The present study was designed aiming to verify the need of inactivating reconstituted nonfat dry milk and the use of skim milk UHT as extender for cooling equine semen. Two experiments were performed. In the first experiment, four diluents were tested: reconstituted not-inactivated dry skim milk, inactivated reconstituted dry skim milk, UHT skim milk A and UHT skim milk B. Twenty semen collections were obtained. semen were cooled at +4°C and evaluated for progressive and total motility 0 , 24 and 48 h after collection. In the second experiment, one hundred and one cycles were studied. Mares were inseminated with semen diluted in inactivated and not-inactivated dry skim milk. Dilution was done in a 1:2 (sêmen:diluem) ratio and the minimal inseminating dosis used was 500x10(6) spermatozoa. It was concluded that it is not necessary to inactivate nonfat dry milk for using it to dilute equine semen and that skim milk UHT may be used to dilute and preserve chilled equine semen.
equine; cooled semen; milk
