6. Retirement and Postretirement Plans

We sponsor five defined benefit retirement plans. Those plans include: a master defined benefit retirement plan, a nonqualified supplemental executive defined benefit retirement plan, and three defined benefit retirement plans covering employees in Germany and France. Benefits for such plans are based primarily on years of service and the employee's level of compensation during specific periods of employment. We contribute funds to trusts as necessary to provide for current service and for any unfunded projected future benefit obligation over a reasonable period of time. All of our plans have a September 30 measurement date. The following table details the components of net pension expense for our defined benefit retirement plans.

	Quarter Ended December 31
	2015			2014
Service cost	$	1.3		$	1.4
Interest cost		2.7			3.7
Expected return on plan assets		(3.3	)		(4.3	)
Amortization of unrecognized prior service cost, net		0.1			0.1
Amortization of net loss		1.1			1.4
Net pension expense	$	1.9		$	2.3

Beginning in fiscal 2016, we elected to change the method we use to estimate the service and interest cost components of net periodic benefit cost for our defined benefit pension plans to a spot yield curve approach. Previously, we estimated the service and interest cost components of pension expense using a single weighted-average discount rate derived from the yield curve used to measure the benefit obligation at the beginning of the period. Under the new approach, we will apply discounting using individual spot rates from a yield curve composed of the rates of return on several hundred high-quality, fixed income corporate bonds available at the measurement date. These spot rates align to each of the projected benefit obligations and service cost cash flows. The service cost component relates to the active participants in the plan, so the relevant cash flows on which to apply the yield curve are considerably longer in duration on average than the total projected benefit obligation cash flows, which also include benefit payments to retirees. Interest cost is computed by multiplying each spot rate by the corresponding discounted projected benefit obligation cash flows. The spot yield curve approach reduces any actuarial gains and losses based upon interest rate expectations (e.g., built-in gains in interest cost in an upward sloping yield curve scenario), or gains and losses merely resulting from the timing and magnitude of cash outflows associated with our benefit obligations. The change does not affect the measurement of the total benefit obligations as the change in service and interest costs offsets in the actuarial gains and losses recorded in other comprehensive income.

We are making this change to improve the correlation between projected benefit cash flows and the corresponding yield curve spot rates and to provide a better measurement of service and interest costs. This change is considered a change in estimate and is accounted for on a prospective basis starting in fiscal year 2016.

In addition to defined benefit retirement plans, we also offer two domestic postretirement health care plans, one of which was assumed in the acquisition of Welch Allyn, that provide health care benefits to qualified retirees and their dependents. The plans are closed to new participants and include retiree cost sharing provisions. Annual costs related to these plans are not significant.

We have defined contribution savings plans that cover substantially all U.S. employees and certain non-U.S. employees. The general purpose of these plans is to provide additional financial security during retirement by providing employees with an incentive to make regular savings. Company contributions to the plans are based on eligibility and employee contributions. Expense under these plans was $6.1 million and $4.2 million in each of the quarterly periods ended December 31, 2015 and 2014.