Is the highland really that good for raising chickens?
Rearing game fowl at high altitude is the favored method by most breeders. The successes in the Philippines of Negros cocks, Zamboanga fowl and the roosters of other highland farms are often credited to high altitude raising. But, is high altitude really the magic formula?
Let‟s have a closer look at the pros and cons of high altitude. Altitude means height above sea level. The higher the altitude the lower is the atmospheric pressure. Temperature and humidity are also low at high altitude areas. These facts contribute to factors that may be beneficial or detrimental to raising chickens.
It is true that at high altitude birds develop several physiological responses to make it possible to live in such an environment that makes a game fowl more physically fit for fighting. After just a couple of weeks, the red blood cells (RBC) and hemoglobin counts of the chicken increase. As a result, there is an increase in the system‟s capacity to carry oxygen in the blood. Moreover, the mean cell volume (MCV), decreases so the total surface of RBC is enlarged, which enhances hemoglobin‟s ability to bind oxygen, and circulate it through the organs in the body.
Birds at high altitude also develop higher respiration frequency. This is in order to maintain adequate oxygen transfer and circulation in the blood. Once the bird is adapted to high altitudes a mutation may ensue that favorably affects amino acid residues that increases oxygen affinity. High oxygen affinity will increase oxygen saturation of blood.
The down side
Birds reared in high-altitude encounter a number of difficulties related to production, health, and mortality. This is because of problems in oxygen intake, low temperature and humidity.
These troubles are encountered when the adaptive mechanism of the chickens are not adequate to handle such difficult conditions.
Reduced oxygen availability or atmospheric tension, dehydration of the incubating embryos, and excessive loss of carbon dioxide may also lead to poor egg hatchability at high altitude areas.
There are remedial measures such as slightly increasing temperature say, by 0.15ºC and keeping the relative humidity is constant at 60%. It is also important to improve oxygen supply to the embryos during incubation. This can be done by opening the setter air inlets more and/or for longer periods as this will allow more air flow and thus more oxygen.
Due to the decreased temperature which often leads to high metabolic rates and increased demand for oxygen, growth rates of chickens are also affected at high altitudes. Enhanced metabolic rate which could be a positive factor at normal altitude, is disadvantageous at high altitude because the lower oxygen uptake would conspire with the higher oxygen demand to cause decrease performance of biological functions. The low partial pressure of oxygen at high altitudes causes hypoxia. This may lead to heart failure.
There is also the question of whether or not the increase in the system‟s capacity to carry oxygen in the blood as result of high altitude raising would count that much in slasher combat where fights seldom last long. However, all things taken into consideration it seems that breeding and brooding and earlier part of ranging are best done in low lands and the later part of ranging and cording, and perhaps conditioning be done at high altitude.
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