22 Comparing Three Extenders: Hashi, Green Buffer and INRA 96, for Chilled Storage of Bactrian Camel Semen

Abstract

Semen preservation remains challenging in the camel industry. The objective of the present study was to compare 3 different extenders for chilled storage of Bactrian camel semen. Semen (n = 9 ejaculates) was collected from camel bulls (n = 2) manually using artificial vagina. Good neat semen, as far as mass vibration concerns, was equally distributed into 3 double-wall vessels filled with 35°C water. The 3 extenders used in the present study were Hashi, Green buffer (IMV, L’Aigle, France), and INRA 96 (IMV). The Hashi extender consisted of Tris, 2.6%; citric acid, 1.35%; glucose, 0.9%; fructose, 0.9%; penicillin G sodium, 1000 IU mL⁻¹; streptomycin sulfate, 1000 mg mL⁻¹ supplemented with 20% plasma egg yolk and 20% camel skim milk; osmolality of 330 and pH of 6.9). Green buffer was supplemented with 20% plasma egg yolk (osmolality of 335 and pH of 6.9). The osmolality and pH of INRA 96 were 310 and 7, respectively. Extenders at a ratio of 1:3 were added to semen followed by pipetting 10 times with an automatic pipettor. The water-jacketed extended specimen was covered with foam and transferred to individual vaccine carrier equipped with 4 ice packs. This system of cooling not only allows the specimen to cool down slowly and reach 4°C after 7 h, but also reduces the viscosity of camel semen. The assessment was carried out 7 and 24 h after semen dilution, when the specimen reached 4°C. Semen viability parameters were assessed after short-term semen preservation in different extenders. Total motility and progressive forward motility were examined subjectively by single operator using Sperm Track (ISAS, Proiser, Spain) after diluting the specimen to achieve 25 × 10⁶ sperm mL⁻¹. Live percentage of sperm was estimated using Eosin B Fast Green staining method. Plasma membrane integrity was assessed using the hypo-osmotic swelling (HOS) test. Following arcsin transformation, data were analysed by GLM procedure followed by Tukey test in SAS (SAS Institute Inc., Cary, NC, USA). At 7 and 24 h, there were no differences among the 3 extenders in total motility of sperm (Hashi: 73 and 67.4%; Green buffer: 71.6 and 62.1%; INRA 96: 70 and 66.2%; P > 0.05), live percentage of sperm (Hashi: 76 and 73%; Green buffer: 70.5 and 65.6%; INRA 96: 77.8 and 70.7%; P > 0.05), or HOS test (Hashi: 52.4 and 45.2%; Green buffer: 49.6 and 40.6%; INRA 96: 57.3 and 51.1%; P > 0.05). However, at the same times, progressive forward motility was similar between Hashi (47.7 and 28.6%) and Green buffer (40 and 23.5%; P > 0.05) but was different between Hashi and INRA 96 (23.6 and 16.7%; P < 0.05). In conclusion, Hashi and Green buffer could be considered suitable extenders to preserve Bactrian camel semen under chilled condition. Further studies with a larger number of bulls and ejaculates are warranted.