Hi
the subject of fertility has reared its ugly head again via some info from Bill Luff and top GMI cows in the CI etc etc. To be devils advocate as always there isnt any dowt that fertility has dropped as yields have gone up, and measurements are easy to calculate on each bull via AI /milk recording but has any body ever measured the diff in fertility between natural services and AI are those farmers that use a greater degree of natural service getting better conception rates than those using mostly AI, We have all served cows 3-4 times then put her with the bull and she holds 1st time, is that because she is later in the lactation and is gaining condition or just there is problem with the freezing/thoring of the semen straw in the first place.
We have just dryed off 6 or 7 cows that have completed lactations of about an average of 8500 lites still doing 18/20litres at drying off but all were served naturally and held first time , never had that before but never had a bull good enough to use so much before. Is it because we are managing them better nutritionaly or natural service against AI??
I do believe we have to keep an eye on fertility but apart from the above how many of us have changed the way we manage our herds along side the increases in genetic gain in the last 10 yrs( how many more litres does the average 2011 cow do now compared to 2000 cow). If our management is the same now as it was 10 yrs ago is it any wonder fertility is falling.
coxy