Like California, at least five other states (Massachusetts, Michigan, Ohio, Oregon, and Washington) have passed laws that will eventually limit the use of so-called battery cages in egg production, and retailers like Walmart and McDonald's have made pledges to do the same. Because this move started earlier in California, and due to the size of that state and the volume of egg production there, California represent a good case to analyze the effects of these laws.
While I've written on this topic a number of times here on the blog (e.g., here), Conner Mullally and I have finally pulled together a revision of our earlier work that is much more comprehensive and hopefully informative.
One question that I haven't seen much addressed is: what happened to egg production in California as result of their animal welfare laws (these laws include passage of Proposition 2 by voters in 2008 which banned the production of eggs from battery cages and the subsequent passage of state law AB 1437 which banned the sale of eggs from battery cages - both were ultimately enforced on January 1, 2015 via California Department of Food and Agriculture (CDFA) rules)?
Before all of this went down, Dan Sumner and other researchers at UC Davis warned that passage of Prop 2 could lead to an exodus of California egg producers and lead California retailers to increase imports of eggs from other states (that's one reason state law AB 1437 came into being - to try to prevent this outcome). The chart below shows our analysis of the number of egg laying hens in California, which generally confirms the UC Davis researcher's conjecture made back in 2008.
We estimate that:
Here is a graph of egg imports into the state, which Conner obtained via a FOIA request from CDFA, along with egg production in the state.
In addition to these production impacts, we were also interested in the impacts on prices paid by food consumers. To address this issue, we obtained retail scanner data from Nielsen.
Here is a graph of the actual (or observed) price of eggs in California compared to our prediction of what egg prices would have been had the new animal welfare laws not gone into place.