ladakh the trans himalayan part of the jammu state of india, is located between the greater himalaya and the karakoram range, known as the “cold desert”, and is comprised of two districts. this area has several peculiar climatic conditions characterised by prolonged sub-zero temperatures, unfertile sandy soils with low water capacities, dryness (less than 30 % humidity), low oxygen content, intense solar radiation, low atmospheric pressure, high wind velocity and rugged terrain. in winter the temperature falls to minus 35 degree celsius and the altitude varies from 10,000 to 20,000 feet from mean sea level (msl). the atmospheric oxygen pressure is 30% lower than msl. the type of cold and desert isn’t akin to the natural environment of poultry, and hatchability is a big problem due to the climate conditions in this region.
for normal hatchability at sea level, the oxygen concentration, barometric pressure, humidity and temperature should be 21%, 740 mm hg, 65% and 99.8 degree fahrenheit respectively.
however in this cold desert area o2 concentration is 30 % lower and temperature ranges from -30 to 30 degree celsius.
in the last two decades, india has reached a level of self-sufficiency in chicken production, and the indian poultry industry has become much more sophisticated.
but the situation in the cold arid part of leh-ladakh still remains challenging. the main reasons for this are the non-existence of many commercial hatcheries, problems transporting day old chicks, poor availability of poultry feed ingredients.
efficient poultry production around the world much depends on local circumstances. high altitude conditions for example, are more difficult situations to deal with than at sea level. this situations begin in the incubation stages, but is also a matter of concern during the growing period. adequate measures are needed in such cases to obtain the best out of a hatching egg.
the high altitude areas are characterised mainly by low atmospheric pressure resulting from two competing forces, namely gravity which causes the air to be as close as possible to the ground, and the heat content of air which causes the molecules to bounce off each other and expand.
in this case, the number of oxygen molecules per breath is reduced, but to a varying extend depending on the magnitude of elevation.
high altitude and hatchability:
research has shown that hatchability of chicken eggs is reduced by 10% at altitude of 305 meters, and by 30 % at 2,130 meters above sea level. three hatching related factors come into play at high altitudes:
1) reduced o2 availability or atmospheric o2 tension.
2) extensive loss of carbon dioxide (co2).
3) excessive water/weight loss by the incubated embryos.
field experience indicates that hatchability at high altitudes may improve if the setter cabinet is increased by 0.15 degree celsius and the relative humidity is kept constant at 60%. it is also important to improve o2 supply to the embryos during incubation. the most practical way to do this and to restore normal hatchability at high altitude is to inject o2 directly into the setter cabinet. but this process is very costly and unsafe. incubating eggs at high altitudes, slower embryos growth, longer incubation periods and lower hatchability have to be expected. the best way to solve these problems is to build a hatchery that can be pressurized to sea level atmospheric pressure. and more practically by good control of egg weight loss and oxygen addition to the setter and hatchers.
sea level air oxygen contains 21 % oxygen but at high altitudes (1500 meters, 4,921 feet) or more the air pressure decreases (there is less air). not only the shortage of oxygen is partially offset at high altitude but it results in eggs losing carbon dioxide and water faster than they would at sea level. the extra loss of carbon dioxide does not appear to affect the embryo.
gases move through the eggshell faster at higher altitude:
at 500 meters the percentage of gases which can cross the eggshell compared to sea level is 6%
at 1000 meter the percentage of gases which can cross the eggshell is 13%
at 2500 meters the percentage of gases which can cross the eggshell is 36%
and at 3000 meters 45%
again the main problems facing chicken embryos when incubated at high altitudes are a reduction of oxygen supply and dehydration. as a result, the hatchability of fertiles eggs decreases with increasing altitude.
it is also very important to realize that breeder flocks adapt to higher altitude by producing eggs with a lower effective pore area and therefore water vapour loss. this means the altitude of the breeder flock relative to the altitude of the hatchery may influence the best choice of the humidity set-point. therefore make sure to be guided by actual egg weight loss in the hatchery, and alter the humidity set-point to achieve the recommended optimum egg weight loss.
