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.
A. To answer your question, beef roasts can be done in a moderately slow oven (325 degrees) and need to be cooked 22-30 minutes per pound, depending on doneness. So for example, a 10 pound beef roast to be done should be cooked approximately 4 hours 10 minutes (at 25 minutes per pound).. To answer your question, beef roasts can be done in a moderately slow oven (325 degrees) and need to be cooked 22-30 minutes per pound, depending on doneness. So for example, a 10 pound beef roast to be done should be cooked approximately 4 hours 10 minutes (at 25 minutes per pound).