Managing Heat Stress in Poultry

Reducing stress in poultry remains a topic of concern with producers and scientists alike. Poultry production efficiency is adversely affected by high ambient temperatures and humidity. As the birds' body temperatures rise, feed consumption, growth rate, feed efficiency, survivability, egg shell and chick quality decline. The problem is particularly severe as the ambient temperature rises since heat loss associated with non-evaporative cooling (heat lost through the skin) declines markedly. During high ambient temperature exposure, the bird's heat load is increased due to the environmental heat gain and the energy cost associated with activation of metabolic processes required for heat dissipation.



Stress is usually associated with physiological and biochemical changes like increased levels of glucose and circulatory cortisol and decreased protein levels in blood. Ambient temperatures >30oC induces heat stress in birds and is the single largest challenge to poultry production in the Indian subcontinent. Methods to alleviate the effect of heat stress focus on handling external and internal factors like cooling poultry houses and manipulating the diet. Chromium (Cr3+) as a dietary additive is being recognized as may be used as one of the tools to handle such stress situation. Nevertheless, dietary Cr supplementation is coming as a new feeding management tool. Cr picolinate is perhaps the most widely explored compound in research work and field trial conducted on Cr.

EnCroMix - the Energy Premix

A Supranutritional solution to combat stress condition in poultry:

EnCroMix is a supra-nutritional organic mineral GRAS category feed additive, a unique formulation of Chromium Tri-picolinate in a stable premixed form developed through in-house R&D at Jubilant Life Sciences Limited, a product of Jubilant's patented process (United States Patent, Patent No: US 6,486,318 B1, Date of Patent: Nov.26,2002). It is widely used in human and animal nutrition as a supplement in general nutrition, sports nutrition as well as therapeutic nutrition.

In chicken EnCroMix is primarily used to get following Benefits:


The supplementation of chromium has been found very useful in improvement of production parameters and product quality in different classes of chickens. The use of chromium (organic and inorganic) in the diet of broilers has been studied under Indian conditions at the West Bengal University of Animal & Fishery Science, Kolkata in great details (Samanta et. Al. 2008, Bhagat and Ahmad et al. 2005). Field trials on broilers and layers both show very encouraging results. This is the best choice as a stress reliever in extreme stress conditions like peak summers, diseases outbreaks, peak winters, managemental operations etc.

Chromium - the essential micromineral

Trivalent chromium (Cr III) is an essential element required for normal carbohydrate, lipid, and protein metabolism in humans and animals. Chromium is biologically active as part of an oligopeptide - chromodulin - potentiating the effect of insulin by facilitating insulin binding to receptors at the cell surface. 



Chromium potentiates the action of insulin in vivo and in vitro (Mertz, 1969, 1993; Mertz et al., 1961). Schwarz and Mertz (1959) identified chromium as the element that restored glucose tolerance in rats. Pechova and Pavlata (2007) have document clearly the various benefits of chromium on:

- Metabolism (of carbohydrates, proteins and lipids),
- Hormonal regulation (of cortisol and insulin),
- Reproduction,
- Growth and body composition and
- Immune function in humans



The Picolinate Advantage

Picolinic acid/ picolinate is a natural amino acid. The animal body synthesizes picolinates in the liver and kidney from the amino acid tryptophan. The human body on an average produces from 5-20 mg of picolinic acid. Picolinic acid has been detected in a variety of biological mediums including blood serum, cerebrospinal fluid (CSF), human milk, pancreatic juice and intestinal homogenates ( Grant et al 2009) . It is also found in many foods and feeds including milk and yeast.



Various studies have demonstrated other major benefits of picolinic acid to animal/ human health. Studies by Melillo et al 1993, Leuthauser et al 1982 have proven the anti-tumor and immunostimulatory activity of picolinic acid respectively. Picolinic acid has been demonstrated to have a protective activity on mice challenged with a fungal infection (Blasi et al. 1993). A more recent study on picolinic acid (Shanshan Cai et al 2006) has found picolinic acid to be a useful as a supportive agent to antimicrobial therapy. Grant et al (2009) in a recent review of picolinic acid has observed that Picolinic Acid possesses a wide range of neuroprotective, immunological, and anti-proliferative affects within the body.

