In this case, a farmer must run more fans to bring in more clean fresh air. Newer vaccines, including molecular recombinants in which genes of immunogenic proteins from infectious agents are inserted into a live viral vector, are also being examined for commercial use. As of April 1, 2017, no new battery cages are able to be installed in Canada. Smallholder poultry production has an important role to play in feeding the world and, to maximise the benefits, it should be accompanied by improvements to local health services and holistic programs that highlight the links between poultry production, human health and nutrition and sustainable ecosystem services. Water is usually provided by overhead nipple systems, and food in a trough along the front of the cage replenished at regular intervals by a mechanical system. This is particularly true for food safety and microbiological quality control. Broilers are not raised in cages.  This is a result of the increased activity in the hens from the additional space and enrichment provided in the furnished housing system. The benefits of higher welfare indoor systems are the reduced growth rate, less crowding and more opportunities for natural behaviour. As fish are poikilotherms, the magnitude of the immune response in most fish is profoundly influenced by water temperature, which may play a causal role in seasonal viral disease patterns in both captive and wild fish populations. , Because broilers are relatively young and have not reached sexual maturity, they exhibit very little aggressive conduct. It has been previously hypothesized that these challenges are, at least in part, responsible for many myopathic conditions and muscle defects that are increasing in both incidence and severity (Velleman, 2015). Thus, the flock prevalence in Danish broiler flocks was reduced from approximately 70% in 1990 to few percent since 2001. The first attenuated vaccine was developed by Louis Pasteur (who was also the first to coin the term “vaccination” in homage to Edward Jenner), in this case to the causative agent of fowl cholera, Pasteurella multocida. In contrast, the table-egg industry is changing rapidly due to animal welfare concerns, particularly in developing countries, and egg-laying hens are now produced in a multitude of systems requiring different types of management expertise. A further application of mass depopulation is to rapidly kill poultry in response to natural disasters, building collapses, and other unpredictable events. Conventional methods for detection, enumeration, identification and classification of microorganisms are described in texts such as the Compendium of Methods for the Microbiological Examination of Foods (Vanderzant and Splittstoesser, 1992), Official Methods of Analysis of the Association of Official Analytical Chemists (AOAC, 1990), the Bacteriological Analytical Manual (FDA, 1992), Standard Methods for the Examination of Dairy Products (APHA, 1985) and Modern Food Microbiology (Jay, 1992). The larger the bird is grown the fewer chickens are put in each house, to give the bigger bird more space per square foot. By 2009, more than 95% of meat chickens (broilers) in the United States were vaccinated by this method. With a 1.80 to a 2.0 feed conversion ratio. Many took to dumping the waste into any available water bodies close to the farm or factory.