the first thing to consider when a hatchery is built at high altitude and when incubated eggs is to insure that egg weight losses are correct. based on the fact that water diffuses through the pores in the eggshell faster at higher altitude. running a higher incubator humidity set-point is required. set-points should be compensated at higher altitude level to compensate the increasing speed of movement of water molecules. (table 2)
egg produced at sea level: hatchery at altitude resulting in reduced hatchability: eggs produced at sea level have relatively large effective pore area and will therefore lose more water at higher altitudes. to compensate, setter and hatchers should be operated at a higher relative humidity. by pre-conditioning the inlet air to a relative humidity of 75 %, with a temperature of 24- 28 degree celsius (optimum). at the same time, the ventilation rate must be increased from normal to sea level, to accommodate the reduced oxygen.
eggs produced at same altitude as hatchery: ventilation rates should be higher than normal for sea level. during humid external conditions, increase ventilation rate may cause reduced humidity in oxygen levels in the air further. this higher ventilation rate may cause reduced humidity in the setters and hatchers. to avoid constant humidifying, humidity set points should be lowered and the resulting more than optional weight loss. 14-15 % preferred in this case.
eggs produced at altitude: hatchery at sea level: the set points for relative humidity need to be reduced to achieve optimum weight loss as the eggs have a reduced effective pore area.
exact set points for relative humidity are dependent on several factors including altitude and eggshell conductivity (age of the flock, nutrition, and genetics). it is highly recommended that relative humidity set points are fine-tuned by weighing trays of eggs before setting and to be repeated at transfer at 18 or 18.5 days.
young breeder age flocks: optimum weight loss %: 10-11%
medium breeder age flocks: optimum weight loss %: 11-12%
old breeder age flocks: optimum weight loss %: 12-13%
the air cell provides an indicator of weight loss. if during an egg breakout it is observed that too many are wet, fully developed embryos will fail to pip. this indicates insufficient weight loss and a shortage of oxygen. in this case, set points for relative humidity should be reduced and/or ventilation rate should be increased.
the second thing to consider when a hatchery is built at high altitude is ventilation and oxygen: maximizing oxygen availability to the embryo is important, but avoiding over-ventilating the setters is important too because by over-ventilating, it is a potential risk of the incoming air will be colder and drier at high altitudes and the setters will be more difficult control their temperatures and humidity set-points.
up to 1,500 meters (4.921 feet), only slight losses in hatchability is expected, especially if egg weight losses is controlled. above 1,500 meters, losses in hatchability have to be expected. above 2,000 meters (6.562 feet), the level of oxygen addition required to achieve sea level oxygen pressure significantly increases the fire risk. from a safety perspective, levels of more than 25 % oxygen are not usually recommended. instead of adding pure oxygen, levels in the incoming air can be increased by using an industrial oxygen concentrator. using this technology at 1,900 meters, it is possible to increase the oxygen concentration of the air to 23 %, which will give a 3 to 5 % hatch help at relatively low cost.
the third thing to consider when a hatchery is built at high altitude, eggshell adaptation: many bird’s species are successful nesting above 4,000 meters. with increasing altitudes, chickens appear to reduce eggshell porosity in order to offset the potentially excessive water loss from the egg.
growing chickens at high altitudes:
reduced fetal growth: at high altitude, the prevailing low oxygen concentration has detrimental effects on embryonic growth and development of chickens. this could be attributed to the decreased efficiency with which the yolk sac is converted to embryonic tissues, and/or the decreased fetal resource uptake by making the yolk sac unusable.
