Mineral Supplementation for Cattle in Panama: a Practical Assessment of Commercial Mineral Mixtures

Four commercial mineral supplements were obtained from the marketplace over a 12-month period at three-month intervals. Samples were analyzed for mineral concentrations, and comparisons were made as to adequacy for grazing beef cattle. There were substantial differences among the mineral supplements. For the four collections per supplement, the coefficient of variation for phosphorus concentration was 6 to 7 percent for two mixtures, compared to 15 to 17 for the remaining two. For one mineral mixture, there was a high variation in composition of most microminerals analyzed. Only four of nine declared mineral concentrations were accurate for one mineral mixture. Zinc was generally offered in only negligible quantities. Cobalt was sometimes offered in excess. Mineral supplementation has a favorable cost-benefit ratio. When only considering calving percentage, a net return of 2.25 to 13.5 dollars would be expected for each dollar spent for a complete mineral supplement.

Mineral deficiencies or imbalances in soils and forages have long been held responsible for low production and reproduction problems among grazing tropical cattle (McDowell 1985, 1992; McDowell et al 1993). Panamanian cattlemen are, in general, well aware of the need to supplement minerals to cattle raised under grazing conditions throughout the year. However, only about 50 percent of them provide salt, and only a small portion would offer a more complete mineral mix (IDIAP/CIID 1985). A number of factors have been identified as limiting the use of complete mineral supplements and include: lack of practical guidelines that may help the producer to select a mineral mixture that is available in the market; the concept among cattlemen that a continuous mineral supplementation program to grazing cattle is prohibitly expensive; and lack of practical and economical alternative means to offer mineral mixtures to cattle under grazing conditions.

In an attempt to provide cattlemen with some alternative answers to the above mentioned limitations, the Department of Animal Production of the Agricultural Research Institute in Panamá, with the assistance of Rutgers University and the University of Florida and with the financial support of the Agency for International Development in Panamá, conducted the present study in Panamá. The objectives of this study were to experimentally evaluate four mineral supplements as to adequacy for grazing beef cattle and to make recommendations for an appropriate mineral feeder.

Duplicate samples from commercially available mixtures of four commercial mineral supplements were obtained over the counter during a 12-month period (May 1986 to May 1987) at approximately three-month intervals. Samples were analyzed for mineral contents according to standard procedures (Fick et al 1979).

With the numerical information obtained on mineral composition from the label of the commercial mixtures, and that reported in the analysis, two evaluations were conducted:

Guidelines on relative effectiveness and daily cost of mineral supplementation to cattle were prepared based on the criteria indicated below:

The results on mineral composition and their corresponding coefficients of variation and A/D values for the four mineral mixtures analyzed are shown in tables 1 and 2.

The coefficient of variation for the phosphorus concentration of the mineral mixtures considered in the study was less for mixtures No. 1 and No. 3 (6 and 7 percent, respectively) as compared to 15 to 17 percent for mixtures No. 4 and No. 3. In the case of microminerals like copper, iron, manganese, zinc, molybdenum, cobalt and selenium, mixtures No. 2 and No. 3 had the greatest consistency, with the exception of molybdenum in Mixture No. 2 and cobalt in Mixture No. 3. Mixture No. 1 had a relatively high variation in the composition of most microminerals analyzed.

Table 1: Macromineral composition of four commercial mineral mixtures for cattle in Panamá (%, mean ± standard deviation).*

