It's possible nutrition could have some minor difference but it's unlikely to be a ph change. For one it's a totally unproven theory and for two as the wikipedia article states you are very unlikely to change the ph of blood and all the fluids it moves around the body. You can change urinary ph only because it's isolated as a way to maintain body ph. The balance of bacteria also helps maintain ph on surface tissue after fluids leave the blood or where they are stored in tissue and organs. Sweat and saliva are minor ways to change the ph of skin or mucus membranes but that's usually a result of health disorders and will show rashes, swelling, infection, fatigue, and overall unthriftiness as microbe levels become harmful. ******l ph can be altered by direct use of things as some misguided attempts at improved hygiene have shown some women but generally only is modified by foods when unhealthy items damage beneficial bacteria leading to infections. While ******l ph does shift on it's own during estrous cycles if it consistently stays anywhere near the alkaline levels that make much difference for sperm it becomes a health issue. You are usually talking about a difference in ph between the female reproductive tract and sperm of around 4 or possibly greater. I would bet any change you can make for a long enough period of time to plan a breeding is going to cause health issues for the doe.
Because of the body's ability to keep a balanced ph and it's need to do so to avoid health problems if I actually thought it made a difference in resulting gender I'd suggest trying to change the ph of semen instead of a doe's reproductive tract. Infertility studies in human and animal have found the ph can vary quite a bit without a health problem present and at a low enough ph it will eventually cause complete infertility. Without a good enough buffer the sperm will not survive the huge ph difference before they fertilize eggs in the female reproductive tract. What has caused such a low ph in studies of otherwise healthy animals is not known though. Another thing to consider is that I found while the theory of killing some to get mostly females works in bird eggs using heat you do so at the sacrifice of how many hatch. Hatching at the extreme range of temps will give you more pullets and cut your hatch rate 20-50% due to all the roosters just staying dead in their eggs. If you have no good way to dispose of roosters that might be worth any lost pullets in the practice but if reducing semen in rabbits results in smaller litters it could have too many negatives for survival of the whole litter and what sales or meat you do get raising the males to be worth it. Lowered sperm survival is considered a fertility issue for a reason.
