Effect of Heat Stress on Buck’s Adaptability and Semen Characteristics

Abstract

The experiment was conducted to investigate the effect of heat stress on adaptability and semen quality of buck. Almost similar 10 Black Bengal bucks were selected for the study at Artificial Insemination Centre, Bangladesh Agricultural University, Bangladesh. Prerequisite biological data were collected from each animal before keeping them sun heat and after 1 hour sun exposure. Different semen characteristics of each animal were measured. Temperature humidity index (THI) was 19.95 in the morning which indicate all the animals were in absence of heat stress and THI was 25.54 in the noon which indicate all the animals were in severe heat stress at noon. Buck 1 and buck 5 were more heat resistant (p<0.01), because their thermolysis capacity (TC) values were less than the others. There were no differences in tunica dartos index and semen characteristics among different bucks (p>0.05). Positive correlation between sperm motility and testis length (p<0.05), and negative correlation between sperm concentration and scrotal skin temperature (p<0.05) were found. From the study it can be concluded that all the bucks were in severe heat stress at noon time and TC can be used as an indicator for selection of buck for heat tolerance.

Exogenous gonadotropin-releasing hormone counteracts the adverse effect of scrotal insulation on testicular functions in bucks

“…For instance, sperm motility, morphology, plasma membrane integrity, and concentrations were adversely affected 5-8 days after insulation with the complete cessation of motility at day 12 in the INS group. These results conform to those reported by Santos and Simplício 4 , who have applied scrotal insulation for a week, and by Rahman et al 45 , who have exposed bucks to hot weather. Additionally, Cruz Júnior et al 44 have reported that the declining values of sperm concentration and motility were observed 1 week after www.nature.com/scientificreports/ insulation in rams, reaching zero motility at week 3, and then increased to the pre-insulated values at week 10 or 11 depending on the breed.…”

Resilience of Small Ruminants to Climate Change and Increased Environmental Temperature: A Review

“…The production and reproductive loss in small ruminants during heat exposure may be partly explained by lower feed intake but is also influenced by altered endocrine and metabolic status [29]. Elevated body temperature in rams during heat stress causes testicular degeneration, reduction in percentage of normal and fertile spermatozoa, low ejaculate volume, high semen pH, diminished sperm motility, increased incidence of abnormal sperm and reduction in sperm quality [30,31]. The reproductive function of rams is compromised above ambient temperatures of 40 • C for 1.5-2 h [29].…”

Effects of Climate Change on Sheep and Goat Breeding

“…Some studies have reported higher pH and darker meat (Kadim et al, 2016;Archana et al, 2018). Increased body temperature in rams during heat stress causes testicular degeneration, a decrease in the percentage of normal and fertile spermatozoa, low ejaculate volume, high semen pH, decreased sperm motility and decreased sperm quality (Hamilton et al, 2016;Rahman et al, 2016). Temperature increases increased the risk of infection in the mammary glands of lactating animals (Koyuncu and Akgül, 2018), and caused a decrease in birth weight and viability of the offspring born in January, February and July, August of pregnant goats.…”