In colder regions, where forage crops are the predominant feed source for heifers, the extent to which forage type affects feeding behaviour and growth rates is unclear. Many feeding decisions for ruminants over winter are driven by cost and environmental considerations. Despite the perceived cost benefits of feeding fodder beet, there is little known on the impact of a low protein diet on heifer development and subsequent growth characteristics. Given the different physical characteristics of fodder beet and kale, this project studied the grazing behaviour and liveweight gain of R1 heifers while grazing crop.
In winter 2019, 93 heifers grazed fodder beet between 13 May and 19 August and 98 heifers grazed kale between 22 May and 11 August. Liveweight and stature measurements were taken at the start and end of the crop feeding period and grazing behaviour was measured using cow manager tags for 2 weeks in July.
Feed and crop:
Estimated DM intake in July was 7.2 and 6.3kg DM/head/day for the fodder beet and kale animals respectively.
Heifers grazing FB consumed a diet of 11.8% crude protein compared with 13.5% for those grazing kale, resulting in similar dietary crude protein intakes.
ME intake of the FB diet was higher than kale resulting in differences in liveweight gain.
Kale heifers spent 134 more mins/day eating compared to FB diet heifers.
FB heifers spent 83 more mins/day ruminating than kale heifers.
Idling and activity times did not differ between treatment groups.