Effect of prolonged subclinical infection with Trichostrongylus colubriformis on the performance and nitrogen metabolism of growing lambs.
Ten 5-month-old lambs, reared free of parasites and prepared with abomasal and ileal cannulas, were paired and given rations of pelleted dried grass by means of continuous feeders. From 7 months of age one of each pair was dosed daily with 2500 Trichostrongylus colubriformis larvae for 34 weeks. An untreated animal served as a pair-fed control to each infected lamb. During 5 experimental periods (pre-infection, and Weeks 6-8, 12-14, 18-20 and 29-34 of dosing) measurements were made of the amounts of N leaving the small intestine, the digestibility of 35[S]-labelled microbial protein in the small intestine, and the amounts of plasma protein leaking into the digestive tract. The infection caused a growth check (P less than 0.05) from Week 6 to approximately Week 13 of dosing. This resulted from inappetence, but also from a disruption in the N digestion and metabolism of the lambs. There was a marked eosinophilia at this time. Measurements of ileal flow rates during Weeks 6 and 12 indicated that significantly more N flowed to the terminal ileum of infected lambs during this period (Week 6, 3.1 g N day-1 P less than 0.05; Week 12, 5.0 g N day-1 P less than 0.001). Plasma N leakage into the intestine during Weeks 8 and 14 was higher in infected lambs (1.2 g N day-1 P less than 0.01 and 0.9 g N day-1 P less than 0.05, respectively) but the digestibility of 35[S]-labelled microbial protein was depressed below that of the controls during the later part of this period, i.e. during Week 13. Continued larval challenge beyond this point caused a less severe nutritional penalty. Voluntary feed intake increased and the animals started to gain weight. The amount of extra N flowing to the terminal ileum of infected lambs was less at Week 18 of dosing (3.5 g N day-1 P less than 0.01) than it had been at Week 12. Similarly, extra plasma N leakage into the tract of infected lambs was less during Week 20 (0.26 g N day-1) than during Week 14. There was however, still a detectable reduction in the coefficient of digestibility of 35S microbial protein in infected lambs during Week 19. By Weeks 29-34 the only detectable difference between the infected and control lambs was in their eosinophil counts.
Kimambo
A E
AE
Rowett Research Institute, Bucksburn, Aberdeen, Gt. Britain.
MacRae
J C
JC
Walker
A
A
Watt
C F
CF
Coop
R L
RL
D000818:Animals; D004802:Eosinophilia / Q000209:etiology / Q000662:veterinary; D005243:Feces / Q000032:analysis / Q000469:parasitology; D007082:Ileum / Q000378:metabolism; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D009748:Nutrition Disorders / Q000209:etiology / Q000662:veterinary; D010270:Parasite Egg Count; D011506:Proteins / Q000378:metabolism; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology / Q000378:metabolism / Q000469:parasitology*; D013462:Sulfur Radioisotopes; D013997:Time Factors; D014252:Trichostrongyloidiasis / Q000662:veterinary*; D014253:Trichostrongylosis / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*
D011506:Proteins; D013462:Sulfur Radioisotopes; D009584:Nitrogen