Short- and long-term effects of intestinal parasitism on growth in sheep

M.J. Young and A.R. Sykes

Animal and Veterinary Science Group, Lincoln University, Canterbury

Proceedings of the New Zealand Society of Animal Production. 1988, 48: 157-162

Forty-eight animals were allocated to 1 of 3 treatments (C = continuous growth; I = infected with 4000 larvae/d of Trichostrongylus colubriformis; P= individually paired with I animals for change in live weight) in a serial slaughter experiment examining the effects of intestinal parasitism on bone and muscle in young growing sheep (25 to 45 kg). Both I and P groups were nutritionally rehabilitated after the I group had undergone an 83 d period of infection. While I and P groups underwent similar changes in live weight during the period of infection, feed intake of the P group became progressively less than that of the I group. By the end of infection I animals were consuming approximately 30% more feed than P animals.

During the period of infection both I and P groups lost live weight. Of the body chemical components, fat was depleted to the greatest degree (48% loss) followed by protein (23% loss). While bone displayed growth in external linear dimensions (length = +4%; diameter = +6%) there were significant reductions in protein (22%) and cortex width (33%). In contrast muscle showed decreases in all chemical components and in diameter. This greater effect on muscle was exaggerated in the I group. Infection led to greater reductions in muscle protein (45% v 34% (I v P)) and muscle diameter (19% v 8%). There were no appreciable differences between the I and P groups for changes in bone variables. While specific effects of infection on growth of muscle were found, change in most variables was largely attributable to the general restriction in growth consequent upon undernutrition.

Subsequent to the period of parasitic infection, compensatory growth occurred such that muscle recovered relative to bone. There was some evidence that full recovery of muscle relative to bone was delayed in animals recovering from a parasitic infection.

Keywords: NZSAPAB; Bone growth; muscle growth; parasitism; Trichostrongylus colubriformis; protein

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