Risk Factors for Parasitism

Researchers assessed the factors associated with the periparturient rise in fecal egg count (FEC) in Katahdin ewes and associated changes in FEC in their lambs. Data came from 1,487 lambings by 931 Katahdin ewes from 11 farms in the eastern United States.

Fecal egg counts were measured in ewes at approximately 0, 30, and 60 days postpartum and in their lambs at approximately 60, 90, and 120 days of age. Approximately 1,400 lambs were evaluated at each measurement age.

FEC peaked at approximately 28 days postpartum. Yearling ewes had higher FEC than adult ewes, and ewes that nursed twin or triplet lambs had higher FEC than ewes that nursed single lambs. In lambs, FEC increased through approximately 120 days of age. Lambs from yearling ewes and lambs nursed in larger litters were, like their dams, at greater risk of parasitism.

Correlations between FEC in lambs at 90 days of age and FEC in ewes at 0, 30, and 60 days postpartum supported the presence of a genetic relationship between these two indicators of parasite resistance.

Source: Journal of Animal Science. Read abstract.