The need for mineral supplementation has long been established. Minerals are needed for normal tissue growth, enzyme function, cell regulation, homeostasis, and immune function. Overall animal performance can be negatively affected when the diet lacks sufficient quantities or mineral ratios are incorrect.  The investment in a sound mineral program can reap dividends in terms of:

• Immune system function

• Reproduction

• Forage digestibility

• Feed efficiency

• Body weight gain – body condition score of brood cows and growth of calves, replacements, and stockers

Mineral Exposure
It is not uncommon for mineral supplements to be exposed to rain, snow, and wind when fed in open troughs or tires. Such exposure to the “elements” can lead to nutrient loss due to leaching after a rain and/or small mineral particles being blown away by the wind. These losses may be manifested economically by increased “shrink” (mineral loss) or by reduced nutrient supplementation to cattle consuming the mineral, which may result in performance reductions.

 

Mineral Leaching
ADM Alliance Nutrition research has investigated the losses associated with leaching of minerals after a simulated rain fall.  Researchers used sixteen different minerals from different feed companies to evaluate the effects of a simulated rain fall.  Seventy-five grams (approximately 2.5 ounces) of each mineral supplement was placed in a cylinder, which had a screen sized only large enough to allow water to run through the mineral (no mineral particles were allowed to escape the cylinder). Two-hundred fifty ml (approximately one quart) of deionized water was poured into each cylinder, and the escaping water was collected for analysis. Collected water samples were analyzed for calcium, phosphorus, salt, copper, zinc, magnesium, potassium, and manganese content. Figure 1 illustrates the range of mineral leaching observed in the study based on one simulated rain fall.  Mineral losses ranged from a low of 1.82% to a high of 8.7%.  Successive rain events would increase the expected leaching. 

 

Economics
The first economic issue to address with leaching is the cost of shrink (mineral loss).  Table 1 shows the cost of these losses for the mineral supplements tested in the study (1.82%, 8.7%, and the average of 4.43% leaching).  For a mineral costing $500/ton, the losses associated with the leaching would range from a low of $9.10 to a high of $43.50/ton, with the average loss being $22.15/ton.  Put in another way, each rain event could cost the producer between $9.10 to $43.50/ton or an average $22.15/ton for a mineral costing $500/ton.

 

Table 1  Effect of Simulated Rain Event on Actual Shrink, $ Loss of Mineral
	Range of Nutrient Loss		Average Nutrient Loss
Mineral Cost, $/ton	1.82%	8.70%	4.43%
400	7.28	34.80	17.72
500	9.10	43.50	22.15
600	10.92	52.20	26.58
700	12.74	60.90	31.01
800	14.56	69.60	35.44

 

The other economic loss associated with nutrient leaching is the possible reduction in nutrient supplementation to the animal.  As each rain event occurs, increasing amounts of mineral are lost due to leaching and consequently are not available for animal use.  Another factor to consider is that non-weatherized mineral products are more prone to caking, which may have a negative effect on mineral consumption, leading to insufficient mineral nutrition.  Mineral nutrition is important as inadequate dietary intake of minerals has been associated with reduced forage intake, lower reproductive efficiency, lower gains, poorer feed efficiency, and lower disease resistance.  Unrecognized mineral status insufficiency (subclinical deficiency) is difficult to detect.  A mineral deficiency typically first impacts the immune system.  Subtle effects on immunity, like immune system defense, can easily go unnoticed.  As mineral status declines overtime, growth and fertility problems may become apparent.  Because health challenges and poor performance can be influenced by many factors, the mineral status of a herd may often be overlooked.

 

Mineral Supplementation Value
The impact mineral supplementation has on performance has been documented by many researchers.  Pregnancy rate and calf weaning weights have responded positively to phosphorus supplementation (Table 2).  In a three-year USDA trial, calcium and phosphorus supplementation of cattle grazing native range responded with increases in conception rate, milk production, and calf weaning weight (Table 3).  Trace minerals are also important to reproduction as evidenced in Table 4.  Economically, a 16 lb weaning weight could provide an extra $19.20 per calf based on a weaned calf value of $120/cwt.  Fewer days to conception and increased conception rates observed in research data cited previously could, on average, improve return by another $24.00 per cow/calf unit. 

 

Table 2  Effect of Phosphorus Supplementation Versus Control
		Improvement over Control
Class of Cattle	Phosphorus/day, g	Pregnancy rate, %	Calf Weaning Weight, lb
Brood cow	2.3	0	14.3
Brood cow	4-8	2.7	17.4
Heifer	4-6	7.0	18.7
Sources: J. Range Manage. 50:2-9 (1997); J. Prod. Agric. 5:409-413 (1992); J. Range Manage. 48:493-497 (1995); J. Range Manage. 53:170-175 (2000).

 

 

 

Table 3 Effect of Calcium and Phosphorus Supplementation on Cow/Calf Performance (native range)
	Performance Advantage over Controls
Conception rate	6%
Milk production	17%
Weaning weight	16 lb
Three-year average cow performance, USDA, North Dakota (1984).

 

Table 4 Effect of Supplemental Trace Minerals on Conception
	Control	Supplemented with Manganese, Copper, and Zinc
Days to first estrus	60	61
Days to conception*	32	21
Services per conception	1.7	1.2
Cows pregnant on first service	40%	84%
Conception rate at end of trial	83.3%	95.0%
*Interval in days between start of breeding season and conception. Source: J.C. Meiske, University of Minnesota

 

Final Analysis
Return on investment can be evaluated in terms of better gains and reproductive efficiency, the ability to digest forages more thoroughly and efficiently, and better immune response.  If mineral is lost to the environment, a reduction in these economic returns will occur.  Evaluation of the mineral feed program for proper feeding management and best type of mineral product to use (weatherized versus non-weatherized) may help reduce losses associated with weather and ensure cattle obtain needed minerals.