Immunological effects of ractopamine in rabbits receiving the viral inactivated rabbit hemorrhagic disease vaccine.

Background: There is an obvious lack of information about the effects of ractopamine, a ß-adrenergic agonist, on the growth performance and immune responses of rabbits, particularly in those receiving the viral rabbit hemorrhagic disease (RHD) vaccine.

Aim: The current study was undertaken to study the effects of ractopamine on growth performances and immunological parameters in rabbits inoculated with the viral RHD vaccine.

Methods: Experimental rabbits were grouped into four groups, the first acted as a control and received distilled water, the second received ractopamine, the third received inactivated RHD vaccine, and the fourth received both ractopamine, and inactivated RHD vaccine.

The potency of newly development H5N8 and H9N2 avian influenza vaccines against the isolated strains in laying hens from Egypt during 2019.

Avian influenza (AI) is a respiratory disease complex syndrome recently recorded in vaccinated flocks causing high economic losses. This study aimed to prepare inactivated vaccine from recently isolated field strains [highly pathogenic avian influenza (HPAI) (H5N8) and low pathogenic avian influenza (LPAI) (H9N2)] and compare the efficiency of the two experimental avian influenza vaccines and some commercial avian influenza H5 and H9N2 vaccines in laying hens. The obtained results indicated that the identified experimental vaccines (H5N8 and H9N2) were protected the flocks from AI as compared to commercial H5N1, H5N3, and H9N2 vaccines, which showed a protection level of 80, 70, and 90%, respectively, indicating a high efficacy for the developed vaccines.