Trace Mineral Supplementation at Pasture: Cattle Performance on Different TM Sources

In volume 8, Issue 23 of Virtual Beef (July of 2009), I wrote an article citing the cumulative research of the National Research Council (NRC) and my recommendations on the mineral requirements of cattle at pasture. The data and the article suggested that if pasture forages were analyzed to ensure sufficient levels of macro-minerals (eg phosphorus, calcium, potassium, magnesium) pasture producers could use properly formulated trace mineralized (TM) salt to meet the remaining TM requirements, most importantly selenium in Ontario conditions.

Since that time, an Ontario Cattlemen's Association (OCA) supported project funded through the Farm Innovation Program (FIP - Agricultural Adaptation Council) has looked specifically at the issues of TM supplementation for backgrounding cattle at pasture. This research was undertaken and continues under the direction of Dr. Peter Kotzeff (Chesley Veterinary Clinic) and myself. At present, we have the 2012 animal performance data on pasture analyzed, and have reached some conclusions to be shared with VB readers. The analysis of blood and feedlot close-out data continues, and will be shared at a later date. So, here is an update on what we have done to date.

2011 TM Project Objective

To determine the effectiveness of selenium (Se) pellets (Australia), TM resin boluses (United Kingdom, and now available here), and the feeding of trace-mineralized (TM) salt on pasture as the sole Se, mineral and vitamin E sources.

Procedure (Methods)

In spring of 2011, approximately 700 head were purchased from various sources. The origin of the cattle included Western Canada, the Ottawa Valley and local sales in the Grey/Bruce area. One-third of all these animals were allocated to each; the Se pellets, the TM resin boluses and neither, such that all animals could be grazed as commercial groups. All animals were offered free-choice TM salt for the duration of their stay at pasture. All cattle weights were taken at turn-out and off-grass processing using both their EID/RFID tags and visual tags. Each animal was tracked for morbidity (health) and performance (total gain and ADG) for their duration at pasture. Within the group, about 85 head were blood sampled at turn-out, and repeated at off-grass processing; 42 will be repeated at feedlot as part of following these animals to market. The blood samples taken were and are to be analyzed for trace minerals (TM), including Se plus vitamin E. As indicated, the blood analysis portion of the project continues and will be reported upon in another edition of VB. This article will focus on animal performance.


The preliminary and main statistical analysis on gain at pasture is complete, although the analysis of forage quality trends is still to be completed, as is the blood data as mentioned previously. One of the greatest challenges with field trials is the variability in cattle sources and pasture locations, plus staggered start/end dates. This makes the statistical analysis complicated, but very real-life! As expected, we found that cattle quality and pasture performance matter, but despite this some TM source specific effects can be teased out. Adjusted pasture performances are given in Table 1 and Figure 1 to demonstrate. Statistical significances are not included in Table 1 or Figure 1, as this graph is just to demonstrate the reality and challenge of pasture quality across diverse locations, whether that is agronomic, management, precipitation or pure chance.

Table 1. Animal performance (average daily gain in lbs) by pasture location.
Pasture Farm
ADG LSMeans1
North Farm
River Ridge
Twin Pine
1 Least square means

Graph - Animal performance by pasture location

Figure 1. Adjusted animal performance (average daily gain in lbs) by pasture location

What we found for our TM treatments (Table 2, and Figure 2) is:

  • the iron-Se pellet does not improve animal performance over free-choice TM salt,
  • the TM resin bolus improves gain, especially on one purchase group (interaction). Although this suggests that the benefit from the bolus was disproportional for this group, the improvement is not economical based on the cost of the product.
Table 2. Animal performance (average daily gain in lbs) by TM source, with 'Control' being TM salt only.
Treatment ADG LSMeans1,2
Control 1.58a,b
Se Pellet 1.53a
TM Bolus 1.71b

1 Least square means
2 Means with differing superscripts are statistically different.

Graph - Animal performance by TM source

Figure 2. Adjusted animal performance (average daily gain in lbs) by TM source, with 'Control' being TM salt only

Including the data from preliminary and background blood and gain work done by Dr, Kotzeff in 2010, this means that by default a properly formulated TM salt appears to be an adequate and economical form of supplementation. Again; this is assuming a producer has ensured her/his pasture forages have sufficient macro-mineral levels. It also means that generally, the most critical aspect of backgrounding is the pasture. This includes all agronomics and management as the key factors for cattle gain with one example shown in Figure 3.

This photo at pasture sampling in September shows some of the challenges experienced that vary from pasture to pasture location.

Figure 3. This photo at pasture sampling in September shows some of the challenges experienced that vary from pasture to pasture location. In this case, it was the obvious impact of low precipitation in late summer allowing a good portion of a coat hanger to be inserted in cracked clay.

Implications Moving Forward

As mentioned, the remaining blood and pasture parameters for 2011 need to be fully tabulated and reported upon. But, we now have more evidence that simple, economical and properly formulated TM programs can work in theory and practice. If such a program is of interest to a producer, he/she can re-visit the VB article mentioned once earlier which first appeared in July 2009.

Dr. Kotzeff and I are continuing the project in 2012, but are currently trying to assess which very specific direction we need to go, considering what we have found. We would like to thank the OCA and AAC through the Farm Innovation Program (FIP) for their continued support, and hope this information is of interest to cattlemen across Ontario.

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