Yeah seems like kangaroo tendons are much stronger than pig/cow ones. Per the article.
Seems pretty obvious, considering the way kangaroo legs work. I'm surprised it took people this long to figure this out, though I guess since pigs and cows are eaten as food so much, there's a huge surplus of their tendons, unlike kangaroos'.
Though according to both the article and comments ITT, kangaroo meat isn’t unheard of in Australia so a surplus does exist. Probably not one for a global application of this procedure, but enough for experimentation. Perhaps by the time we perfect this lab-grown tendons may be a superior source, or other animals can be used.
THere are more Kangaroos than people in Australia, and while it is a food source, there is ample surplus.