No abstract

Two experiments were performed with post-valve T-cannulated growing pigs, using five animals in each experiment in a change-over design to evaluate the effect of inclusion of four different dried forage meals on ileal crude protein (CP) and amino acid (AA) digestibilities. The control diets (C1 and C2) were barley-based and the experimental diets were formulated by replacing the barley with 100 or 200 g/kg of either lucerne (Medicago sativa) or white clover (Trifolium repens) meal in Expt 1 and red clover (Trifolium pratense) or perennial ryegrass (Lolium perenne) meal in Expt 2. A decrease (P < 0·05) in the apparent ileal digestibility of CP and most of the essential and nonessential AA was found with the inclusion of lucerne, white clover and perennial ryegrass meal in the barley-based diets. When red clover meal was included, only the apparent ileal digestibilities of CP, leucine, phenylalanine, tyrosine and glutamic acid were found to decrease (P < 0·05). The estimated apparent ileal digestibilities of most essential AA in the forage meals were lower than in the barley-based diets. The ileal flow of glucosamine and ornithine was found to increase (P < 0·05) with increasing proportion of fibre in the diet, suggesting an increase in endogenous N secretions and small-intestinal microbial activity. With the minor changes found for ileal essential AA digestibilities with forage meal inclusion in the diet the present data confirm the potential of forage meals as a source of protein in pig diets.

Ileal digestibility of amino acids in barley-based diets with increasing inclusion of lucerne leaf meal (LLM; 0, 50, 100 and 200 g/kg) was studied in a change-over experiment with post-valve T-caecum cannulated growing pigs. The apparent Heal digestibility of crude protein, as well as of most of the essential (EAA) and non-essential amino acids (NEAA) was not significantly affected by the dietary inclusion of LLM. The exceptions were cystine, methionine, phenylalanine, glutamic acid and serine, all of which showed a significant (P< 0·05) reduction in apparent Heal digestibility with increasing inclusion of LLM. In contrast, the calculated true Heal digestibility of all EAA (with the exception of arginine and lysine) and the NEAA glutamic acid and serine were significantly (P< 0·05) reduced with the inclusion of LLM. Associated with an increased crude protein intake, there was a significant (P< 0·05) increase in the amount of absorbed EAA when the proportion of LLM was increased in the diet. With increasing proportion of fibre in the diet, there was a significant (P< 0·05) increase in the Heal flow of glucosamine.It can be concluded from the present data that the inclusion of LLM in a barley-based diet for growing pigs will result in an improvement in the absorbed amino-acid profile due to a significant increase in the absorption of all of the EAA.

The net absorption of amino acids (AA) in young pigs fed a barley-based control diet (C) and diets where barley was replaced by 200 g/kg fresh weight of dried lucerne (Medicago sativa; L20), white clover (Trifolium repens; W20) or perennial ryegrass (Lolium perenne; PR20) meal was studied. Castrated male pigs were fitted with permanent catheters in the hepatic portal vein and mesenteric artery, and the hepatic portal net absorption of AA was estimated from the porto–arterial plasma concentration differences and the hepatic portal-vein blood flow. In general, the essential AA (EAA) concentrations in the hepatic portal vein reached peak levels 90 min after feeding and thereafter exhibited a transient decline. Maximum porto–arterial differences were reached between 1 and 3 h postprandially for most of the AA. The cumulative net absorption of non-essential AA (NEAA) and EAA did not differ significantly between the barley-based diet and diets W20 and PR20. Due to a lower intake of AA on diet L20, the cumulative net absorption of NEAA and EAA was significantly (P<0·05) lower than diet C. With the exceptions of the EAA arginine, cystine and valine, and the NEAA glutamic acid + glutamine and glycine, there were no significant differences in the absorption coefficients for the EAA and NEAA between the diets. In addition, the pattern of the total EAA in the mixture absorbed postprandially did not differ significantly between the diets. The present study gives support to the contention that the replacement of barley AA with forage meal AA in a barley-based diet for growing pigs should be expected to result in minor differences in the net portal flux of AA.

Young pigs were fed diets to which 0, 2.5, or 5 mg/kg of purified nivalenol (NIV) had been added. The exposure continued for 3 weeks without any signs of feed refusal, vomiting, or change in clinical appearance, and there were no changes in body or organ weights due to the exposure. However, the concluding macroscopic examination revealed gastrointestinal erosions and signs of nephropathy in most of the exposed pigs. There were no differences in total or differential blood leukocyte counts between control and exposed pigs in blood samples collected after 0, 1, or 3 weeks, nor in the number of thymocytes at the end of the trial. Spleen cell numbers showed a dose‐dependent decrease after 3 weeks of exposure that was statistically different from controls in pigs exposed to 5 mg NIV/kg. Flow cytometric analysis of lymphocytes revealed decreased numbers of both the CD4+ and the CD8+ subpopulations in the spleen at this point in time, reflecting the lower numbers of splenocytes; but no proportional changes were seen. In blood, exposure to NIV caused a transient decrease in the proportion of CD4+ cells after 1 week of exposure. Analysis of IgG and IgA in plasma showed a time‐dependent tendency of increasing plasma concentrations of IgA and decreasing concentrations of IgG in the 2.5 mg/kg group, but differences in Ig levels between experimental groups and controls were not observed at any time. No differences were seen in the mitogen‐induced proliferation by lymphocytes from blood, spleen, or thymus. In conclusion, exposure of young pigs to NIV in the diet caused pathological alterations in the kidneys and gastrointestinal tract and reduced the number of splenocytes. The results also indicated that exposure to NIV caused a time‐dependent increase in IgA production in the 2.5 mg/kg group. Nat. Toxins 5:238–246, 1997. © 1998 Wiley‐Liss, Inc.