As soon as the testicles have desended I believe, which happens around 6 months, or earlier, I think. However, unless a female is in heat she cannot get pregnant. Females generally have their first heat between 6 & 12 months of age though. So a 5 & 7 month old pair is very risky. That is plenty old enough to get spayed & neutered even for the most conservative vet or owner.
A sirloin roast of 8- to 12-lbs will take 16-20 minutes for rare, 20-22 for medium rare, 23-25 for medium, and 26-30 for well done. A boneless top round, by contrast, will take 28-30 minutes for rare, 30-33 for medium rare, 34-38 for medium, and 40-45 for well done.If you roast at 325Â°F (160Â°C), subtract 2 minutes or so per pound. If the roast is refrigerated just before going into the oven, add 2 or 3 minutes per pound.ow long and at what temperature should I cook a beef roast in the oven? Roasting is a great cooking method for a large, tender cut of beef  such as a rib or sirloin roast.
The secret to tender, moist top round roast is to cook it slowly in a small amount of liquid. Spray the bottom of a pan that has a tight lid with vegetable spray. Add two tablespoons of oil. Season the roast and brown the top round, on all sides, over moderately high heat.Add the braising liquid to the meat in the pan.You will need one fourth of a cup of liquid for a four pound roast. Use beef broth, leftover wine, dark beer or water. Choose from A, B or C below for the cooking method.dd two tablespoons of oil. Season the roast and brown the top round, on all sides, over moderately high heat. Add the braising liquid to the meat in the pan. You will need one fourth of a cup of liquid for a four pound roast.