...depends. If she is post calving and not yet bred, help her cycle with a prostaglandin (pgf) to bring her into heat. A heat cycle is the best way to 'flush' any potential infection from the uterus. If she comes into a good heat from the pgf short cycle her in 11 days with another dose of pgf. Then let her cycle normally till breeding time. Again how much mucus...? Heavy clumps? Trace amounts? Trace amounts and if breeding by a bull (high volume of sperm) she may breed fine. If breeding by AI, watch the inseminating rod as it is retracted and see if there is white mucus on the sheath. If the semen is cheap enough, double dose her.