Page 11 - Atahua Angus Sale 2021 ebook
P. 11

Angus Pure Index (API)

                        New Zealand Angus AngusPure Index - Predicted Response


                     Expected Change in Individual Traits











                       CEd  CEm  GL  BW  200W  400W  600W  MCW  Milk  SS  DC  Cwt  EMA  Rib  Rump  RBY  IMF

             Above the 0 line (X axis) selects for more positive numbers and below the line selects for more negative numbers.
        For some traits (e.g. growth), a positive response is desirable and for others (e.g. days to calving), a negative response is desirable.

       Genetic Selection of bulls using only the API tool will on average over time develop a cow herd with the following:
       •   Improved weaning rate through increased fertility and easier calving
       •   A slowly increasing cow weight/size, and milk production
       •   Progeny will be prime at heavy carcase weights where the improved marbling and subsequent eating quality traits
         can be expressed.

       These characteristics are ideal for an environment where the cow herd can be managed with extra feed if seasonal feed
       deficits occur.

                        Checking individual EBVs relevant to your herd is advised.

       Comparison of SRI and API
       SRI is a maternal trait emphasised index. API is also a maternal driven index with added carcase trait emphasis.

       API selected animals can produce more net profit per animal through extra performance when feed is abundant.
       Finished progeny can be taken to heavier weights with increased likelihood of achieving marbling premiums.

       SRI selected animals can produce more net profit per animal through extra performance in environments where
       the cow herd is likely to be challenged by regular seasonal feed deficits, maintaining body condition is critical
       to longevity and feeding out is not a viable option.

         Checking individual bull EBVs to make sure the index and the EBVs match your expectations are advised.
                          Using the flow chart may help you with your decisions.


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