Beef Herd Fertility Management – Montana Style

Recently, along with some Zoetis colleagues, I had the opportunity to make an educational trip to Mid-West Montana, USA to find out more about their beef herd fertility management systems.  We were hosted by Jason and Jody Swanz from Snowy Mountain Cattle Co. near Judith Gap who run around 550 Angus breeding cows on their ranch. Cows calve February-April and then graze extensive pastures until early July when they must be moved to higher mountain pasture areas as the lower plains will be suffering from drought.  Cows are still mostly moved by cowboys on horseback! Alfalfa hay is made in early season for winter feed but seasonal droughts make it a very narrow harvesting window.  Calves are castrated with rubber rings, hot branded and tagged when young and at weaning are sold off the farms to grower/feedlots.  Pneumonia/clostridial vaccines are used routinely in all calves prior to, or at, feedlot entry.  These beef farmers work in extreme conditions with very cold/snowy winters and hot dry summers.

                                                             Swanz Ranch cow on typical June pasture

Breeding Management

We also visited the Stevenson Angus Ranch near Hobson which is home to the longest established Angus bull sale in USA.  In common with many progressive herds in Montana the herd is bred using a mix of synchronised artificial insemination (AI) and natural service during a compact 9 week breeding period.   

Genomic testing is used to identify superior heifer and bull calves as part of the breeding programme. Angus is the dominant sire breed but we also saw Simmental bulls being used – not recognisable to us as in North America they have been outbred to produce black bulls that look nothing like the European Simmental breed!

                                          Black Simmental bull                                                                                Stevenson Ranch Angus cows and calves


How is synchronisation/AI used?

Cows and heifers are synchronised in large batches using intra-vaginal CIDR® implants to allow single fixed-time AI.  Use of AI allows selection of genetically superior sires with easy calving traits and helps produce a tight calving pattern with 65-70% of females calving in first 21 days. Sweeper bulls are used to follow up the AI with yearling bulls commonly utilised along with mature bulls.

Rocky Mountain Oysters – would you eat them?

We had lunch at local tavern with Darrell Stevenson and were encouraged to taste local dish made from best quality Montana bull calf testicles – I have to admit they were tasty but could have been chicken nuggets!



More like this:

Can beef fertility management improve cattle productivity?

Fertility Management: Taking things to the next level

How to manage breeding by AI in your beef herd


CIDR® contains 1.38 g progesterone: POM-V.

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