SummaryVarious amoWlts of DL-methionine or L-cysteine were infused directly into the abomasum of sheep as supplements to a diet of chopped wheaten and lucerne hay, and effects on wool growth and sulphur content of wool were measured.Small amoWlts (0·5-2·0 g/day of L-cysteine or equimolar amounts of :ilL-methionine) increased wool growth by as much as 100%. Similar maximum levels of wool growth were obtained with cysteine or methionine. When larger amoWlts of L-cysteine (6·0-8·0 g/day) were given, the rate of wool growth was reduced to slightly below the maximum response. Administration of equimolar amoWlts of DL-methionine caused a substantial reduction in wool growth; in one experiment the rate of wool growth was depressed to slightly below the pretreatment values.The proportion of the supplementary sulphur accoWlted for in the extra wool grown was inversely related to the amount of amino acid given. With 2·0 g/day of L-cysteine (or equivalent DL-methionine) 23-49% of the supplementary sulphur was recovered in wool.D-Methionine and methionine hydroxy analogue (MHA) were also effective in stimulating wool growth; D-methionine appeared to be less effective than DL-methionine whereas MHA was equivalent to DL-methionine.All sulphur supplements were effective in increasing the sulphur content of wool and similar maximum values were obtained with each supplement. In contrast to effects on wool growth, high levels of L-cysteine or DL-methionine did not depress the sulphur content of wool.

1. When the diet of sheep is supplemented by the abomasal infusion of sulphur-containing amino acids or casein, a special group of proteins, with a very high content of sulphur (about 8.3%), is incorporated into the high-sulphur proteins of wool. These special proteins cannot be detected in control wool from the same sheep. 2. This is a naturally occurring process, as these special proteins are found in wool from sheep on a high level of nutrition under ordinary conditions of feeding, and in wool of an inherently high sulphur content. 3. This represents a control mechanism in protein synthesis that has not previously been observed, and may be further evidence that the high-sulphur proteins of wool are produced by an unusual synthetic route.

Vol. 80 STUDIES ON ALKALINE PHOSPHATASES 9 of inactivated (heated at 80°for 30 min.) intestinal mucosa of hens, and the optimum pH for the enzyme of mature fowl was not altered by inactivated mucosa of chicks. 3. A mixture of the enzyme preparations of chicks and mature fowl exhibited a pH-activity curve and quantitative reaction velocities which would be expected from a combination of two enzymes possessing different pH optima.4. In rabbits the shift in pH optima for intestinal phosphatase was to lower values with increasing age, the major change taking place in the first 2 months of life.5. There was no change in pH optima of the phosphatase of intestinal mucosa of rats as their age increased from 6 weeks to 1 year. The pH optima for the phosphatase of a preparation of the whole duodenum of 1-day-old rats were higher than those of the mucosal enzyme of older rats.6. The pH optima for the phosphatases of bone, liver and kidney of fowl and rabbits appeared to be constant regardless of their age.

The utilization of nitrogen was examined in sheep fed several diets; in some experiments the diet was supplemented with soluble casein given directly into the abomasum through a fistula. Casein supplements per abomasum were almost completely digested and absorbed. At the highest level of casein supplementation (55 g casein nitrogen per day) 95% of the casein was digested and absorbed. An increase in nitrogen intake resulted in an immediate increase in nitrogen balance, followed by a gradual return towards a stable level. There was also an immediate response of faecal and urinary nitrogen excretion to a change in nitrogen intake. Most of the adjustment in urinary nitrogen excretion occurred within 4 days, this period being followed by a gradual change towards a stable level of excretion during the next 6 weeks. Much higher levels of nitrogen retention were obtained from casein administered per abomasum than from similar levels of nitrogen given per os. Changes in wool production also occurred following changes in the nitrogen intake per 0s. The observed changes were variable, depending on the sheep and the feed change involved, and periods of up to 10 weeks were required before the rate of wool production became stable following a change in nutrition. Casein supplementation per abomasum resulted in a substantial increase in wool production and in a rapid increase in wool fibre diameter; most of the increase in fibre diameter occurred in the first week of supplementation. The efficiency of conversion of dietary nitrogen into wool nitrogen was much higher in experiments where a casein supplement was administered per abomasum than in experiments involving normal feeding; possible reasons for this difference are discussed.

The effect on wool growth and the sulphur content of wool of supplements of L-oyswine, DL-methionine, and casein, given per abomasum a�s a continuous infusion, has been examined.