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Effect of dietary dry matter intake on endogenous nitrogen flows in growing lambs
- Gao, W., Gao, X., Chen, A., Zhang, F., Chen, D., Liu, C.
- Journal of animal physiology and animal nutrition 2017 v.101 no.5 pp. e383
- average daily gain, body weight, cages, cannulas, digestibility, digestive tract, dry matter intake, duodenum, ileum, isotope dilution technique, lambs, leucine, males, nitrogen, rumen, stable isotopes
- The effect of dietary dry matter intake (DMI) on endogenous nitrogen (N) flows at different part of the digestive tract of growing lambs was determined using a ¹⁵N isotope dilution technique. Three Kazakh male lambs (30 ± 2.75 kg of body weights and 4 months old, average daily gain 200 g/day) were fitted with ruminal, duodenal and ileal cannulae and raised in metabolic cage individually. The experiment was conducted in a 3 × 3 Latin square design with three lambs, three DMI levels (1100, 920 and 736 g/day respectively) and three periods. Each period lasted 18 days, consisting of 10 days for adaptation, 8 days for the continuous infusion of l‐[¹⁵N]leucine, during which the intestinal flow of N and ¹⁵N enrichment were determined. The total endogenous secretions in the forestomach (Sfₛ) were decreased (p = 0.0512) with increased level of DMI. On the contrary, endogenous nitrogen (EN) secretions into the small intestine (Sᵢ) increased (p = 0.0249) significantly with the high level of DMI (HI) group compared with that of low level of DMI (LI). Total absorption from forestomach was reduced (p = 0.0121) with increased level of DMI, whereas total absorption from small intestine for HI group increased (p = 0.0116) significantly compared with that of LI treatment. The real digestibility of N in the rumen accompanied with the increase in feed intake is decreased (p = 0.081). In contrast, there were no effects of DMI level on the computed real digestibility of N across both small intestine and whole tract. The results of this study indicate that the total flows of EN at duodenum may be unaffected by the level of DMI; however, the EN flow at ileal level increased from 12% to 37% with the increase in DMI level, corresponding to 33% of total N flow at ileum.