In an effort to show vedic culture as a barbarian culture, the early indologists created all kinds of non sense. Here we can find one more of them described: “After the animal is purified by the priest, the principal wife sleeps near the horse and says:“O Horse, I extract the semen worth conception and you release the semen worth conception’” [Yajur Veda 23/20]The horse and principal wife spread two legs each. Then the Ardhvaryu (priest) orders to cover the oblation place, raise canopy etc. After this, the principal wife of the host pulls penis of the horse and puts it in her vagina and says: “This horse may release semen in me.” [Yajur Veda 23/20]
Rebuttal: Here is the Sanskrit verse and its translation for Yajur Veda 23/20
tau ubhau chaturah padah samprasarayava swarga lokam prasuvava vrshavaaji raghu rathau dadati Yajur Veda 23/20
tau = we two ; ubhau = both ; chaturah = intelligent ; padah = subject ; samprasarayava = reach out ; swarga lokam = heavenly planet ; prasuvava = command ; vrshavaaji = horse ; raghu = Lord ; rathau = chariots ; dadati = provides
Translation: We both command the intelligent horse as our subject to reach out for heaven (where) the Lord provides (us) the chariots.
The real meaning here is that by performing Ashwamedha yajna, one can get the blessings (written as chariots) of the heavenly King, Indra.
A question then arises on how terminologies such as ‘semen’ and ‘conception’ got embedded into the manuscripts. It was the heinous work of early Indologists, namely, William Jones, Max Mueller, and Pargiter. (…)
Let me explain how the verse in Yajurveda 23.20 is distorted to satisfy the whims and fancies of the fabricators. The word rathao (chariots) is replaced by retau, which means ‘semen’. Next, dadati (gives) is replaced by dadhatu, which means ‘insert’. Finally, raghu (King) is strangely replaced by retaudha, which means ‘conception’. Even in the fabricated verse, it should be retaudheya and not retaudha for the sentence to be grammatically correct. This is how charlatans get caught when they distort the meaning of the verses.” *
I think most part of “hindus” nowadays won’t like to think that this kind of sacrifice with the horse really used to happen as it was described by these early indologists. What also means they wouldn’t be proud of keeping these sacrifices alive, since they are not the true thing. Why then would they be happy to keep alive the artificial situation of treating women as inferior or denying so many rights they always had and they don’t have anymore in Indian society? People who deny facts like that women could choose their own husband, that they could study scriptures and take part in yajnas, that they could instruct their husbands and really rule over his home and family, also gotta defend the realization of these sacrifices with the horses as described in the beginning of this post then, if they are not too hypocritical.

http://www.hindujagruti.org/news/6411.html