The bitch is responsible for the size of a litter-- because litter size is primarily dependent on the number of eggs that are released. So our male dogs have little to do with litter size unless they are not producing any or very few live sperm.
That said, male dogs can produce viable sperm into their teens, although my research is that the quality is not as high after 6 or 7 yrs of age-- it is usually good enough to use in natural breedings but not as long lived and therefore not optimal for freezing or doing fresh chilled. I use progesterone testing prior to my breedings, even natural ones, but I would consider it a must when breeding a male over 6 yrs old just like it would be a must if doing AI using shipped sperm. It helps increase the chances of live sperm meeting fertile eggs.
I have a male papillon with a propensity for producing girls-- one male and ten females to be exact. Of course all I have really been wanting out of him is a boy LOL! |