Page 11 - Tangihau 2020
P. 11


         TransTasman Angus Cattle Evaluation calculates       200-Day Wt (kg), 400-Day Wt (kg), 600-Day Wt (kg)
         predictions of genetic merit called EBVs for a range of   Estimates the genetic differences between animals
         traits on a national across-herd basis.              in liveweight at 200, 400 and 600 days of age. For
                                                              example, if you have two bulls, one with a 600 day
         The EBVs are calculated using information on the     weight figure of +70 and the other with a figure of +80,
         animal’s own performance plus the performance of     you would expect the bull who is +80 to sire calves
         all known relatives (sire, dam, half-sister and brother   that would average 5kgs heavier at 600 days than the
         etc.), the relationship between the traits and the   other sire (the sire provides 50% of the genes to the
         pedigree links between animals and between herds.    calf, 10kgs divided by 2). A higher positive value for
                                                              these growth figures is better.
         EBVs are based on all the available pedigree and
         performance records provided by breeders in          Mature Cow Weight (kg) This figure provides an
         Australia and New Zealand, along with available      estimate of the genetic differences between animals
         overseas genetic information.                        in cow weight at 5 years of age. We try to keep this

         EBVs are expressed in the units of measure for       figure below the 600 Day Weight Figure. Where this
         each particular trait, and are shown as positive (+)   is the case in the catalogue we have highlighted the
         or negative (-) values. The average EBV for different   mature cow figure in red.
         traits changes over time as the breed makes genetic   Milk (kg) The Milk Figure provides an estimate of
         progress. The averages for calves born in 2011 are   the genetic differences between animals in milk
         shown at the bottom of each page and the percentile   production, expressed as a variation in the 200-
         bands are shown on Page 16. The averages and         day weight of their daughter’s calves. Angus cattle
         percentile bands are the easiest way to compare the   generally don’t have a problem providing enough milk
         merits of particular animals.                        for their offspring so we don’t need to worry too much
                                                              about pushing this figure. Too much milk can lead to
         Accuracy (%) Provides an indication of the reliability
         of an EBV. As more performance information becomes   udder problems and difficulty getting back in calf, so
         available on an animal, its progeny and relatives, the   keep it positive but keep in mind the implications of
         accuracy of its EBVs for particular traits increases.   too much milk.
         The higher the accuracy, the less chance that the    Scrotal Size (cm) This figure tells us about the scrotal
         figure for each EBV will change.                     circumference of an animal at 400 days of age.

         Calving Ease Direct (%) CE Dir This tells us the     We measure scrotal size because there is a strong
         amount of calving ease we can expect from a          positive correlation between scrotal size and fertility in
         particular bull, relating directly to the females he is   the male and female offspring. The larger the testicles,
         joined to. The calving ease figures will generally only   the more likely that bull will sire more fertile daughters
         appear on the chart of a sire, but can also appear   and get more females in calf. A higher positive value
         on a younger bull’s chart if there has been a lot of   is better.
         information gathered on his relatives. A positive value   Days to Calving DC (Days) This tells us about female
         here is better.                                      fertility. It is expressed as the number of days from the
                                                              start of the joining period until subsequent calving.
         Calving Ease Daughters (%) CE Dtrs This tells us
         the amount of calving ease we can expect from a      A more fertile cow i.e. one that gets in calf earlier is
         particular bull’s daughters. A positive value here is   obviously more beneficial in a breeding program. A
         better.                                              negative value here is better.

         Gestation Length (Days) This figure gives us a       Carcase Weight (kg) Carcase weight provides us
         value relating to the number of days from the date of   with an estimate of the variation in carcase weight of a
         conception to the calf birth date. A shorter gestation   particular animal’s progeny at slaughter (this figure is
         length is better as it gives more time for the cow to   adjusted to 750 days of age). The higher the number
         get back into calf and there is less chance of the   the better.
         calf getting too big in the uterus and increasing the   Eye Muscle Area (cm2) Results from ultrasound
         chances of calving difficulties. A negative value here is   scanning of cattle at 15-18months of age are used to
         better                                               calculate the expected genetic differences between
                                                              animals in eye muscle area at the 12th/13th rib site, in
         Birth Wt (kg) Birth weight gives us an indication of
         how much the calves of a particular animal will weigh   a 400kg carcase. This figure gives us a good idea of
         at birth. This figure should be monitored, but be    the muscling ability of the animal. The more muscling
         careful not to go too low as this can cause problems   an animal possesses the better. Therefore a higher
         with calf mortality and calving ease down the track.   positive value is better.
         We must also remember that only a small percentage   Rib and Rump Fat (mm) Ultrasound scanning data
         of calving ease is related to birth weight.          is also used to calculate these figures which estimate

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