Dr Ajmal Khan
AgResearch, New Zeeland
Dr Ajmal Khan has a PhD in Animal Nutrition and the majority of his research work as a graduate student was focused on enhancing the feeding value of crop residues and improving feed management for ruminants (buffalo, zebu, crossbred cattle). In 2005, Khan joined the National Institute of Animal Science as a post-doctoral fellow and was later appointed as a scientist at Seoul National University in South Korea where he led research aimed at improving feeding and weaning systems for calves. While in South Korea, Khan delivered multiple projects to the feed and livestock industries – ranging from feed management to the evaluation of ruminally-protected nutrients in cattle.
In 2008, Khan became part of the Animal Welfare Program at The University of British Columbia, Canada, where he undertook research to improve welfare and performance of dairy cows and calves around physiological transitions. In 2014, he accepted a senior scientist role with AgResearch Limited, New Zealand. He is currently working closely with New Zealand dairy and livestock industry stakeholders to improve the performance and welfare of dairy cattle in pastoral systems. Khan has presented his work at many conferences and has co-authored 70 peer-reviewed research manuscripts.
Weaning strategies to improve performance and welfare of young ruminants
Dr Ajmal Khan, Senior Scientist in Ruminant Nutrition at AgResearch, New Zealand, was the final speaker at the two-day international symposium during Trouw Nutrition's official opening of their new Calf & Beef Research Facility in April. Dr Khan's talk focused on best practices in weaning that would aid in improving both the performance and welfare of young calves.
Performance and welfare in young ruminants
What does Dr Khan mean by "performance" and "welfare"? He emphasized both short and long-term performance goals. In the short term, he explained that the primary objectives are survival, health, growth and cost. In the long term, he also stressed the goals of growth and health, but added reproduction, milk yield, longevity, efficiency and profitability. Without looking out for calf welfare, however, these performance goals cannot be met.
Dr Khan then explained that young calves have nutritional, behavioural, environmental and social needs. If these critical needs are met in a rearing system, then young calves will have lower incidences of disease, less hunger distress and less behavioural or social deprivation. Indeed, if all the necessary welfare goals are put in the forefront, the result, says Dr Khan, is a healthy adult animal, ready for a lifetime of high performance.
It can be quite a challenge. But, as Dr Khan makes clear, there are certain weaning strategies that can help in achieving all of these goals!
Which weaning strategies work best?
Dr Khan's research shows that greater milk access prior to weaning is a key strategy for reducing hunger and lowering weaning distress, while simultaneously supporting greater body weight in calves going through the weaning transition. Additionally, he conveyed that weaning distress reduces significantly when calves are pair housed, and that such social housing can improve calf performance both around weaning and after weaning.
Dr Khan also described an additional strategy which promotes successful weaning: adding hay to calves' dry matter intake, along with their starter feed. In fact, says Dr Khan, early access to hay not only promotes rumen development, but it also promotes higher dry matter intakes both before and after weaning.
Additionally, Dr Khan is a big proponent of gradual weaning, as, amongst other things, it encourages solid feed consumption. He emphasized that the smoothness of the weaning process is absolutely critical. Abruptly cutting calves off from milk supplies stops the smooth development of the rumen and can have a detrimental effect on the health and performance of young calves. As calves are born without fully developed rumens, they rely on milk to meet their nutrient demands for both maintenance and growth. Dr Khan stressed that abruptly shifting calves from milk to solid feed, or doing so too soon, puts calves at risk for poor growth and performance, post weaning.
What is too soon?
Dr Khan emphasized that weaning should not occur until calves reach at least eight weeks of age. Waiting this long tends to reduce the growth dip that generally happens at weaning, especially given the fact that many calves are now being fed a higher plane of nutrition, pre-weaning. When coupled with Dr Khan's recommendation of giving calves access to forage, such as hay, along with their starter, and utilising a step-down method of weaning, even smoother rumen development is promoted!
Ultimately, the task of weaning can be stressful for both calves and those who care for them. But, if Dr. Khan's recommendations are followed, the stress can be lessened and calves can be well on their way towards a lifetime of positive outcomes.