ENVIRONMENTAL POLLUTION AND ITS EFFECT ON ANIMAL PERFORMANCE: 2. WATER POLLUTION AND ITS EFFECT ON ANIMAL PRODUCTION AND REPRODUCTION PERFORMANCE
Environmental pollution may be defined as the unfavorable alteration of surroundings. These alterations largely are caused by product of manís and animalís activities. Through direct or indirect effects of changes in energy patterns, radiation levels chemical and physical constitution and abundance of organisms. Water pollutants, which include toxic metals (lead, cadmium, mercury and copper). The effects of water pollutants cause anemia and damage of the internal organs (lung, liver and kidney) in affected animals. It is affect on enzymatic activities in the various tissues. Affected animals were associated with obvious decrease in fertility, semen volume, sperm density, sperm motility and increase in embryonic mortality and sperm abnormality. It is vitally important to remember that all animals have to provide with not contaminated water.
Environmental pollution can classified as follows: air pollution, water pollution, solid waste pollution, land pollution, marine pollution, noise pollution, radiation pollution and thermal pollution (Katyal and Satake, 1993).
The term of water pollution is referred to the addition of an excess amount of material (or heat) that is harmful to humans and animals or other living creature. Water is pollute by different sources that can be classified as domestic, industrial, agricultural and shipping waters (< biblio >).
1-Domestic water pollutants arise from wastewater of homes and commercial establishments and that, which transmitted, by sewers to a municipal waste treatment plant.
2- Industries pollutants such as petro-chemical camplexes, fertilizer factories, oil refineries, pulp, paper, textile, sugar and steel mills, tanneries, distilleries, coal washers, synthetic material, plants for drugs, fibers, rubber, plastic. The industrial wastes of these factories and mills include heavy metals (copper, lead, mercury, arsenic, cadmium, etc.), detergents, petroleum, acids, alkalis, phenols, crabmeats, alcoholís, cyanide, chlorine and many other inorganic and organic toxicants.
3- Agricultural waters pollution that includes sediments, fertilizers, and farm wastes. These pollutants can all enter waterways as runoff from agriculture lands.
4- Shipping water pollution that includes both human sewage and other wastes. The most important of which has been oil. Industrial wastes (heavy metals) are consider to be the greatest dangerous of water pollutants that comprises the harmful effect on animal health, their productivity and reproductively performance. Therefore, this article review will concentrate to illustrate the effect of these heavy metals as water pollutants on productive and reproductive performance.
There are three toxic minerals (lead, Cadmium, and mercury) all these metals cause harmful effects on animal health, productivity and reproductively performance.
Lead is considered to be a major environmental pollutant and has been the cause of more accidental poisoning in domestic livestock than other substance (NRC, 1972). Lead poisoning causes anemia, affects enzymatic activities in various tissues (Szilagyi et al., 1995). And damage alimentary canal, lungs, liver and kidneys (Woidicd and Plannhauser,1977).
A number of studies have been done on the effect of lead on animal performance, blood components changes, some physiological reactions and reproductive system of different species of animals. Hammond et al. (1989) showed a decreased in body weight and weight gain in weaned rats exposed to lead acetate of dose 0, 250 and 500 PPM supplied in drinking water. Manal Zaki et al. (1996) reported that, the exposure of male New Zealand white rabbits to lead (0, 100, 500, and 2500 PPM) lead in drinking water for 6 weeks decreased in body weight (6.85 %) and feed intake (28.75 %). Respiration rate and rectal temperature were declined by lead acetate. A slight decrease in the weight of testis, adrenal and spleen were observed in lead treated rabbits, meanwhile, liver and kidney weight were increased. Hemoglobin concentration, red blood cells, packed cell volume and total leukocyte counts were gradually declined. However, blood glucose was increased in lead acetate treated rabbits.
2- Lead and Cadmium
Lead and cadmium act synergistically in affecting animal performance (Wiersma et al., 1986). A numerous works will be review to illustrate the effect of both lead and cadmium in affecting on the reproductive performance in female animals in term of embryo development, reproductive organ and endocrine system. Also will be reviewing the adverse effect on reproductive function in male animals in term of semen quality and blood biochemical in different species. Hazelhoff (1987) and Odendro (1989) in laboratory animals have been shown that lead and cadmium accumulate in mother organism, pass through the placenta barrier and have adverse effects on the embryos and pregnancy. Soukupova and Dostal (1991) reported that the intake of low cadmium doses (0.2-2 mg/kg) during pregnancy is not lethal, but decreases the percent of neonates, while high doses up to 40 mg/kg result in abortions, low weight at birth and congenital abnormalities (Baranski,1986). Simeonov et al. (1995) studies the effect of lead and cadmium distribution in organs of sheep and their fetuses. They used 18 pregnant ewes. The sheep were distributed in three groups. The group 1 (control), the group 2 and 3 received 11.7 mg/kg lead acetate and 1.2 mg/kg cadmium chloride, respectively through a probe after the morning feeding every five days during pregnancy. The results indicated decrease in fetus weight due to the decreased placenta transport of nutritive substances and disturbances in the metabolic mechanism in mother and fetuses, which is a result of the lead and cadmium intoxication. Lead and cadmium deposition sexual organs of sheep (ovary, uterus wall) and internal organs (liver and kidney). They also reported the increased lead concentration in fetuses, sexual organs that is a prerequisite for occurring of functional abnormalities in their future development and maturation.
The effects of lead and cadmium on semen quality and blood biochemical parameters of cockerels were studied by Abaza et al. (1996). Their results indicated a direct effect of cadmium and lead on the testis function of cockerels. It is manifested in noticeable decrease in semen volume, sperm density, sperm motility and an increase in sperm abnormality. The results also showed a noticeable decrease in the plasma calcium, sodium, potassium and iron concentration.
Exposure of different organisms to mercury (Hg) is of a great concern because it is highly toxic, persistent and can undergo food chain implication. Increased concentration of mercury in blood was associated with several changes in the reproductive functions of male and female rats and mice (Khera, 1973) and monkeys (Mohamed et al., 1987). Including decreased fertility and increased embryonic mortality. Maha Zaghlool et al. (1996) studied the effect of increasing doses of mercuric acetate on semen quality and quality in male rabbits. They used 12 mature male New Zealand White rabbits at six months of age. The animals were divided into three equal groups. Group 1 used as a general control (untreated) during 18 weeks period. Group 2 was left with no treatment for six weeks, then exposed to low dose of mercuric acetate (20 PPM Hg/L water) for six weeks, followed by a dose of 100 PPM for six weeks. Group 3, after the six weeks preliminary period, animals were treated with 100-PPM Hg/L water for six weeks and with 500-PPM Hg for another six weeks. Semen samples were collected and evaluated. The results indicated that there was a significant decrease in semen ejaculate volume, sperm concentration, initial fructose concentration and osmolarity in rabbits treated with mercuric acetate compared with control animals. Meanwhile, percentage of dead and abnormal spermatozoa and methylene blue reduction time were significantly increased in the semen of treated animals. These deleterious effects of mercury on semen quality and quantity were dose dependent.
In conclusion, Environmental protection is a must.
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