After a meteoric rise in popularity over the last decade, some in the sector are scaling back fodder beet use, citing increased system complexity, stress on staff and animal health and performance concerns.
Two DairyNZ lead research projects are seeking to better understand the issues relating to milk production and composition, environmental impact, mineral requirements, and system performance when fodder beet is eaten.
Fodder beet vs maize silage
The Forages for Reduced Nitrate Leaching (FRNL) programme has compared fodder beet with maize silage as a supplement for lactating cows. When offered the same allocation (four kilograms of dry matter per cow per day: kg DM/cow/day) there was no difference in urinary nitrogen (N) concentration between cows eating maize silage and those eating fodder beet, but milksolids production was improved by eight percent with fodder beet. Offering 6kg DM/cow/day of fodder beet reduced urinary N concentration but milk solids did not improve.
We observed that cows were refusing fodder beet at the higher allocation. And while clinical acidosis was not observed, behavioural observations suggested 6kg DM/day was at the upper limit of fodder beet allocation, and that some cows may have been experiencing sub-clinical acidosis. Milk composition results support this conclusion: increasing fodder beet intake reduced milkfat content and had a significant negative effect on the milk fatty acid profile, increasing the proportion of short chain fatty acids. Results of this study support the recommended upper limit of 40 percent of dry matter intake (DMI) as fodder beet for lactating cows.
Fodder beet vs kale
At the Southern Dairy Hub (SDH) last winter, we investigated the immediate and carry-over effects of crop type (kale vs fodder beet) on cow performance. In the first six weeks of winter, and in the absence of phosphorus (P) supplementation, blood P concentrations of cows eating fodder beet halved from two to one millimole/litre (mmol/l).
This highlights the importance of providing P supplementation when feeding fodder beet.
Blood magnesium concentrations were lower in cows grazing kale and were at the low end (0.75-0.8 mmol/l) of the normal range. Cows wintered on fodder beet lost less body condition in early lactation. The six-week in-calf rate (77 to 81 percent) and not-in-calf rate (two to eight percent) were similar between winter diets, but five percent more fodder beet cows were treated as non-cyclers.
In June this year, the team at SDH will begin farm systems comparisons to investigate the finer details of fodder beet feeding on animal performance and the environment. Keep an eye out for the results.
Research was completed as part of the FRNL programme with principal funding from the New Zealand Ministry of Business, Innovation and Employment. The programme is a partnership between DairyNZ, AgResearch, Plant & Food Research, Lincoln University, the Foundation for Arable Research and Landcare Research. Learn more at dairynz.co.nz/FRNL
- Fodder beet and maize silage reduce urinary N concentration by similar amounts when offered at the same level.
- Avoid feeding more than 40% of DMI as fodder beet to lactating cows.
- Supplement over-wintering fodder beet diets with phosphorus.
This article was originally published in Inside Dairy May 2018