Physiological Response, Semen Quality and Blood Metabolites of Friesian Bulls Treated with Zinc-Selenomethionine under Hot Summer Conditions in Egypt

Abstract

The present study aimed to evaluate the impact of administration of zincmethionine and selnomethionine to Friesian bulls during hot summer conditions in Egypt on physiological thermoregulatory response, sexual desire, some physical and chemical semen characteristics and blood metabolites. Twenty sexually mature Friesian bulls were divided into five similar groups (4 bulls/ each). Bulls in the 1st group were unsupplemented and served as a control, while those in the 2nd,3rd,4th and 5th groups were orally supplemented with zincmethionine (Z-Met) at a levels of 2 and 4 mg/kg of BW/day and selenomethionine (Se-Met) at a levels of 0.3 and 0.6 mg/kg of BW/day, respectively, for two months as preliminary period and other three months as a main collection period. Rectal and skin temperatures, pulse rate (PR) and respiration rate (RR) were measured once each week through the experimental period. During the main collection period, semen was collected twice weekly and evaluated for semen-ejaculate volume (SEV), percentage of progressive sperm motility (PSM), live sperm (LS) and sperm abnormalities (SAB), sperm-cell concentration (SCC/ml) and total-sperm output (TSO/ejaculate). Blood samples were collected pre-treatment and monthly during the main collection period to determine concentration of total proteins (TP), albumin (AL) and globulin (GL); thyroxin (T4), triiodothyronine (T3), cortisol and testosterone hormones and zinc (Zn) and selenium (Se) levels in blood plasma. Also, activity of ALT, AST, ALP, ACP, SOD and GSH enzymes, as well as concentration of fructose, zinc and selenium were estimated in seminal plasma.The obtained results revealed that reaction time (RT) was shorter (P<0.05) and blood plasma testosterone concentration was higher (P<0.05) in all treated groups than the control group, begin the shortest (P<0.05) and highest (P<0.05) values of RT and testosterone concentration were recorded for bulls treated with Z-Met, especially in G3 group. Physical semen characteristics (SEV, PSM, LS, SCC/ml, TSO/ejaculate and SAB) were improved (P<0.05) in all treated groups as compared with the control one, being the best (P<0.05) values for bulls treated with Z-Met, especially in G3 group. Also, bulls treated with Z-Met in G3 group showed the lowest (P<0.05) activity of ALT, AST, ALP and ACP enzymes, highest (P<0.05) activity of SOD and GSH enzymes, and fructose, Zn and Se concentrations in seminal plasma as compare to other treated groups and control one. Bulls treated with Z-Met and Se-Met showed increased (P<0.05) levels of AL, T4, T3, Zn and Se, while GL and cortisol levels decreased (P<0.05) in blood plasma as compared to control one. In conclusion, orally administration of zincmethionine and selenomethionine to Friesian bulls had a valuable impact on sexual desire, semen quality and blood metabolites. Therefore, it can be recommended to treating the Frisian bulls with zincmethionine at a level of 4 mg/kg of BW/day during two preliminary months and three main semen collection months for improving the sexual desire, semen quality and blood metabolites under hot summer conditions in Egypt.