depreciation on livestock i.e cow

As per section 36 (1) (vi) of the Income Tax Act, 1961.  It very clearly states that in respect of animals which have been used for the purposes of the business or profession otherwise than as stock-in-trade and have died or become permanently useless for such purposes, the difference between the actual cost to the assessee of the animals and the amount, if any, realised in respect of the carcasses or animals.

As such no Depreciation on live stock. and when they die... just reduce the amount which was added at the time of their purchase

Read more at: https://www.caclubindia.com/forum/live-stock--108692.asp

Livestocks are not subject to depreciation.

Depreciation is not charged on live stock. However, at the time animal died or become permanently useless for such purposes,  the actual cost to the assessee of the animals can be reduced from and the amount realised in respect of the carcasses or animals.