Be careful what you feed: Feeding patterns in newly weaned calves can set the stage for behaviour and weight gain issues
With so many farmers now opting for an elevated plane of nutrition (EPN) and higher calf performance, the growth and performance gains that farmers enjoy prior to weaning should continue in the months after weaning. It has been shown that with dairy cattle, certain post-weaning feeding practices can create behavioural patterns that persist into later life. But, just how can farmers best manage calf nutrition post weaning in order to set the stage for the continued growth and performance gains they desire, while also creating positive behavioural patterns? And, what is the role of dry total mixed ration (TMR) in setting patterns for young calf behaviour post weaning? A new joint study from the University of Guelph, Wageningen University, and Trouw Nutrition R&D, sheds some light on the subject.
In the study spanning 12 weeks, 10 three month-old bull calves were randomly assigned to one of two treatments, 40 days after weaning. One group received a TMR containing 85% concentrate and 15% chopped wheat straw for 10 weeks, while the second group received the same 85% / 15% mix for the first 5 weeks, but was then switched to a TMR containing 70% concentrate and 30% chopped wheat straw for weeks 6 through 10 of the study. Both groups were then switched to a silage-based TMR for weeks 11 and 12 (42.3% corn silage and 57.7% haylage).
Lower concentrate percentage in TMR leads to lower DMI and lower ADG
Once the calves in the second group were switched to the 70% concentrate/ 30% chopped wheat straw diet, declines in both dry matter intake (DMI) and average daily gain (ADG) were noted. In weeks 6 through 10 of the study, DMI for the 70% group was 5.53 kg per day vs. 7.38 kg per day for the 85% group. The researchers noted that the lower DMI in the 70% group was due more to issues of physical rumen fill than with the increase in neutral detergent fibre that comes with a diet higher in straw. This lower DMI resulted in lower ADG for the 70% group as well (1.25 kg per day vs. 1.59 kg per day for the group maintaining the 85% / 15% TMR diet). This meant an almost 12 kg difference between the two groups by the time the study reached its 10th week.
However, once the calves were fed the same silage-based diet in weeks 11 and 12 of the study, no intake differences were noted between the treatment groups, suggesting, that the "prior feeding program had no effect on the ability of calves to transition to consume and digest a silage-based diet." The question then becomes, why dilute the TMR with more straw if doing so creates no advantage for the 70% group and indeed lowers the growth goals for that group?
Feeding patterns can condition behavioural patterns as well
While there were no differences in intake between the two groups in the last two weeks of the study, there were differences in negative behaviours that seemed to carry over from the 5 weeks during which they ate differently. Calves that had been in the 70% group continued to spend more time feeding, especially in the hours just after feed delivery, as well as more time feeding at night, just as they had done when they were on the higher straw diet. As noted by Groen et al. in the study, "This type of feeding pattern, in particular engaging in a long meal following feed delivery could be undesirable if carried into adulthood, where it can have negative effects on rumen fermentation patterns." Therefore, any nutritional strategy, such as diluting dry TMR concentrate with more straw, as was done in this study, which promotes longer meals particularly after feed delivery, should be avoided. These kinds of feeding patterns can persist thereby embedding behaviours that could have negative consequences for production in later life.
The decision of how to manage calf nutrition post weaning impacts more than just immediate growth goals, but it also has long-term consequences for behaviour and, ultimately, production. If poor feeding patterns are set up in the period post weaning, the negative effects will ripple out beyond the transition to silage-based feeds and indeed, the hard-fought gains made pre-weaning could be lost.