one of my cows took 2 years to be served kindly advice
Sorry for that. Otherwise several issues can lead to prolonged conception interval. This could either be physiological or environmental. The age at first calving and the calving process weather it was normal, assisted,or dystocia have much bearing on the period it takes for the uterus to come back to it's normal cyclic state. The best practice is always to seek veterinary attention to have the uterus checked and ovaries palpated to determine their cyclic state. Lack of essential minerals too can lead to prolonged return to cycle. Phosphorus must be readily available for the cow to show heat signs. Excess iron in the mineral lick has negative impact too. The list is endless so the best procedure is to have clear pre and post partum checks. Breeding or fertility is a chain and any disconnect at some point breaks the chain. Semen quality, breeding technique and technicians are part of that chain.