Full Length Research Paper

Testicular development and relationship between body weight, testis size and sperm output in tropical boars

S. O. C. Ugwu, A. E. Onyimonyi* and H. Foleng

Department of Animal Science, University of Nigeria, Nsukka, Nigeria.

*Corresponding author. E-mail: onyimonyi@yahoo.com.

Accepted 16 February, 2009

Ten boars selected from each group of local Nigerian (LNB), Large White (LW) and LNB x LW (F1) crossbred boars were studied to determine the pattern of testicular development by external testicular measurements (length and width of testis) and to find out the relationship between external testicular dimensions body weight and sperm output. The results showed that LW boars were superior to both LNB and LNB x LW (F1) boars in all testicular and body weight measurements, while LNB x LW (F1) boars showed remarkable improvement over the LNB parent in all measurements. Rapid growth of the testis occurred in LNB from 14 – 30 weeks of age and 14 – 32 weeks of age in the crossbreds. Rapid growth of testis occurred from 12 – 32 weeks in the LW boars. These periods coincided with the phase of rapid gain in body weight in the various groups. Significant (P < 0.05) between genotype differences were observed in body weight and testicular measurements. Sperm output/48h was highest in LW boars and lowest in LNB boars. Correlations between body weight testicular measurements and sperm output per 48 h were positive and highly significant (P < 0.01) in all groups with r² value ranging from 0.74 – 0.90. Sperm output was highly correlated (P < 0.01) with body weight in all genotypes with r² values ranging from 0.85 – 0.91. The results generally indicate that measurements of external testis dimensions, body weight and sperm output characteristics can accurately guide the assessment of the reproductive performance of boars.

Key words: Testis size, body weight, sperm output, boars.