Mineral Nutrition of Pre-weaned Calves: Mineral Source Preferences and Requirements
By Juliana Ranches1, Gracia M. P. Hernandez2, and Corinna T. Cauchy3
1Assistant Professor and Extension Beef Specialist, Oregon State University, Eastern Oregon Agricultural Research Center (EOARC)
2 Graduate student, Oregon State University, Department of Animal and Rangeland Sciences
3Undergraduate student, Oregon State University, Department of Animal and Rangeland Sciences
Mineral nutrition of cattle is an important topic within the broad subject of ruminant nutrition. Adequate mineral nutrition is vital for optimal cattle development and the lack of proper mineral supplementation often results in diminished performance, poor health, and lower reproduction efficiency, ultimately leading to reduced profit.
It is well known that grazed forage is the primary source of macro and micro minerals for grazing cattle. Among the required minerals for cattle, many are usually found in practical feedstuffs in sufficient concentrations to meet the cattle requirements. However, some minerals are frequently found in insufficient concentrations in grazed forage and/or in diets and supplements fed to cattle. The variation of mineral concentrations in forages and feedstuff can be partially explained by factors such as soil type and fertility, forage type, seasonality, and precipitation. Therefore, a mineral supplementation program aiming to improve the mineral status of cattle should be in place to optimize cattle performance, health, and reproduction.
The requirements of most minerals are not constant and are affected by several dietary and physiological factors that affect either absorption or metabolic demand. Among the physiological factors, age, sex, level of production (maintenance, growth, reproduction, and lactation) are usually the factors with the highest consideration for estimation of nutritional requirement. The requirements for minerals especially trace minerals, are continually becoming better understood, however, most of the literature has focused on mature cattle and there is a paucity of information for younger animals such as calves before weaning.
A successful mineral supplementation program should also take into consideration the needs of young calves. Although mineral requirements for calves are not well established, calves should be provided with mineral supplementation from early ages, which can be considered a precautionary measure to avoid problems such as mineral deficiencies. Greater attention should be given prior to weaning as this management practice is challenging for the calves – separation from the dam, new environment exposure, commingling, etc. – and is likely to increase their mineral needs.
Delivery Methods of Mineral Supplements
As previously discussed, forage is a major source of minerals for mature cattle and so it is for calves. Additionally, for nursing calves, milk can contribute to their daily intake of minerals. Milk is clearly a rich source of macro minerals, such as calcium (Ca), phosphorus (P), and potassium (K), however, milk has a much less satisfactory concentration of trace minerals such as selenium (Se), copper (Cu), and zinc (Zn).
Therefore, a successful mineral supplementation program should target the requirement of mature cattle but also include the needs of younger calves. The method of delivering minerals chosen by the operation should be thought to include younger calves. Each delivery strategy differs depending on the operation’s logistics, labor availability, and expenses but the following should be considered:
Free-choice loose supplements: is the most commonly used strategy of mineral supplementation. When proving free-choice loose supplements to pairs it is important to make sure that calves also have access to the feeder. Often mineral feeders are placed out of reach of calves; therefore reducing the opportunity for a calf to became familiar with the supplement and compromising the consumption of the supplement. In grazing pastures with pairs, consider using feeders that are placed to the ground level for easy access of calves. In a study using automatic feeders, McCarthy et al., (2021) reported that the number of time cows spent at the mineral feeder was positively correlated with cow mineral intake and this response was also observed for calves. Interestingly, the authors also reported a positive correlation for the time cows spent at the feeder with calf mineral intake, suggesting a social learning behavior linking the dam visits to the mineral feeder and the consumption of mineral supplements by the calves.
Mineral compressed blocks: as an alternative to salt-based loose supplements the use of blocks, such as molasses blocks fortified with minerals, is a good strategy to increase mineral consumption of calves. Bailey and Welling, (2007) evaluated the consumption of molasses blocks fortified with trace minerals vs. loose mineral supplements offered to mature cows and reported greater consumption of blocks when compared to loose mineral supplements. The greater intake observed for molasses blocks fortified with minerals was likely due to the improved palatability of such supplements when compared to salt-based loose mineral supplements. This rationale can easily be applied to calves, as this category of animal is often more selective when considering palatability.
