Intensity of Parasitic Infections
Chinese researchers conducted a study to compare the infection intensity of gastrointestinal parasites on farms with different feeding and management regimes: confinement (indoors), semi-confinement (3-4 hr grazing per day), and grazing (semi-desert grassland/rangeland). Two farms from each type were included in the study. Thirty young sheep (6-12 months) from each farm were sampled for fecal egg count (FEC).
There was a statistical difference in FEC among the three regimes. EPG was low in confinement, moderate in semi-confinement, and high in grazing. Teladorsagia (Ostertagia) was the primary worm species; Haemonchus sp. was less prevalent. While OPG counts were numerically different -- high in confinement, moderate in semi-confinement, and low in grazing -- there was no statistical difference (P<0.05) among regimes. E. parva was the primary genus of coccidia.
Because L3 larvae do not survive in hay or silage, sheep in confinement do not generally get infected with worms. Coccidia, on the other hand, can cause infections in various production environments. However, infection intensity tends to be greatest when animals are raised in high density, which is more common to confinement.
When animals are raised under grazing situations, control programs usually need to be more focused on worm control (though coccidiosis can still be a problem), whereas in confinement situations, coccidia control is more important. Any shifts in feeding and management need to reflect this.