SUMMARYProtein synthesis was measured in wether sheep by constant intravenous infusion of [3H]tyrosine. The specific radioactivity of plasma tyrosine at plateau was used to calculate tyrosine flux and the rate of protein synthesis in the whole body was estimated. For wethers fed hay and concentrates tyrosine flux was 2·46 mmol/h and protein synthesized was 5·29 g/kg body weight per day. Corresponding values for wethers fed barley straw were 30–35% lower.Fractional rates of protein synthesis in individual muscles were between 2 and 3% per day for diaphragm, longissimus dorsi, gastrocnemius, semitendinosus and vastus lateralis muscles from wethers fed hay and concentrates, but the value for vastus intermedius was higher. Corresponding rates for wethers fed barley straw were 18–36% lower.

SUMMARYProtein synthesis was measured in non-breeding sheep and in sheep at two stages of lactation by constant intravenous infusion of [3H] tyrosine. In early lactation plasma tyrosine flux was 50% higher than in non-breeding ewes and it remained somewhat higher in late lactation. Estimates of protein synthesis per day in the whole body showed similar changes.In early lactation the weights of the longissimus dorsi and semitendinosus muscles were respectively 37 and 28% lower than those for non-breeding ewes, but both muscles regained weight in late lactation. There were corresponding changes in the total protein, total RNA and total lipid contents of both muscles.The fractional rates of protein synthesis in the longissimus dorsi and the semitendinosus were between 2 and 3% per day, but it was higher in heart muscle. At both stages of lactation the synthesis rate in the longissimus dorsi was similar to that in nonbreeding ewes, but in the semitendinosus and in the heart synthesis rates were lower in lactating animals. In both skeletal muscles the total protein synthesized per day was lower in early lactation because their total protein contents were lower at this time. It is concluded that the maternal skeletal muscles may undergo a controlled depletion during lactation.

A process for the removal of cationic fission products from milk is described in which no prior acidification is necessary. The milk is treated at 40 °C by 2 beds of suitably charged cation exchange resins, one of which is of the carboxylic acid type and the other of the sulphonic acid type. On the first bed all the metallic cations of the milk are replaced by K+and H+, and on the second the ionic composition is restored. During processing the pH is reduced from 6-8 to approximately 6-2 and is restored to 6-8 by the addition of alkali metal carbonates to the milk after treatment.On a pilot plant of capacity 1600 1 (30 resin bed volumes) per 5-h day it was found that the radiochemical efficiency was approximately 80 % for 85 Sr and 97 % for 137 Cs.The process caused some losses of vitamins, especially of thiamine, and an increase in the lead, copper and iron contents all of which, however, were at an acceptable level. Other changes in chemical composition were negligible and enzymic clotting time remained unchanged. Flavour and appearance of the product were satisfactory and it was satisfactorily both roller-and spray-dried. The process is discussed with reference to an earlier method in which prior acidification is necessary. It is concluded that the double-bed process is somewhat more efficient for the removal of fission products and that a full-scale plant would be little or no more expensive to erect and only slightly more expensive to operate.A process for the removal of cationic fission products from milk was patented in 1962 by Murthy, Campbell, Mazurovsky & Edmondson, and plants based on this process have been set up both in America Producer's Creamery Company, 1965) and in Britain (Glascock, Hall, Suffolk & Bryant, 1968). The method consists essentially of the passage of milk, acidified with citric acid to pH 5-2-5-3, through a cation exchange resin of the sulphonic acid type charged with a suitable mixture of the ions of Ca, K, Na and Mg. The ionic composition of the resin is chosen so that little or no change in the ionic composition of the milk occurs except that 96-98 % of the ^Sr and about 75 % of the 137 Cs are removed. Milk treated in the pilot plant set up in Britain has been subjected to analysis and to tests of its nutritional quality (Braude, Glascock, Newport & Porter, 1969). Although the analysis revealed no change in composition likely to prove deleterious 218 R. F. GLASCOCK AND D. T. W. BRYANT to the consumer, it was concluded from experiments with baby pigs that the nutritional value of the milk was adversely affected by treatment in the plant. This adverse effect was shown by a higher mortality in the animals given treated milk than in those given untreated milk, although post-mortem findings in both groups revealed no specific cause of death. These results were not in agreement with those of American workers (Isaaks et al. 1967), who, however, gave their animals a much smaller ration which, as is suggested in the paper by Braude et al. (1969), may have masked the effect observed in our ...

AS previously described, the process consists essentially of the passage of milk at pH 5-2-5-25 through an ion exchange resin charged with a suitable mixture of the ions of Ca, K, Na and Mg.When citric acid was used for reduction of the pH and 30 resin bed volumes (r.b.v.) were treated, the concentration of residual 85 Sr was reduced to 2-4 % whether it had been introduced in vivo or in vitro. There was no evidence that repeated use of the resin bed resulted in diminished radiochemical efficiency.About the same efficiency of removal of 133 Ba was obtained but this efficiency was achieved with 137 Cs only if not more than 15 r.b.v. were treated. If 30 r.b.v. were treated the concentration of residual 137 Cs was as much as 30%.When hydrochloric acid was substituted for citric acid the residual concentration of 85 Srwas 1 1 % .Analyses of milks processed after adjustment of pH with either citric or hydrochloric acid showed the products to be satisfactory. The only important constituent lost was thiamine. Concentrations of heavy metals remained well below maximum values. Although the flavour of milk was detectably changed by the treatment it was still acceptable.The results are discussed in relation to the problem of achieving maximum decontamination and to the design of a large scale plant.

SummaryThe nutritional quality of milk treated by 2 previously described processes for the removal of cationic fission products has been evaluated by the use of the baby monkey (Macaca irus).The first process involves acidification of the milk to pH 5·2–5·3 and, when the treated milk was tested on baby monkeys, it was found to be nutritionally unsatisfactory. This result confirmed those previously obtained with baby pigs, from which it was concluded that the process cannot be recommended for the treatment of milk intended for young babies.Two resin beds are used in the second process and no acidification is involved. Milk treated by this process was first tested on baby rats and pigs and then on baby monkeys. No change in the nutritional value of the milk was detected and it was concluded that this is the process which should be used if it should ever become necessary to remove fission products from milk intended for young babies.