Selecting a ram with data

The question

Faraón is a 104 kg Dorper, Katún an 80 kg Katahdin. Which one should cover the crossbred ewes this season?

The concept

A ram's value is not his own weight but what his lambs do. The relevant figures are his index values and their accuracy, how many progeny back them, and how related he is to the ewes he will cover. A "proven" sire is one with enough recorded progeny for his EBVs to rest on their performance rather than on pedigree.

The data behind it

In the demo, Katún has Growth 0.398 (percentile 73) and Faraón -0.609 (percentile 26); on Flock, Katún -0.199 against Faraón -0.370; on Prolific Flock Faraón is ahead (-0.439 vs -0.651). Both have a rating of 50, 30–31 eligible progeny and 13–16 daughters. The threshold for "proven" (minimum number of offspring) is set in Settings › Genetics.

How to read it in BreedIQ

Sires & Replacements › Sires lists proven sires with bars that show the percentile for the chosen index, and a head-to-head table where ▲ marks the better value on each metric: the three indices, adjusted growth (z), rating, eligible progeny and daughters. The full table adds the evidence column (Proven) and sons/daughters counts. Unproven candidates and non-active rams can be included with the two checkboxes.

For a specific ewe, the profile's "Find matings" button and Reproduction › Mating open the mating matrix, which ranks rams for a ewe by predicted merit minus expected inbreeding, under a breeding objective (Balanced, Growth, Maternal, Prolific, Purity).

Decisions it supports

If this season's lambs go to market, Katún's growth advantage is the deciding figure. If you are building the maternal line, neither ram is above the base on the Flock Index, so the decision may be to buy outside or to use the mating matrix to pair each ram with the ewes where inbreeding is lowest. The matrix lets you load a whole lot of ewes at once.

Limitations

Both rams have a rating of 50 and indices flagged partial on the Flock Index: the comparison is reliable for growth and weaker for maternal traits until their daughters lamb. The inbreeding coefficient shown for an animal is only as deep as its pedigree (the demo shows "Pedigree too short to confirm"). Group matings of around 20 ewes per ram are a management convention, not a value the app imposes; record the mating mark in the lot and the paternity will be inferred from the service when the lambing is recorded.