This page contains a Flash digital edition of a book.
WHAT’S NEW IN PLI? P


rofitable Lifetime Index (£PLI) has become a familiar breeding tool since its launch in 1999 and, over the years, has gained increasing acceptance among the breeding fraternity. As selection for PLI has gained momentum, we’ve seen significant improvement in the genetics of the national dairy herd for all of its constituent parts. This includes big gains in production alongside improvements in somatic cell count and lifespan, while the introduction of Fertility Index to PLI in 2007 has led to improvements in female fertility too (see Graph 1). The multi-trait index itself has always blended production, fitness and functional type traits and has also periodically been revised. “This is because the index needs to be under regular review to reflect changes in the national cattle population as well as revised projections in the long-term markets for UK milk,” explains Marco Winters, head of genetics for DairyCo. Alongside this, the industry’s knowledge is constantly improving, thanks to the collection of increasing amounts of data by organisations like CIS and Holstein UK.


The upshot is that the Genetics Advisory Forum on which industry representatives sit (including from Holstein UK), feels it is time for another revision.


The new £PLI launched this August places an increased emphasis on health and fitness at around 68% of the total index (previously it was 55%), and reduces the emphasis on production, now at 32%. Within this shift, there’s a greater emphasis on female fertility;


60 THE JOURNAL AUGUST 2014


£PLI undergoes a significant change this August and should better equip cattle breeders to improve their herds to meet the UK industry’s long-term demands


both direct and maternal calving ease have been introduced; and a new figure has been added to reflect the costs of maintaining the cow (see pie chart). “We all know it costs more to feed a larger cows than a smaller cow but, until now, we haven’t had the means to account for this in the index,” explains Mr Winters. “However, economic modelling undertaken at Scotland’s Rural College (SRUC) now allows an accurate prediction of maintenance costs to be made, using traits which are routinely measured during type classification.


“This means that, all else being equal, a bull breeding a smaller cow of say 600kgs will have a higher PLI than a bull breeding a larger cow of say 700kgs, if they’re both genetically capable of giving the same amount of milk at the same level of fitness,” he says. “This would probably seem logical to most producers who know that the heavier cow costs more to maintain.”


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124