The easiest way to find the card is during the Dead Man's Party quest, in the barn, near one of the point of interests. However, it can also be found anytime you visit Brunwich.
It is possible to summon the Bovine Defense Force card in the same round after playing this card by using a scorch effect on this card. However since this card has 0 strength the only way this is possible is if it's the only unit card in play or all other unit cards are hero cards.
It is ill advised to add this card to the Monsters Gwent deck. As the special ability of the deck may select this card as the one to be carried over to the next round. As a result the Bovine Defense Force card will not be summoned and since the card has 0 strength it will have no benefit for the next round. A real no pros all cons situation.