|Livestock Research for Rural Development 14 (4) 2002||
Citation of this paper
Zinc concentration was measured in 32 salt
formulations collected from the states of Mato Grosso, Mato Grosso
do Sul and
Thirty-one samples had values above 300 ppm (range 90 to 8,260 ppm), the maximum recommended value.
These results show the necessity to monitor the industry, because some mineral mixtures can be dangerous to animal health and the environment, and therefore could impair food safety.
The increased competition in the Brazilian market for the commercialization of mineral salt mixtures for animal consumption is one of the main reasons why the mineral mixture industry looks to reduce costs with the aim to win competition and guarantee future business. At present, there are around 5,500 formulations of mineral mixtures being sold throughout the Brazilian market (Marçal et al 1999).
In order to be profitable and maintain its business, the
mineral mixture industry has neglected some important aspects related to quality. Some of
these aspects are the quality of the raw material sources used in mineral salt mixtures.
The materials chosen are usually those most accessible in price, including those of
It is believed that some of these raw material sources may be
contaminated with toxic elements, such as heavy metals and radioactive substances,
generating a subject of concern among nutritionists, clinical veterinarians and
technicians that work in the area of health and animal production.
For this reason, a research project was launched with the intention to evaluate the
level of pollutants in mineral formulations used as cattle feed supplement in
Multiple samples of the main formulations in markets in three Brazilian states were
collected from the stock of selected rural properties in a time frame of 15 months. These
samples were combined, forming a representative "pool" sample of approximately
The samples were stored in transparent plastic containers, previously identified and then analyzed at the
National Commission of Nuclear Energy (CNEN) Laboratory of Poços
de Caldas, Minas Gerais,
Statistical analyses were made with the SAS/Basic program, as described in SAS Procedures Guide (1990).
In most of the samples (Table 1; Figure 1), the zinc concentration was higher than the acceptable maximum limit of 300 ppm as recommended by the AAFC (2001).
Table 1: Zinc concentrations in individual samples of mineral salt
Tangará da Serra
Tangará da Serra
Tangará da Serra
Bom Jesus de Goiás
Figure 1. Average values (n=32) for zinc concentrations in mineral salt from three states in
[AAFCOI: Recommended maximum according to AAFCO 001]
This preliminary study shows that the levels of zinc in almost all the mineral formulations was of the order of ten times the recommended levels. These findings imply that very probably contaminated raw material has been used in the mineral mixtures with the intention to decrease production costs of the final product (Marçal et al 2001).
The next phase of our studies will be to evaluate possible
sub-clinical effects of zinc toxicity in cattle receiving the mineral mixtures with the
highest zinc concentrations. These sub-clinical effects are likely to be manifested in a
depression of feed intake and in induced deficiencies of copper and iron (McDonald et al
These results show the necessity to monitor the feed industry and when failures are found the proper recommendations should be made. Apart from toxic effects of excessive zinc levels in the feed, there is also the potential negative effect on the environment, as the excretion of unabsorbed quantities of the metal will contaminate soil, plants and water.
The following conclusions can be drawn:
AAFCO 2001 Official guidelines for contaminant levels permitted in mineral feed ingredients. Association of American Feed Control Officials Incorporated. Indiana. pp: 292-293.
J 1993 Fosfato bicálcico feed
grade. Apostila Serrana. Cajati. 17p.
IBGE 2001 Anuário estatístico do Brasil. In: Efetivo pecuário. v.54.pp:3-62.
Marçal W S 1996 Valores sanguíneos de bovinos Nelore, em pastejo de Brachiaria decumbens, suplementados com sal
mineral naturalmente contaminado por chumbo. Tese de Doutorado, Universidade Estadual
Paulista, UNESP, Campus de Botucatu, São Paulo. 164p.
W S, Gaste L, Liboni M, Pardo P E, Nascimento M R and Hisasi C 1999 Lead Concentration in mineral salt mixtures used
in beef cattle food supplementation in
W S, Gaste L, Liboni M, Pardo P E, Nascimento M R and Hisasi C 2001 Concentration of lead in mineral salt mixtures
used as supplements in cattle food. Experimenthal and Toxicologic Pathology,
Martin I C T
1993 Nutrição mineral de bovinos
de corte 2ª ed.
McDonald P and Edwards R A, Grenhalgh J F D 1987 Animal nutrition, 4ª ed. Burnt Mill, Longman. pp:90-116.