The restrictive laws have taken hold so far in states that have relatively small agriculture industries for animals and animal products and fewer large-scale farming operations. But producers in big farming states see the writing on the wall. Backed by state farm bureaus, large-scale industrial farmers are pushing for changes that would make it harder for states to further regulate the way they do business. North Dakota and Missouri adopted amendments in the last few years that enshrined into their constitutions the right of farmers and ranchers to use current practices and technology. Legislatures in many states, including Indiana, Mississippi, Nebraska and West Virginia, considered proposed amendments this year. And Oklahoma voters this month rejected a similar amendment sent to them by the Legislature. Farmers acknowledge that some people who do not spend much time on farms may object to some of their practices. But they say that they do not abuse animals and that their practices are the most efficient and safest way to keep up with demand for food. And, they say, complying with restrictions on raising poultry and livestock like those approved in Massachusetts are costly for them and for consumers.