Nitrogen transactions in the digestive tract of lambs exposed to the intestinal parasite, Trichostrongylus colubriformis

Abstract

1.Ten 5-month-old lambs (29 (SE 1.2) kg), reared parasite-free and prepared with rumen duodenal and ileal cannulas, were paired and given rations of Ruminant Diet AA6 (90 g/kg live by means of continuous feeders. From 6 months of age one of each pair was dosed daily with 2500 Trichostrongylus colubriformis larvae for 14 weeks. Untreated animals received the amount of ration consumed by their infected pair-mates the previous day.2. During three periods, ((1) the week before and the first 2 weeks of dosing with infected larvae, (2) during weeks 5-7 and (3) during weeks 11-13 of dosing) all lambs underwent a series of experiments to determine their nitrogen balance, the amounts of N leaving the small intestine, the amount of 5'CrC1,-labelled plasma protein leaking into the small intestines, and the disappearance of 35S-labelled bacteria from the small intestine.3. The infection caused varying degrees of feed refusal in all infected animals. As a result the values for N balance and for the flow of N at the ileum during the latter two periods were regressed against dry-matter intakes for each group in each period.4. The infection caused a reduction ( P < 0.05) in N retention and increased ( P < 0.05) flow of N at the ileum. The increase in N flow at the ileum of infected lambs was greater ( P < 0.01) at weeks 11-13 of dosing (infected-control 3.6 g N/d (standard error of difference (SED) 0.57), P < 0.01) than at weeks 5-7 of dosing (infected -control 1.5 g N/d (SED 0.57), P < 0.05).5. There were no between-treatment or between-period differences in the disappearance of 35S-labelled bacteria from the small intestines of infected or control lambs, but the infection did cause an increase in plasma N leakage during both periods. During weeks 5-7 and 11-13, plasma N leakage in infected lambs was 1.1 g N/d ( P < 0.01) and 1.7 g N/d (P = 0.056) respectively higher than that in the control lambs.6. A proportion of the endogenous secretions which enter the small intestine is likely to be resorbed before the ileum. It was calculated that to account for the extra non-ammonia-N (NAN) flow at the ileum up to 3-5 g NAN/d during weeks 5-7 of dosing and 15-20 g N/d during weeks 11-13 of dosing could have entered the small intestine as mucin and sloughed cells.7. The results seem to indicate that the nutritional penalty associated with the development of resistance to infection is greater than that associated with the primary infection.

Intestinal amino acid absorption in lambs fed fresh Lucerne (Medicago sativa) during an established Trichostrongylus colubriformis infection

“…Possible reasons for the discrepancies between the current study and previous studies with respect to DM flow at the ileum (Gregory et al, 1985), N flow (Poppi et al, 1986;Kimambo et al, 1988) and intestinal absorption (Yu et al, 2000) may be due to the infection procedure used, namely the short-term dose in the current study and the trickle dose methods used by these authors. It is likely that the damage caused by the larvae could affect the ability of the intestine to transport AA.…”

“…Previous estimates (MacRae et al, 1997a;Yu et al, 2000) have suggested that around 20% of dietary AA is used by the small intestine. This difference may be due to feeding fresh (current study) rather than conserved forages (Poppi et al, 1986;MacRae et al, 1997a;Yu et al, 2000), as fresh forages tend to have a higher post-absorption AA availability than conserved forages (Ulyatt, 1981).…”

Metabolic consequences of intestinal parasitism

“…The N balance of infected lambs was 3-4 g N/d less than that of the pair-fed control lambs and blood P concentrations were approximately 50% of normal. Using cannulation techniques to determine digesta flow, Poppi et al (1986) found that the amount of N at the terminal ileum of infected animals was significantly elevated (PcO.05) during weeks 5-7 and 11-13 of dosing (see Fig. 2).…”

“…Most studies have adopted larval dosing procedures which continue for 14-15 weeks (Sykes & Coop, 1976;MacRae et al 1982;Poppi et al 1986); however, Kimambo et al (1988~) dosed lambs daily with T. colubriformis larvae for 34 weeks. The growth rates of these animals and of non-parasitized control lambs pair-fed are shown in Fig.…”

Estudo da inter-relação parasito hospedeiro em bovinos infectados com Cooperia punctata. Efeito da suplementação protéica sobre as alterações fisiopatológicas em bezerros com infecção única.

“…Estas perdas são constituídas pelo extravasamento de plasma nas áreas lesadas pelos nematóides, pela descamação do epitélio atingido e pelo aumento na produção de muco (POPPI et al 1986;BOWN et al 1991a). De todas estas fontes responsáveis por perdas protéicas, a única até hoje quantificada foi a que envolve extravasamento de proteínas plasmáticas, e somente para infecções com os parasitas abomasais Haemonchus e Ostertagia (ABBOTT et al, 1985b;PARKINS & HOLMES, 1989;GENNARI et al, 1991).…”