Its April and summer heat has started. For broiler farmers in India, summer management of poultry is all about Fans, Foggers, Sprinklers, Curtain management, Space management, feeding time, Feeder lifting, Electrolyte supplementation, Mortality control etc. Ambient temperature for rearing birds is 24 to 26°C. Temperature above that gradually induces stress. Intensity of stress increases proportionately with increase in temperature. Gastrointestinal tract (GIT) weight, activity including enzyme secretion, enzymatic activity, nutrient absorptive surface area and villi dimensions are reduced significantly due to intense heat stress. According to studies done, body weight is reduced by approximately 15-20 % with an increase in 10°C than ambient temperature. Also, there is 5 % reduction in feed intake for every 1°C rise in temperature between 32-38°C.
Apart from managing the house temperature, there is also a requirement to make changes in the nutrition and formulation of birds for summers. In this article, we will be covering different practical changes in feed formulation for broiler diets in summer.
Increase DAA levels of diets
Bird utilizes much more amino acids during heat stress. Supplementation of good quality protein rich raw materials with higher digestibility is required in summers. Ideal protein formulation with digestible amino acid levels suits perfectly for summers. For summers, the digestible amino acid levels need to be increased 3-5%. Cost of this addition can be minimized either by use of cost effective local available ingredients or by including a Multi-Protease in the diets. Cost of Multi-Protease can be easily adjusted by considering 0.2% CP or 1% DAA matrix. Incorporation of good Multi-Protease enzyme is most ideal to reduce amino acid variability, protein wastage, litter ammonia and stress. It will balance all essential amino acids, optimize performance, and reduce cost of production.
Apart from this, deficiency of arginine and lysine increases heat load which must be taken care of in feed formulations. Additional fortification of Lysine, Methionine, Lysine to Arginine ratio will ensure better breast meat yield in summer stress. Arginine, Tryptophan, Valine and Glutamine are known for their direct/ indirect response to immunomodulation and feed intake.
Formulation Tips
- Increase Digestible Amino Acid levels of diet by 3-5%
- Use either protein ingredients to increase amino acids or Multi-Protease
- Multi-Protease is cost effective way to optimize Amino acids without change in diet
- Breakeven point of Multi-Protease comes at 1% DAA or 0.2% CP replacement
- Lysine, Methionine, Arginine, Tryptophan, Valine and Glutamine levels are important
Increase AME of diet
During summer feed intake will drop due to stress and limited feeding hours. To compensate nutrient requirement, it is suggested to increase the AME of diets by 40-50 Kcal/kg. And this increment is suggested to be provided through fat/oil. Increasing fat levels in diet generally reduces digesta passage time and optimizes absorption of nutrients. Fat metabolism also has the lowest heat increment ensuring body cooling effects. Good quality fat and oil also enhance palatability and optimizes finished feed energy levels. If Me is enhanced by use of grains and oil seed meal, it’s better to make sure Non-Starch Polysaccharides levels are within limits. These Anti-nutritional factors increase gut viscosity and may result in feed passage. If these levels are high use of a good thermostable Xylanase, Beta-Glucanase, Mannanase, Cellulase and Amylase can help.
Formulation Tips
- Increase AME of diet through oil by 40-50 kcal/kg
- Use good quality oil with Antioxidants and Emulsifier
- Select oil based on Lipid Evaluation Test (MIU, FFA, PV, FA Profile and AME calculation)
- Use thermostable Multi-NSP enzymes if ME is increased through grains and oilseeds
Dietary Electrolyte Balance (DEB) Impact
DEB is calculated as (% of Na/ 23 + % of K/39.1 – % of Cl/35.5) * 10,000 Where 23, 39.1 & 35.5 denotes atomic weight of each Na, K & Cl electrolytes respectively and 10,000 is the multiplication factor. We have observed a severe bicarbonate ion (NaHCO3) loss during summer stress & respiratory alkalosis. Increase of NaHCO3 in diets are recommended to control the loss and reduce stress. Keeping optimum DEB in summer is essential for better feed intake, day gain, feed conversion ratio (FCR), osmotic balance and effective evaporative cooling of body to relieve stress. Increased DEB by 10 to 15% in summer is recommended than winter. Use of potassium chloride (KCl), ammonium chloride (NH4Cl), NaHCO3 along with regularly used NaCl will help in attaining desired levels of DEB. Practically, the DEB levels are kept more than 220 during summers. Na comes in diet from Salt, Soda bicarbonate, MBM, Fish meal and K comes from Soya and other salts. In a well-balanced diet with high soya and MBM DEB is never a challenge. Challenge comes when lots of alternates are added which is also less digestible.
Formulation Tips
- Keep DEB levels over 220 in summer
- Increase DEB with Salt, Soda bicarbonate, Potassium Chloride addition
- DEB is higher for high Soya based diet
- If alternate ingredients are used more add salts to balance DEB
- Addition of electrolytes through water can also help in temporary basis
Other Additives
There are some additives which have a significant role to play under heat stress. These additives can assure you a high ROI and are worth including in feed. Other essential additive levels need to be increased based on feed consumption. All Vitamin and Mineral levels need to be increased by 10-20% during summer stress so that even if bird consumes less feed, these essential nutrient levels are maintained in birds. Storage of vitamins, enzymes, and probiotics in a cooler place of feed mill avoids the efficacy loss due to environmental extremities.
Inclusion of Vitamin C and Vitamin E at a level of 100-200 ppm is recommended for stress relief and immunity. Similarly, minerals like Manganese (Mn), selenium (Se) and zinc (Zn) plays key role in improving immunity. Supplementation with Vitamin D3 is useful during summer stress to fulfil any deficit of calcium absorption and for better bone mineralization. Choline chloride dosage may be increased during summer stress to ensure effective utilization of fat & nutrients, prevent fatty liver & partial methyl donor effects. Addition of betaine that acts as a methyl donor and maintain osmotic balance of body will be useful as an on-top application during intense summer stress. Some anti-coccidial decrease tolerance to heat and some depresses water intake. These should be avoided for summers. Nicarbazine and Monensin are not suggested to use. Other additives which always aids are immunomodulators, emulsifiers, probiotics, gut health promotors, broad spectrum toxin binders and enzymes.
Formulation Tips
- Increase Vitamin and Mineral levels by 10-20%
- Vitamin C, Vitamin E, Vitamin D3, Choline and Betaine inclusion is beneficial
- Anticoccidials Nicarbazine and Monensin needs to be avoided
- Storage of additives needs to be done at a cooler place
- Immunomodulators, probiotics, enzymes, emulsifiers, broad spectrum toxin binders etc. are always helpful
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