Impact of Gastrointestinal Parasitism
Mexican researchers used data from published literature to determine the impact of gastrointestinal parasitism on dry matter intake (DMI) and live-weight change (LWC) in lambs. They conducted a meta-analysis on the data from 22 experiments from 20 papers.
Data showed that the interaction between worm burden and crude protein (CP) had an impact on the DMI of lambs. The best model for LWC was the interaction between energy (ME) and worm burden. In addition, the association of CP and worm burden was a model that predicted LWC.
In 59% of experiments, there was a negative impact of parasitism on DMI. In 73% of experiments, there was a negative impact of parasitism on LWC. The meta-analysis showed an interaction between parasitism and the consumption of nutrients (energy + protein). Infected lambs must be supplemented with protein and energy to reach a LWC similar to that of non-infected animals.
The researchers calculated a metabolic cost of infection: 0.30 mg CP/kg LW0.75 and 0.056 kJ ME/kg LW0.75 for each adult parasite in lambs.