Effect of a dietary antioxidant supplementation on semen characteristics of the Colombian horse

Cooling equine semen increases production of reactive oxygen species (ROS). Elevated concentrations of ROS have detrimental consequences by causing changes in membrane permeability. Although there are reports of antioxidant supplementation to improve sperm quality in horses, there are few reports on the Colombian breed. The objective of this study was to evaluate the effect of nutritional supplementation with a variety of antioxidants on semen characteristics of Colombian horses. Six (n=6) Colombian Creole stallions aged between 5 and 15 years were collected 3 times a week using a Missouri artificial vagina for 20 weeks. Stallions were randomly allocated into a control (C) or a supplementation group (SG) with Natural Fertility®. Cobalamin 0.36 mg/day; pyridoxin 16 mg/day; retinoic acid 366799 IU/day; alpha tocopherol 1600 IU/day; ascorbic acid 4000 mg/day; folic acid 1200 mg/day; lysine 640 mg/day; methionine 960 mg/day; threonine 400 mg/day; arginine 400 mg/day; L-Carnitine 10000 mg/day; omega 3 3200 mg/day; zinc 1200 mg/day; copper 44 mg/day, chromium 6 mg/day and selenium 8 mg/day, was added to the basal diet (hay, mineralized salt, 2 kg of grain and water). Repeated measures design with a wash-out period of 2 weeks between treatments was used. During a periodof 8 weeks, semen was analyzed twice a week for motility and kinetics using a Sperm Class Analyzer (SCA®) system; sperm vitality (SV) and acrosomal Integrity (AI) by fluorescent microscopy, abnormal morphology (AM) by supravital stain, and plasmatic membrane Integrity by hypoosmotic test (HOST). Reactive oxygen species and total antioxidant capacity (TAC) by ferric reducing antioxidant power assay (FRAP) were assessed by spectrofluorimetry. Comparison of means was performed using Tukey's test with p≤0.05; using SAS program 3.81. SG increased the beat cross frequency of semen with 36.68 Hz ± 0.89 vs. 32.67 Hz ± 0.73 (C). In addition, a higher AI was found for SG (82.92 ± 0.72 %) compared to C (78.51% ± 0.83). SG also increased the TAC of seminal plasma (15.35± 0.92 μmol Trolox/L) compared to C (18.86± 1.75 μmol Trolox/L). In the individual analysis it was found that SG increased the total and progressive motility of the semen of two horses, however it reduced both parameters for two other individuals, compared to C. In conclusion, supplementation of the diet of horses with a supplement that provides vitamins, minerals, amino acids, and omega 3 can increase the antioxidant capacity of seminal plasma, as well as sperm quality, however this may be subject to a differential effect on each horse.