The sequence of presentations was just great! Just like in a calf’s life, it started with colostrum, followed by some insights in rumen development, and finalized with rearing strategies. It basically covered key points needed to provide calves with a good kick start for a productive life.
Nutritional regulation of growth and metabolic development in calves
Colostrum and milk Dr. Steele introduced the idea of feeding colostrum for an extended period of time. Although IgG’s are the spotlight among the bioactive components of colostrum, oligosaccharides and fatty acids deserve some attention as well. Oligosaccharides which are abundant in both colostrum and transition milk play an important role in gut health. These biomolecules not only promote the growth of beneficial bacteria, but also fight against pathogens. Although there is some variability in the amount of fat in colostrum and milk, what is really interesting is the variation in fatty acid profile through time. Dr. Steele highlighted how Butyric acid is low in colostrum. And as he said, the exciting reason for this is that Butyrate would stimulate enterocytes and decrease IgG absorption. He followed with a comparison of the different milk feeding programs, restricted, enhanced and even ad libitum. Finally, he addressed milk replacers’ composition. One of the presented studies evaluated high fat and high lactose formulations and the other included high protein as well. A point worth remarking is the fact that the effect of different formulations was not the same for feeding strategies. All in all the presenter made strong emphasis on the need for calf nutrition studies to follow animals in time and look at the long-term effects.
Low rumen pH in calves: Problem or opportunity?
To address the question in the title Dr. Laarman divided his talk into three sections. He started with an overview of rumen development and the physiological principle behind it. Volatile fatty acids (mainly butyrate) produced in solid feed fermentation, are the stimulators of papillae development. He emphasized on the VFA transport pathways in the enterocyte. Transporters are part of cell pH regulation, in fact the enterocyte needs a pH of 7.4. Among these pathways passive diffusion, which is unregulated, deserves special attention. In the second section, the researcher explained how rumen pH in calves has been monitored under the traditional thought that if rumen pH becomes too low due to fermentation rumen pH it could result in decreased stater intake. However, Dr. Laarman later presented some results that contradict that idea. When presenting ruminal pH by age group reported by different studies, he remarked that all these ranges fall below the threshold for subacute ruminal acidosis in cows! In addition,
ruminal pH tends to be more stable in adult cows. Having shown that rumen pH in calves has a completely different behavior. For the third part, Dr. Laarman presented the studies he has performed to address how rumen pH changes on time as well as its impact on growth. A very strong point he made was that VFA pKA is 4.8, this means lower pH results in more protonated VFA, which leads him back to passive diffusion. Once in the cell, the VFA is dissociated, maintaining the diffusion gradient. Adaptations
in the membrane transporters were also found but he mentions they still need a deeper understanding. In conclusion, Dr. Laarman suggested a new model. In this model low pH is actually common and does not affect performance, It is indeed a factor involved in rumen development. This model also suggests physiological function not to be associated with morphology, of course, he says more research is needed
and they are going in that direction.
Preweaned calf rearing options for dairy producers
Dr. Heins started his presentation by listing the key aspects for raising healthy dairy calves with cleanliness at the top of the list. Attention to details, housing, comfort, and feeding strategy were also mentioned as important factors for growth success. Individual housing has advantages when it comes to spread of disease, and feed control. Therefore it is still the preferred method in industry for raising calves. However, aspects such as maternal care, socialization and reduced space are a concern, especially among consumers. Moreover, group housing has gained interest in research due to the fact that cows are social animals. It also offers advantages at the management and welfare level including reduced labor, possible automation as well as reduced stress. The milk feeding method becomes complicated in group settings, sometimes compromising control and cleanliness. Feeding level is another aspect that deserves attention when it comes to housing. According to Dr. Heins, ad libitum feeding was a common question among producers. To address this inquiry they conducted a study using an automated feeding system (Holm & Laue HL 100). In this study, they looked at calves fed ad libitum vs calves fed 8 liters per day through 56 days. Not only did they find a wide range of variability in intake levels when calves were fed ad libitum, but they also found higher average daily gains associated with higher intakes. Following
their results, Dr. Heins presented another study, this one regarding the housing system.
The pilot study compared calves individually fed, calves fed in groups, and calves fed by their mother. The results showed calves fed by their mother had higher weights at weaning compared to the other two treatment groups. Dr. Heins pointed out that calves fed ad libitum in an autofeeder system had similar growth rates to calves fed ad libitum by their dam. Finally, Dr. Heins presented a larger study they were conducting which includes more combinations of settings and feeding strategies. The researcher mentioned they were using sensors, looking at many variables and aspects of growth for this larger study. He wrapped up by mentioning the importance of growing healthy fast-growing calves.
Maria is a Master’s student at Purdue University in Dr. Jacquelyn Boerman’s lab. She is interested in precision dairy technologies and how we can use these data to learn about animal behavior and apply it to better management practices and welfare.