More than 40 million farm animals are estimated to die each year in the UK before they reach the slaughterhouse, according to a report to be published this week which urges the government to introduce measures that would compel farmers to disclose the numbers.

The report, The Uncounted Dead: Farming’s unofficial victims, by Animal Aid, an organisation opposed to meat eating, is the first to put a figure on the number of animals that die before slaughter. The true number is currently unverifiable because neither the government nor the industry collate or publish data on animal fatalities. Farmers are required to report an animal’s on-farm death only if it is caused by a notifiable disease, such as foot and mouth or BSE.

In 2013, more than 989.6 million farmed animals were slaughtered for meat in the UK, according to official figures. Of these, 2.6 million were cattle, 10.3 million pigs, 14.5 million sheep, 17.5 million turkeys and nearly 945 million chickens. Based on the percentages of animals that do not make it to slaughter, quoted in the farming trade press, Animal Aid estimates that each year some 250,000 cattle, 750,000 pigs, 750,000 turkeys, 2.5 million sheep, 38 million chickens and 600,000 rabbits, ducks, and geese die before they are slaughtered for human consumption.

In total, Animal Aid estimates around 43 million farmed animals die each year before they can be slaughtered, their deaths caused by disease, exposure, starvation, fires, floods, road crashes and neglect.

Among the case studies cited in the report are 700,000 chickens that drowned last December in sheds on two Lincolnshire farms hit by a massive tidal surge. Other cases include the 2,000 pigs that perished in a fire in East Lincolnshire in February 2010 and where an additional 670 died in a second blaze six months later, and that of 50 lambs that plummeted to their deaths into a well on a farm in Shropshire.

The report also highlights the example of a lorry that was carrying nearly 7,000 former egg-laying hens that crashed in May 2014 on the M62, leaving 1,500 birds dead and many more with severe injuries.

Andrew Tyler, Animal Aid’s director, acknowledged that his organisation was opposed to meat eating and had an agenda in producing the report, but suggested that all consumers had an interest in animal welfare.

“Whether people are meat eaters or vegetarians, it will surely be of concern to them that millions of farmed animals perish every year as a result of fires, floods, road collisions, disease and neglect,” Tyler said. “Moreover, these casualties, whose deaths are often traumatic and agonising, receive virtually no official recognition. No figures are published pointing to the true scale of the phenomenon and there are scant regulatory measures in place to reduce, for instance, the incidence and impact of farm fires and flooding.”

Tyler suggested that the meat industry’s desire to keep food costs down could be having an effect on animal mortality rates.

“Many of the problems outlined in our report result from the commodification of farmed animals,” he added. “With producers and retailers intent on maximising their profits and reducing their costs, the lethal and traumatic consequences are felt by animals in farms around the country. In fact, as we now see, many millions die even before they can be slaughtered.”

In response to the report, Derby North MP Chris Williamson is to table a series of parliamentary questions calling on the government to publish accurate pre-slaughter mortality figures. He said he also wanted to see the introduction of mandatory hazard inspection regimes and emergency evacuation plans, to minimise the risk posed by farm fires, and a prohibition on farmers rearing animals in sheds on flood plains.

“I know that some animals die before they reach the slaughterhouse, but I was staggered by the scale of the deaths revealed by Animal Aid’s disturbing report,” Williamson said. “With as many as 43 million farm animals killed by fires, floods, disease or poor husbandry every, year before they even reach the abattoir, Defra [the department for environment, food and rural affairs] must take action. The secretary of state should instruct her officials to map and publish the scale of the problem, and then introduce mandatory new safeguards to minimise this suffering.”

But Phil Bicknell, head of food and farming at the National Farmers Union, said UK farms were already subject to stringent compliance visits: “I think it’s fair to say that the UK has some of the best welfare standards and health status of most other countries in Europe. Ultimately, it is not in a farmer’s interest to have high farm mortality as it clearly impacts on the farms’ profitability.”

He said he was not swayed by the argument for farmers to collate the number of their animals that die before slaughter: “We’re looking for government to address the issue of red tape on farms rather than increase it. Regulation is the number one issue that negatively impacts on our members.”