Nursing changes as you meet this milestone of milk making. Any nursing is beneficial, and other sources of nutrition need to take priority. It's a gradual transition from 6 months introducing foods your milk is a meal to 1 year. Think of your milk as a super nutritious beverage packed with protein. This is the time I recommend transitioning away from pumping during the day. As Baby enjoys more food and other beverages, nursing can continue indefinitely.
Volume decreases as food intake increases from averages of 30oz/day to 18oz/day. These numbers reflect nursing dyads not supplementing with other milk. That is not common for American dyads. Once other food is introduced, "exclusive" does not apply. Through the first year, milk is a meal. In the second year of life, Baby's food is primary source of nutrition. Introducing other milk does not mean the same thing as before introducing solids.
Breastmilk changes over time. It concentrates down to more fat and protien, less water and sugar. Notice how much fruit they enjoy? It's a good source of water and sugar.
The immunity support remains to the very last drop.
“Some of the immune factors in breastmilk have been shown to increase in concentration as the baby gets older and nurses less, so older babies still receive lots of immune factors. So as a baby starts to nurse less (weaning) and milk supply decreases, the concentration of immunities increases. This isn’t age-dependent, but depends on the amount of milk that baby is removing from the breast. [source: Goldman AS et al. “Immunologic components in human milk during weaning.” Acta Paediatr Scand. 1983 Jan;72(1):133-4.]” With a table.
Volume and Composition