this, one of the main elements of the project has been to gain a better understanding of the conditions in calf rearing houses within Northern Ireland.

This understanding will help identify the influence of key factors, linked to poor environmental conditions and failure to deliver expected growth, such as building design, hygiene practices and calf nutrition.


In spring 2019, AFBI alongside the CAFRE dairy advisory team, completed assessments on 66 dairy farms across Northern Ireland. These assessments specifically focused on calf housing and rearing systems.

Detailed information on management practices, animal health and performance and the physical characteristics of the rearing house, including ventilation and hygiene assessments, were recorded.

As expected, a large variation in housing design, management and calf and house performance was observed. However, one common theme was aligned with hygiene.

Hygiene of the calf’s environment plays a key role in the prevalence of calf enteritis and respiratory disease, with calves most vulnerable to disease during the milk feeding period.

As part of the OptiHouse project, members of the AFBI technical team collected samples from the calf house environment.

This included milk or milk replacer to be fed to calves, calf starter feed, water from drinkers and swabs from bedding and feeding equipment.

The samples were then analysed for indicators of potential disease causing organisms including total viable bacterial counts (TVC), coliforms and E.coli.

Findings of analysis

One of the key findings from this analysis highlighted the need for better hygiene with regard to water quality.

Water is a driving factor for concentrate intake and therefore is essential for rumen development. Providing calves with clean drinking water and maintaining high levels of hygiene for drinking facilities, is therefore vital.

However, currently, there are no set standards for drinking water quality in calves as there are within the pig and poultry sectors.

When the drinking water samples collected within the calf houses were compared with the Red Tractor pig standards, only a small proportion of the samples met the standards.

Preliminary results from samples taken from calf feed and feed preparation equipment, have also indicated a high level of bacteria, thus putting young calves at high risk of ill health.