Rates of Production of Individual Volatile Fatty Acids in the Rumen of Lactating Cows

The rumen fermentation rates in individual lactating cows were measured in four different experiments. The results disclosed that the amounts and proportions of volatile acids formed could vary widely. In one case, a marked difference in the proportions of the acids produced arose within the experiment and correlated with a difference in the proportion of methane formed.

The average rate of production per day was 10.5 moles butyric acid, 12.8 moles propionic acid, and 40 moles acetic acid. Manometric estimations of rate gave lower results than those obtained by the zero-time method, due to delay after sampling and to failure of the acids to liberate stoichiometric quantities of carbon dioxide.

For those experiments in which zero-time rates were estimated, the average specific absorption rates, i.e., the amount absorbed per hour per micromole of acid in the rumen, were 0.37 for butyric acid, 0.38 for propionic acid, and 0.26 for acetic acid.

The carbon dioxide, acids, and microbial cells produced in the rumen fermentation are estimated to account for about 90% of the carbon found in the milk and respiratory CO₂ of the cows. The carbon dioxide from the fermentation was about 27% of the carbon dioxide exhaled.

     

Serum-γ-Glutamyltranspeptidase (γ-GT) and Aspartate-Aminotransferase (AspAT) Activities in Adult Cattle with Chronic Fasciola Hepatica Infection

Sera from adult cattle with fluke-infected and normal livers were analyzed for γ-GT and AspAT activities. The analyses revealed no significant increases in either γ-GT or AspAT values of the animals with fascioliasis as compared with the non-infected animals. The advanced chronic stage of the infection characterized by hepatic fibrosis, limited injury of parenchyma and low fluke burdens may explain the lack of enzymatic increase.     

Selenium and Vitamin E Deficiency in Pigs

The effect of selenium (Se) and vitamin E (Vit. E) on reproductive performance, growth and health was studied in pigs. Two levels of Se were used, 0.03 and 0.06 nag per kg feed. The major component of the experimental diets was barley originating from soil which had formerly produced crops with a very low content of Se. Prior to seeding, the area was divided into 2 plots, 1 of which was treated with Se in the form of sodium selenite, 100 g Se per ha. The use of Se enriched fertilizer was an effective way of increasing the Se concentration of the grain. Thus the concentration of Se in the barley produced on the treated area was 5 times higher than in barley from the untreated one. Vit. E was added at a level of 30 i.u. per kg feed, and the concentrations were approx. 15 and 45 i.u. in the basal and experimental diets, respectively. The higher level of Se or Vit. E was not significantly associated with milk yield of the sow, litter size, birth weight or haemoglobin levels. However, there was a tendency to an increase in milk yield of the sows following additions of Se plus Vit. E, and litter size was slightly higher from sows which had received an addition of Vit. E. The concentration of Se and Vit. E was much higher in colostrum than in sow milk, and additions of dietary Se and Vit. E were associated with marked increases in the concentrations of these compounds in both colostrum and sow milk. There was a moderately improving effect of a high Se concentration in feed on growth rate and feed utilization. Low dietary levels of Se and Vit. E were followed by increased mortality rate in piglets; iron toxicity in connection with iron treatment was observed in piglets on low dietary Vit. E. Symptoms characteristic of PSE were not observed in the Se and Vit. E deficient pigs.     

Clinico-Pathologic Findings in Young Pigs Fed Different Levels of Selenium,Vitamin E and Antioxidant

A randomized, blocked 23 factorial experiment was conducted with 48 young pigs. The treatment factors were: 2 levels of selenium (55 and 115 µg/kg), 2 levels of vitamin E (3 and 53 mg/kg) and 2 levels of the antioxidant feed additive Ethoxyquin (0 and 150 mg/kg). All pigs were kept in single pens and fed ad libitum throughout the experimental period of 9 weeks, i.e. from 3 to 12 weeks of age. Plasma, heart, liver and muscle Se levels as well as whole blood glutathione peroxidase activity (EC 1.11.1.9 GSH-Px) were significantly higher in pigs given a dietary supplement of Se than in pigs given no supplement of Se (P ≤ 0.001). The Se-supplemented pigs showed a tendency to lower mean serum transaminase activity (ASAT and ALAT) than unsupplemented pigs, but the influence was significant (P ≤ 0.05) only for the ALAT activity. Blood vit. E levels were higher for pigs receiving a supplement of vit. E than for unsupplemented pigs (P ≤ 0.001), and so was the resistance of red blood cells against lipid peroxidation (ELP), as expressed by lower ELP values. There were no effects of Ethoxyquin supplementation on the biochemical variables included in the study. The histological examination of heart muscle showed that the score for changes was negatively influenced by both Se and vit. E supplement (P ≤ 0.001) and to some extent also by Ethoxyquin supplement (P ≤ 0.05). The histological picture of m. long dorsi was influenced only by the vit. E supplement (P ≤ 0.01). No histological changes were found in the liver in this study. There were inverse relationships between whole blood GSH-Px defluorescence time and blood Se, and between ELP and whole blood vit. E (P ≤ 0.001).     

The Exchange of Radioactive Magnesium in the Tissues of the Cow,Calf and Fetus

Calves and pregnant cows were injected with tracer doses of radioactive magnesium and killed at intervals. The pattern of exchange of the isotope with intracellular magnesium in various tissues was broadly similar to that reported for other species except that the equilibration rate was much slower than in the rat. An exception was that the testis magnesium in the 6 week old calves used exchanged more rapidly than in 150 g rats. The exchange of isotope from maternal plasma to fetal tissues was extremely slow.