It seems logical that delivering liquid rations to preweaned dairy calves more frequently throughout the day would help improve their performance.
But a summary of consensus data from research studies considered when developing the NASEM 2021 dairy nutrition standards produced little evidence of that being the case. Those studies generally showed that feeding calves more than two times per day had no repeatable effect on average daily gain (ADG) or health, given equal total nutrients delivered per day.
A couple of historic studies even showed little difference in performance when calves were fed only once per day. However, the NASEM reviewers expressed concern that 1X feedings would result in delays in disease detection due to calves potentially being observed less frequently.
In those studies, performance was improved when greater feeding frequency resulted in more total nutrients delivered per day. Another potential noted benefit was that spreading out feedings could improve abomasal health.
More recently, a study published in the journal Nature and conducted by a team of Iranian dairy researchers attempted to parse the dual influence of nutrition volume and feeding frequency.
That team hypothesized that greater feeding frequency, particularly when calves are fed high volumes of milk, would improve calf performance due to the previously cited influence on abomasal processing.
Specifically, the Iranian researchers noted, “Previous studies have shown that increasing the amount of milk or milk replacer increases the reflux of milk not the reticulorumen and decreases the abomasal emptying rate. Thus, increasing the frequency of milk feeding may reduce meal size, accelerate abomasal emptying, better regulate the rate of nutrient entry into the small intestine, reduce energy loss during abomasal fermentation of carbohydrates, and thereby improve nutrient utilization and efficiency.”
Their study included 48 Holstein heifer calves started on a common colostrum and transition-milk protocol. On the 4th day of life, they switched to pasteurized whole milk and assigned to one of four feeding groups:
- Medium-rate milk feeding (6 L/day) fed 2X.
- Medium-rate milk feeding (6 L/day) fed 3X.
- High-rate milk feeding (8 L/day) fed 2X.
- High-rate milk feeding (8 L/day) fed 3X.
All calves were fed using a step-up, step-down approach to smooth transitions to starter grain, and were weaned at 56 days of age and observed until 70 days of age. They then were raised in a common group and monitored for a wide range of performance factors through their first 305-day lactations. Results included:
- ADG was not affected by the interaction between milk feeding levels and feeding frequency.
- Regardless of feeding frequency, ADG was higher for high-rate-fed calves compared to the medium-rate-fed animals both preweaning and postweaning.
- Calves fed more milk were inseminated earlier with a lower age at first insemination.
- Compared to the medium-rate group, the high-rate group showed significantly more milk production and energy-corrected milk in their first 305-day lactation.
The researchers concluded that increased milk volume has greater impact on the short- and long-term performance of heifer calves than does small changes in meal size created by greater feeding frequency.
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