Fig 2: Chromium action on energy metabolism through insulin regulation

Studies on Poultry

Sahin et al 2009 is the most recent publication on the use of chromium supplementation on summer stress. This review was published in the journal Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources. The authors have reviewed extensive literatures and conclude the following benefits of supplementation of chicken with chromium.

Chromium supplementation

- Decreases levels of blood corticosterone
- Regulates the blood levels of glucose
- Reduces inflammation and oxidative stress markers
- Increases weight gain in thermal poultry
- Improve the metabolizability of organic nutrients
- Retention of trace elements and
- Improves meat quality in stressed poultry

Studies of supplemental EnCroMix on different class of chicken:

A. Studies On Broilers:

Study 1: Effect of supplemental EnCroMix on Broiler performance under stress condition:

In a very detailed study at the West Bengal University of Animal & Fishery Science, Kolkata, Samanta et al (2008) have observed the different parameters of production influenced by EnCroMix supplementation in heat stressed broiler birds. Notable improvements in live weight (16%) and FCR (14%) than control were recorded in chromium supplemented broilers (Table 1)

In the same study it was observed that supplementation of heat stressed birds with EnCroMix lead to increase in carcass yield by 152 g, breast meat yield by 63 g and leg meat yield by 40 g (Table 2).

In the same study it was observed that heat stress leads to a 2.3% rise in circulating cortisol in the broilers in control group. EnCroMix supplementation @ 250 g/Mt reduces serum cortisol by 7.6% (Table 3).

A number of authors confirm decreased sensitivity to stress in Cr supplemented animals through a reduced concentration of cortisol in blood (Chang and Mowat, 1992; Moonsie-Shageer and Mowat, 1993; Mowat et al., 1993;Underwood and suttle,1999; Spears, 1999; Pechova et al., 2002c; Pechova and pavlata, 2007).

Ward et al. (1993) reported a tendency for 200 ppb Cr from Cr picolinate to increase protein percentage and decrease fat percentage in carcasses of 3-week-old broiler chicks. They concluded that dietary Cr from Cr picolinate affected growth, metabolism and carcass composition of broilers.

Dietary supplementation of Cr3+ reportedly improved animal metabolism and enhanced production performance and the composition of animal products (Spears, 1999). Dietary Cr3+ supplementation positively affected growth rate and food conversion in poultry at an inclusion level ranging from 0.1 to 1 mg kg-1 diet ( Cupo and Donaldson,1987; Lien et al. 1999; Sahin et al 2002; Amatya et al, 2004).

Hossain et al. (1997) observed that the body weight of broilers at 3 and 6 weeks was significantly influenced by Cr in the diet. Since effects on broiler carcass composition are cumulative, the length of feeding and market age are important factors in determining effects of Cr on carcass composition. The improvement of breast meat yield was 7 and 11% of the control, respectively.

Study 2: : Effect of supplemental EnCroMix used along with AGPs to assess the results on Broiler performance under stress condition:

A field investigation carried out in Tamil Nadu (India) with EnCroMix supplementation on broilers has a positive correlation with the action of Antibiotic Growth Promoter. There was a significant increase in Body weight (70g over control and 40 g over AGP), FCR (1 point reduction over both groups) and Mortality (0.7% reduction over control and 0.4% reduction over AGP (Table 4)

Study 3: Effect of supplemental EnCroMix on Broilers on Immunity:

Bhagat et al (2008) conducted molecular investigations on the effects of supplemental chromium (Cr) on interferon γ) expression in response to Newcastle disease virus (NDV) vaccine chicken. Their findings prove that supplementation of Chromium Tripicolinate (EnCroMix) appropriate dose is helpful to enhance the IFN-γ mRNA expression in response to NDV. This is clear evidence that EnCroMix influences the genetic mechanism of immunocompetence in broiler chicken.

Reference: Research in Veterinary Science 85 (2008) 46-51

The immune function may be affected in association with insulin and/or cortisol activity, but it can just as well be mediated by production regulation of certain cytokines (Borgs and Mallard, 1998).

B. Study On Layers:

Study 1: Effect of supplemental EnCroMix on Layers performance under stress condition:

In another field trial in Tamil Nadu (India) completed recently in 2010 the same results were demonstrated on a layer flock where the mortalities due to rising temperatures were controlled by the supplementation of EnCroMix @ 250 gm/ton of feed (Figure 1).