**1. Introduction**

The first group of zeolite minerals was discovered in 1765 by a Swedish mineralogist A.F. Cronstedt who described several species found in well-defined crystals. He noticed that some heated minerals began to lose their constituent water with a boiling-like appearance, hence the name of zeolite (from the Greek words "zeos" and "lithos" which translate as "boiling stone") [1].

Zeolites are natural, hydrated, crystalline aluminosilicates made up of threedimensional networks extended by AlO4 and SiO4 linked together by oxygen atoms, which make up a rigid, open, honeycomb-like skeleton, generally including cations which neutralize the excess negative charge of aluminum tetrahedra and water molecules. Each AlO4 tetrahedral network supports a net negative charge that is balanced by a cation, usually from the I-A or II-A group (Ca, Mg, Na, K, Fe). These ions are not part of the zeolite network and can be changed by other cations such as heavy metals (Hg, Pb, Cd) or ammonium ions [2–4].

There are 67 natural zeolite minerals accepted by the Natural Zeolites Commission of the International Zeolite Association (IZA) and all have a unique three-letter code [5].

Clinoptilolite of sedimentary origin, generally the most used natural zeolite, is authorized by the Commission Implementing Regulation (EU) no. 651/2013 as a feed additive for all animal species [6]. In the United States, clinoptilolite belongs to the sodium aluminosilicate category and has the status of Generally Recognized as Safe (GRAS) (Code of Federal Regulations CFR, Title 21, Section 182.2727) [7].

Due to their main properties: adsorption, molecular sieving and cation exchange, zeolites have a wide use in many areas. For example, in agriculture, natural zeolites are used to obtain fertilizers capable of better nitrogen retention and in a slow and controlled release of fertilizers, nitrogen use efficiency (NUE) increase [8, 9]. In aquaculture industry natural, synthetic or modified zeolites are used as adsorbents for ammonia removal from fish farming ponds and transportation tanks, as a cation-exchanger for removal of different toxic heavy metals from fresh water and sea water cultures and as a feed supplement to enhance fish growth [3]. Also, zeolites can increase the nutrient (by addition of micronutrients) and water use efficiency of drylands (by their water holding capacity) [9]. Natural zeolites are used in wastewater, surface waters, ground and underground water, drinking water treatment [10, 11], in decontamination of radioactive waste water [12] and in agro-industrial wastewater treatment due to their exceptional cationic exchange and adsorption properties [13]. In construction field through their excellent properties, mainly porosity, specific weight and adsorption, they can be used as a building stone [14], in zeoponic substrates—artificial soils developed by the National Aeronautics and Space Administration—for plant growth in space [15], and as potential slow-release carriers for herbicides, insecticides and other organic compounds, protecting in this way the environment from chemicals [16].

In animal production, alternative products as zeolites are a solution to ensure health, productive performance (yield and quality of carcass, milk yield), to reduce the effects of mycotoxins on animal health status, to remove selectively pathogens from the animal gut without reducing microbial richness and finally to increase farm profitability. All of these effects has been extensively studied in the last decade [17–28] and are schematic represented in **Figure 1**.

Clinoptilolite is also used as a biomedical feed ingredient due to its beneficial properties as a growth-promoter and immunostimulant and can constitute an alternative to antibiotic growth promoters [29], since European Union legislation has banned the use of antibiotics for growth promotion in 2006, because the overuse of antibiotics in animals can contribute to emergence of antibiotic resistance [30].

Zeolites can have a protective effect in intoxication and in reducing parasite infestations. These effects are evidenced by researchers who observed that clinoptilolite (2 g/kg) could have some protective effect in organophosphorus poisoning in sheep by protecting the rumen flora and by preventing the decrease of cholinesterase activity [31]; in lead intoxication in mice, clinoptilolite given in 10/1 ratio

**125**

NH4 +

tion of NH4

+

clinoptiloliten is reported [38].

phosphorus, that set up a week postpartum [40].

*Zeolites Applications in Veterinary Medicine DOI: http://dx.doi.org/10.5772/intechopen.87969*

(clinoptilolite/Pb) adsorbed 91% of Pb, and when supplementing 3% clinoptilolite feed to pigs that received 150 ppm CdCl2, clinoptilolite prevented Cd-induced anemia by adsorption of Cd [32]; and in reducing the excretion of cysts in goat kids with giardiasis [33]. It also had beneficial effects in infestations with nematode larvae in lambs, producing an increase in feed consumption and in body mass [34]. Some types of zeolites are studied for their adsorption properties in order to improve the life of people suffering from chronic kidney disease, who need to undergo weekly hemodialysis. Dialysis membranes made from zeolite and polymer are studied in order to improve the performance of hemodialysis. Nanofiber membranes made from zeolite and polyacrylonitrile (PAN) adsorb creatinine, with the best results for 940-HOA (beta) zeolites (25,423 μg/g in 625 μmol/L creatinine solution) [35] and P87 zeolite in combination with polyethersulfone, used because of their improved resistance to fouling, thermal stability, chemical resistance and due to their high adsorption level of indoxyl sulfate (550 μg/g membrane) [36]. When zeolite was used along polyethersulfone (PES) and dimethyl formamide (DMF) in proper concentration: 17:0.5:82.5 (PES:zeolit:DMF), creatinine concentration decreased by 91.99%, which

suggests the possibility of using these membranes in haemodialysis [37].

