WASHINGTON — The House Agriculture Committee has approved a five-year farm and nutrition bill that gives farmers new ways to protect themselves from bad weather and poor prices and slices about 2 percent off the $80 billion the government spends every year on food stamps. The 35-11 committee vote comes three weeks after the Senate passed its version of the half-trillion-dollar bill and shifts the focus to the full House as Congress seeks to come up with a consensus bill before the current farm bill expires at the end of September. House Republican leaders have shown little enthusiasm for taking up legislation that faces opposition from conservatives who say it is too expensive.