The absolute imperative of maximising rumen development throughout the rearing period of all calves and weanlings was emphasised repeatedly at a recent young stock performance seminar, hosted, by United Feeds.
Courtesy of his presentation, Aaron Brown – Technical Sales Manager with Trouw Nutrition, specifically characterised the maturation of the rumen at two levels: the growth of the muscular wall that surrounds the organ and, in addition, the multiplication of the epithelial layer that directly interacts with the nutrients ingested by the animal.
The greater the development of the epithelial layer: the greater the ability of a young animal to absorb nutrients and to grow.
Aaron pointed out that the presence of butyrate is directly associated to the development of the rumen in calves. This is linked to the presence of starch in the diet, therefore driven by concentrate intake.
The Trouw Nutrition representative defined weaning as the transition-off a milk-based diet. There are a number of ways in which this can be monitored. One is directly associated with young calves reaching the stage when they are consuming at least 2kg of concentrate, consistently, on a daily basis.
“Others highlight that appropriate time of weaning is when calves have consumed approximately 32kg of concentrate from birth, indicating adequate exposure of the rumen to starch.
“However, there are two overarching criteria that should be met: weaning must be a gradual process and it would be unwise to wean a calf before it has reached eight weeks of age.
“The transition to the weaned state must be managed to ensure calves receive their full energy requirement to sustain growth and not compromise daily live weight gain.”
Maximising concentrate intake from the earliest possible stage in the calf’s life is critically important. Aaron discussed a number of factors that directly impact on this issue.
Water
“Young calves must have access to clean water from the outset. The bacteria that are required in the rumen to drive its development live in an aqueous environment.
“This being the case, drinkers should be cleaned regularly. Trials have indicated that drinkers located at the back of pens tend to get dirty much faster than those placed at the front. Cleanliness not only impacts disease exposure but also palatability.
“So it’s important that all calf drinkers are cleaned out on a regular basis.”
Aaron continued:
“It is also imperative that milk intakes are not restricted for the sake of solid feed intake during the first four weeks of life; during this period solid feed intake is negligible regardless of milk allowance so milk intake should be the priority to ensure adequate consumption of nutrients. Research trials have confirmed that restricting milk will also compromise immunity in young calves when faced with a disease challenge.”
Forage
Having access to a high-quality forage is also important for calves at all stages in their development.
Straw, as opposed to hay, is the preferred forage source of calves.
“Hay will deliver increased weight gains in calves. But this tends to be a result of increased gut fill only,” Aaron commented.
According to the Trouw representative, forage availability minimises the risk of acidosis when pellets are offered to young calves. The larger particle size of the forage source also delivers a scratching effect, which helps to clean the epithelial wall. If this is not achieved, the absorption capacity of the developing rumen is reduced. Chopped straw with a particle size of five centimetres or less is ideal.
Concentrates should be offered on an ad lib basis to young weanlings in the weeks directly after weaning to maximise nutrient intake levels maintaining their large energy demand.”
Other factors impacting on starter intake are the actual composition of the concentrate offered, house design and grouping of calves.
Aaron Brown again:
“Starter feeds should be in the range of 16% to 18% protein, having high levels of starch. Trials have confirmed the benefits of adding Sodium Butyrate to calf starter products can encourage starter intake.
He continued:
“Where housing is concerned calves should have access to 30cm of trough space per head. Light duration in sheds will also have an impact on the length of time that calves remain feeding.
“Autumn born calves will respond to lighting periods that correspond to those that predominate during the spring and summer months of the year.”
He concluded:
“Research has also confirmed that calves experience less stress when grouped together. So, the faster this can be achieved the better the performance levels that can be secured.”
