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

Thesis 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>