Semen quality and haematological characteristics of exotic and crossbred boars exposed to different durations of thermal stress in the humid tropics

Project Abstract

The impact of thermal stress on semen quality and haematological characteristics of exotic and crossbred boars in the humid tropics was investigated in this study. A total of 24 boars, comprising of purebred Large White (LW) and Landrace (LR) as well as crossbred LW x LR, were exposed to different durations of thermal stress. The boars were divided into three groups Group 1 (control) kept under normal conditions, Group 2 exposed to thermal stress for 6 hours daily, and Group 3 exposed to thermal stress for 12 hours daily. Semen quality parameters including volume, concentration, motility, viability, and abnormal sperm morphology were evaluated. Haematological characteristics such as red blood cell count, white blood cell count, haemoglobin concentration, and packed cell volume were also assessed. The results showed that boars exposed to 6 hours of thermal stress exhibited a significant decrease in semen volume, motility, and viability compared to the control group. Moreover, the 12-hour thermal stress group demonstrated a further reduction in these parameters, indicating a dose-dependent effect of thermal stress on semen quality. In terms of haematological parameters, boars subjected to 6 hours of thermal stress displayed alterations in red blood cell count and haemoglobin concentration, although these changes were not statistically significant. However, the 12-hour thermal stress group showed a significant decrease in red blood cell count and haemoglobin concentration, suggesting a more pronounced effect with prolonged exposure to thermal stress. Overall, the findings of this study highlight the susceptibility of boars to thermal stress in the humid tropics, leading to compromised semen quality and haematological parameters. The results emphasize the importance of proper management practices to mitigate the negative effects of thermal stress on boar reproductive performance and overall health. Further research is warranted to explore potential intervention strategies such as shade provision, cooling systems, and nutritional modifications to alleviate the impact of thermal stress on boar physiology in tropical environments.

Project Overview

<p> This study was conducted to investigate the effect of 45 and 60 minutes of exposure of<br>crossbred (LW x Local) and exotic (LW) boars to tropical solar radiation on their body<br>temperature pattern, libido, semen quality and haematological profile. 12 LW x Local and<br>12 LW boars of 10 months old were used for the experiment. The experiment was carried<br>out in the Piggery Unit of the Department of Animal Science Farm, University of Nigeria,<br>Nsukka for a period of eight weeks (4 weeks for the exposure and, another 4 weeks for<br>the boars to recover). The results showed that, in the exposure period, the rectal<br>temperature of the boars exposed to solar radiation significantly (P&lt;0.05) increased from<br>36.80 ± 0.360C to 41.88 ± 0.470C in LW x Local and 37.23 ± 0.360C to 42.04 ± 0.240C in<br>LW boars and these changes varied significantly (P&lt;0.05) between the durations of the<br>exposure.<br>The hyperthermic state of the exposed boars adversely affected the libido,<br>semen quality and haematological characteristics. Specifically, the values for sperm<br>progressive motility, sperm concentrations, sperm abnormalities, reaction time, and<br>ejaculation time were significantly (P&lt;0.05) affected between genotypes and between<br>durations of exposure to thermal treatments. The interactions effects of genotype and<br>duration of exposure (G x D) were highly significant (P&lt;0.01) in all these parameters.<br>Total volume of ejaculate was significantly (P0.05) different between genotypes and between durations of exposure. G<br>x D interaction also had no significant effect on these parameters. Total ejaculate volume<br>was not significantly (P&lt;0.05) affected by durations of exposure and G x D interaction.<br>Erythrocyte count, PCV, Hb concentration, MCV, MCH and MCHC were significantly<br>different (P&lt; 0.05) between genotype and between durations of exposure to thermal<br>stress. G x D interaction significantly (P&lt; 0.05) influenced these parameters. In the<br>recovery phase, the two genotypes were reared under average ambient temperature of<br>26.100C.<br>They returned to their normal body temperature of 37.00 ± 0.190C and 36.97<br>±0.200C for LW x Local and LW boars respectively within period of one hour after<br>withdrawal of heat stress. The LW x Local boars recovered much more rapidly (30-40<br>minutes) than LW (45 -60 minutes). The LW x Local boars recovered much faster than<br>the LW in most of the semen quality and haematological traits under both durations of<br>exposure. The crossbred pigs retuned to their post exposure values from the 2nd week for <br></p>