Global segment net sales declined $133.8 million, or 13%, to $923.4 million. Volume declined 12%, primarily due to the decline in demand for frozen potato products outside the home as a result of the pandemic’s negative impact on restaurant and other foodservice-related traffic in the U.S. and in most of our key international markets. Price/mix declined 1% as a result of negative mix.
Foodservice segment net sales declined $132.5 million, or 22%, to $477.8 million. Volume decreased 27% due to the decline in demand for frozen potato products outside the home as a result of the pandemic’s negative impact on restaurant and non-commercial customers, such as lodging and hospitality, schools and universities, sports and entertainment, and workplace environments. Volume trends weakened during the latter weeks of the quarter, reflecting the negative impact on restaurant traffic, especially at full-service restaurants, related to government-imposed social restrictions and reduced outdoor dining due to the onset of colder weather. Price/mix increased 5%, reflecting the carryover benefit of pricing actions implemented during fiscal 2020, partially offset by unfavorable mix as sales of Lamb Weston branded and premium products softened.
Retail segment net sales increased $33.2 million, or 13%, to $294.6 million. Price/mix increased 7%, largely driven by favorable mix from increased sales of branded products. Volume increased 6% due to increased sales of frozen potato products for in-home consumption following government-imposed social restrictions. Sales volumes of premium and mainstream branded offerings more than offset the decline in sales volumes of private label products, which reflects incremental losses of certain low-margin private label business.
Net sales in our Other segment declined $7.5 million, or 9%, to $71.8 million, compared with $79.3 million in the first half of fiscal 2020, largely due to lower volumes in our vegetable business, partially offset by favorable price/mix.
Product Contribution Margin
Compared with the prior-year period, Lamb Weston’s product contribution margin for the first half of fiscal 2021 declined $89.3 million, or 17%, to $433.6 million. The decline was driven by lower sales due to the pandemic, as well as higher manufacturing costs, which were largely due to COVID-related costs, and input cost inflation.
Global segment product contribution margin declined $61.1 million, or 26%, to $170.5 million in the first half of fiscal 2021. Lower sales volumes, higher manufacturing costs and unfavorable mix drove the decline. Global segment cost of sales was $751.8 million, down 9% compared to the first half of fiscal 2020, primarily due to lower sales, partially offset by the higher manufacturing costs described above.
Foodservice segment product contribution margin declined $40.3 million, or 19%, to $173.5 million in the first half of fiscal 2021. Lower sales volumes, higher manufacturing costs, and unfavorable mix drove the decline, partially offset by favorable price. Cost of sales was $302.9 million, down 23% compared to the first half of fiscal 2020, due to lower sales volumes, partially offset by the higher manufacturing costs described above.
Retail segment product contribution margin increased $8.5 million, or 15%, to $65.9 million in the first half of fiscal 2021. Higher sales volumes, favorable mix and a $4.3 million decline in advertising and promotional expenses drove the increase, which was partially offset by higher manufacturing costs. Cost of sales was $227.8 million, up 15% compared to the first half of fiscal 2020, primarily due to higher sales volume and the higher manufacturing costs described above.
Other segment product contribution margin increased $3.6 million to $23.7 million, as compared with $20.1 million in the first half of fiscal 2020. These amounts include a $12.1 million gain related to unrealized mark-to-market adjustments and realized settlements associated with commodity hedging contracts in the first half of fiscal 2021, and a $7.3 million gain related to the contracts in the first half of fiscal 2020. Excluding these adjustments, Other segment product contribution margin declined $1.2 million, largely due to higher costs in our vegetable business.
Selling, General and Administrative Expenses
Compared with the prior-year period, selling, general and administrative expenses declined $8.2 million, or 5%, to $162.0 million. The decline was largely driven by lower incentive compensation expense, cost management efforts, and