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Hi
the subject of fertility has reared |
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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
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Any work on fertility is done within the black& white sector and then the equations are applied retrospectively to the other breeds. I remember listening to John Woolliams who stated that 40% of services in "commercial" herds are not recorded at all and therefore "true" fertility is a very difficult thing to identify.
The Guernsey herd with the "best" fertility as defined by Calving Index ie the lowest average days between calvings,has a routine whereby cows are inseminated twice to AI and then at the third or subsequent service are served naturally by one of a team of four bulls that are penned alongside the collecting yard.
This herd of over 300 milkers will AI twice a day after the milking is finished and so cows are served "early" in the cycle which of course mimics the behaviour of a bull, and incidentally the herd achieves a high proportion of heifer calves.
Management is of course the key, the herd that I milk at weekends, had a "problem" with fertility with cows served in late summer for which the bull literally got the bullet, but 60% of the same group of "empty" cows held to the first service once on winter rations !
What were you feeding your cows 10 years ago compared to last year?
With our ever shrinking genetic pool and the over use of "good" bulls to chase desirable traits how does Guernsey in-breeding compare in herds compared to ten years ago?
How many of us actually use the information available re fertility indices and own herd in-breeding?
We haven't run a sweeper bull for seven years now currently 61% of the herd calve below 385 days, the breed average is 38.5%! I know calving interval is little use to Mike as he is in a unique situation but one question to throw open to others is when do you start serving your cows? The best quality eggs are from 45 - 100 days post calving - are people just leaving it too late and then blaming poor semen quality instead of poor egg quality?