Figure 3 Average lifetime yield per Angularity classification catego- ry, of Holstein heifers classified between 2000 and 2002 inclusive. Data analysis byCDI


20000 22500 25000 27500 30000 32500 35000 37500 40000


1 Coarse 2 3 4 Classification as a HEIFER 5 6 Open Rib


being optimum. Udder depth for example, in Figure 2, shows scores five, six and seven as being associated with the highest LTY. Traits such as chest width and rump angle also follow this pattern. Other traits, however, do show a more straightforward pattern of association, where LTY increases with each score category all the way to nine. We see this pattern for example with angularity (Figure 3) as well as rear udder height, stature and locomotion. Thus, the relationship between classification score and LTY varies across traits and while only six traits are presented here, for a comprehensive selection of charts for each trait see the CDI website. What can be concluded about the relationship between classification score and lifetime yield?


The dataset presented here is not edited for some effects that would influence LTY in particular. It is likely that not all culling would have been involuntary and some cows will have left the herd while still functional milkers. Culling may also have taken place as part of a drive for genetic improvement within the herd.


Furthermore, some breeders selecting for higher type merit may also 62 THE JOURNAL AUGUST 2015 7 8 9


run more intensive systems and thus feed cows more, resulting in higher milk production. These factors will explain a part of the association between classification scores and LTY. However, they do not negate the fact that under UK husbandry practices, heifers with higher classification scores go on to produce more milk over their lifetime. Classification score is, therefore, a good predictor of lifetime yield.


Summary • Classification is an impartial conformation scoring system for Holsteins


• Classification tells us about the form and function of the live cow


• Classification increases the knowledge of heifer genetic merit for type


• Classification data underpins genetic and genomic evaluations for type traits


• Heifers with higher overall classification scores typically remain on farms longer and produce a higher lifetime yield


To arrange classification of your herd, please contact Jackie Clark on 019230695211 or email


jackieclark@holstein-uk.org


LTY Milk kg


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