Photosynthetic cells contain chlorophyll and other light-sensitive pigments that capture solar energy. In the presence of carbon dioxide, such cells are able to convert this solar energy into energy-rich organic molecules, such as glucose.
Yes, you can add a little lemon juice or vinegar to the goat's milk to make it into a buttermilk or kefir. This will lower the pH of the milk, and allow it to release the CO2 stored in the sodium bicarbonate (baking soda), causing the bread to rise. Goat's milk generally has less fat and more vitamins.
However, unless you make your own buttermilk from cream, it will not have the same tangy flavor. To make buttermilk from cream, combine 1 tablespoon of buttermilk with 1 cup of cream and let it sit, covered with a napkin, for up to 24 hours. Refrigerate it for six hours and stir it before using.