On Charity Entrepreneurship’s blog we’ve just published our first priority report that is part of ongoing research process so there will be more reports coming. We expect to go through 4 phases of research that will progressively narrow down a very large option space in order to arrive at 2-5 recommended charities to found in the animal advocacy movement.
Our priority ask reports are focused on what are the particular improvements or changes that can be “asked” for from corporations, governments, or individuals. This particular report is focused on the food fortification of factory farmed animals’ feed. It considers multiple micronutrients and supplements that could be added to an animal’s feed to increase its welfare.
You can download the full report here: http://www.charityentrepreneurship.com/blog/food-fortification-of-factory-farmed-animals-food-ask-report
Something I looked for in the report, but didn't spot: Are there any small higher-end meat producers, known for treating animals more humanely than the biggest producers, who have tried to optimize their feed in the way you describe, and maybe even measured the results?
Given the sheer number of farms in the world, and the growing trend in farms trying to appeal to meat-eaters with at least a mild concern for animal welfare, I'd be surprised if farmers weren't experimenting with different feed mixes they'd created themselves.
Short response:
Some farms (e.g. GAP farms) do have better nutritional practices, although there is not great specific data from them. That being said, there is other evidence that both calcium has an impact and theoretical reasons why a large number of farms would not supplement well. Farms do experiment with food a lot but not generally with welfare in mind. It’s not currently an issue at the front of consumers’ minds.
Longer response:
One of the requirements for Global Animal Partnership (GAP) certified farms is "Hens must be provided with sufficient calcium in their diet to maintain hen's health and eggshell quality." There are approximately 20 chicken farms signed up to this program and they might provide an adequate level of calcium. Welfare of hens is measured individually for every farm, but according to my knowledge, they are not conducting any studies. Fortunately, evidence base for calcium and phosphorus supplementation is pretty strong. For example, according to this analysis for hens at age 462-543 days of life increasing dietary calcium
from 24-25 to 36-40 g/kg decreased mortality by 5.5% (22.8% -> 17.3%) and improved egg production, shell weight (SW) and shell thickness (ST)
from 36-40 g/kg to 49 g/kg by next 5.4% (17.3% - 11.9%) but did not affect egg production but increased SW and/or ST.
Farmers do prepare their own fortified feed premixes, but it is unlikely that they provide an adequate level of nutrients because the currently recommended dosage is not optimal. One study compared turkey's health benefits of currently recommended by National Research Council (NRC) dosage of phosphorus and diets that were 0.06% higher than NRC recommended levels; 0.1% higher than the medium diet, and 0.1% higher than the high diet.In addition to lower body weights, turkeys fed with the NRC recommended diet had higher incidences of bone fractures and reduced the walking ability, indicating that feeding nonphytate phosphorus at levels above NRC recommended levels resulted in improved growth and better skeletal integrity compared to NRC recommended levels. Similarly, the level of calcium can affect skeletal properties and body weight. For example, Tatara et al. (2011) reported improved skeletal properties and increased body weights in turkeys provided with 95% or more of NRC recommended calcium compared to those provided with 85% of NRC recommended calcium. (source, page 281)
Additionally given that economically, phosphorus is the third most expensive component in a non-ruminant diet after energy and protein, it is less likely that chickens in the standard farm have an adequate level of this mineral. One of the biggest feed distributors, DSM, that additionally seems to focus on animal welfare outside of the profitability of having healthy animals, supplement feed with vitamins, but not dietary minerals like calcium.
The evidence is strong enough to research this, ask more deeply, and we are planning to conduct more research to determine the exact level of nutrients in chicken's diet and evaluate the change in welfare points cause by fortification. Interestingly, feed (as well as chickens) is often provided to the farmers by large food companies (e.g. Tyson Foods who contract out the raising of the birds to the farmers, so we will compare the level of nutrients added by Tyson Food to the optimal dosage to determine if the ask is still more cost-effective than other interventions we are investigating.