In animal husbandry, natural and synthetic zeolites have been mostly used to improve productive performance. The proposed mechanisms involved in achieving the increase in productive performance in animals are: ammonia binding, reducing toxic effects of ammonia produced by intestinal microbial activity; low passage rate of digesta through the intestines and more efficient use of nutrients; enhanced pancreatic enzymes activity-favorable effect on feed components hydrolysis over a wider range of pH, improved energy and protein retention; elimination of myco-

Due to the beneficial effects of the gradual release of ammonia ions on microbial synthesis in the rumen, zeolites are used especially in high non-protein nitrogen feed ratio. *In vitro* and *in vivo* experimental studies have shown that 15% of ruminal

can be adsorbed by zeolites, thus reducing the toxic effects of urea (increased

in the rumen [32]. Also, a decrease in ruminal pH in diets with 1%

rumen pH and ammonia concentration in rumen and blood). Thus clinoptilolite (6%) in the feed of dairy cows receiving urea significantly reduced the concentra-

Milk fever and ketosis are the most common metabolic diseases that occur in cows with high milk production. Cows that received zeolite (1 kg zeolite/day for 4 weeks before calving) did not experience subclinical hypocalcemia [39]. Also, the administration of zeolite A (sodium aluminosilicate) to pregnant cows during the dry period (1.4 kg zeolite A/day in the last 2 weeks of gestation) reduced the incidence of milk fever. The mode of action of synthetic zeolite A is to reduce the bioavailability of fodder calcium at the gastrointestinal level (calcium binding capacity of zeolite is 110 mg/g Ca at pH 11), stimulating Ca-homeostatic mechanisms before calving. At calving, the plasma level of calcium was significantly higher in the experimental group (*p* < 0.0001); with a slight drop of inorganic magnesium and

When clinoptilolite was administered (2.5%) in the last month of gestation, the incidence of milk fever was 5.9%, compared to 38.9% in the control group. Also, clinoptilolite (2.5%) administered during the dry period reduced the incidence of ketosis (5.9%) by improving the energy metabolism through increased production of propionate in the rumen and by better recovery of feed [32]. Katsoulos

**2. As dietary supplements in animal nutrition**

toxin growth inhibitory effects [32].

**Figure 1.**

*The main applications of zeolites in veterinary medicine.*

#### *Zeolites Applications in Veterinary Medicine DOI: http://dx.doi.org/10.5772/intechopen.87969*

*Zeolites - New Challenges*

Due to their main properties: adsorption, molecular sieving and cation exchange, zeolites have a wide use in many areas. For example, in agriculture, natural zeolites are used to obtain fertilizers capable of better nitrogen retention and in a slow and controlled release of fertilizers, nitrogen use efficiency (NUE) increase [8, 9]. In aquaculture industry natural, synthetic or modified zeolites are used as adsorbents for ammonia removal from fish farming ponds and transportation tanks, as a cation-exchanger for removal of different toxic heavy metals from fresh water and sea water cultures and as a feed supplement to enhance fish growth [3]. Also, zeolites can increase the nutrient (by addition of micronutrients) and water use efficiency of drylands (by their water holding capacity) [9]. Natural zeolites are used in wastewater, surface waters, ground and underground water, drinking water treatment [10, 11], in decontamination of radioactive waste water [12] and in agro-industrial wastewater treatment due to their exceptional cationic exchange and adsorption properties [13]. In construction field through their excellent properties, mainly porosity, specific weight and adsorption, they can be used as a building stone [14], in zeoponic substrates—artificial soils developed by the National Aeronautics and Space Administration—for plant growth in space [15], and as potential slow-release carriers for herbicides, insecticides and other organic

compounds, protecting in this way the environment from chemicals [16].

[17–28] and are schematic represented in **Figure 1**.

In animal production, alternative products as zeolites are a solution to ensure health, productive performance (yield and quality of carcass, milk yield), to reduce the effects of mycotoxins on animal health status, to remove selectively pathogens from the animal gut without reducing microbial richness and finally to increase farm profitability. All of these effects has been extensively studied in the last decade

Clinoptilolite is also used as a biomedical feed ingredient due to its beneficial properties as a growth-promoter and immunostimulant and can constitute an alternative to antibiotic growth promoters [29], since European Union legislation has banned the use of antibiotics for growth promotion in 2006, because the overuse of antibiotics in animals can contribute to emergence of antibiotic resistance [30]. Zeolites can have a protective effect in intoxication and in reducing parasite infestations. These effects are evidenced by researchers who observed that clinoptilolite (2 g/kg) could have some protective effect in organophosphorus poisoning in sheep by protecting the rumen flora and by preventing the decrease of cholinesterase activity [31]; in lead intoxication in mice, clinoptilolite given in 10/1 ratio

**124**

**Figure 1.**

*The main applications of zeolites in veterinary medicine.*

(clinoptilolite/Pb) adsorbed 91% of Pb, and when supplementing 3% clinoptilolite feed to pigs that received 150 ppm CdCl2, clinoptilolite prevented Cd-induced anemia by adsorption of Cd [32]; and in reducing the excretion of cysts in goat kids with giardiasis [33]. It also had beneficial effects in infestations with nematode larvae in lambs, producing an increase in feed consumption and in body mass [34].

Some types of zeolites are studied for their adsorption properties in order to improve the life of people suffering from chronic kidney disease, who need to undergo weekly hemodialysis. Dialysis membranes made from zeolite and polymer are studied in order to improve the performance of hemodialysis. Nanofiber membranes made from zeolite and polyacrylonitrile (PAN) adsorb creatinine, with the best results for 940-HOA (beta) zeolites (25,423 μg/g in 625 μmol/L creatinine solution) [35] and P87 zeolite in combination with polyethersulfone, used because of their improved resistance to fouling, thermal stability, chemical resistance and due to their high adsorption level of indoxyl sulfate (550 μg/g membrane) [36]. When zeolite was used along polyethersulfone (PES) and dimethyl formamide (DMF) in proper concentration: 17:0.5:82.5 (PES:zeolit:DMF), creatinine concentration decreased by 91.99%, which suggests the possibility of using these membranes in haemodialysis [37].
