A copyright gives the creator of a literary, artistic, musical, or other creative work the sole right to publish and sell that work. This work includes photographs and in fact according to the Federal Copyright Act of 1976, photographs are copyright protected the moment they are created. It is not necessary to formally register a copyright, however it may be beneficial in order to give notice to the public that a copyright exists and deter another person from using a photographers work as their own.
If a person uses someone else’s image without their permission it is known as copyright infringement. See Copyright.gov, Copyright in General, https://www.copyright.gov/help/faq/faq-general.html#what (last visited February 29, 2020) and See Copyright.gov, Photographs, https://www.copyright.gov/registration/photographs/ (last visited February 29, 2020)
Professional photographers at livestock shows have a copyright on each image they take. Whether or not the photographer watermarks or files a copyright on the photos, they are considered the property of the photographer and sharing or printing these photos would be copyright infringement. Likewise, photographs taken by farm or ranch owners of land or livestock, are property of the photographer and may not be reproduced without the photographer or image owner’s permission.