the extent to which fetal growth is reduced is so much influenced by the material residential location. in one study, the fetal mass was reduced by 45 % when the breeder flocks were kept at sea level and their eggs were incubated at high altitude, and by only 22 % when the breeder flocks were kept at high altitudes and their eggs were also incubated at high altitudes, suggesting hereditary effects on their adaptability to lower oxygen concentration. adaptation can develop through a greater ability of the embryo to form hemoglobin in the red blood cells, in addition to the greater utilisation of the yolk sac which acts as a nutrition resource.
growth performance: high altitudes also affect growth rates at post-hatching stages. this is due to the decreased temperature at high altitudes which often leads to high metabolic rates, with a resulting increased demand of oxygen. at normal attitudes the increased metabolic rate could be a positive factor affecting growth, but at very high altitude, the lower oxygen uptake would conflict with the higher oxygen demand. this would inevitably result in decreased performance in terms of growth and other biological functions.
the reduced post-hatching growth of chickens could further be attributed to the incidence of ascites and other disease problems induced by high altitude.
health and body condition: the low partial pressure of oxygen at high altitudes causes hypoxia (inadequate oxygen supply) with long lung activity and higher arterial pressure. the affects the working of the heart and may lead to heart failure and accompanying systems called ascites. in order to solve this problem, addition of oxygen has been applied with success, but the costs of this solution is high. increasing the ventilation rate could provide more oxygen, but as the humidity level at high altitudes is naturally low, humidity is lowered further and other problems may rise.
the low humidity at high altitudes may affect the bird’s health and body condition through different ways. the skin becomes so dry and itchy that can develops cracks. the mucus membranes lining the nasal and throat may also become dry and cracked, thereby giving a direct path for germs and bacteria to enter the blood stream and cause a number of disease problems.
physiological adaptation: during continuous exposure to high altitude, birds develop several physiological responses to make it possible to live in a low 02 environment. the increases of red blood cell number (rbc) and amount of hemoglobin (hb) are the most important hematological acclimatisation which appears after 1-2 weeks. as a result there is an increase of oxygen-carrying of blood which acts as a compensatory mechanism to the stimulus of reduced oxygen saturation. further, at high altitude, there is a decrease in mean cell volume (mcv), so the total surface of rbc is enlarged, which is advantageous for hemoglobin to bind oxygen, and helps prevents the increase of blood viscosity that results from polycythemia.
adequate oxygen transfer: the reduced environmental oxygen availability at high altitude stimulates higher respiration frequency which plays an important role in maintaining adequate oxygen transfer to the blood. in one study, the respiration rate per minute at sea level was 31.0, and was increased to 35.3 at 3,200 meters altitude. this mechanism also increases the exhalation of co2 and thereby serving to counteract the acid-base problems arising from hyper ventilation.
at high altitude, birds may also develop special mutations that alter the amino acid residues in hb and hence increase o2 affinity. the higher affinity in this case may increase oxygen saturation of blood and hence compensates for the reduced partial pressure of oxygen. this latter aspect, however, is considered to be a characteristic of only those birds which are genetically adapted to high altitudes and may not be generalised to all breeds of chickens
feeding and management: for high altitude chickens, diets should be duly supplemented with anti-oxidants such as vitamin e. this helps improve performance, by alleviating much of the oxidative stress problems caused by reduced oxygen partial pressure, increased ultra-violet light, and increased metabolic rates at high altitudes.
a study was conducted in a himalayan area of north of india, where altitude varies from 3,050 to 3,600 meters above sea level, with atmospheric oxygen pressure being 30% short relative to the sea level. in this study, broiler chickens were fed on 200 mg of vitamin e per kg of feed for six weeks, and had better performance compared to the control chickens receiving diets devoid of vitamin e.
the improved performance with vitamin e supplement could be attributed to the improved feed intake and utilisation of the supplied nutrients, particularly protein which is essential for health, body weight gain and survivability. the vitamin also improves blood characteristics, mainly due to its effects on hematopoietic organs and erythropoiesis, thereby increasing rbc and hb levels and helps adaptation to high altitudes.
