I. Acetate, propionate, butyrate and glucose w-ere each administered intravenously (2.09 M J (0.5 Mcal)/d) to lambs on either high-concentrate (HC) or high-roughage (HR) diets in two experiments with 4 x 4 Latin square design. During a control period all animals received a saline infusion. 2.In lambs on the HC diet glucose was the most effective metabolite tested for improving nitrogen retention. Acetate was 5 I yo, butyrate, 75 yo, propionate, 90 yo as effective as glucose in promoting N retention. Propionate infusion was most effective in increasing N retention in lambs on the HR diet. Acetate was 60 %, butyrate, 75 ?A, and glucose, 80 "/o as effective as propionate. Glucose infusion did not lower plasma urea N (PUN) concentration in lambs receiving the HC diet, but the three volatile fatty acids (VFA) did lower it ( I ' < 0.01). All energy sources significantly reduced the PUN concentrations with the HR diet, but differences between sources were not significant.3. Plasma concentrations of valine, isoleucine, leucine and phenylalanine were depressed to 57,71,89 and go % of their control values during glucose, propionate, butyrate and acetate infusion. Plasma concentrations of lysme and methionme were significantly decreased from control values ( P < 0.05) but there was no significant difference between energy sources.Lysine, valine, isoleucine and leucme were significantly (P < 0.01) higher in lambs given the HR diet than in lambs given the HC diet. The concentration of alanine was greater ( P < 0.05) during glucose infusion than during acetate and butyrate infusions, indicating net synthesis of alanine and possibly other non-essential amino acids during glucose infusion, since the plasma free amino acid N concentration increased despite decreased concentrations of plasma essential amino acids during glucose infusion. 4. The results indicated that glucose and propionate were superior to acetate and butyrate as energy sources for protein formation.5 . The poor relationship between PUN and N balance and plasma free cssential amino acids suggested that P U N concentration may have been inappropriate to assess the protein status under some dietary conditions. The three major volatile fatty acids (VFA) produced by rumen fermentation have not been widely investigated as sources of energy in protein synthesis in Iambs. Rook, Balch, Campling & Fisher (1963) and Orskov & Allen (1966) found no significant differences between the effects of the three major VFA on nitrogen retention when they were infused into the rumen or given as their salts in the food. Eskeland, Preston & Pfander (1971) and Eskeland, Pfander & Preston (1973) found that propionate promoted a higher N retention than butyrate, and acetate was the least effective when the respective energy sources were administered intravenously on an isoenergetic basis. All VFA were utilized less efficiently than glucose.The free amino acid concentration in blood of simple-stomached animals has been
I . Glucose, and acetic, propionic and butyric acids, the major energy sources available to ruminants, have been comparatively evaluated as energy sources for growth in lambs. The energy sources wcrc administered intravenously at 2.092 and 2 . j 10 MJ metabolizable energy per 24 h for periods of 9-12 d. Nitrogen was given in excess of requirement so that growth rate was limited by energy, as indicated by the increased N retention after intravenous administration of energy.2. The N-balance results from the trials showed that propionic acid promoted a significantly ( P < 0.01) higher N retention than acetic acid. In some of the experiments there were no significant difYerences between propionic and butyric acids, and in others, no significant differences between acetic and butyric acids. Compared with isoenergetic glucose infusion, all volatile fatty acids were less efficiently utilized than glucose. The mean values for N balznce (gjd) were 2.37 during control infusion, 6.53, 571, 5.48 and 4 5 9 during glucose, propionate, butyrate and acetate infusions, respectively.3. All energy sources reduced the faecal N excretion significantly. The greatest reduction was observed during butyrate treatment. The mean values for faccal N excretion (gjd) w-ere 4.24 €or control, 4.00 for acetate, 3.89 for propionate, 3.83 for glucose, and 3.76 for butyrate infusion. The reduced faecal N excretion after hutyrate infusion partly accounts for the increased N retention with that treatment.
Japanese quails were exposed to dietary methyl mercury chloride in graded amounts from 2--8 ppm through a series of multiple-generation experiments with the experimental periods lasting from 6--12 weeks, starting with the experimental diets when the birds were 6 weeks old. Cadmium chloride was added to diets with and without mercury and fed to groups in three of the five experiments. Hatchability was depressed at 8 ppm mercury. The mortality of chicks from 8 ppm exposed parents was 100% in the first two generations, while chick mortality at the 4 ppm level in the same experiments was 54--63%. After six generations mortality in chicks hatched in 8 ppm group was reduced to about 50%. Cadmium supplementation at a level of 5 ppm counteracted the mercury-induced toxicity but failed to be effective in preventing the effects of mercury toxicity when added at 15 ppm level. Significant toxic effects of cadmium alone did not occur until the level was raised to 60 ppm. The morphology of mercury-induced encephalopathy was similar to the brain lesions reported in other bird species, with the injuries predominantly being localized to the cerebellar cortex and medulla.
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