IMPACT OF GELATIN AND α–CHYMOTRYPSIN SUPPLEMENTATION IN RABBIT SEMEN EXTENDER ON KINDLING RATE AND LITTER TRAITS

Document Type : Original Article

Authors

1 Anim. Prod. Res. Instit., Agric. Res. Cent., Egypt

2 Animal Production Research Institute, Agriculture Research Center, Egypt.

Abstract

The present work was carried out to study the effect of addition gelatin and α-chymotrypsin to semen rabbit extender on semen quality and litter traits during incubation at 37oC for up to 4 hours and storage at 5oC for up to 72 hours of V.line rabbits. Twenty sexually mature bucks and eighty multiparous does of V.Line rabbits in various parities were used. A base extender was prepared (Tris-citric acid-glucose) used a basal buffer.  The basal extender was divided into five portions and treated as following: (1) Tris-based extender (control), (2) Tris-based extender + 1gm gelatin/100ml, (3) Tris-based extender + 1gm gelatin/100ml+ 100mg α-chymotrypsin/100ml (4) Tris-based extender + 1gm gelatin/100ml + 200mg α-chymotrypsin/100ml, and  (5) Tris-based extender + 1gm gelatin/100ml  + 400mg α-chymotrypsin/100ml. The concentrations of total free amino acids were determined in the five portions extenders. Semen was collected by artificial vagina twice weekly for ten consecutive weeks. Semen ejaculates were evaluated microscopically and only the ejaculates with advanced sperm motility ≥ 70% were pooled and used. Semen from different bucks was pooled and divided into five equal portions and each portion was diluted with one of the previous prepared extenders. The final dilution of all groups extender was 1 semen: 4 extender. Thereafter, each extender semen portion was divided into two sub-portions; the first portion was incubated at 37 ◦C for 0, 2 and 4 hours, while the second portion was stored at 5 ◦C for 24, 48, and 72 hours.  Fresh semen samples were also collected and treated as described above and used immediately for artificial insemination.
The obtained results indicated that the total free amino acids for treated extender groups were higher (P<0.05) compared with those for control group.  Extender supplied with the high level of α-chemotrypsin (400mg) showed the highest increase (P<0.05) of all free amino acids with the lowest (P<0.05) content of ammonia. 
Irrespective of cold temperature (5oC) and incubation time (37oC) added with gelatin and α-chemotrypsin to Tris-buffer extender increased (P<0.05) percentages of advanced sperm motility and decreased abnormality and dead sperm. The percentages of advanced sperm motility decreased (P<0.05), while sperm abnormal and dead spermatozoa increased (P<0.05) by elevated storage temperature or incubation time. Concentrations of ALT and AST in seminal plasma were reduced (P<0.05) in the treated groups. However, the activated of ALT and AST enzymes activities increased (P<0.05) by either the elevated storage temperature or by incubation time. Values of thiobarbituric acid-reactive substances (TBARS) and superoxide dismutase (SOD) decreased (P<0.05) in treated samples compared with the control group. However, the levels of TBARS and SOD increased (P<0.05) and glutathione (GSH) decreased (P<0.05) by advancement of incubation time or by storage temperature. Kindling rate of females artificially inseminated with semen extender supplemented with different levels of α-chemotrypsin and gelatin were improved (P<0.05) compared with the control group. In addition, the total and live litter size at birth, litter size at weaning, bunny weight at birth and bunny weight at 28 days were increased (P<0.05) in treated groups than the control.  However, there found no differences between 200 and 400 mg α-chymotrypsin on these trait.
In conclusion, rabbit semen extender supplementing with gelatin and α- chemotrypsin not only enhanced the semen quality and extended its storagability but it also improved its subsequent impacts on the reproductive performance.
                   
 

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