not possible

 
A Vedic sacrifice is not an ordinary performance. The demigods used to participate in such sacrifices, and the animals sacrificed in such performances were reincarnated with new life. In this age of Kali there are no powerful brahmanas who can invite the demigods or give renewed life to animals. Formerly, the brahmanas well conversant in Vedic mantras could show the potency of the mantras, but in this age, because there are no such brahmanas, all such sacrifices are forbidden. The sacrifice in which horses were offered was called asvamedha. Sometimes cows were sacrificed (gavalambha), not for eating purposes, but to give them new life in order to show the potency of the mantra. In this age, therefore, the only practical yajna is saṅkirtana-yajna or chanting of the Hare Krsna mantra twenty-four hours a day.    (More...)
So Krsna says that you don't require to perform different yajnas. That is not possible in this age especially. It requires large amount of wealth to perform such yajnas. Nowadays people are suffering for want of sufficient food grains, and in the yajna tons and thousands of mounds of food grains are offered in the fire. That is good. But there is no food grains; there is no ghee. That is not possible in this age. Therefore yajna is not possible. The... You can perform very easily the saṅkirtana-yajna. Then everything will be performed. Yajnaih saṅkirtana-prayair yajanti hi sumedhasah [SB 11.5.32]. Those who are intelligent person, they can perform yajna, saṅkirtana-yajna. This is recommended in this age. Other yajnas is not possible. Krte yad dhyayato visnum tretayam yajato makhaih [SB 12.3.52].    (More...)