From Lorenzo’s Desk

Lorenzo Frers | RSG Head of Laboratories

This month’s topic: WHAT IS A CASA TEST?

CASA (Computer Assisted Sperm Analysis) is a laboratory method that uses a microscope, camera, and specialized software to automatically measure sperm characteristics in a semen sample.

What does CASA measure? 

CASA can evaluate many parameters, the 3 we will highlight are

• Sperm concentration (number of sperm per mL)
• Motility (percentage of moving sperm or how much of it is dead)
• Progressive motility (sperm moving forward effectively)

Typical post-thaw CASA benchmarks for bulls

That means that if a straw passes acceptable CASA parameters it is good to use?

Absolutely not for two main reasons  

1. It will need a reliable, fixed sperm morphological test to evaluate abnormalities as a percentage (see our previous newsletter article)
2. Not all CASA are the same!!  

ICAR (International Committee for Animal Recording) notes that laboratories using different CASA equipment, settings, chambers, and thresholds, which can produce different results from the same semen sample. [icar.org]. Therefore since last year they have introduced a Bull Proficiency test to validate and create an international standard for CASA systems.

At RSG, we test 3 straws of every batch of semen produced with an independent third-party lab with over 10 years of experience in CASA analysis. (Ash Scientific) This lab is one of the few in New Zealand that has been ICAR proficiency tested this year validating its accuracy against international standards.

Practical takeaway 

If you’re aiming for top quality semen ask for a post-thaw report on

• Concentration, Total Motility and Fast progressive : CASA with ICAR proficiency test
• Morphological normality test report

 ICAR Proficiency Test on Bull Semen (PT BS)

Bull semen analysis is one of the parameters used to assess bull fertility and conception rate in the female served. A robust quality system (QS) to analyse bull semen is strategic for Artificial Insemination (AI) organisations to provide a qualified product to the breeders and farmers. Furthermore, also the instrument manufacturers need QS to evaluate their products and different calibration settings.  

To analyse bull semen, computer assisted semen analysis (CASA) and flow cytometry are largely used alongside the microscope method. Nowadays, there is no international standard method for bull semen analyses, consequently the criteria and performance of these tests have not been established. For this reason, it is necessary to collect data on the methods used and to provide tools for their analytical quality control.  

ICAR has developed a new service of proficiency testing on bull semen matrix (PT BS) in order to:  

Assess the analytical comparability for different parameters between the different users (7.1.1)  

Provide each participant with feedback on their own objective performance and a robust tool for quality control over time (7.1.2)  

RSG NZ Reproductive Technician’s Perspective

Leandro Arreseigor | RSG Reproductive Technician

With the TVR season just around the corner, our reproductive team is already preparing for a busy few months. RSG NZ will be working across two donor centres and three satellite locations to support both contract heifer programs and private client herds.

Appointment availability is filling quickly, so we encourage clients to book early—even if your procedures are still one or two months away. Planning ahead helps ensure we can accommodate your preferred timing and provide the best possible service throughout the season.

If you’re considering TVR this season, now is the time to get in touch with your RSG NZ Client Service Representative to secure your spot.

Javier Balladares | RSG Reproductive Technician

Looking ahead, there is growing confidence across the sector, supported by stronger dairy goat milk prices and improving wool markets. With this positive momentum, I believe there is a great opportunity for producers to continue investing in genetics and advanced reproductive technologies as we head into 2027.

We’re excited about what’s ahead and look forward to continuing to work alongside our clients to build stronger, more productive breeding programs.

Healthy Calves, Happy Clients 

As calving season continues across New Zealand, we are thrilled to be receiving overwhelmingly positive feedback from clients regarding the performance of RSG New Zealand embryos.

Breeders and farmers are reporting smooth calvings, healthy calves, and excellent outcomes throughout the season. From embryo production through pregnancy establishment and now successful calvings, the RSG and Trans Ova system continues to prove its ability to consistently deliver high-quality embryos that perform from start to finish.

Seeing healthy calves arrive with minimal issues is a testament to the quality of our program and the trust our clients place in RSG New Zealand.

Thank you to our clients for sharing your success. We look forward to celebrating many more healthy calves throughout the remainder of the season.

Payment Reminder

As we head into another busy breeding season, we kindly ask clients with overdue invoices to arrange payment at their earliest convenience.

Keeping accounts up to date allows our team to continue providing the high level of service and support you expect from RSG New Zealand. If you have any questions regarding your account, please don’t hesitate to contact our team—we’re happy to assist.