Research round-up: calf weaning is tricky business, but weaning later and smarter, along with a high plane of nutrition prior to weaning, provides benefits for calf health and lifetime performance
During the weaning period, calves are susceptible to a number of health-threatening complications. Levels of gastrointestinal tract (GIT) stress, diarrhoea and other illnesses can be either exacerbated or curtailed in function of how and when weaning occurs. Also, the quality and quantity of feed introduced during this critical period can also impact calf health and overall well-being. In terms of performance, higher calf growth rates prior to weaning can set the stage for continued growth post weaning and a lifetime of enhanced productivity. With more farms opting for the health and performance benefits of a higher plane of nutrition prior to weaning, it's a good time to look at which weaning practices are best adapted to supporting continued performance gains. A review of recent research suggests that it may be time to rethink some commonly held notions.
Later weaning positive for health and performance
No matter how you go about it, the weaning process creates stress in calves as one digestive system replaces another. Yet, several recently published studies show that the choice to wean later, rather than earlier, can have significant health and performance benefits.
The key is gastrointestinal tract permeability. This permeability—present during the pre-weaning period—can leave calves vulnerable to pathogens once the weaning process begins. In a 2015 study conducted by the University of Saskatchewan, the University of Alberta, and Trouw Nutrition R & D, Wood et al. found that, as calves age, the permeability of the GIT decreases, enabling calves to better fight off diseases including diarrhoea, the leading cause of calf death. Their data suggests that by weaning later, calves benefit from a fortified (less permeable) GIT, thereby reducing one important factor of vulnerability.
Another 2015 study, this one conducted by the University of Alberta and Trouw Nutrition R & D, Meale et al., additionally showed that later weaning reduces systemic stress as indicated by a more gradual increase in ßHBA over the weaning process. ßHBA, the predominant ketone in cows and a stress marker, is related to better rumen development and a gradual increase is essential for truly successful weaning.
The same study (Meale et al., 2015) suggests that later weaning also holds performance benefits. While some reduction of ADG is inevitable during weaning, the study found that later weaning mitigates these losses. Indeed, in their comparison of calves weaned at 12 and 8 weeks, when weighed at the same time post weaning, the 12 week weaned (WW) calves had an average body weight that was 4.2% higher than that of the 8 WW calves.
This performance advantage is supported by a separate 2015 study out of the University of Alberta, the University of Guelph, and Trouw Nutrition R & D, in which Eckert et al. found that later-weaned cows (in this study 8 weeks vs. 6 weeks) had 50% higher ADG during weaning and 66% higher ADG one week after weaning. Most importantly, these higher growth rates were maintained for months beyond weaning. In the study, at the age of three months, the 8 WW calves were 9 kg heavier than those weaned at 6 weeks. At the age of five months, the gap between the two groups had grown to 11 kg.
Elevated plane of nutrition with step-down weaning aids outcomes
The Eckert study cited above also showed that, when combined with an elevated plane of nutrition (EPN), later weaning and a step-down transition to solid feed positively impacts well-being and performance. In the study, a protocol including a pre-weaning EPN, combined with a step-down approach to solid feed and weaning at 8 vs. 6 weeks resulted in a smoother transition from liquid to solid feed with fewer signs of systemic and digestive stress. Also, better pre-weaned nutrition lead to greater overall weight gain, especially in the 8 WW calves. As mentioned, these advantages didn't stop at weaning, but included long-term growth advantages.
Prescription for health and performance
While there are many important variables involved in the weaning process, the research cited here suggests that an elevated plane of nutrition pre-weaning, combined with a step-down process at weaning and a later age at weaning, point towards optimal calf health and lifetime performance benefits.