Abstract:
Medicinal plants have been found to be effective in a wide range of applications in ruminant
animals. However, some plant extracts may be toxic to animals, depending on their seconday
metabolite composition and dose, and therefore, animal trials are needed to validate their safety
when used as anti-methanogenic additives. This study investigated the effect of three plant extracts
used as anti-methanogenic dietary additives, on the haematology and serum biochemical parameters
in sheep. Methanolic extracts of Moringa oleifera (MO), Jatropha curcas (JC) and Aloe vera (AV) were
orally dosed as experimental treatments for 75 days to sheep, and their effect on the haematology and
serum biochemical parameters of SA Mutton Merino (SAMM) lambs were compared with sheep on
a control treatment without any additive treatment. Extracts of MO, JC and AV were extracted in
100% methanol, freeze-dried, and reconstituted in distilled water. A total of 40 lambs were ranked
according to their body weight into a group of four and one sheep at a time was randomly allocated
into four dietary treatments which include a control treatment, and treatment with either MO, JC or AV
extract. Lambs were drenched twice daily with doses equivalent to 50 mg/kg dry matter intake (DMI)
based on previous week feed consumption. Blood samples were collected via jugular vein puncture
and analysed for haematology and serum biochemistry parameters, using standard procedures.
The results of the haematological analysis showed that most haematological parameters were not
affected by plant extract used as anti-methanogenic additives (p > 0.05), except for higher white
blood cell (WBC) and lymphocytes counts recorded in control lambs and lambs in the AV treatment.
All serum biochemical properties (except alkaline phosphatase) were not different (p > 0.05) between
the control and lambs treated with plant extracts. Alkaline phosphatase was influenced by the
plant extract (p < 0.05), with lambs receiving MO, JC and AV having lower alkaline phosphatase
concentrations compared to lambs on the control diet without any additive. The result of the study
showed that extracts of MO, JC and AV were not toxic to sheep when used as antimethanogenic
additives at the recommended dose of 50 mg/kg dry matter feed which had proved previously to be
effective in reducing enteric methane emission. Therefore, these plant extracts could be used safely as
alternative dietary additives to reduce enteric methane emission and boost the productivity of SA
Mutton Merino sheep.
