REGULAR ARTICLES Potential of coconut water to enhance fresh semen quality and fertility in rabbits O. A. Jimoh 1,2 Received: 11 January 2019 /Accepted: 8 July 2019 # Springer Nature B.V. 2019 Abstract Coconut water as a natural diluent was evaluated on rabbit semen quality, conception and litter size in artificially inseminated does. A total of 10 bucks and 90 does, all crossbred New Zealand White × chinchilla, were used for the trial. Pooled semen was obtained from bucks using artificial vagina. Semen diluents were prepared at 0%, 20%, 40%, 60% and 80% and control 50% normal saline and designated as T1, T2, T3, T4, T5 and T6 respectively, in a completely randomised design. Semen analysis was conducted on fresh semen and the various diluted semen immediately at 37 °C. Fifteen does each were randomly allotted to the different treatment and were inseminated with their respective treatment diluted semen using the standard procedure, and conception rate, litter size and productivity index at birth were assessed at kindling. Result obtained revealed that spermatozoa motility and structural membrane integrity of the diluted semen were significantly (p < 0.05) affected by the percentage of dilution. The range of values obtained for spermatozoa motility, structural membrane integrity and acrosome integrity is within the accepted values for good-quality semen. Conception rate, litter size and productivity index at birth were highest in does inseminate with T4 (60%), and the least values were obtained in T5 (80%). In conclusion, coconut water is a suitable diluent for rabbit semen for on-farm artificial insemination, the optimal dilution rate of coconut water in rabbit semen is 60%, which guarantees high conception, litter size and productivity index at birth. Keywords Coconut water . Diluent . Fertility . Insemination . Spermatozoa motility Introduction Artificial insemination (AI) technique is favourable and most suitable for rabbit production. Semen diluents remain the pri- mary challenge, owing to the high cost and unavailability of commercial extenders owing to importation in developing countries. Production costs are forcing farmers to consider more economical ways of maintaining gene pools and suc- cessful breeding via artificial insemination. The diluents used for semen extension play a significant role (Dumpala et al. 2006) in the success of artificial insemi- nation. The dilution of semen is associated with a reduction in cell viability and fertilizing capacity. The quality of extended semen is affected by handling procedures, which are related to the generation of an imbalance among reactive oxygen species (ROS) (Balogun and Jimoh 2017). Spermatozoa are unique in structure and chemical composition and are characterised by high proportions of polyunsaturated fatty acids (PUFAs) in the phospholipid fraction of their membranes (Balogun et al. 2017). However, high level of PUFAs increases the suscepti- bility of cells to free radical attack and lipid peroxidation (De Lamirande et al. 1997), which degrades membrane structure, sperm metabolism and DNA integrity (Balogun et al. 2016). Uncontrolled production of reactive oxygen species that ex- ceeds the antioxidant capacity of the seminal plasma leads to oxidative stress, which is harmful to spermatozoa (Desai et al. 2010). Although several diluents and protocols have been developed to freeze rabbit sperm, obtaining excellent results for fertility rate with some of them (between 70 and 80%; Viudes-de-Castro et al. 2005), Viudes-de Castro and Vicente ( 1996) found similar results for fresh and frozen semen in prolificacy (8.1 vs 8.0 total born, respectively). However, when frozen rabbit sperm * O. A. Jimoh abubakarjimoh2011@gmail.com 1 Animal Physiology Laboratory, Department of Animal Science, University of Ibadan, Ibadan, Nigeria 2 Agricultural Technology Department, Federal Polytechnic Ado Ekiti, Ado Ekiti, Ekiti State, Nigeria Tropical Animal Health and Production https://doi.org/10.1007/s11250-019-02011-z