Tonometer for Measuring Testicular Consistency of Bulls to Predict Semen Quality

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Abstract
An instrument, called a tonometer, was designed to measure testis consistency in bulls. Two force-deflection readings of the testis were obtained as a measure of consistency. The objective was to relate this to the quality of sperm produced. When the instrument was used by different experienced personnel and applied to the same series of bulls repeatability was high (r≥.89). When 150 bulls were remeasured after 1 yr. repeatability was 0.49, indicating that consistency of the testes had changed somewhat during 1 year. This was suggested by manual palpation also. Semen was collected four times per wk. for 4 weeks from 64 Holstein bulls ranging from 17 to 150 months of age. Among-bull correlations between the ratio of two tonometer force-deflection measurements and tests of semen quality such as % unstained sperm, % normal sperm, % motile sperm after 1 day of storage at 5° C, % motile sperm after pellet and ampule freezing and nonreturn rate ranged from 0.59 to 0.94. Nearly all correlations were highly significant statistically (P<.01). The results indicate that the tonometer provides a simple quantitative means of predicting semen quality and potential fertility in dairy bulls. Further investigation of the usefulness of the tonometer in evaluating breeding potential in young bulls under range conditions, where it is difficult to obtain representative semen collections, is needed. Copyright © 1969. American Society of Animal Science. Copyright 1969 by American Society of Animal Science

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