No abstract

No 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

No abstract

No abstract

Diets containing 0, 5, 15, 30, and 60 ppm of cadmium were fed to male lambs for 191 days to ascertain what effect cadmium might have on the tissue concentrations of copper, zinc, iron, and manganese. The cadmium content of all tissues increased with an increase in dietary cadmium. The iron concentration of the ileum tissue was significantly depressed in the cadmium-treated groups compared with that of the controls. Liver copper, iron, and manganese were significantly depressed and liver zinc significantly increased by varying levels of dietary cadmium. The copper concentrations of the spleen and testicles were significantly decreased by all levels of cadmium while the copper and zinc concentrations of the kidneys were significantly increased in the 30 and 60 mug Cd/g and 15, 30, and 60 mug Cd/g groups, respectively. In general, cadmium had no significant effect on the rumen, abomasal, heart, or lung concentrations of copper, zinc, iron, or manganese.

Numerous experiments on the absorption of acetic, propionic and n-butyric acids have provided considerable information on the rates at which individual acids disappear from the rumen under the conditions of the experiment and of the concentrations appearing in the blood stream, but none of these experiments simulates normal conditions sufficiently to allow deductions to be made of the quantities of these acids normally absorbed.Recently, Johnson (1951) studied the concentrations of these acids in the rumen of fasting goats and sheep after the administration of large quantities of propionic and n-butyric acids, and came to the conclusion that butyric acid was absorbed in greater quantity than propionic acid. It is known that more butyrate can be absorbed from the rumen than can be accounted for by the butyrate entering the blood stream (Masson & Phillipson, 1951), and this is due to metabolism of butyrate by the rumen epithelium (Pennington, 1952) which in vitro is more pronounced than metabolism of propionate or acetate. The experiments described here were designed to study (a) the absorption of these three acids quantitatively by introducing a steady inflow of a solution of these acids at a suitable pH and in amounts that would maintain the concentrations in the rumen at physiological levels, and (b) to see whether the information so gained could be used to determine the rates of absorption in unanaesthetized sheep that were fasting or feeding. METHODS ExperimenkaZOne-year-old Scottish Blackface sheep, with the rumen previously cannulated, were used. The sheep were starved for 18 hr prior to the experiment to facilitate the removal of food from the rumen. The rumen was emptied and washed clean with warm saline. The sheep were anaesthetized by the intravenous injection of pentobarbitone, and the rumen was isolated in the manner described by Danielli, Hitchcock, Marshall & Phillipson (1945 ABSORPTION OF FATTY ACIDS FROM RUMEN 103The solution introduced into the rumen was Krebs's bicarbonate Ringer in which NaCl was substituted by sodium acetate, propionate and n-butyrate to give concentrations of 63 ±9, 21 i 3, and 15 ± 3 m.equiv/l. These concentrations are within the range usually found in the rumen. A similar solution, except that it contained different proportions of the three acids, was introduced into the rumen from a burette at the rate of 1 ml./min. The concentrations of acids in this solution were adjusted as the experimental series progressed until the concentrations in the rumen were steady throughout the experimental period. In this way the rate of introduction of acid served as an index to the rate of absorption. The solution in the rumen was gassed with carbon dioxide at 15 min intervals throughout the experimental period.In later experiments comparisons were made between solutions at neutral and acid pH values, and between the presence or absence of inorganic ions and carbon dioxide.Experiments on two unanaesthetized sheep were conducted in a metabolism cage. Both were accustomed to standing in th...

Three replicated tests were to define the conditions needed to use house crickets (Acheta domesticus) to evaluate forages. Crickets were placed on various proportion of forage-to-concentrate mixtures to determine the relative proportions best suited for cricket survival, growth, and maturity. The concentrate portion alone was adequate to support nominal cricket performance. Forages used were timothy, alfalfa, and alfalfatimothy (1:1). Forages replaced from 0 to 100%, in increments of 10% of the concentrate portion. A diet of 40% concentrate and 60% roughage was suitable for evaluating growth and survival effects. The 28-day tests were not long enough to evaluate fully the effects of diet on maturity.