NZMW & NZTW

Thanks to a major upgrade of the SIL genetic engine, every ram sold by a SIL breeder now has a single “index” figure:

The higher the number, the better the ram.

Dual purpose rams have a “Maternal Worth” figure (NZMW)
The average NZMW is 1600

Terminal rams have a “Terminal Worth” figure (NZTW)
The average NZTW is 1150*

Again, the higher the figure, the better the ram.

* Note that terminal rams have lower scores than maternal rams, simply because their figure is calculated from a smaller number of traits.

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Maternal Worth (NZMW) or Terminal Worth (NZTW)?

If you’re breeding both terminal and replacement stock, then look at rams with a NZMW figure.
If you’re only breeding terminal stock, then look for rams with a high NZTW figure.

Which traits feed into NZMW and NZTW?

Or, if you’re more visual:

 

Getting your eye in

Health traits

If you want to target specific traits, like FE tolerance or resistance against internal parasites,
the indexes can do that.

If you want facial eczema tolerance, identify breeders who prioritise FE,
then ask them for: NZMW + X*

If you want resistance to internal parasites, identify breeders who prioritise this trait,
then ask them for: NZMW + FEC*

The higher the number, the better the ram.

* X = FE trait; FEC = internal parasite resistance trait

To re-cap

Test yourself

Here are four good rams:

Ram A – NZTW of 1200 
Ram B – NZTW of 1360 
Ram C – NZMW of 1640
Ram D – NZMW of 2210

Q1: You run a breeding/finishing sheep policy. Which ram would you choose?
Q2: You buy in old ewes and put them to a terminal sire. Which ram would you choose?

Answers: Q1 = D; Q2 = B

Hover mouse over answers to read

Here are another four good rams:

Ram W – NZTW of 1390
Ram X – NZTW of 1110 
Ram Y – NZMW of 2250
Ram Z – NZMW of 1530

Q1: You run a breeding/finishing sheep policy. Which ram would you choose?
Q2: You buy in old ewes and put them to a terminal sire. Which ram would you choose?

Answers: Q1 = Y; Q2 = W

Hover mouse over answers to read

Key message

This season, ask your ram breeder for:

NZMW figures if you breed your own replacements
NZTW figures if you need a terminal sire

The higher the number, the better the ram.

Other tools

In order to make the use of genetics on farm easier, B+LNZ Genetics is developing a series of tools for commercial farmers.

FlockFinder Smartphone app

The free FlockFinder app helps you locate genetics you want. It’s easy to use and allows you to search for ram breeding flocks in New Zealand, based on your search criteria. You can search by breed, location, owner name, stud prefix, SIL flock number or by the traits recorded including DNA parentage. Once you’ve identified a breeder, the app allows you to phone or email them directly from your smart phone, or view their website. Once loaded, FlockFinder works offline. It does not require a continuous internet connection to perform further searches. The app can be downloaded at either the Apple App Store or Google Play.

BreederFinder

BreederFinder provides you with contact details for owners of SIL flocks. Searches can be made using a variety of criteria – even partial flock or owner names. The tool searches through all SIL flocks that are actively recording performance information.

Bull selection

In a commercial beef herd, without cow recording, the bull contributes about 80% of the herd’s genetic improvement. The decision you make about which bull to buy this season will affect your business for four cow generations. Taking 10 minutes to read the below document now should yield you an exceptional return.

The importance of performance recording
Genetic improvement should be the key objective for a stud breeder. Genetic improvement occurs when the sire team you select are of higher merit than the cows in your herd and ultimately breed calves that are superior to their parents. Read our six top tips below to help you identify where you can improve your performance recording.