the supply of b vitamins such thiamine, riboflavin and niacin should also be considered ay high altitudes. these vitamins help improve performance by releasing energy from the feed and hence compensate for the low energy intake observed under high altitude stresses.
animal origin sources: it is also important to supply adequate amounts of iron at high altitudes where atmospheric pressure is lower and there is less oxygen in each breath. in this case iron would increase the oxygen-carrying of blood and facilitates its utilisation by the cells, and would hence improve performance and adaptation to high altitude.
the diet of high altitude should be duly manipulated so as to contain haem-iron sources such as from animal origin, supplying at least 80 mg of iron per kg of feed, with the protein and energy components to be kept at optimal ratios for each production stage.
reduced metabolic rate: in high altitude cases where the ascites problem is likely to prevail, it may be beneficial to adopt the feed restriction system (50% of the energy required to support normal growth rate), especially for birds exposed to low ambient temperature from three weeks onwards.
this is probably due to the reduced metabolic rate during the restriction period, suggesting a possible acclimatisation effect on development of ascites under cold/high altitude conditions. alternatively, the avoidance of low temperature by slightly heating the houses could be an effective means of reducing the incidence of ascites at high altitude, but may not be recommended for high altitude farmers who cannot afford to heat their broiler houses during cold seasons.
oxygen supplementation effects in a hatchery at high altitude and growth performance of broilers reared at low altitude:
a study was conducted to investigate the effect of oxygen supplementation on broiler eggs in a hatchery at high altitude on the growth performance and ascites syndrome of broilers reared at low altitude.
the treatment groups were
1) first group: low altitude with non- oxygen supplemented in the hatchery
2) second group: high altitude with oxygen supplementation in the hatchery
3) third group: high altitude with no oxygen supplemented in the hatchery.
growth performance, heart weight, concentrations of the hormones t3, t4, t3/t4 and plasma concentrations of haematocrit, hemoglobin, glucose and parameters of ascites syndrome during the growing period were investigated. a total of 243 one day broilers were used for this study. during the growing period, excluding days 7, 28 and 35, oxygen supplementation at high altitude did not affect the live weight of broilers compared to group 3 and group 2. the cumulative feed consumption was determined to be lower in group 2 and the same group 1 and on the 42nd days old. between 21st and 42nd days, the group 1 had better feed conversion ratio (fcr) than group 1 and group 3. chick weight (cw), yolk sac weight (ysw), and chick heart weight (chm) were higher in group 1 than group in group 2 and group 3.. at 42 days old, there were no differences between the groups in heart weight, right ventricle weight (rv), left ventricle and septum (lv sept), total ventricle (tv) weight and the rc: tv ratio. the plasma t3 level was lower in the group 1 than in the group 2 and 3 and t4 levels were higher in group 2 than in the other groups at 42 days old. the hypoxic conditions that occurred the embryonic stage- which altered endogenous functions of prenatal chicks and affected several blood parameters, and oxygen supplementation at high altitude- improved chick quality. however, it did not improve subsequent fcr and feed consumption performance of chickens when they were reared at low altitude.
1) the partial pressure of oxygen (o2) becomes lower with increasing altitude (visschedijk, (1985) and a decrease in barometric pressure and o2, partial pressure at high altitude causes a lack of o2 (hypoxia), carbon dioxide (co2) (hypocapnia) and water (dehydration) in chickens (visschedijk, 1991).
2) growth increases the need for o2 (beker et al, 2003, and rapidly growing broiler chickens need o2 for their metabolic requirements (julian et al, 1989).
3) as the o2 level decreases with altitude, exposure to chronic hypoxia increases mortality and decreases growth as a result of adaptation (julian 2000, villamor et al, 2004.
4) the hypoxic condition during incubation decreases chick weight (dzialowski et al, 2002, sharma et al, 2006, zhang et al, 2008).