Macro-element	Commercial Mixtures**
	Composition	No. 1	No. 2	No. 3	No. 4

Ca	Declared Analyzed CV, %* A/D, %**	7.7 7.9±2.9 37 103	25.5 20.8±6.0 29 82	22.0 15.7±3.6 23 71	16.0 11.9±1.2 10 74
P	Declared Analyzed CV, % A/D, %	10.0 12.2±0.7 6 122	19.6 16.9±2.8 17 86	ND 0.07±0.005 7 ---	21.0 17.4±2.6 15 83
Na	Declared Analyzed CV, % A/D, %	16.0 16.9±2.6 15 106	2.4 2.4±0.03 13 100	ND 0.04±0.011 28 ---	0.06 0.07±0.006 9 117
K	Declared Analyzed CV, % A/D, %	ND 0.86±0.03 50 ---	ND 0.01±0.007 70 ---	ND 0.08±0.011 14 ---	0.08 0.05±0.007 14 63
Mg	Declared Analyzed CV, % A/D, %	ND 0.34±0.17 50 ---	1.2 0.97±0.07 30 81	ND 0.27±0.07 15 ---	0.65 0.35±0.16 46 54

* Each supplement is the mean of four replications analyzed in duplicate.
** Represents four prominent mineral supplements available in Panamá. Mixture No. 4 is marketed in Panamá, with no label or indication of quality composition. Therefore, No. 4 mineral composition levels used for comparison to the analyzed values were obtained from manufacturer's published data.
*** CV, coefficient of variation in percent.
**** A/D, ratio analyzed/declared in percent.

Table 2: Micromineral composition of four commercial mineral mixtures for cattle in Panamá (ppm, mean ± standard deviation).*

Micro-element	Commercial Mixtures**
	Composition	No. 1	No. 2	No. 3	No. 4

Cu	Declared Analyzed CV, %* A/D, %**	2000 746±26 3 37	500 349±26 7 70	5800 5207±362 7 90	ND 9±1.2 13 ---
Fe	Declared Analyzed CV, % A/D, %	5000 13921±3753 27 278	1000 1470±162 11 147	40000 51402±1183 5 129	ND 13996±983 7 ---
Mn	Declared Analyzed CV, % A/D, %	2500 2087±602 29 83	1000 1032±43 4 103	18000 18080±1183 7 100	ND 386±50 13 ---
Zn	Declared Analyzed CV, % A/D, %	10000 4904±1404 29 49	2400 2442±11 5 102	2000 1989±229 12 99	ND 135±57 42 ---
Mo	Declared Analyzed CV, % A/D, %	ND 14.5±7.5 52 ---	10 31±12 39 310	ND 4.9±1.0 20 ---	ND 22.7±2.8 12 ---
Co	Declared Analyzed CV, % A/D, %	20 8.3±4.7 57 42	30 33±1.1 3 110	700 521±117 22 74	ND 7.4±3.1 42 ---
Se	Declared Analyzed CV, % A/D, %	20 8.8±1.2 14 44	10 11±0.6 5 110	ND 0.08±.03 38 ---	ND 0.46±.09 20 ---

As far as the accuracy on the declared composition, for Mixture No. 1 only four of nine mineral concentrations specified contained 100 percent or more of the declared amounts. One other element was close to 85 percent of the specified concentration, and the remaining four elements were present in amounts less than 50 percent of the declared amount. For Mixture No. 2, out of the 11 elements listed on the tag and analyzed, seven were in agreement and four more analyzed between 70 to 86 percent of the declared amount. Mixture No. 3 declared only six elements on its tag, out of which three analyzed 100 percent or more of the declared amount, and the other three were between 71 to 90 percent of stipulated value.

In order to determine the most economical source of minerals from the commercially available mixtures, it was necessary to calculate the relative cost for each mineral of interest (Table 3). These values are obtained from the current commercial cost and the mineral concentration as indicated on the label. If manufacturers' declaration on labels could be accepted as precise in every case, this evaluation would be a simple mathematical calculation. Unfortunately, product labels are often unreliable, casting doubts on the usefulness of the above approach.

Table 3: Unit cost of some elements from commercially available mineral mixtures for cattle in Panamá (dollars US/100 g of the element. August 1988).

