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Do You Follow the Stars?

22 September 2022
Type Media Article

Austin Callaghan, Drystock Advisor, Teagasc Claremorris.

The Beef Data & Genomics Programme was launched in 2015 and suckler farmers have participated in that programme since then. It brought production index ratings of cattle for breeding (replacement) and beef (terminal) purposes to the fore. These ratings were available prior to this, but the BDGP programme required farmers to focus on the replacement (breeding) of the females, cows and heifers in the herd. This programme did cause a furore when launched with much comment then and since on the replacement value / star ratings. Some of the benefits and purpose of the replacement value / star ratings may have been lost in this debate.

The replacement value was the main focus of the programme. Its aim was to improve the breeding performance of the sucker herd and at the same time improve on the quality and weight characteristics of the offspring. See Table 1 for the traits that combine to make up the replacement value or star rating. The percentage emphasis of each trait within the rating / value is listed.

Table 1: The Replacement Value / Index.  
Fertility (Age 1st Calving, Calving Interval, Cow Survival) 23%
Milk 18%
Calving Traits (Calving Difficulty, Maternal Calving Difficulty, Gestation, Mortality) 16%
Beef Traits (Carcase Weight, Carcase Confirmation, Cull Cow Weight) 21%
Feed Intake 18%
Docility 4%
Total = 100%

Overall the replacement index value focuses on 3 main areas which are shown below in Table 2. This data is available through ICBF for herd plus members.

Table 2: Euro Star Report with Female Replacement Values

Animal No. Index Value (€) Carcass Weight (Kg)

Milk (Kg)

Calving Interval (Days)

Female 1 €133 +22.3 +3.3 -2.83
Female 2 €96 +28.4 -1.2 -2.61
Female 3 €131 +15.4 +5.3 -3.1
Female 4 €169 +4.6 +13 -6.57
Female 5 €131 -2.8 +11.9 -2.94
Female 6 €45 +27.8 -3.85 +0.17
Female 7 €64 +15 +5.1 +5.57

For each animal on your farm the rating has 3 areas which combine to give the overall value / star rating. It's important to understand this as the replacement value / star rating only partially indicates likely performance and it’s important to see where your breeding herd is excelling or lacking in each of these areas. The cow, heifer or bull will all have a replacement value. It may be appearing as a 5 star for example but why is the cow 5 star? Is the cow likely to breed females that will have a good breeding performance? Will these females reduce the calving interval? On the table above you can see where female 3 & 4 will breed females that reduce the calving interval by 3 – 6 days. This may appear as only a few days overall. But remember the female could also add days so you could have an overall difference of 3 - 10 days between 2 females. If this is repeated through a number of generations it will result in good or poor breeding performance within the herd. The target is the cow should calf every 365 days. The average calving interval in our national suckler herd is 388 days.

You also need to select cows / heifers that are likely to breed replacement heifers that have good milking ability that will result in heavier calves at weaning. The replacement index is there to assist in improving the breeding performance, to improve the quality of the herd and the live weight of the weaned calf.

The index has attracted much comment since 2015. No one has said the index is perfect. Farmers should work with it and gain a better understanding of its function. There’s no point driving in the dark when selecting suitable replacements. Obviously it’s important to select quality animals. However, will this female wean calves with good weights (milk) and will she improve breeding performance (calving interval). The replacement value / star rating will provide guidance on this.

When selecting suitable breeding animals visual assessment is also vital when it comes to selecting on quality and docility. In addition in terms of good breeding performance good nutrition is vital. Inappropriate feeding of cows for example prior to calving will have a dramatic effect on subsequent breeding performance.