I am a prior vet assistant, and 43 year surgical scrub tech to RN. I can't tell from the photo which organ is outside the body, but any organ exposed is really bad. You don't have access to sterile saline, which is the only thing safe to use to keep the organ wet. The next best thing would be cooled boiled water. If you can't afford or justify the expense of a vet to DO the treatment (surgery and antibiotics for the inevitable infection) then yes, trying to close the wound with ANYTHING would be cruel. I would end her suffering immediately if veterinary treatment (not just vet advice) isn't an option. I can close wounds, and have stapled and sewn more than a few, and done some minor surgery at home, but I would refuse to close this wound on the grounds that the chances of recovery are so slim that trying would be cruel. I'm sorry. Skin tears can be closed (loosely, to allow for drainage) and even some wounds into the muscle. But when the membrane that encloses the organs (called the peritoneum) is torn, peritonitis (inflammation of the peritoneum from infection) follows. It is horribly painful, and without professional surgical intervention and the CORRECT antibiotics at the correct dosage and frequency, the patient will die. Think of untreated appendicitis. This injury is too serious. I urge you to do the kind thing for your duck, and as soon as physically possible.