Update - Okura Manhatten ET SJ3 – a truly global sire
Manhatten continues to dominate Jersey bull rankings in New Zealand as he has done since his first daughters came into milk in spring 2003. With 6600 daughters now in his production proof he maintains a BV (protein) of 37kg which is 8kg higher than the second ranking Jersey bull for protein. He remains in high demand from farmers internationally and for 2007 is once again AmBreed’s highest selling bull of all breeds.
His influence is likely to be felt for generations to come. Manhatten’s first crop of sons will graduate next year when their daughters come into production. In NZ about 100 sons are under test with AmBreed alone testing twenty.
His genetic influence will also be felt through his daughters – not surprisingly he is becoming pre-eminent as a sire of bull mothers.
New Zealand farmers continue to use Manhatten very heavily even though he has now been available for five seasons. In fact, those who have milked his daughters have tended to become even stronger supporters of him.
On the flip side, AmBreed continues to try to understand the basis of that small percentage of his progeny which are not normal. During each spring/summer of 2005 and 2006 AmBreed received reports of about 120 “abnormal” progeny and to date this spring we have received written reports of a further 30 “abnormals”. The following summarises what we know about this condition:
· affected animals are Jersey and crossbreds (including some out of pure Friesian and Ayrshire cows) indicating we are not dealing with a recessive genetic condition confined to the Jersey population
· symptoms in young calves are typically: weak at birth often not standing for 3 or more days; some calves have twitchy muscle movements in their shoulder and flank regions; many are long gestation calves even though overall Manhatten is a short gestation bull
· symptoms which become more obvious in older animals (4 to 12 months) are trembling and poor hind-limb coordination – this closely resembles ryegrass staggers
· affected animals are normal in appearance apart from the tremor and stagger
· analysis of the database shows that death rate around birth for Manhatten progeny is not different to death rates in progeny of other Jersey bulls
· cows which have produced an “abnormal” Manhatten calf in one year have always (to our knowledge) produced a normal calf the next year when repeat mated to Manhatten. In 2006 there were several cows deliberately remated to Manhatten and all produced normal progeny in 2007
· conversely, cows may produce a normal calf in one year then an abnormal the next year
· some properties have reported several cases in one year but zero or very low incidence in the subsequent year. Conversely properties may have zero incidence for one or even several years, may suddenly experience the problem
· in AmBreed’s experience animals which are identified with the condition do not improve sufficiently to enter the milking herd. AmBreed’s recommendation is for farmers not to persevere with affected young cattle
· during 2007 AmBreed has monitored the progress of 8 affected rising 2-yr-olds which were thought to be in calf. None calved successfully (although one is still to calve) with all proving to be empty or slipping or dying through misadventure in late pregnancy: in other words none got through to calving
· postmortem examination of 22 offspring has shown nothing obvious compared to normal cattle
Both major NZ AI companies have informed their sire proving herds of the Manhatten situation and requested information about the progeny of Manhatten sons. To date the companies have received no confirmed cases of these sons having bred progeny showing the same abnormality as some of Manhatten’s own progeny. This is reassuring in that it points to the “abnormality” having a relatively weak genetic component.
Several AmBreed staff believe that the problem probably stems from Manhatten progeny being susceptible to an unknown environmental influence that affects the foetus and causes long gestation and the associated problems: this susceptibility is influenced by many genes (ie not by a single gene) and is no different to some bulls breeding progeny susceptible to a disease like facial eczema, bloat etc.
AmBreed continues to work on the problem and informs the farming community of our knowledge through the catalogue and updates on the website. The vast majority of farmers continue to reuse Manhatten – in their eyes the quality of his daughters is clearly exceptional.
If you have any Manhatten calves you would like to tell us about please click here for the Abnormal Calf Report Form (104 kb)
