The first experiment was carried out in vivo to study the effect of dietary nitrate on feed digestibility and nitrogen balance of the ruminants. Seven Japanese Corriedale wethers, about 40kg in body weight, were used. All animals were placed in the digestion crate and were fed twice daily. Before the treatment period, all feces and urine were collected for seven days to obtain data as controls. Potassium nitrate of 0.05% of body weight was mixed with concentrate ration and was given to the animals for seventeen days. The last seven days, total feces and urine samples were collected and studied feed digestibility and nitrogen balance. It was observed that dietary nitrate seemed to improve the apparent digestibility of dry matter and crude protein as much as 2.6 to 7.6% and 6.2 to 9.6% respectively. However, nitrogen retention was not improved by dietary nitrate. Excretion of nitrogen into urine increased and effect of nitrate on crude fiber, crude fat and N. F. E. digestibility was not apparent. To study the effect of nitrate on cellulose digestion by bovine rumen microorganisms in vitro, an artificial rumen described by UESAKA et al.⁵ (1962) was used. Nitrate nitrogen concentration in the washed suspension fluid were set as follows; 1.73, 8.66, 17.33, 23.36, 46.72, 86.64ppm. When nitrate was not added to the rumen fluid, 80% of purified cellulose was digested during 24 hour fermentation. The higher the nitrate concentration was, the lower the cellulose digestibility was. The relationships between the amount of nitrate and cellulose digestibility were as follows; nitrate nitrogen 8.66ppm, cellulose digestibility 65%; 17.33ppm, 27%; 23.36ppm, 21%; 46.72ppm, 20% and 86.64ppm, 12.5% respectively. When the concentration of rumen microorganisms was halved, nitrate seemed to depress the cellulose digestibility and it was lowered to 31% even at 8.66ppm. On the other hand, when the concentration of microorganisms was doubled, the effect of nitrate seemed to be reduced. Cellulose digestibility was around 73 to 80% up to 23.36ppm of nitrate, but it went down to 20% at 86.64ppm.

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In this experiment, the comparison of controlled-feeding and full-feeding on the utilization of dietary NPN-substitute and the changes of blood ammonium and serum urea levels after feeding experimental feed were tested by using eight hogs of crossbred and nine hogs of Large White. For the NPN-substitute feeds, 20% of crude protein in the control feed, formulated similar to that in the previous report, were substituted by 1.1% of urea or 2.4% of di-ammonium phosphate (DAP) supplemented with 0.3% of L-lysine. During the ureasubstitute feeding period, full-feeding group showed good daily gain of 628g, contrast with the controlled-feeding group's 485g, and also showed a better feed conversion. In the cass of DAP feeding, full-feeding group again showed a slightly faster weight gain, but controlledfeeding group showed a better feed conversion. Ammonium level in blood has been at 1-4 μg/ml which lies well within the normal limits. However, urea level in serum showed a rapid rise from the start of urea-substitute feeding.

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This trial was conducted, utilizing four fistulated Holstein cows in a Latin-square design, to investigate the effects of level of corn silage intake on VFA production and other condition in the rumen of cow. Corn silage was offered at levels of 14, 21, 28 and 35 kg, respectively, per day. The silage offered twice daily in equal amounts at 9 a. m. and 9 p. m. The concentration of ammonia nitrogen and VFA, and pH values were determined on rumen liquor taken immediately before feeding and at hourly intervals over a 11-hr. period after feeding. The principal results obtained were as follows: The concentration of total VFA and the molar proportion of acetic acid showed significant changes by levels of corn silage intake. The concentration of total VFA and the molar proportion of butyric acid increased lineally as levels of corn silage intake increased, but pH and the molar proportion of acetic acid decreased.

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This trial was conducted, using four fistulated Holstein cows in a Latin-square design, to investigate the effects of level of grass silage intake on VFA production and other condition in the rumen of the cow. Grass silage was offered at levels of 18, 27, 36, and 45kg, respectively, per day. The concentration of ammonia nitrogen and VFA, and pH values were determined on rumen liquor taken immediately before feeding (9:00a.m.) and at hourly intervals over a 11-hr. period after feeding. The principal results obtained were as follows: The concentration of ammonia nitrogen and VFA, and the molar proportion of butyric acid were significantly (P<0.05) influenced by level of grass silage intake. The concentration of ammonia nitrogen and total VFA increased lineally as levels of grass silage intake increased, whereas pH dropped. The molar proportion of acetic acid decreased lineally as levels of grass silage intake increased, but the molar proportion of butyric acid increased.

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The thoracic ducts of five goats, including two goats fitted with abomasal fistula, were cannulated, enabling lymph to be collected. Effect of safflower oil feeding on the transport of lipids from the small intestine to the thoracic duct were studied by determining the changes in the output of lipids in the thoracic duct lymph. The lymph flow and the output of total lipids transported via the thoracic duct over 24 hours were 2.0l and 6.7g in the alfalfa hay cube feeding, 3.1l and 20.0g in the oral feeding of safflower oil and 2.1l and 11.7g in the infusion of safflower oil into the abomasum. The output of triglycerides transported via the thoracic duct increased by the feeding or the infusion into the abomasum of safflower oil. The increase in the output of triglycerides was accompanied by the increase in the output of phospholipids and a significant positive correlation was observed between the outputs of triglycerides and phospholipids. The concentrations of triglycerides and phospholipids in chylomicrons and chylomicron-free lymph began to increase by the feeding or the infusion into the abomasum of safflower oil and reached a maximum value at 19-21 hours or 10-12 hours, respectively. A significant positive correlations were observed between the concentrations of triglycerides and phospholipids in chylomicrons and chylomicron-free lymph. The proportion of C_18:0 in triglycerides in chylomicrons and chylomicron-free lymph decreased until 4 hours after the oral feeding of safflower oil, but thereafter it continued to increase with time. The proportion of C_18:2 in triglycerides in chylomicrons and chylomicron-free lymph reached the maximum value at 4 hours after the feeding of safflower oil. With the infusion of safflower oil into the abomasum, the proportion of C_18:2 in triglycerides in chylomicrons and chylomicron-free lymph markedly increased, whereas the proportion of C_18:0 and C_18:1 decreased.

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