Optimal nutritional management is essential for preventing and controlling major poultry diseases. This article highlights feed strategies and natural additives that support bird health and enhance disease resistance in production flocks.
The article explores targeted nutrition approaches for preventing and managing conditions such as coccidiosis, salmonellosis, ascites, leg disorders, nervous system diseases, tuberculosis, and sudden death syndrome (SDS). It also examines how specific feed additives can aid disease control and improve overall flock performance.
Coccidiosis: Protein management
Starting with coccidiosis, the supply of protein should be reduced under certain disease conditions. If the level of dietary protein is maintained at a high level in this case, there will be increased activity of the enzyme trypsin in the small intestine of the bird. This will, in turn, lead to a faster release of coccidia from their oocytes, which eventually become so active that they become less responsive to vaccination. The feeding regimen can also affect the severity of coccidiosis. Workers have observed that starving chickens before oral vaccination reduces infection, probably because ex-cystation is lower due to the lowered trypsin level induced by starvation.
Salmonellosis: Feed additives
The use of sodium diformate at 0.6% in poultry diets can provide effective, efficient, yet safe protection against Salmonella and other antibiotic-resistant pathogens while maintaining higher levels of Lactobacilli and Bifidobacteria (Table 1). These results clearly show the beneficial effects of sodium diformate against pathogenic bacteria, leading to a state of balanced, healthy microbial life in the gut of treated chickens.
Ascites: Antioxidants and feed restriction
The incidence of ascites may be reduced when a feed restriction regimen is used from either 4-11 or 7-14 days of age, limiting daily intake to 75% of the ME required for normal growth. Also, the presence of major antioxidant compounds such as vitamin E, selenium, vitamin A, vitamin C, and glutathione in the circulation or at the level of the respiratory membrane plays a vital role in protecting against cellular damage, preventing hypoxia induction, and thus reducing the incidence of ascites.
Leg problems: Minerals and mycotoxins
Calcium and phosphorus play a vital role in healthy bone growth. A deficiency of these elements can lead to chondroplasia and/or osteoporosis, causing a variety of leg disorders in chickens. The optimal ratio of calcium to phosphorus in broiler chicken starter and grower diets is about 2:1. Broilers have a relatively high utilisation of calcium from various sources in the diet. However, phosphorus is usually present as phytate phosphorus, resulting in a low utilisation rate. Therefore, non-phytate phosphorus sources are usually considered for incorporation into diets. This will increase plasma phosphorus concentrations and tibial ash and phosphorus content.
Vitamins are also necessary for preventing leg disorders:
- A deficiency in vitamin B6 can affect the structural integrity of collagen in the bone matrix, thus altering fracture strength.
- Vitamin D deficiency in the diet can reduce the absorption of calcium and phosphorus, thereby leading to chondroplasia and rickets.
- Vitamin E, which has strong antioxidant properties, helps maintain normal muscle structure and peripheral blood vessel function. Thus, a deficiency of vitamin E can lead to muscle dystrophy, resulting in impaired mobility and an increased incidence of leg deformities, particularly lateral or medial deviation of the distal tibia or proximal talus.
Strict control of mycotoxins in poultry feed is a key measure for reducing leg problems in chickens. Mycotoxins cause skeletal disorders such as rickets by impairing the liver and kidneys’ ability to convert vitamin D3 and absorb it. Storage of feed under proper temperature and humidity, control of insects in feed, and chemical treatment with formic acids are all effective means of controlling mycotoxins and preventing leg disorders and other health-related issues.
Nervous system diseases: Vitamins
Riboflavin, or vitamin B2, is an essential water-soluble vitamin involved in energy production and the metabolism of fats, proteins and carbohydrates. Riboflavin deficiency is associated with demyelination of peripheral nerves and consequent difficulties with locomotion and other neurological problems.
Vitamin E deficiency may cause nutritional encephalomalacia or Crazy Chick disease, which is characterised by brain damage (softening/necrosis), loss of coordination, tremors, convulsions, paralysis and often death. The disease can be prevented by providing fresh, balanced feed with an adequate supply of vitamin E. Supplementation of selenium at a dietary level not exceeding 5 mg/kg has been reported to enhance the preventive effect of dietary vitamin E.
Tuberculosis: Vitamin A
There is a linear relationship between dietary vitamin A intake and diseases associated with M. tuberculosis. Increasing the level of this vitamin from 2,200 to 4,400 IU/kg results in increased serum immunoglobulin specific to this infection and reduced mortality.
Sudden death syndrome (SDS): Energy regulation
Sudden death syndrome (SDS) is a metabolic problem that occurs in all countries where broilers are grown rapidly under intensive conditions. Mortality may start as early as three to four days, but most often peaks at around three to four weeks of age, with the affected birds being found dead on their backs. Mortality may range from 1.5 to 2.0% in mixed-sex flocks and as high as 4% in male flocks. Reducing energy intake by changing feed texture or density (mash), or management methods such as feed restriction or long dark periods, will reduce mortality from SDS. A mortality level of 0% has been reported for feed-restricted birds compared to 3.33% under ad libitum feeding.
Natural additives: Disease prevention
Onion powder: It was found that the incorporation of onion powder (Allium cepa) at 5 kg/tonne in broiler diets as a feed additive significantly minimises coccidian infection and susceptibility to other diseases through improved feed conversion ratio, weight gain and feeding efficiency in treated chickens, with a subsequent reduction in mortality rate in comparison to other birds in the control group.
Black cumin (Nigella sativa) is another natural product that can be used in poultry feeding. It contains about 30% protein, most of the essential amino acids, and has a biological value of 1.6 compared to a value of 1.2 for most grains commonly used in poultry feeding. In one feeding experiment, the incorporation of 2% black cumin into laying diets improved egg production, increased male fertility and increased hatchability. This was attributed to the stimulatory effect of black cumin on the thyroid gland and its inhibitory effect on bacterial infections, which, in turn, improves the birds’ general health and production.
Chilli pepper (Capsicum annuum) has also been proven to play an important role in improving the immune function of broilers. It increases the bursa of Fabricius weight relative to body weight compared with broilers in the antibiotic and control groups. The bursa of Fabricius is an essential immune organ in broilers, and its relative weight is a key indicator of health status. In addition, lower concentrations of pro-inflammatory cytokines were observed in broilers fed the capsicum extract, showing the extract’s anti-inflammatory effects in broilers, which are attributed to its effective regulation of the pro-inflammatory factors.
Garlic powder (Allium sativum) has also been successfully used in feeding poultry. It helps overcome the problems of the formation of varying amounts of undesirable cholesterol resulting from the greater amount of saturated fatty acids relative to the unsaturated ones in each molecule of fat formed in the chick’s body. It was found that incorporating 3-5% garlic powder into the diet increased the activity of enzymes that convert cholesterol into bile acids, which are eventually catabolised in the body, so a negligible amount is disposed of in the carcass.
