Four new Herefords Australia BreedObject selection indexes are to be released with the publication of the October 2019 Hereford BREEDPLAN analysis. These are the Southern Self-Replacing Index (SSR), the Northern Self-Replacing Index (NSR), the Southern Baldy Maternal Index (SBM) and the Northern Baldy Terminal Index (NBT). These four selection indexes have been developed by Herefords Australia, along with staff from the Animal Genetics and Breeding Unit (AGBU) and Southern Beef Technology Services (SBTS). Extensive consultation was undertaken as part of the development process, with seedstock and commercial Hereford producers, feed lotters and processors involved. This was done to ensure that the new Herefords Australia selection indexes are representative of the varied production systems that Australian Herefords are run in, including both straight-bred and cross-bred production systems.
Description of the New Herefords Australia Selection Indexes
Each of the new selection indexes describes a different production/market scenario and relates to a typical commercial herd using Hereford bulls. Producers are advised to use the selection index that most closely aligns to their production system. All four selection indexes are focussed on maintaining and improving eating quality. Significant premiums are applied for increasing marble score up to a marble score of 3. Pressure is also applied to early life growth to maintain low ossification scores and good MSA compliance. In addition, each selection index targets the following specifications.
Southern Self-Replacing Index – Estimates the genetic differences between animals in net profitability per cow joined in a commercial self-replacing purebred Hereford herd targeting the domestic market. Daughters are retained for breeding and so maternal traits are of importance. Steers are slaughtered at 18 months of age to produce 300 kg carcases with 10 mm P8 fat depth. A moderate cost is applied for cow feed costs during the annual feed shortage period.
Northern Self-Replacing Index – Estimates the genetic differences between animals in net profitability per cow joined in a commercial self-replacing herd targeting the domestic market. This index is suitable for use by both straight bred Hereford herds and in crossbreeding programs where Hereford bulls are being used over a Bos indicus based cow herd. Daughters are retained for breeding and so maternal traits are of importance. Steers are slaughtered at 18 months of age to produce 340 kg carcases with 12 mm P8 fat depth. A high cost is applied for cow feed costs during the annual feed shortage period.
Southern Baldy Maternal Index – Estimates the genetic differences between animals in net profitability per cow joined in a commercial crossbred herd using Hereford bulls over Bos taurus females (e.g. Angus). A portion of the heifers are retained for breeding and so maternal traits are of importance. The steers and surplus heifers are destined for slaughter at 18 to 19 months of age. Steers produce 300 kg carcases with 10 mm of P8 fat depth, while heifers produce 270 kg carcases with 12 mm of P8 fat depth. A moderate cost is applied for cow feed costs during the annual feed shortage period.
Northern Baldy Terminal Index – Estimates the genetic differences between animals in net profitability per cow joined in a commercial crossbred herd using Hereford bulls over Bos indicus/Tropical females (e.g. Santa Gertrudis) where all progeny (male and female) are destined for slaughter. Steers and heifers are slaughtered at 18 to 19 months of age. Steers produce 340 kg carcases with 14 mm of P8 fat depth while heifers produce 300 kg carcases with 17 mm of P8 fat depth.
Further details, including profit driver (blue), EBV weightings (red) and predicted response (green) graphs for each of the new selection indexes, are available in the Interpreting Australian Hereford Selection Indexes tip sheet. This tip sheet is available on both the Herefords Australia website HERE and the BREEDPLAN website (http://breedplan.une.edu.au/).
Using the New Herefords Australia Selection Indexes
To assist Hereford producers identify which of the new Herefords Australia Selection Indexes they should be using, a flow chart has been developed. For commercial producers, this should assist in identifying which selection index best suits an individual production system. For seedstock producers, this is a tool that can be provided to commercial clients (e.g. in sale catalogues) to assist in identifying which of the new Herefords Australia Selection Indexes is best suited to their situation.
It is important to remember that producers should not just use the selection index with the highest value; while a bull ranked highly for the Southern Self-Replacing Index may be a suitable choice for a Victorian producer targeting straight-bred Hereford cattle for the domestic market, he is unlikely to be the most suitable bull for a commercial producer in Northern Queensland targeting flatback progeny in a terminal system. Instead, a Northern Queensland producer in this situation would be best to utilise the Northern Baldy Terminal Index. Of course, seedstock producers with clients located across a range of production systems may need to consider multiple selection indexes within their own breeding programs.
There are two Herefords Australia Selection Indexes suitable for producers in winter-dominated rainfall regions, where feed costs are inherently lower (e.g. southern New South Wales, Victoria, Tasmania, southern South Australia and south-west Western Australia). For those living in one of these regions and producing straight-bred Herefords for the domestic market, then the Southern Self-Replacing Index will be the selection index of choice. For those living in these regions but using Hereford bulls in a cross-breeding program (e.g. to produce Black or Red Baldies), then the Southern Baldy Maternal Index is the most suitable selection index.
The remaining two Herefords Australia Selection Indexes have been designed for producers in summer-dominated rainfall regions, where feed costs are inherently higher (e.g. Queensland, northern New South Wales, northern Western Australia, northern South Australia and the Northern Territory). For those in these locations that keep a portion of heifers (whether they be straight-bred Hereford heifers or flatback/baldy heifers), then the Northern Self-Replacing Index will be the selection index of choice. For those in these regions that don’t keep any replacement heifers (e.g. all heifers are sent for slaughter), then the Northern Baldy Terminal Index is the most suitable selection index.