Benefit Plans

Our employees ceased to participate in the Pfizer, Inc. U.S. qualified defined benefit plans and the U.S. retiree medical plan effective December 31, 2012, and liabilities associated with our employees under these plans were retained by Pfizer. Pfizer is continuing to credit certain employees' service with Zoetis generally through December 31, 2017 (or termination of employment from Zoetis, if earlier) for certain early retirement benefits with respect to Pfizer's U.S. defined benefit pension and retiree medical plans. Pension and postretirement benefit expense associated with the extended service for certain employees in the U.S. plans totaled approximately $2 million in each three month period ended October 2, 2016, and September 27, 2015, and $5 million in each nine month period ended October 2, 2016, and September 27, 2015.

The following table provides the net periodic benefit cost associated with our international defined benefit pension plans:



	Three Months Ended						Nine Months Ended
	October 2,			September 27,			October 2,			September 27,
(MILLIONS OF DOLLARS)	2016			2015			2016			2015
Service cost	$	3		$	2		$	7		$	6
Interest cost	—			1			2			3
Expected return on plan assets	(1		)	(1		)	(2		)	(2		)
Amortization of net actuarial loss	1			—			1			1
Curtailment gain	—			1			(1		)	1
Net periodic benefit cost	$	3		$	3		$	7		$	9

Total company contributions to the international pension plans were $1 million and $7 million for the three and nine months ended October 2, 2016, and $3 million and $6 million for the three and nine months ended September 27, 2015, respectively. We expect to contribute a total of approximately $9 million to these plans in 2016.