Limit feeding of heifers – a relatively new approach to dairy heifer development – involves feeding a nutrient-dense ration in a restricted quantity. Such rations are composed of higher levels of concentrate, high-quality forages, or a combination of the two. Research has shown this feeding strategy results in a decrease in fecal excretion and nitrogen waste, lower feed costs, increased feed efficiency, and effective control of average daily gain (ADG).
The challenges of limit feeding include decreased feeding and lying time, increased unrewarded time at the feedbunk (visiting the feedbunk but not receiving feed), more vocalizations and more inactive standing time. In addition, rations high in concentrates, when consumed rapidly, leave heifers susceptible to subclinical depression of rumen pH (SARA).
A team of Canadian researchers led by Trevor DeVries at the University of Guelph conducted a study to explore whether providing more ample bunk space, and/or feeding more frequently, could help alleviate some of the drawbacks of limit feeding. The research, published in the March 2013 Journal of Dairy Science, found that when limit-fed heifers were not allowed adequate bunk space for all animals to eat at the same time, the level of competition at the feed bunk increased, time spent feeding decreased, and variability of growth between heifers increased.
The trial consisted of 16 heifers of approximately six months of age, fed in four groups of four animals each. Each group was exposed to each of the following treatments:
- 1x/day feeding with 0.29 m/heifer of bunk space
- 1x/day feeding with 0.40 m/heifer of bunk space
- 2x/day feeding (delivered two hours apart) with 0.29 m/heifer bunk space
- 2x/day feeding (delivered two hours apart) with 0.40 m/heifer bunk space
The researchers concluded that, overall, providing sufficient feed bunk space to allow all limit-fed heifers to feed at the same time improves feed efficiency and average daily gain and reduces variability in feeding time. Delivering feed more frequently resulted in heifers being more consistent in the amount of time they spent feeding, but this did not translate into improved ADG. Further, delivering feed 2x/d did not alleviate all the impacts of reduced bunk space. While delivering feed 1x/day resulted in increased competition at the bunk, it also enabled heifers to gain adequate weight and spend more time feeding each day, provided they had enough bunk space to feed simultaneously.
Source: March 2013 Journal of Dairy Science