Key result
In ovo Marek's vaccination does not harm early chick quality while 18-hour holding worsens outcomes.
Why the study?
Does in ovo administration of Marek's disease vaccine compared to subcutaneous administration affect early post-hatch quality in broiler chicks?
RCT (n=3,900)
Randomly set
Does in ovo administration of Marek's disease vaccine compared to subcutaneous administration affect early post-hatch quality in broiler chicks?
In ovo administration of the Marek's disease vaccine is a viable alternative to subcutaneous injection that does not negatively impact early post-hatch chick quality.
Supports in ovo Marek's vaccination as alternative without harming early chick quality; leaves open validation in commercial poultry settings.
Effects of method of administration [moa; in ovo (i.o.) or s.c.] of the Marek's disease vaccine and pre-placement holding time (pht) on early post-hatch male broiler chick quality was investigated. Sixty-five Ross × Ross 708 broiler hatching eggs were randomly set in each of 15 replicate trays (blocks) belonging to each of 4 pre-assigned moa and pht treatment combinations (3,900 total eggs) in a single stage Jamesway incubator. Eggs that were i.o.-vaccinated received injections at 18 d of incubation and male chicks from eggs that were not i.o.-injected were vaccinated by s.c. injection at hatch. The i.o. injections (50 μL) were delivered by a commercial multi-egg injector and the s.c. injections (200 μL) were delivered by an automatic pneumatic s.c. injector. Male chicks from each moa group also were subjected to either a 4 or 18 h pht. At hatch and placement total and yolk-free BW; body length; body mass index; yolk sac weight; yolk-free body and yolk sac weights as percentages of total BW; and yolk-free body and yolk moisture concentrations were determined. Chick BW also was determined at 7 d of age. Hatchability of fertile eggs was not affected by i.o. injection. However, at hatch, body length was increased and body mass index was decreased in response to i.o. injection. No main effect of moa or an interactive effect with pht was observed for the above variables at placement. However, body length was longer and body mass was lower in the 18 h than in the 4 h pht chicks. Placement yolk sac and body weights, and the 7 d BW of 18 h pht chicks was also lower than that of 4 h pht chicks. In conclusion, prolonging pht for 14 h adversely affected early chick quality, whereas i.o. injection did not negatively affect the early post-hatch quality of Ross × Ross 708 broiler chicks whether or not they were held for 4 or 18 h prior to placement.
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Peebles et al. (2016) conducted an RCT in Marek's disease vaccination in broiler chicks (n=3,900). In ovo administration of Marek's disease vaccine vs. Subcutaneous administration (200 μL) was evaluated on Early post-hatch chick quality (hatchability, body weight, body length, body mass index). Prolonging pre-placement holding time to 18 hours adversely affected early chick quality, whereas in ovo injection of Marek's disease vaccine did not negatively affect early post-hatch quality.
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