Economics of trace mineral salt

A number of recent studies have shown that adding trace minerals to animal diets benefits animal productivity even when no deficiency symptoms are obvious. For example, a Texas study demonstrated the effectiveness of feeding supplemental zinc, copper and manganese to improve reproductive efficiency of cows grazing native range. The four treatments studied were: (1) control (no supplementation); (2) 2.2 pounds of grain-urea mix; (3) grain mix plus 15 grams phosphorus and; (4) grain mix plus phosphorus plus the three trace minerals. The average length of time from the start of the breeding season to conception was 42, 35, 29 and 22 days respectively for the four nutritional treatments. The seven-day earlier conception rate would result in approximately 14 pounds increased weaning weight due to trace mineral supplementation alone. Applying recent economics, the return on investment is approximately 29:1 for trace mineral supplementation. The authors stated that, "Possibly, specific nutrient requirements, especially trace minerals, are at times of greater importance than body conditions for satisfactory reproductive performance in the beef cow."

Alberta researchers have also documented the value of trace mineral supplementation for their beef producers. In “Farming for the Future” demonstration projects trace mineral supplementation improved weaning weights by 14 to 26 lbs per calf and yearling weights on pasture were increased 20 to 36 lbs. These improvements occurred without clinical trace mineral deficiency symptoms and where producers did not perceive that growth rates were impaired. In a review on trace minerals, Dr. A. A. Jimenez stated that some deficiencies of trace minerals in dairy cows have been implicated in reproductive problems such as retained placenta, anestrus, infertility and abortions. He also stated that trace mineral fortification of dairy cows producing 65 pounds of 3.5% fat-corrected milk amounted to 0.11% of the total feed costs. Similar responses to trace mineral supplementation have occurred in growing pigs.

Researchers at the University of Nebraska conducted a growing trial with or without trace mineral supplementation of pigs on pasture. On average, trace minerals increased gains 0.09 lbs per day. The study showed that the cost of trace minerals amounted to 4.7 cents per pig, but returned $1.64 per pig. Consequently for every penny invested in trace minerals, the producer would have received 35 cents in return. Another swine study showed that omitting salt and six trace minerals from a corn-soy diet resulted in a 17% depression in growth rate. Although impossible to calculate return on investment in trace minerals because the diet was deficient in salt, this trial affirms the necessity of fortifying corn-soybean meal based diets with trace mineralized salt. Similarly, a study at Ohio showed that deleting trace minerals from growing-finishing pig diets lowered feed intake and gain but did not affect feed efficiency. When trace minerals were added back to the diets, an immediate growth response was observed. A Purdue study with growing pigs showed that adding a trace mineral mixture improved gains 15.4% compared to controls fed no trace minerals. Research by Edmonds and Arentson showed that deleting trace minerals from the diet of finishing pigs can reduce the nutrient concentration of the meat. Ham from pigs without trace mineral supplementation has significantly lower copper concentrations compared to those that were supplemented. Other researchers are concerned that removing trace minerals may compromise the welfare of the animals.

These are only a few of the many examples that could be cited on the value of adding trace minerals to animal diets. Responses to trace mineral supplementation can be subtle and not easily measured. For example, small changes in fertility, immunity, or longevity are economically important, but difficult to connect with a given trace mineral. Australian researchers reported that when sheep were supplemented with cobalt while grazing a pasture known to be cobalt deficient, a measurable response was only observed in 9 of 14 years. Some consumers have questioned the wide spread practice of trace mineral supplementation when clinical trace mineral deficiencies are not observed. Their concern is that trace minerals may be stored in the body and that meat products may contain abnormally high levels. Irish researchers measured the copper, selenium, and iodine concentrations in tissues from 2,612 cattle harvested in the late 1990s. This followed marked improvements in blood copper and selenium concentrations due to increased supplementation over the past 20 years. Only 0.3, 2.3, and 4.0% of the cattle had high copper, selenium, or iodine concentrations, respectively. The term “high” means above of the normal range of concentrations, but not anything approaching toxicity. The conclusion of this study was that current levels of trace mineral supplementation posed absolutely no threat to the human food chain.