Excessive temperatures may be an impediment in livestock manufacturing significantly in tropical areas. Broilers are extra vulnerable to excessive ambient temperatures as a result of they lack sweat glands to dissipate warmth from their our bodies. This text goals to elucidate dietary methods to assist alleviate warmth stress.
Suttisak Boonyoung, Ph.D., Nutritionist, Cobb Asia Pacific
Warmth stress happens when the ambient temperature is greater than the thermo-neutral zone. Warmth stress may be labeled into 2 essential varieties primarily based on the length of publicity: quick time period (acute, lower than 1 week) or long run (power, larger than 1 week). Warmth stress can affect hen physiology and development efficiency resulting in welfare issues and financial losses in broiler manufacturing. Any indicators of warmth stress ought to be addressed instantly. This text goals to elucidate dietary methods to assist alleviate warmth stress.
Warmth stress impacts on broiler development efficiency and physiology
The detrimental impacts of warmth stress on broiler development and physiology are proven in Determine 1. Warmth stress can lower feed consumption and physique weight. The discount of feed consumption is a mechanism to cut back metabolic warmth manufacturing. In distinction, water consumption will increase which may negatively affect litter high quality. At excessive physique temperatures, a broiler’s respiratory charge will enhance to advertise evaporative cooling by means of panting. This reduces blood CO2 and causes respiratory alkalosis.
Warmth stress additionally has an antagonistic affect on the immune system effectivity by decreasing the lymphoid organ weights together with the thymus, spleen and bursa of Fabricius. Nutrient utilization is adversely impacted, which, in flip, might compromise intestine well being. As well as, warmth stress usually has a detrimental affect on meat high quality by decreasing muscle water holding capability and rising fats deposition and drip loss. Durations of excessive warmth publicity result in muscle breakdown to supply amino acid substrates for gluconeogenesis. Warmth stress also can trigger oxidative stress by elevating free radicals. Free radicals can injury intestinal cell membranes and important parts leading to apoptosis, intestinal irritation, and leaky intestine syndrome.
Nutrient and feed formulation methods
Protein and amino acids
Throughout warmth publicity, proteins denature and protein synthesis is impaired. Furthermore, the discount of feed consumption throughout warmth stress causes decrease protein and amino acid consumption that can negatively affect development. Choice of protein sources which might be excessive in digestible protein and amino acids, can cut back the affect of warmth stress by enhancing protein utilization and decreasing warmth manufacturing throughout digestion. The ratio of every amino acid (Preferrred amino acid) ought to be balanced to enhance protein utilization. The applying of artificial amino acids is one consideration to take care of balanced amino acids within the weight loss plan.
Dietary electrolyte stability (DEB) to stop alkalosis
Electrolytes are solubilized compounds that assist to take care of acid-base stability during times of respiratory alkalosis. In broiler vitamin, the primary electrolytes are sodium (Na), potassium (Ok) and Chlorine (Cl). Sodium chloride (NaCl) and Sodium bicarbonate (NaHCO3) are regularly used as Na and Cl in broiler diets and Ok is often obtained from soybean meal. For Cobb diets, every mineral has a minimal requirement akin to 0.16 to 0.23% for Na, 0.16 to 0.3% for Cl, and 0.6 to 0.95% for Ok (please consult with our broiler vitamin dietary supplements for extra particulars obtainable at Cobb-Vantress.com). To keep up electrolyte stability, the diets should preserve the proper ratio of cations (Na, Ok) and anions (Cl).
Nutritional vitamins and minerals to bind free radicals
Nutritional vitamins and minerals have antioxidant properties that may cut back the detrimental affect of free radicals brought on by warmth stress. Vitamin E, a lipid-soluble vitamin at 100 to 250 mg/Kg can enhance broiler development efficiency throughout warmth publicity. Despite the fact that birds can synthesize vitamin C from glucose within the kidneys, the supplementation of vitamin C at 200 mg/Kg within the weight loss plan can cut back the detrimental results of warmth stress. Selenium is a crucial mobile antioxidant and has a minimal requirement of 0.35 mg/Kg feed. This mineral additionally has a synergistic impact with vitamin E.
