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Sperm chromatin in beef bulls in tropical environments

D'Occhio, M. J. and Hengstberger, K. J. and Tutt, D. and Holroyd, R. G. and Fordyce, G. and Boe-Hansen, G. B. and Johnston, S. D. (2013) Sperm chromatin in beef bulls in tropical environments. Theriogenology, 79 (6). pp. 946-952. ISSN 0093-691X

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Article Link(s): http://dx.doi.org/10.1016/j.theriogenology.2013.01...

Abstract

Sperm chromatin status was assessed in 565 Zebu and Zebu crossbred beef bulls in extensive tropical environments using the sperm chromatin structure assay (SCSA). The SCSA involved exposure of sperm to acid hydrolysis for 0.5 or 5.0 minutes, followed by flow cytometry to ascertain relative amounts of double-stranded (normal) and single-stranded (denatured) DNA, which was used to generate a DNA fragmentation index (%DFI). With conventional SCSA (0.5-minute SCSA), 513 bulls (91%) had <15 %DFI, 24 bulls (4%) had 15 to 27 %DFI, and 28 bulls (5%) had >27 %DFI. In 5.0-minute SCSA, 432 bulls (76%) had <15 %DFI, 68 bulls (12%) had 15 to 27 %DFI and 65 bulls (12%) had >27 %DFI. For most bulls, the SCSA was repeatable on two to four occasions; however, because most bulls had <15 %DFI, repeatability of the SCSA will need to be determined in a larger number of bulls in the 15 to 27 %DFI and >27 %DFI categories. The %DFI was negatively correlated with several bull semen parameters and the strongest negative correlation was with normal sperm. There was a strong positive correlation between %DFI and sperm head abnormalities. Based on these findings, most Zebu beef bulls in extensive tropical environments had relatively stable sperm chromatin. Based on the apparent negative correlations with conventional semen parameters, we inferred that the SCSA measured a unique feature of sperm quality, which has also been suggested for other species. Further studies on the relationships between sperm chromatin stability and fertility are required in beef bulls before chromatin status can be used as an additional predictor of the siring capacity of individual bulls in extensive multiple-sire herds. (C) 2013 Elsevier Inc. All rights reserved.

Item Type:Article
Business groups:Animal Science
Additional Information:D'Occhio, Michael J. Hengstberger, Kirstin J. Tutt, Desmond Holroyd, Richard G. Fordyce, Geoffry Boe-Hansen, Gry B. Johnston, Steve D. Meat and Livestock Australia; Queensland Fertility Group The authors thank the many cattle station owners who provided bulls for the study and station staff for their expert assistance. The study was supported, in part, by Meat and Livestock Australia (Dr Wayne Hall) and the Queensland Fertility Group (Mr Keith Harrison). Elsevier science inc New york
Keywords:Bull Sperm chromatin Semen parameter Sperm chromatin structure assay frozen-thawed semen structure assay northern australia dna fragmentation field fertility fertilization heterogeneity spermatozoa insulation integrity
Subjects:Animal culture > Breeding and breeds
Animal culture > Cattle
Deposited On:27 Nov 2013 06:55
Last Modified:27 Nov 2013 06:55

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