Mastitis resistance now in breeding data

The Mastitis Resistance Australian Breeding Value (ABV) is one of eight new or updated health and type traits released by DataGene today. These include:

The three new or updated health ABVs will complement on-farm management practices.

Farmers will now have more Holstein bulls to choose from if they want their cows and heifers to calve more easily.

Thanks to the inclusion of genomics in the updated Calving Ease ABV, most Holstein bulls have a Calving Ease ABV, including - for the first time - young genomic sires.

To breed for improved Calving Ease, farmers should select bulls with a Calving Ease ABV of at least 103.

The new Gestation Length ABV gives farmers a breeding tool to manage late-calving cows, help tighten calving patterns and avoid culling and induction.

The ABV identifies bulls and cows whose calves are born earlier than their expected due date. Cows that calve earlier are in-milk for more days before re-joining and have longer to recover post-calving.

To breed for a shorter gestation, look for bulls and cows with a Gestation Length ABV of less than zero. Every 1 ABV is about 1 day shorter gestation.

Farmers milking all breeds of dairy can now select to directly improve the mastitis resistance of their next generation.

Even young genomic animals now have a Mastitis Resistance ABV.

Previously, the Cell Count ABV was used an indirect selection criterion for mastitis resistance but this new ABV draws on three sets of information to directly target mastitis.

These include: 305-day somatic cell count, udder depth and clinical mastitis records. The Cell Count ABV will continue to be published as it is a useful tool to breed cows that contribute to a lower bulk milk cell count.

To breed replacements with improved mastitis resistance, select animals with a Mastitis Resistance ABV of greater than 100.

Dairy farmer Tim Humphris who milks a herd of 400 Aussie Reds and three-way crosses at Nirranda South, Western Victoria, said the mastitis resistance data was an improvement over cell count ABVs.

"I certainly consider Cell Count when I look at selecting my bulls, but the Mastitis Resistance ABV will give me more confidence," Mr Humphris said.

"To me, it's more important to reduce clinical cases of mastitis than have a cow with a lower cell count.

"We have an 80,000-100,000-cell count, so it isn't really an issue.

"But I'd really like to reduce the cases of clinical mastitis.

"The economic impact of a mastitis case is far greater than a cow with a slightly higher cell count."

The updated the Overall Type ABV had been introduced to help breeders identify animals with higher classification scores, DataGene's Michelle Axford said.

The change had been reflected in DataGene's latest bull and cow rankings as Overall Type and Mammary system are included in the three indices: Balanced Performance Index (BPI), Health Weighted Index (HWI) and Type Weighted Index (TWI).

The new type traits complete the set of composite traits, giving farmers an overview of an animal's strengths for rump, feet and legs as well as dairy strength.

The new and updated type breeding values are published for Holsteins, Red Breeds, Guernseys and Ayrshires.

Type ABVs are unchanged for Jerseys.

The new ABVs are the result of DairyBio research, drawing upon records supplied by Ginfo herds.

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