Generally, the addition of nutritional vitamins and minerals 10 to twenty% above the minimal requirement may help forestall vitamin deficiencies since feed consumption can lower underneath warmth stress. Seek the advice of along with your nutritionist earlier than making any massive changes in feed formulations.
Zinc can enhance broiler efficiency and forestall lipid oxidation in muscle, and is essential as dietary lipid may be simply oxidized at excessive temperatures. Lipid oxidation may be prevented by including antioxidants to the weight loss plan (BHA, BHT and ethoxyquin).
Enzymes
Enzyme supplementation can enhance nutrient digestion and cut back metabolic warmth. There are lots of commercially obtainable cereal-based enzymes. Such enzymes assault non-starch polysaccharides or NSPs. Many of the NSPs are within the cell partitions of cereal grains akin to wheat, corn, oats and even soybeans, and embody xylans, beta-glucans and mannans. Throughout scorching climate, some nutritionists have had success utilizing enzymes that concentrate on all three NSPs. Supporting feed digestion will decrease warmth manufacturing. Relying upon the enzymes obtainable in particular areas, multiple enzyme product could also be wanted to focus on totally different NSPs.
Feed formulation and feed high quality
Feed may be formulated to assist alleviate the impact of warmth stress. The partial substitute of power sources from carbohydrates to lipids is a typical apply as a result of lipids generate a decrease warmth increment than carbohydrates. Lipids additionally benefit from slowing feed passage within the intestine giving extra time for nutrient digestion. The number of high quality elements containing a excessive ratio between web and metabolizable power (NE/ME) is another choice to cut back metabolic warmth manufacturing.
Feed high quality is one other consideration to alleviate warmth stress in broiler. Usually, broilers generate extra warmth and use greater power for his or her consuming exercise when given mash feed in comparison with pelleted feed. So, good pellet high quality can alleviate warmth stress by decreasing power used throughout consuming exercise. Usually, high-quality pellets (<1000 um) shouldn’t compose greater than 10 to fifteen% of the weight loss plan. The pellet sturdiness index (PDI) ought to be greater than 95%. 
Different dietary approaches
There are different feed components that may cut back the affect of warmth stress. Betaine is a methyl donor and may enhance development efficiency and meat high quality. The supplementation of betaine at 1000 to 2000 mg/Kg feed improved feed consumption and development in warmth pressured birds.
Probiotics and prebiotics are feed components that may elevate intestine well being impaired by warmth publicity. It will end in improved broiler development efficiency. Phytogenic compounds akin to Sanguinarine and curcumin had been additionally reported to assist handle warmth stress circumstances as a consequence of their anti-inflammatory and antioxidant properties. Consider any feed additive totally earlier than utilizing it as part of regular formulation.
Water administration
Water performs many physiological roles in broilers. Throughout warmth stress, water is misplaced by means of the respiratory tract during times of panting. In response, water consumption is elevated in broilers as a way of sustaining thermoregulatory. Water administration throughout warmth publicity is essential to cut back warmth stress. Electrolytes and nutritional vitamins may be added into the consuming water together with sodium bicarbonate, potassium chloride, and vitamin C. Nevertheless, the addition of electrolytes by way of consuming water ought to be monitored to stop moist litter circumstances and biofilms within the water system. It is vitally essential to watch the temperature of the consuming water and preserve it under 25 °C in scorching environments.
Abstract
Warmth stress could cause points for broiler efficiency and meat high quality significantly in tropical areas. Diet and feed high quality are partial methods to alleviate the detrimental results of warmth stress. Farm administration can be an essential key to assuaging this concern. In whole, warmth stress should be addressed by a collective effort of administration and vitamin.
