The attention of the consumer dollar was being divided on non-essential items which meant less was spent on food, he said.
Carter stood down as chairman last month, he told the Herald on Monday.
There was a number of things that influenced pork sales.
"There are triggers like school holidays where the pig industry comes under pressure people go out and eat more often, fast food gets a lift, traditional meals are consumed less often."
During a Lotto jackpot the industry ended up with excess pork.
"People seem to spend less on protein foods."
The difference between the pork industry and other industries is that they didn't have a seasonal production system, however there were seasonal consumer trends.
During those off times, after Easter and before Christmas, was when the industry lifted the amount of promotion it was doing in a bid to curb the trough in the season.
"We try to understand consumer trends and behavior to mitigate downsides for farmers.
"It's recognising short weeks and recognising it is a celebratory meat. It is for special occasions, the only protein that can be eaten for three meals."
The information on spending habits was taken from vendors' feedback nationwide letting the industry know what weeks were good and what was bad.
A Lotto jackpot would almost always result in a low sales week
"This is from feedback from vendors saying sales are up or down."
The industry was coming under hard times fighting for the attention of local consumers and the import pork market.
Currently 42 per cent of pork was produced in New Zealand and 58 per cent was imported.
46,000 tonnes of pork was produced a year and on average 23kg of pork was consumed per year.
"This time of the year is an off period for the pig industry, it goes flat. Consumption and demand comes up for Christmas."
Director of MEAT David White said during his time with Carter the bizarre connection of pork and Lotto was raised.
"Sometimes these declines would happen for one week, at others for two or sometimes three or more.
"It made little sense until someone made the connection between that and Lotto jackpotting,' White said.
A Countdown spokeswoman said sales could fluctuate for a number of reasons such as "price, the time of year, specials, seasons" so it was hard to say what impact Lotto had specifically on pork sales.
"Christmas is obviously the country's biggest ham season."
Foodstuffs and Lotteries New Zealand were also contacted on Monday night for comment.
