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Evaluation of Alternative Selenium Supplementation Strategies for Cattle on Ontario Pastures
Research Lead: Christoph Wand , Ontario Ministry of Agriculture and Food
Executive Summary
Objective
To examine the effectiveness of selenium (Se) pellets (Aus), TM resin boluses (UK), and feeding of trace-mineralized (TM) salt on pasture as the sole Se, mineral and Vitamin E sources, and to understand the nature of trace-minerals in Grey/Bruce Pastures.
Procedure (Methods)
- In 2011 approximately 750 head, and in 2012 550 head were purchased from various sources including Western Canada, Ottawa Valley and local sales
- 1/3 of the 750 animals were allocated to each Se pellets (Aus), TM resin boluses (UK), and neither in 2011
- In 2012, ½ of approximately 550 animals received the TM resin boluses, and the other half not
- All animals offered free choice TM salt in both years
- Animal weights were taken at turn-out and off-grass processing
- All animals were tracked for morbidity (health) and performance (gain, ADG)
- ~85 head were blood sampled at turn-out, and repeated at off-grass processing; 42 will be repeated at feedlot re-implant in 2011. Blood was analyzed for trace minerals (TM), including Se plus Vitamin E.
- In 2012 intensive pasture monitoring for trace minerals including selenium was undertaken to explain the underlying conditions the cattle experience, in the stead of intensive blood sampling.
Results
- Pasture location and time (year, agronomics, management & rain, etc) remains most important factor for gain
- Se pellet does not improve animal performance over TM salt
- TM Resin bolus improves gain, especially on one purchase group in 2011 Improvement is not economical but may hint at trace minerals other than Se being limiting. This may include Zinc and Copper as supported by 2012 survey of trace mineral levels on Grey and Bruce County pastures where these two minerals were also universally low.
By default, TM salt is an adequate form of supplementation but may require extra attention for Zn and Cu.
The effectiveness of selenium (Se) pellets (Aus), TM resin boluses (UK), and feeding of trace-mineralized (TM) salt on pasture as the sole Se and mineral sources was carried out. This indicated that the issue might not be selenium alone as but may hint at trace minerals other than Se being limiting such as Zinc, Copper was supported by 2012 survey of trace mineral levels on Grey and Bruce County pastures where these two minerals were also universally low.