
Gizzard Lesions
The muscular stomach or gizzard is located immediately after the proventriculus in poultry. Unlike the proventriculus, which produces a number of juices or enzymes that are used in the digestion or breaking down of food into its constituent nutrients, the gizzard serves a more mechanical purpose, aiding digestion by particle size reduction and regulation of feed flow.
The gizzard consists of a number of layers of tissues, some of which contain straight tubular glands. The innermost layer is a strong, flexible skin that is able to withstand the potentially damaging effects of the muscular action grinding the food, often in the presence of stones or other insoluble material. The glands of the gizzard produce a keratinised liquid material which hardens when in the surface to replace tissue worn away by the grinding action of the organ.
In spite of being a fairly strong organ, the occurrence of gizzard erosion or lesions in the mucosal lining (koilin) of the gizzard is often reported by field veterinarians in broiler and commercial layers operations. In some cases, these lesions are already observed in day-old chicks before placement in the broiler house and prior to feed consumption. For young chicks, studies point to post hatch stress or the presence of mycotoxins in breeder diets (which then carry-over into the egg) as possible factors. For older animals, a whole set of potential causes are worth consideration.
These tables provide checklists of the potential causes, description and corrective actions to take when birds present gizzard lesions or gizzard erosion.
Mycotoxins
Potential cause | Checklist | Corrective action |
---|---|---|
Type A-trichothecenes particularly T-2 toxin and DASMild to severe disruption of the koilin layer, which in severe cases causes lesions in the underlying tissues. |
|
|
Nutrition
Potential cause | Checklist | Corrective action |
---|---|---|
Biogenic amines
| Ensure only high quality fishmeal or animal by-products are incorporated into the diet. |
|
High levels of copper sulphate in dietCuSO4 can promote gastric lesions especially at proventriculus and gizzard level.
| Check formulation to ensure that levels of copper sulphate are at the correct level in premixes. |
|
Rancid fatsLow quality fats (long storage, overheated) can have high levels of superoxide radicals and hydroxyl radicals. | Quality of fats in term of peroxide value, rancidity and free fatty acids. |
|
Acetylsalicylic acid and sodium salicylateUse of salicylates may induce proventriculus and gizzard ulceration. | Level of tannins in some raw materials (sorghum) and in tannin-based products. |
|
TanninsToxic levels of tannins in the feed cause esophageal and gastric edema, hemorrhagic ulceration, necrosis and sloughing of the mucosal lining. |
|
|
Pathogens
Potential cause | Checklist | Corrective action |
---|---|---|
Adeno virus contamination
|
|
|
Newcastle diseaseSlight wounds, hemorrhage and necrosis of proventriculus - more often than generalized lesions. | SPF embryonated chicken eggs test and PCR. |
|
Infectious bursal disease (IBDV/ Gumboro)IBD is very immunosuppressive and causes lesions at the junction of the proventriculus-gizzard. |
|
|
Candida albicans (Candidiasis)Thickening of the mucosa in the crop with white to off-white, raised circular or rugose lesions. | Observation of gross lesions. Diagnosis can be confirmed by demonstrating tissue invasion histologically and by culture of the organism. | Improve sanitation and minimize antibiotic use in poultry. |
Others
Potential cause | Checklist | Corrective action |
---|---|---|
Prolonged periods without feedHyper-production of HCl in the proventriculus causes erosions in the gizzard. | Check that feeder systems are working correctly | Reduction of the transport time. |
Delay in pulling chicks resulting in a long period in the hatcher. | Check egg setting times and egg ages. | Adapt setting times to ensure a short hatch window. |
High temperatures in the hatcher (specially between 17 - 20 days)Hyper-production of HCl. | Check the temperature during the incubation period. | Adjust the temperature and properly calibrate the incubation machines. |