The use of lactose, glucose, and white sugar in creep feed for suckling piglets

Asking the experts: what are the biochemical reactions of lactose in the body of suckling piglets? Can glucose replace the energy portion of lactose? Are there differences in the stages of use for glucose, white sugar, and lactose? What are their optimal usage amounts? What are their respective maximum limits?
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I am not very clear either, just passing by and preparing to learn. Lactose is easily converted into lactic acid in the intestinal tract.
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It probably cannot replace it, not very clear