5) however (bahodoran et al, 2010) found that bodyweight of newly hatched chicks from high altitude incubator was significantly higher than of chicks incubated in a low altitude zone.
6) additionally, giussani et al (2007) showed that o2 supplementation of eggs incubated at sea-level could prevent high-altitude induced growth restriction completely.
7) celen et al (2009), found no positive impact of additional o2 supplementation at high altitude during the incubation period on weight of chicks from 31 and 55 weeks of age in broiler breeders.
8) meshew (1949), found that o2 supplementation to the hatchery at high altitude resulted in a slightly hatching weight of chicks and turkeys than no supplemented incubation.
previous studies suggested that o2 and co2 exchanges are important for embryonic development during incubation and especially for chick embryo survival (tona et al, 2005).
9) at high altitude, chronic hypoxia is a more serious problem during incubation because it affects chick embryo survival and hatchability, and has detrimental consequences for bodyweight and post-hatch bird performance (decuypere et al, 2001, chan & burggren, 2005).
10) this could be because of decreased efficiency in foetal resource uptake from the yolk sac, which is converted to embryonic tissues, thus making it unusable (esmail, 2012). the importance of the yolk sac is not restricted to the life of the embryo in avian species, but extends to post-hatch life (romanoff, 1960). inefficient foetal resource uptake from the yolk sac increases the incidence of ascites, which has become of increasing concern, because of its association with increased mortality and decreased weight gain (julian, 1993)
11) oxygen concentration plays a major role the onset of ascites, reduction in atmospheric o2 concentration effectively induces ascites. it is therefore important to keep the o2 concentration above 19.6 % to minimize ascites-related anomalies and maximize performance (beker et al 2003)
12) fast growing chickens breeds are more likely to suffer from ascites because of their rapid growth and high metabolic rate both of which require more o2 (acar et al, 1995). the peak of ascites incidence occurs during weeks 5 to 6 of the growing period (coleman & coleman, 1991).
13) a higher metabolic rate is associated with increased secretion of the hormones= thyroxine (t4) and triiodothyronine (t3), which are important growth promoters in chickens (gonzales et al 1999, yahav, 2000, luger et al, 2001). thyroid hormones regulate the metabolic rate during the post-hatch period (gabarrou et al, 1997, decuypere et al, 2000) and are linked with ascites susceptibility (hassan zahed et al, 2004). this becomes even more apparent under adverse environmental conditions, such as high altitude (hassan zahed et al, 2004)
14) before a bird exhibits gross ascites syndrome lesions, commonly the right ventricle to total ventricle (rv; tv) ratio changes in the concentrations of haemoglobin (hb), haematocrit (pcv) (yerssin et al,1992), glucose in the liver(diaz-cruz et al, 1996), blood gases and other parameter changes can be detected ( huchzermeyer & deruyck,1986). it is generally accepted that the greater right ventricle to total ventricle ratio (rv: tv) (0.29 vs 0.20) is an indication of ascites (julian, 1993, owen et al, 1995).
15) in previous research, sahan et al, 2011 demonstrated that o2 supplementation at high altitude during the late incubation period of broiler eggs increased hatchability and embryonic survival rates because of decreased hypoxic stress
the aim in this study therefore was to investigate the effect of high altitude o2 supplementation on growth performance and ascites susceptibility of broiler chicks reared at low altitude.
the hypoxic conditions during the hatching period affected several blood parameters, such as plasma t3, plasma t3/t4 and hb levels in one day old chicks. at high altitude, the supplemental o2 during the hatching period improved chick quality, but did not improve the subsequent fcr and feed consumption performance of chickens when they were reared at low altitude. better growth and feed consumption performance was observed for the broiler chicks that were hatched and reared at low altitude.
the result of this study may help to clarify the effects of high altitude and o2 supplementation during hatching on the growth performance of broiler chicks, because many broiler producers obtain their chicks from high altitude hatcheries and rear them at many altitudes.
samir r. fanous [email protected]