Intravenous energy infusion in lambs: effects on nitrogen retentin, plasma free amino acids and plasma urea nitrogen

Abstract

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

The relationship between feed efficiency and the circadian profile of blood plasma analytes measured in beef heifers at different physiological stages

“…Similar to urea, plasma acetate levels are known to be associated with diet composition and time of feeding (Preston and Leng, 1987). In addition, acetate is important for the retention of nitrogen, with a greater effectiveness in roughage diets (Eskeland et al, 1974), as were used in this study.…”

Seasonal variations in blood parameters of the Amazonian manatee, Trichechus inunguis

“…Further, Colares (1991b) demonstrated that besides the reduced plant availability during the dry season, a decrease in the relative amount of protein and an increase in lipid content of several species of plants occurs. Several authors have indicated that blood urea could be a good indicator of the animal nutritional status, since it rapidly changes with variations in diet protein content (Eggum, 1970;Kumar et al, 1972;Eskeland et al, 1974;Brown et al, 1978;Hellgren et al, 1993). A positive correlation between these parameters was also observed in the Amazonian manatee (Fig.…”

Effect of different molar proportions of isoenergetic volatile fatty acids on the nitrogen retention of lambs sustained by total intragastric infusions

“…In normally-fed lambs, Eskeland et al (1974) reported that intravenously administration of propionate was more effective than acetate and butyrate in promoting the N retention, and acetate and butyrate were 60% and 75% as effective as propionate in promoting the N retention, respectively. Abdul- Razzaq and Bickerstaffe (1989) reported that the rumen fermentation pattern influences the protein turnover rate, protein synthesis and protein retention efficiency in lambs, and the protein gain of the body tended to be higher in propionate-rich pattern than in acetate-rich pattern.…”

“…Acetic, propionic and butyric acid account for the major part of ruminal VFA which is absorbed and utilised as the major energy source by ruminants. Eskeland et al (1974) reported that intravenous administration of acetate, butyrate or propionate promoted nitrogen (N) retention in the body of lambs. Savary-Auzeloux et al (2003) also reported that intraruminal infusion of propionate induced protein synthesis in the liver of lambs.…”