Surreal illustration of a bull formed by sperm cells, symbolizing fertility.

Is Your Dairy Bull Up to Par? Understanding Sperm Morphology

Soraya Malik in Science & Nature December 2025 • 4 min read.

"A look into the health and fertility of Friesian Holstein bulls in Indonesian AI centers."

For dairy farmers, especially those raising Friesian Holstein (FH) cattle in Indonesia, artificial insemination (AI) is a cornerstone of breeding programs. AI relies on the quality of semen collected from bulls at Artificial Insemination Centers (AIC). These bulls are carefully selected as donors, ensuring that only the highest-quality frozen semen is distributed across the nation to improve breeding outcomes.

A key method for gauging a bull's fertility potential is the Breeding Soundness Evaluation (BSE). Worldwide, BSE helps assess the breeding potential of bulls, boars, and stallions. This evaluation includes assessing general reproductive organs, scrotal circumference, sperm motility, and sperm morphology.

While BSE is applied in Indonesian AI centers, semen analysis is often limited to sperm concentration and motility. Sperm morphology, which is the study of sperm abnormalities and normal structure, hasn't received as much attention. Considering this gap, this article focuses on evaluating sperm morphology, especially primary sperm abnormalities, in FH bull semen from three AI centers in Indonesia. By understanding sperm morphology, farmers and breeders can make more informed decisions, ultimately boosting the success of their breeding programs.

Decoding Sperm Morphology: What's Normal and What's Not?

Surreal illustration of a bull formed by sperm cells, symbolizing fertility.

Sperm morphology involves assessing the physical characteristics of sperm cells. A healthy sperm has a specific structure, and deviations from this structure can impact its ability to fertilize an egg. These deviations are classified as abnormalities. Identifying and understanding these abnormalities is crucial for determining the fertility potential of a bull.

Sperm abnormalities are broadly categorized into three groups:

Primary Abnormalities: These affect the sperm head and acrosome (the cap-like structure containing enzymes essential for fertilization).
Secondary Abnormalities: These impact the midpiece, particularly the cytoplasmic droplet, which provides energy for the sperm's journey.
Tertiary Abnormalities: These involve damage to the sperm tail, affecting its movement and ability to reach the egg.

This study primarily focused on primary abnormalities. The researchers analyzed semen samples from 22 Friesian Holstein bulls across three AI centers in Indonesia, with results showing that all 22 bulls had a low sperm abnormality rate (less than 10%). The most common primary abnormality observed was pear-shaped sperm (0.81±0.93%), while detached heads were the least frequent (0.01±0.04%).

Optimizing Your Breeding Program: Key Takeaways

The study revealed that the sperm abnormality rates in Friesian Holstein bulls from three AI centers in Indonesia were generally low, suggesting that these bulls are suitable for breeding programs. However, there were variations between AI centers, with one center (B) showing a higher primary sperm abnormality rate than the others. This highlights the influence of environmental and management factors on sperm quality.

While the Indonesian National Standard (INS) sets a sperm abnormality rate of 20%, this includes both primary and secondary abnormalities. Since secondary abnormalities can be self-selected during sperm motility examination, focusing on primary abnormalities is critical for accurate assessment. Regular evaluation of sperm morphology, with an emphasis on primary abnormalities, can help identify potential fertility issues early on.

By prioritizing sperm morphology assessments and addressing factors that contribute to sperm abnormalities, dairy farmers can optimize their breeding programs and improve the overall fertility and productivity of their herds. It's recommended to have semen evaluated individually and not in random, thus, FH bull semen samples presenting a high sperm abnormality rate will not be processed into frozen semen.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.14710/jitaa.35.2.90-94, Alternate LINK

Title: Sperm Morphological Assessments Of Friesian Holstein Bull Semen Collected From Three Artificial Insemination Centers In Indonesia

Subject: General Veterinary

Journal: Journal of the Indonesian Tropical Animal Agriculture

Publisher: Institute of Research and Community Services Diponegoro University (LPPM UNDIP)

Authors: B. Purwantara, R.I. Arifiantini, M. Riyadhi

Published: 2010-06-15

Everything You Need To Know

Why is artificial insemination so important for dairy farmers?

Artificial insemination (AI) is crucial for dairy farmers, especially those raising Friesian Holstein (FH) cattle in Indonesia. AI allows for the distribution of high-quality frozen semen from selected bulls across the nation, improving breeding outcomes. The study underscores the significance of assessing sperm morphology, which directly impacts the success of AI programs by identifying potentially infertile semen.

What exactly is sperm morphology, and why is it important?

Sperm morphology is the study of sperm abnormalities and normal structure. It is important because it directly impacts a bull's fertility potential. The presence of abnormalities, such as pear-shaped sperm or detached heads, can hinder the sperm's ability to fertilize an egg. Assessing sperm morphology helps farmers and breeders make informed decisions about which bulls to use in breeding programs, thereby increasing the likelihood of successful conception.

What are the different types of sperm abnormalities, and why do they matter?

Primary abnormalities affect the sperm head and acrosome; Secondary abnormalities impact the midpiece, particularly the cytoplasmic droplet; Tertiary abnormalities involve damage to the sperm tail. The study focused on primary abnormalities, which are crucial because the head and acrosome contain the genetic material and enzymes needed for fertilization. High rates of any of these abnormalities can indicate reduced fertility in the bull. The specific abnormalities observed in the study, such as pear-shaped sperm and detached heads, directly impact fertilization success.

What is a Breeding Soundness Evaluation, and how does it relate to this study?

A Breeding Soundness Evaluation (BSE) is a comprehensive assessment of a bull's breeding potential. It includes examination of reproductive organs, scrotal circumference, sperm motility, and sperm morphology. The study specifically focused on sperm morphology. While sperm concentration and motility are often assessed, morphology provides deeper insights into the sperm's ability to fertilize an egg by identifying structural defects.

What were the main findings of the study regarding sperm morphology in Friesian Holstein bulls?

The study found low sperm abnormality rates in the Friesian Holstein bulls across the three Artificial Insemination Centers (AIC) in Indonesia, suggesting they are suitable for breeding. However, variations in abnormality rates were observed between different AICs, indicating environmental and management factors. These factors, such as the bull's diet, health, and handling, can influence sperm quality, highlighting the need for consistent management practices to optimize breeding outcomes.