HARRISBURG — An admission by state agriculture officials Wednesday that fewer than half the large breeding kennels in Pennsylvania were meeting the full requirements of the 2008 dog law and that the state had decided not to enforce some provisions of the law touched off a series of heated exchanges between officials and animal-welfare advocates. Officials told members of the governor’s Dog Law Advisory Board — meeting for the first time since Gov. Corbett took office 15 months ago — that only 17 of 52 commercial kennels were in compliance with regulations governing temperature, humidity, ventilation, and ammonia levels that were supposed to take effect almost one year ago, prompting one board member to ask why they were allowed to stay in business if they were violating the law.