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In a previous experiment, it was found that the physical properties of isolated soybean protein substituted for part of the milk protein in a diet for artificially reared piglets greatly influenced apparent N digestibility and performance. The present experiment, in which a water-soluble and an insoluble soybean protein isolate were compared, was undertaken to determine the reasons for the differences mentioned above. The results indicated that the use of a soluble soybean protein isolate, which was partly hydrolyzed, enhanced in vitropeptic and tryptic proteolysis and in vivogastric proteolysis. In addition, the physical properties of the protein sources were important in regulating digestive physiology, as acid and pepsin secretion, measured in gastric contents sampled for 3 hr after feed intake, differed markedly between the two diets. Results are discussed in relation to the clotting behavior of the diets in the stomach and the feeding management procedures used for the artificial rearing of pigs.

The importance of the relative partititipn of “soluble” whey protein and immobilized clot protein in milk replacers for piglets was studied. About 40% of the milk protein in an all-milk diet (MA diet) was replaced with three types of isolated soy protein with different physical properties. One was totally soluble in water (diet W+), the second was easily dispersed in water (diet C+) and the third was totally insoluble (Diet W−). Performance and apparent N digestibility were studied in artificially reared piglets from 12 to 40 days of age. Performance (daily gain and feed efficiency) differed only in the fourth experimental week, when the piglets on diets W+and C+performed markedly better than those on diet W−. The reference diet (MA) produced intermediate results. The best apparent N digestibility throughout the experiment was obtained with diets W+ and MA (94.9 and 93.5%). The apparent N digestibility was lowest with diet W−, while diet C+gave intermediate results. The apparent N digestibility coefficients for the last two diets, however, increased with age (86.4 to 91.9% and 89.9 to 94.6%, respectively). Results are discussed in relation to the nutrient content of the diets, clot properties, relative partitition of clot and whey quantities and origin and nature of the protein.

Production rates of metabolites from a lactose diet were studied in vitroincubating stomach, ileal and cecal contents, collected from cannulated young pigs. Incubating stomach contents, bacterial activity was quantitatively not important after 4 hr of incubation. The bacterial activity in ileal contents on the other hand was characterized by an important production of lactic acid and volatile fatty acids. Addition of virginiamycin and spiramycin resulted in decreased organic acid production and in sparing of a measurable quantity of glucose. The fermentation of cecal contents was characterized by a pronounced volatile fatty acid fermentation, stimulated by spiramycin and decreased by virginiamycin. Bacterial production rates were also assessed by a dynamic incubation system to better imitate the intestinal transit. By combination with some in vivodata the sparing of carbohydrates with antibiotics could be expressed as a higher availability of the net energy content required for growth. The percentage calculated approximates the growth promoting ratio in vivo.

A gastro-intestinal cannulation technique in pigs adapted from Hinkson's rumen cannulation technique is described. Two types of cannulas are used, one for insertion at operation and one for replacement. The technique and materials described have the advantage of being simple, inexpensive and of having no protruding external parts. The technique for replacement of the cannula allows long term experiments to be conducted using the same pigs.

1. Methane was produced in vitro by incubating cell suspensions of rumen bacteria with glucose, under nitrogen. The amount of methane produced varied considerably and was lowered by high glucose concentrations. Carbon dioxide, acetic acid, propionic acid, butyric acid and lactic acid were also produced. An oxidation–reduction balance of near unity could be calculated, although carbon recovery was low. Under the experimental conditions, rumen bacteria used most of the metabolic hydrogen produced during the oxidation of glucose to form lactic acid. 2. Lower methane production at high glucose concentrations was balanced by higher lactic acid production. Low pH values due to a high production rate of lactic acid might explain the inhibition of methane production. 3. No lactic acid, less methane, but considerably more propionic acid were formed when nitrogen was replaced by carbon dioxide in the incubation system.

Two types of indwelling cecal cannulas have been constructed and used successfully in approximately 60 pigs. One cannula was constructed from a piece of PE-320 polyethylene tubing, one end of which was fitted with a female Luer-Slip Adapter, Size D. The second cannula was constructed from polyethylene drying tubing. Polyethylene liners made from the caps of disposable acid bottles were used as washers. The completed cannula was stoppered with a No. 0 rubber stopper. The cannulas were simple to construct and economical.The pigs were fasted for 12 hr. prior to surgery and anesthetized via the anterior vena cava. The surgical site was the middle of the left para lumbar fossa. The techniques used in surgery and for introducing the cannulas are presented. Cannulated pigs were used in various studies related to digestion and absorption in the colon and for the collection of cecal contents. One type of cannula is suited only for the introduction of liquid materials and the other for introduction of both dry or liquid materials and the withdrawal of ingesta.

Methane production from pyruvate by mixed rumen bacteria in vitro was nearly totally inhibited by chloral hydrate (0.1 μmole/ml of incubation fluid). This effect was accompanied by an accumulation of gaseous hydrogen and an increase in propionic acid production. Infusion of chloral hydrate (4 g/day) into the rumen of a sheep produced the same effects. Evidence is presented for a direct toxic effect of chloral hydrate upon methane bacteria. Results are discussed in terms of fermentation balances.

Six pigs were provided with colon cannulas introduced into the first portion of the colon via the cecum. Vitamin B12labeled with Co57was introduced into the colon. By the collection of feces and urine during a 7-day period, together with analysis of organ tissue, it was demonstrated that 41.6 to 58.0% of the radioactive cobalt was absorbed. Based upon the charcoal adsorption of radioactivity present in the feces, it appeared that some vitamin B12was metabolized during its passage through the lower digestive tract.