	Commercial Mineral Mixture
Element	No. 1*	No. 2**	No. 3***	No. 4****

Macromineral
Calcium	0.50	0.79	1.38	0.55
Phosphorus	0.32	0.97	None	0.38
Micromineral
Copper	53.1	469.9	41.7	None
Iron	2.8	111.6	4.0	4.7
Manganese	19.0	158.9	12.0	171.0
Zinc	8.1	67.2	109.1	---
Cobalt	4771.0	4969.7	None	---
Selenium	4500.0	14909.1	None	None

* Mixture No. 1: $4.50 for 11.36 kilograms ($.40/kg).
** Mixture No. 2: $41.0 for 25.00 kilograms ($1.64/kg).
*** Mixture No. 3: $2.00 for 0.92 kilograms ($2.17/kg).
**** Mixture No. 4: $15.00 by 22.7 kilograms ($.66/kg).

The results of relative effectiveness and daily cost are shown in Table 4. A wide range was observed in the supply of theoretical mineral requirements as well as the daily cost of supplementation. Out of the three macrominerals looked at--calcium, phosphorus and sodium--only sodium was covered in at least 50 percent of theoretical requirements. Of the microminerals investigated (copper, iron, manganese, zinc, cobalt and selenium), great discrepancy was observed among mixtures. Zinc was offered in only negligible quantities by seven mixtures, while cobalt was present in excess in two mixtures. The comparative daily cost of supplementation (60 grams per head) varied from 0.83 to 5.2 cents.

Table 4: Percentage mineral requirements supplied by commercial mineral mixtures for cattle commonly used in Panamá.*

Mineral Mixture	Elements										Daily** Cost (¢)
Ingredient	%	Ca	P	Na	Cu	Fe	Mn	Zn	Co	Se

NaCl Mix No. 2	70 30	12	12	82	6	3	8	9	60	20	3.4
NaCl Mix No. 2	50 50	21	20	59	10	4	12	15	100	30	5.2
NaCl Mix No. 3	98 2	1	---	115	6	7	9	0.5	60	---	0.8
NaCl Bone meal	50 50	24	12	59	---	---	---	---	---	---	1.0
NaCl Bone meal Mix No. 3	49 50 1	24	12	57	3	3	0.4	0.2	30	0.5	1.1
NaCl Bone meal Mix No. 3	45 45 10	25	11	53	30	33	4	2	300	5	2.1
NaCl Mix No. 4	60 40	10	17	70	0.2	34	4	0.6	20	1	1.8
NaCl Mix No. 4 Mix No. 3	59 40 1	10	17	70	3	37	8	0.8	50	1	1.9
NaCl Mix No. 4 Mix No. 3	45 45 10	25	19	53	30	71	47	3	330	1	3.1
Mix No. 1	100	16	29	51	45	84	50	59	50	50	2.4

*Cattle mineral requirements in total daily dry-matter intake: Ca, 0.3%; P, 0.25%, Na, 0.2%, Cu, 10 ppm; Fe, 80 ppm; Mn, 25 ppm; Zn, 50 ppm; Co, 0.1 ppm; Se, 0.1 ppm (McDowell, 1985).
**A 60-g per head daily intake of commercial mineral mixture was considered.

A cost-benefit ratio on a mineral supplementation program for cattle in Panamá using August 1988 prices indicated a theoretical high return. This calculation was based on the following assumption and prices:

A. An annual mineral supplementation cost per head, considering an average intake plus waste of 100 grams per head a day:

In a herd of 100 cows, supplementation with salt alone costs $400.00 a year, while a mineralized salt supplementation program would cost $800.00, a difference of $400.00 more a year. If a weaned calf has a value of $180.00, 2.2 more weaned calves in the heard of 100 cows should pay the extra cost of a proper supplementation. A summary of mineral supplementation trials for cattle conducted in Latin America (1) shows a range of response in the number of weaned calves due to supplementation, from 5 to 30 more calves per 100 cows. Based on this, a net return of $2.25 to $13.5 could be expected for each dollar spent on a complete mineral supplement. It is important to realize that the cost-benefit ratio in this example considers only the direct effect on number of weaned calves and does not take into account other collateral beneficial effects like liveweight, body condition and improved general health of dams and calves. All these traits are of economic importance and should make mineral supplementation an even more financially attractive proposition. In a four-year supplementation study from Colombia, supplemental minerals dramatically increased all parameters of production (Miles and McDowell 1983). Multiplication of the weaning percentage by the weaning weight gave 88.7 kg of calf produced per cow with complete minerals, compared to 44.8 kg with common salt alone.

