Reproductive Performance of the Saanen Bucks under the Tropical Climate of the Sudan

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Date
2015-06-22
Authors
Adam,Ahmed Abdelgadir
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Publisher
University of Khartoum
Abstract
This study was carried out on six mature Saanen bucks two years old imported from the Netherlands for grading up of local goat breeds. The bucks were kept under natural light regime in the subtropical climate of the Sudan. The experiment was designed to investigate the existence of any seasonal variation in mating behaviour spermatic activity, semen characteristics and freezability. Semen was collected by means of an artificial vagina at weekly intervals and criteria such as ejaculate volume, sperm motility, concentration, percentage dead and percentage abnormal spermatozoa and survival of spermatozoa after freezing-thawing were monitored. The collected semen was maintained at 30°C until diluted. The milk diluent and the Tris-based diluents were added to the semen in one step or two steps to achieve a dilution rate of, 1:4 after cooling to 5°C semen was aspirated into 0.5 ml polyvinyl straws and equilibrated with the diluent components before freezing in liquid nitrogen. Every month the scrotal circumference was measured. The Saanen bucks were found to have a definite breeding season (early autumn through winter) and ejaculated semen into an A.V. with satisfactory quality during this period. Libido as assessed by the reaction time was significantly (P<0.0I) higher in autumn and winter with an average value of 61.98±7.34 sec. The semen was characterized by an ejaculate volume of 0.77 ml, concentration of 2.77x l09 sperm/ml, mass activity of 3.19, active sperm cells were 68.57%, 15.49% were dead and 8.56% had abnormal morphology. The season affected all the ejaculate characteristics analysed except the volume of ejaculate and mass activity of spermatozoa. Nevertheless, the pooled seminal volume, when repeated collections were performed, was highly significantly different (P<0.0I) in autumn than in other seasons. During autumn semen quality was high since an average ejaculate contained only 7.15% abnormal cells, only 12.15% dead spermatozoa and more forward moving cells (71.73%) than at other seasons. The poorest quality semen was collected during summer with the highest incidence of spermatozoa with morphological abnormalities (11.61%) and highest percentage of dead sperm cells (19.32%). However, the magnitude of these seasonal effects was not sufficient to prevent the bucks being used for breeding throughout the sexual activity period. The freezability of unwashed Saanen spermatozoa varied with the season of semen collection. Satisfactory results were obtained only in autumn and winter. An average of 30.03% and 33.44% spermatozoa survived the deep freezing process for the one and two-steps methods of dilution, respectively. A non-significant difference between the two methods of dilution was recorded
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Keywords
Reproductive Performance;Saanen Bucks;Tropical;Sudan
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