You should do a literature review to find the appropriate values for both sensible heat production (SHP) and latent heat production (LHP).
From a cursory look, it looks like there is readily available data in the literature, usually expressed in $W/kg$ of poultry.
Here's one example, taken from a 2003 article "Sensible and Latent Heat Productions from Broilers in Laboratory Conditions" (PDF):
When initial DB temperature was 24.8 ± 0.2 °C and RH was 71%, SHP and LHP were 2.1 ± 0.3 W/kg and 4.0 ± 0.4 W/kg respectively
This other 2001 Article "Heat and Moisture Production of Poultry and Their Housing Systems: Broilers" (PDF) includes regression analysis of heat production as a function of a few parameters such as body mass (kg), air temperature, etc. It might be useful to draw conclusions if your broilers are in non-standard conditions for eg, but it also show you heat production as a function of body mass (which is by design the goal of the growth cycle...)
Speaking about harsh conditions (but really mostly because I find it hilarious), this 2004 paper "Ventilation, Sensible Heat Loss, Broiler Energy, and Water Balance Under Harsh Environmental Conditions" (PDF) could be of interest, and most of all has this picture of an IR chicken that I can't resist sharing:
Once you have this data, and knowing the poultry density and average body mass, in E+ you can use a People
object to describe your poultry by adjusting the input as necessary.
Is there a human-to-chicken conversion factor you can use to scale down the occupancy, e.g., 1 person is the equivalent of 20 chickens? Also, this is BY FAR my favorite UnmetHours question of all time. There isn't a close second.
Hahaha! As much as I love the new "chickens" tag, I don't know if we should keep it as it might not be used that often ;)
trying to be constructive here... I think a better keyword would be "agricultural buildings" or "agriculture". When I was modeling evaporative cooling about 20-30 years ago, I found that it was used widely in poultry farms as an economical way to reduce indoor temperatures, so I hope that you consider evaporative cooling in your simulations. As far as how outlandish the question about chicken heat gain might seem, it seems perfectly appropriate for the circumstance. I still remember chuckling that the ASHRAE HOF has values for the latent heat content of broccoli.