The objective of the current study was to investigate the influence of synergism of the dry powder of Alpinia galanga rhizomes (AGR) and/or zinc sulfate in the diet on semen quality and reproductive traits of California rabbit bucks. The study was conducted in two stages. First stage: appreciation of semen characteristics, 36 California rabbit bucks (aged 5 months) with average body weights of 2980 g were divided randomly into six treatments (six individuals each). The treatment groups were: first group, control fed basal diet (C); second group, fed basal diet plus 1 g AGR/kg dry matter (DM) (AGR1); third group, fed basal diet plus 2 g AGR/kg DM (AGR2); fourth group, fed basal diet plus 200 mg Zn/litre drinking water (Zn); fifth group, fed basal diet plus 1 g AGR/kg DM and 200 mg Zn/litre drinking water (AGR1 + Zn); sixth group, fed basal diet plus 2 g AGR/kg DM and 200 mg Zn/litre drinking water (AGR2 + Zn). Second stage: the previous bucks were used to determine the efficiency of semen on reproductive fertility traits, 48 mature does (aged 6 months, nulliparous) with an average body weight of 3050 ± 20.7 g were divided randomly into six treatments and inseminated with previous groups of treated bucks. The results of the first stage, recorded high activity on gonadotropins hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH), free testosterone (FT), progesterone (P4) and oestrogen (E217β) concentrations for AGR1 + Zn and AGR2 + Zn compared with the control group. Groups AGR1, AGR2, AGR1 + Zn and AGR2 + Zn had significantly lowered concentrations of triglycerides, total cholesterol, low-density lipoprotein, and malondialdehyde (MDA), whereas high-density lipoprotein and total antioxidant capacity (TAC) were increased significantly compared with the control group. The group supplemented with AGR with or without Zn had significantly improved ejaculate volume, advanced motility, sperm concentration, and cell integrity. Fertility rate and litter size were improved in all groups compared with the control. It was concluded that supplementing diets with Alpinia galanga and Zn significantly increased sperm percentage, motility and reproductive hormones (testosterone, FSH, LH, E217β, P4). This suggested that this plant when used may be favourable for improved sperm quality and fertility parameters.

Alpinia galanga is an important species cultivated as a culinary spice and is the type species of the genus. It is hence a member of sect. Alpinia subsect. Alpinia (with non-tubular bracteoles). However, molecular phylogenetic analyses suggest that A. galanga is closely related to A. nigra in sect. Allughas (with tubular bracteoles). This clade, which includes A. conchigera, is strongly supported with a bootstrap value (BS) of 100% and a decay index (DI) of >+6. These results are based on the internal transcribed spacer (ITS) region of the 18S–25S nuclear ribosomal DNA. The region (405–423bp) was sequenced from 17 accessions representing 16 taxa of Zingiberaceae, including 15 species of Alpinia and one outgroup. The sequence divergence ranged from 0.5 to 15.6% among the ingroup and from 10.1 to 13.3% between the ingroup and the outgroup. The results also strongly support the sister relationship of A. rafflesiana and A. javanica in section Allughas (BS=100%, DI=>+6), thus the whole section is paraphyletic. Section Alpinia subsect. Catimbium is monophyletic (BS=100%, DI=+5). On the other hand, sect. Alpinia subsect. Alpinia is paraphyletic (BS=100%, DI=>+6) with respect to sect. Alpinia subsect. Catimbium. The results from a phylogenetic analysis of a subset of the taxa using the spacer between trnL (UAA) 3′ exon and trnF (GAA) of chloroplast DNA confirmed the position of A. galanga in sect. Allughas. It appears that A. galanga has evolved within sect. Allughas and the absence of tubular bracteoles is a convergence with sect. Alpinia, possibly as a result of evolution under domestication.