Alkaline and acid phosphatase, β-glucuronidase and electrolyte levels in fractionated stallion ejaculates.

This research article investigates how the levels of certain components vary across different fractions of stallion ejaculate and between different stallions. The researchers found that sperm-rich ejaculate fractions contain high levels of specific enzymes and inorganic phosphate, and these levels relate positively to sperm concentration. The study also discovered that subfertility in stallions may be linked to certain ratio differences in these components.

Study Design and Methodology

• The objective of the research was to discern the levels of various components such as Na, Cl, K, Mg, Ca, inorganic phosphate, and enzymes like alkaline phosphatase, acid phosphatase and β-glucuronidase in different parts of the ejaculate, along with their differences between various stallions.
• To facilitate this, analyses were performed on semen collections from a number of stallions. The collections were undertaken using a specialized computer-controlled collection apparatus that separately collected different “jets” of the ejaculate into five cups.
• The researchers then singled out two cups – one with the highest sperm concentration (HIGH) and another with the lowest concentration (LOW) – for further analysis.
• The experiment was divided into three trials. In the first trial, semen was collected from three reproductively normal stallions. The second trial featured ejaculates from two normal stallions and two subfertile stallions. The third trial included semen collections from seven stallions with varied reproductive history.

Findings

• It was observed that the fractions rich in sperm contained the highest levels of the enzymes alkaline phosphatase, acid phosphatase, β-glucuronidase, as well as inorganic phosphate. Moreover, these levels directly correlated with the sperm concentration.
• The researchers found considerable differences in the ratios of inorganic phosphate and chloride within the HIGH and LOW ejaculate fractions of subfertile stallions compared to fertile ones.
• The results showed that the concentrations of calcium and magnesium were highest in the ejaculate fractions with low sperm content. However, no significant differences were found between the fertile and subfertile stallion groups in this regard.
• Potassium, sodium, and chloride concentrations, on the other hand, were similar in both HIGH and LOW fractions as well as in whole ejaculate samples. The pre-sperm fluid had the highest concentrations of sodium and chloride.

Implications

• The research results suggest that the composition of seminal plasma (SP) could potentially explain some of the observed variation in the storage tolerance of different ejaculates and ejaculatory fractions. This could indicate that the composition of SP could serve as a useful marker for analyzing the health and fertility status of stallions.
• The significant differences between subfertile and fertile stallions in regards to certain component ratios suggest that these could potentially serve as indicators of fertility and could aid in diagnosing subfertility in stallions.