Mineral Sources and Preference by Pre-weaned Calves
When considering the palatability of supplements, the chemical sources of minerals should be taken into consideration, especially when working with young calves.
In a recent study Ranches et al., (2021) evaluated calf preference of molasses blocks fortified with different mineral sources. Calves had simultaneous access to three molasses blocks each fortified with different mineral sources (hydroxychloride, inorganic/sulfate, and organic).
Molasses block intake was greater for blocks formulated with hydroxychloride source of minerals. Therefore suggesting a greater preference by calves of hydroxychloride sources of minerals over inorganic (sulfate) and organic sources. Because hydroxychloride sources have lower solubility when compared to other inorganic and organic sources of minerals, this response is believed to be linked to a “metallic-taste” created by the more soluble sources, resulting in aversion and therefore a lower consumption of the supplements fortified with inorganic and organic sources of minerals.
Current Studies on Mineral Requirement of Pre-weaned Calves
In the study discussed previously (Ranches et al., 2021) authors reported that Bos Indicus influenced calves failed to maintain an adequate mineral status of Se and Cu when consuming a diet that met the trace mineral recommendations of mature cattle. These findings have led to current research trials to understand the actual trace mineral requirement of calves.
A two-year study was conducted Eastern Oregon Agricultural Research Center (EOARC) in Burns (Oregon). The objective of the study was to evaluate different two levels of trace mineral supplementation to calves and the subsequent effects on mineral status at weaning and performance post-weaning.
Approximately 84 days prior to weaning, 24 calves/year (Angus × Hereford) were randomly assigned to one of two treatments: (1) Control: trace mineral supplementation was provided based on current recommendations of nutrient requirements for beef cattle (NRC, 2016); and (2) Super: trace mineral supplementation was provided at levels above the current recommendations of nutrient requirements for beef cattle (NRC, 2016). Total weekly intake of the mineral supplement was provided to calves individually in three feedings events (Monday, Wednesday, and Friday) during the week.
Liver samples were collected at beginning of the study and at weaning to evaluate calf mineral status. No differences in mineral status were observed at the beginning of the study (as desired). As supplementation progressed, calves assigned to both treatments successfully maintained adequate mineral status until weaning regardless of the level of trace mineral supplementation.
At weaning, no treatment differences were observed for liver Se concentration of calves. However, a treatment difference was observed for liver Cu concentration at weaning, where calves assigned to Super treatment tended to have greater liver Cu concentration than calves assigned to Control treatment.
Although no differences were observed in the present study for Se, the results obtained for Cu status corroborated the hypothesis that greater supplementation levels resulted in greater mineral status.
As more information regarding mineral nutrition of young beef calves (and mature cattle) is developed it is important to attain the basics; make sure all animals including calves have free access to a good source of mineral supplement, and supplement intake meets the target recommendation of the product (at least for the mature cattle).
Bailey, D. W., and G. R. Welling. 2007. Evaluation of low-moisture blocks and conventional dry mixes for supplementing minerals and modifying cattle grazing patterns. Rangel. Ecol. Manag. 60:54–64. doi:10.2111/05-138R1.1. Available from: http://dx.doi.org/10.2111/05-138R1.1
Mccarthy, K. L., M. Undi, S. Becker, and C. R. Dahlen. 2021. Utilizing an electronic feeder to measure individual mineral intake, feeding behavior, and growth performance of cow-calf pairs grazing native range. Transl. Anim. Sci. 5:1–9. doi:10.1093/tas/txab007.
Ranches, J., R. A. De Oliveira, M. Vedovatto, E. A. Palmer, P. Moriel, L. D. Silva, G. Zylberlicht, J. S. Drouillard, and J. D. Arthington. 2021. Low moisture, cooked molasses blocks: A limited intake method for supplementing trace minerals to pre-weaned calves. Anim. Feed Sci. Technol. 273:114793. doi:10.1016/j.anifeedsci.2020.114793. Available from: https://doi.org/10.1016/j.anifeedsci.2020.114793