Rooney Mara, who welcomed her son, River, with Joaquin Phoenix back in September of 2020, commemorated her first Mother’s Day with an open letter celebrating all mothers of the animal kingdom.

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The message was published in partnership with animal protection organization Farm Sanctuary on behalf of its Mother’s Day fundraising campaign. In its released quotes, the Carol actress expressed her sentiments on the universal sanctity of motherhood, particularly in the wake of the globe’s ever-increasing economic and environmental crises, and highlighted the invaluable purity of bond shared between a mother and child.

“As a new mom, Mother’s Day has taken on a special meaning this year,” she wrote. “Raising our baby, River, has opened my heart to a whole new life filled with hope and more determination than ever to create a kinder and more sustainable world.” She added, “I feel so fortunate to be able to nurture my son in all of the ways that nature intended, and I wish all mothers in the animal kingdom could experience that sacred maternal bond with their young, devoid of exploitation by humans.”

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An outspoken animal rights activist, Rooney advocates for sustainable, cruelty-free means of living and a decreased global dependence on the meat industry. For instance, she cofounded in 2018 the high-end vegan fashion line Hiraeth. (Stranger Things actress, as well as fellow vegan, Sadie Sink was the first to wear the label on the red carpet.) In 2019, Mara led National Animal Rights Day alongside Phoenix in a summer demonstration. And later that same year, she released a documentary with anti-animal cruelty organization Animal Equality,titled With My Own Eyes, which exposes the horrific extent to which farm factories enforce inhumane conditions on captive animals in slaughterhouses.

Particularly disturbed by the degrading conditions of pig maternity wards, she reflected, “I kept thinking about my sister who just had a baby, and thinking about how beautiful that was—that instant desire to nurture and protect your child. So I can’t imagine how awful it must be to be literally trapped and crushing your own babies and not be able to do anything about it.”

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Mara’s remarks serve as a reminder that humans are not the only animals to be celebrated and cherished this Mother’s Day. The actress continues to raise awareness of the oppressive conditions of any and all forms of motherhood, and hopes that it will in some way push institutional reform in the meat industry. “You have to at least acknowledge and look at where this is coming from and what is happening to these animals,” she reportedly said.

This article originally appeared on Harper’s BAZAAR US