Dr Steve, you will surely find the article at the following address ;Tropical Animal Health and Production, 2015. Dec;47(8):1531-7. doi: 10.1007/s11250-015-0894-4.
We also inform that similar studies were also conducted with male castrated and female pigs, and the results were all similar to this work. The study conducted with females is published in full here at ENGORMIX: https://en.engormix.com/pig-industry/articles/nutritional-plans-digestible-lysine-t42808.htm