If a beef-finishing operation is examined, the same extra cost of $400.00 per 100 head mentioned above for the supplementation with mineralized salt over salt alone could be considered. An increment in weight gain of 4.4 kilograms per head in a year, or its equivalent to 12 grams per day, could cover the extra cost of supplementation. Under almost any conditions, an increase in liveweight gain of at least 200 grams could be expected when mineralized salt substitutes for salt alone. This rate of gain would represent an annual increase of 68 kilograms more per head with a value of $62.00 per head and of $6200.00 for the entire herd of 100 head, therefore, a return of $15.50 for each dollar spent. Here again, no account is made of cumulative benefits from supplementation other than from weight gains.

A mineral box design (Zorrilla-Rios et al 1987) has been developed and tested under field conditions for a year. It consists of a 55-gallon plastic drum cut transversally in half. Out of the two free borders from each half drum, a second cut with the shape of a ring of approximately 1 1/2 inches is made. From each ring, a 4 to 5 mm section is taken off at any point and the rings are molded to the internal phase of the free edges of the half drums. The purpose of all this is to give firmness to the free edges.

Along the free borders of each half drum, eight sets of three circular notches are made. The mineral salt will flow out of the half drum through these holes. The half drums are then crossed internally with 25 to 30 segments of nylon string going from top to bottom and from opposite sides. The purpose of the string is to prevent any caking of mineral salt inside the drum. To facilitate evaporation of moisture inside the drum, make six openings in the wall of the drum as close as possible to the bottom of each half drum. Holes designed with a 45-degree angle to the wall serve this purpose. A one-fourth inch hole at the bottom of each half drum is needed and also a 3- to 4-inch hole in the bottom half of the original drum. The mineral salt will be poured through this opening to fill feeder once in position.

The next step in the construction of the mineral box is the base upon which the half drum will rest. This is made out of a disposed truck tire, 20 inches in size, cut in half. Four to six one-half inch perforations are made to allow drainage of accumulated rain. The internal circular space is sealed with a lid made out of wood and secured to the tire with a piece of wire. Two more wooden wheels are constructed, one 18 inches and the other 16 inches wide. These two wheels and a 14-inch plastic bowl are placed on top of each other in order to construct a cone, with the purpose of compelling the mineral salt to flow closer to the wall vs. settling in the center. An opening is made in the center of all three wooden wheels and the plastic bowl to allow a double nylon string to pass through all the way from the bottom of the 20-inch wooden wheel up to the top of the half drum. A double knot is made at the bottom end of the double nylon string, while the other end is threaded to a piece of stick. Clockwise torsion of the double nylon string will eventually have a tourniquet action which in turn will keep in position the half tire base and the half drum container.

The mineral box is placed on top of two 20-inch used tires and secured in place by means of three poles buried in the ground at equal distances. This mineral box is designed to function both during the dry and the wet season and does not depend on a roof. To keep the mineral mixture from hardening inside the drum and to maintain a good flow out, all that is required is to rotate the half drum to the left and right two to three times a week during the usual checking of the cattle. Simultaneously, sufficient pressure should be maintained on the tourniquet to keep the drum firmly pressed against the base.

The capacity of a mineral box constructed under these specifications is for 120 to 130 pounds and could supply the needs of 25 to 30 cows for approximately 30 days. It is portable, assisting in achieving a more uniform grazing of the paddocks, and once cattle have reached a stable consumption of the mineral salt on offer, it can be a reasonable vehicle to provide specific drugs or additives to cattle.