Water is essential for life, and should therefore be regarded as a major factor in poultry rearing and management. Many aspects related to water functions, quality and other requirements are of major importance when attempting to have better flock performance.
By Dr. Salah H. Esmail , Cairo, Egypt
Water is the most important of all nutrients, amounting to approximately 58% of the content of chickens and 66% of eggs. It serves as a medium in which nutrients are transported, wastes eliminated, and body temperature maintained. It also serves as a source of minerals, providing about 20% of sodium, 7% of calcium, 5% of magnesium, and 15% of sulphur requirements of poultry. It should not be overlooked as a source of such nutrients, particularly in tropical and subtropical areas where mineral deficiency might be a problem.
Water was also found to be an effective means of improving feed efficiency. A new system of providing oxygenated water to poultry was developed lately by H2O Technologies in Washington. The addition of oxygen to water helped increase metabolic rates in broilers, resulting in a 32% increase in feed efficiency and 12% reduction in feed costs. These results are certainly promising for most poultry enterprises aiming at achieving target slaughter weights in shorter periods of time.
In cases where water supply is restricted, there is a marked drop in feed intake, probably due to the reduced rate of digestion by delaying movement of feed from the crop (Table 1), with a resulting depression in weight gain. Chicks subjected to prolonged water deprivation develop nephrosis, polycythemia, shrivelling of the skin around the legs, and other gross signs of dehydration. Adult hens deprived of water show necrosis of the ovaries, proventriculitis, and nephrosis, with a marked decrease in egg size and eggshell weight. Very thin shelled eggs are produced after 48 hours of water restriction, followed by the production of some shell-less eggs before egg production ceases entirely.
Standards for water quality should include factors that affect health, taste, solid build up within the water systems, and toxicity. Given in Table 2 are the main factors to be observed for poultry production. In addition, water should not be allowed to remain static, or else it will become stagnant. It should also be remembered that in some climates, particularly in the tropics and subtropics, water may provide a chance for mosquitoes and other insects to lay eggs. Hence, all external reservoirs must be well covered and internal drinkers should be cleaned regularly.
Quality in relation to source
Most public supplies nowadays are regarded as safe sources of water. In some countries, however, public supplies may not be reliable even for human consumption. Reports from Sudan, for example, have revealed that water from public supply stations is not provided continuously, and that there are periods of cessation each lasting for several days or even weeks. Further, quality tests have revealed presence of a wide range of microbes causing diseases such as diarrhoea, malaria, yellow fever, and typhoid, with tremendous amounts of solids and impurities which make water look like mango juice or diluted molasses with a taste being totally unacceptable. Such supply problems and quality factors have forced many farmers in this country to stop their cropping activities and poultry rearing business on the grounds that if water is not suitable for human consumption, it would usually be so for animals and other living creatures.
Artesian wells may be used as an alternative source of pure and safe water, but many of them may contain excess salts or may be over–acid. As indicated in Table 2, the optimum pH of water should range from 6.0 to 8.0. At higher pH values there is an indication of water being contaminated with salts such as sodium bicarbonate. Ingestion of bicarbonate-contaminated water often leads to reduced utilisation by animals of some dietary minerals such as calcium, phosphorus, magnesium, and potassium. Acidic water, on the other hand, is more prone to parasitic infestation and could also lead to serious health problems. There is a strong relationship between water acidity/alkalinity and the depth of wells from which water is extracted. At 30 meters deep, water was found to be acidic, while in depths of 100 meters or more the water was usually alkaline. The pH in water was optimal with wells having a depth of 50-60 meters. Although such a relationship may vary from one part of the world to another depending on geological factors, the depth of wells used in the poultry industry should be one factor to be considered when attempting to obtain clean and safe water. In cases where such an approach is not feasible, then the use of acidifiers or the buffering agents should be considered for control of water pH. These agents should be provided at the levels recommended by the manufacturers, and be used on a constant and regular bases. Irregular supply of such agents or drastic change in the provision thereof may affect patterns of water and feed consumption by poultry and may also lead to sub-clinical intestinal problems.
Water and heat stress
Most water intake charts are based on an environmental temperature of 21ºC, with the intake value increasing by about 7% for each 1ºC above 21ºC. Under extremely hot conditions however, the overall activity of the bird decreases and water intake also tends to decrease. This adversely affects feed intake, weight gain, egg production, shell quality, fertility of males, and carcass composition, with many health problems being encountered, as indicated earlier. This is particularly true for chickens reared under the open-house system in tropical and subtropical areas, the case in which water consumption can be enhanced through one or more of the following strategies:
1. Use of water troughs
It is a common practice in many tropical areas to use water troughs in place of the nipple or bell–type drinkers, at least during the hot seasons. It is believed that with such a system birds will not only be allowed to get enough water but will also have the chance to submerge their heads and combs in water and hence reduce the heat load by evaporation of water from these body parts. Given in Table 3 are the water troughs requirements for poultry at different ages.
2. Provision of cold water
In south west Nigeria (a humid – tropical area characterised by ambient temperature over 30ºC during the hot-dry months lasting from mid-January through mid–April), a study was conducted to evaluate the effect of cold water (8.0ºC) and ordinary water (29.5ºC) on production parameters of broiler chickens for a period of four weeks. With cold water, the effects of heat stress were alleviated and the birds were able to gain more weight and to have higher feed efficiency. Birds were also more responsive to vitamin C supplementation (500 mg per liter of water) when offered cold water, as they had better survival and higher carcass quality, with a special reference to the breast meat yield (Table 4).
3. Proper beaktrimming
It has been demonstrated that poorly debeaked birds may not be able to drink sufficient water to sustain maximum production. Where the lower beak of the bird is too long, then a difference of up to 20% in egg production can exist compared to the properly debeaked birds with the same level of water in a trough.
4. Use of flavours
Although chickens have only a few taste buds compared with other animals (316, 1706, 2755, 19904, and 20000 buds in chickens, dogs, cats, pigs, and cows, respectively), they still have a well defined sense of taste, and will accept or reject certain flavours. Generally, birds prefer water which is slightly acidic or supplemented with products such as thiamine and sugars, while rejecting other flavours such as xylose and saccharine. It is to be noted though that products of a given flavour may not always be compatible with the bird’s taste, and this should force the need for trying different products to ensure that they cause no decrease in water consumption or development of unwanted decline in production.
Photos courtesy of Viola Holik, Lohmann Tierzucht, Tanzania
* References are available from the author