search.noResults

search.searching

saml.title
dataCollection.invalidEmail
note.createNoteMessage

search.noResults

search.searching

orderForm.title

orderForm.productCode
orderForm.description
orderForm.quantity
orderForm.itemPrice
orderForm.price
orderForm.totalPrice
orderForm.deliveryDetails.billingAddress
orderForm.deliveryDetails.deliveryAddress
orderForm.noItems
HEAL ▶▶▶TH


and within sheds is paramount, including dedicated clothing and footwear per shed, avoiding the movement of equip- ment between houses and on and off farms, along with con- sistent and effective rodent and insect control. On top of the basics, the complete and effective removal of litter between flocks is recommended, especially after an out- break. Clean out may require an extended period of time in addition to the use of an appropriate cleaning and disinfec- tion protocol. Reducing primary disease carriers/intermediate hosts is one of the key steps in the strategy for blackhead control. Consistent, early and scheduled worming following veterinarian advice, will help reduce exposure to cecal worms and eggs and the Histomonads they carry. The most effective solution may be to treat for more than one day (3-5 days). Product rotation is also recommended every 3-4 flocks, or when a product appears to be ineffective. Deworming pro- grammes need to take into account the parasite prepatent period (24-36 days) when establishing the frequency of the treatments.


Cecal lesions to- gether with liver lesions are rep- resentative of a blackhead infection.


with liver lesions are representative of a blackhead infection. On a microscopic level the protozoa can easily be found in af- fected ceca and livers. This may be confirmed with histopa- thology by taking tissue samples to confirm the presence of histomads, at least for the first case in an outbreak.


Control and prevention Due to the limited number of medications available to treat blackhead, prevention is the key. Good biosecurity between


Vaccination Histomonas vaccination based upon an attenuated clonal strain of H. meleagridis has been shown to be highly effective in experimental trials. Further efforts are needed to standard- ise production and optimise administration of the vaccine in the field, plus there is no commercially available vaccine. Re- cent research has shown that allowing conditions that im- prove bird comfort and reduce stress may reduce the chance of the birds showing clinical disease, even in the presence of Histomonas.


Reducing vector and co-factors of blackhead


Besides cecal worms and earthworms, other organisms may serve as mechanical disease carriers. • Control measures should include the reduc- tion of darkling beetles, flies, and rodents and other pests. There should be zero tolerance for the presence of pests. • Minimise the possibility of flooding that may increase the presence of earthworms. • Disinfect any flooded areas to reduce the potentially increased presence of earthworms in dirt floor housing.


Coccidiosis Blackhead is more likely to spread to the liver when coccidiosis is not under control. • E. tenella, in particular, has been identified as an aggravating factor for blackhead.


16


• The number of birds with severe lesions in- creases when both Histomonas and E. tenella are present in the bird. • In many instances there have also been blackhead cases identified right after active infections of E. necatrix, E. brunetti and E. maxima.


Intestinal health With the withdrawal of effective treatments, there is growing interest in the development and use of alternative intestinal health prod- ucts to mitigate blackhead disease issues. • Proper brooding management. • Nutritional products include: prebiotics, probiotics, organic acids, plant extracts, essential oils, enzymes, and volatile fatty acids, among others.


▶ POULTRY WORLD | No. 5/6, 2021


• There is limited research currently available which supports the effectiveness of these products.


Control of E. coli Although H. meleagridis is considered the causative agent of blackhead, it has been demonstrated that the parasite fails to cause clinical disease in the absence of bacteria. Several control strategies for E. coli have been used that appear to decrease the severity of blackhead or may help in the face of an outbreak. • Live or inactivated E. coli vaccines. • Organic acids via feed or water. • Yeast cell-based products that trap the bacteria and minimise their replication in the ceca.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44