Effect of the infection with the nematode Haemonchus contortus (Strongylida: Trichostrongylidae) on the haematological, biochemical, clinical and reproductive traits in rams
This study aimed to investigate the effect of Haemonchus contortus infection on rams’
haematological, biochemical and clinical parameters and reproductive performances. A total
number of 12 Barbarine rams (control and infected) were included in the experiment. The
infected group received 30 000 H. contortus third-stage larvae orally. Each ram’s ejaculate was
immediately evaluated for volume, sperm cell concentration and mortality rate. At the end of
the experiment (day 82 post-infection), which lasted 89 days, serial blood samples were
collected in order to assess plasma testosterone and luteinising hormone (LH) concentrations.
There was an effect of time, infection and their interaction on haematological parameters
(p < 0.001). In infected rams, haematocrit, red blood cell count and haemoglobin started to
decrease from 21 days post-infection. There was an effect of time and infection for albumin.
For total protein, only infection had a statistically significant effect. For glucose, only time had
a statistically significant effect. Concentrations were significantly lower in infected rams
compared to control animals. A significant effect of infection and time on sperm concentrations
and sperm mortality was observed. The effect of infection appears in time for sperm
concentrations at days 69 and 76 post-infection. Sperm mortality rate was significantly higher
in infected animals at day 46 post-infection when compared to control group (p < 0.05). Finally,
plasma testosterone traits (average concentration, cumulated levels during the sampling
period and pulse frequency) were depressed in infected rams when compared to control
counterparts; none of these endocrine traits were affected for plasma LH.