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‘ ABOVE Dairy Co’s Marco Winters.


The percentage weightings of traits within the new £PLI


Trait


Production Feet & Legs Lifespan


Direct Calving Ease Fertility


Maternal Calving Ease


SCC Udder Maintenance %


29.3 3.7


13.5 2.2


21.8 0.4


10.4 2.6


16.1


However, this change begs a further question about cull cow and calf values which are likely to be greater for the bigger cow. “This, too, has been built into the index,” explains Mr Winters. “A consideration is made for the extra profit potential for the bigger calf and cull, but set against this are the rearing costs which are higher for the heavier heifer.”


Other changes to £PLI include a noticeable upscaling of the figures, with the best Holstein bulls in the August proof run having PLIs in the region of £600. “This is partly explained by inflationary increases and the different market conditions in which dairy farmers operate today,” explains Mr Winters. “However, we may have underestimated the value of good genetics in the PLI’s previous calculation and, with the benefit of 15 years of using the index, we now have more confidence in its value. “Independent work had also shown its actual value to be greater than its previous nominal value, so this also corroborates the new figures,” he says. With more evidence than ever before supporting the value of PLI, UK producers


We all know it costs more to feed a larger than a smaller cow but, until now, we haven’t had the means to account for this in the index


PLI: the effects of the changes


• Protects milk quality • Increases emphasis on female fertility • Improves functional type (legs, feet and udders) • Increases emphasis on longevity • Reduces costs associated with maintenance • Improves udder health • Improves calving performance • Significantly increases the overall value in £


’ explains Marco Winters


INDEX UPDATES


PLI


Pie chart


are strongly urged to use the index as their primary selection tool. “They should not be tempted to be led by other countries’ rankings that have been designed for different local conditions with other markets and farming systems in mind,” he says. “Despite the


fact that some individual animals may rank well on both the UK and foreign country indexes, we know from research that using a foreign index ultimately gives UK breeders suboptimal results. “There’s no doubt that using multi-trait selection indexes works across a population and since PLI has been designed for use on our own national herd producing milk for sale to domestic buyers, there’s no question that it should be used by UK cattle breeders.”


THE JOURNAL AUGUST 2014 61


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