I. Pelleted diets containing concentrates and 0, 20, 40 or 60% chopped straw were fed ad lib. for 5 h daily to four cows. Voluntary intake, digestion and rate of passage of these diets were examined, and also the behaviour of the cows and the amount of material in the rumen before and after feeding.2. Least dry matter (7.5 kg) was consumed when there was no roughage in the diet. When roughage was present, its level had no effect on dry-matter intakes, which were 10.7, I 1-3 and 107 kg for 20, 40 and 60 yo roughage respectively. Digestible energy intakes were greatest with diets containing 20 or 40 % roughage.3. The digestibilities of the dry matter of the four diets were 81, 69, 59 and 55 % in increasing order of roughage content. The proportion of total digestion which occurred in the rumen decreased as the roughage content of the ration increased. The rate of breakdown of cotton threads in the rumen increased as the roughage content of the diet increased. 4.Rates of passage varied greatly between cows and there were no differences between treatments in passage rates through the entire alimentary tract. The diets on which the cows consumed the largest amounts of digestible energy (20 and 40 yo roughage) passed through the rumen more slowly, and through the hind gut more quickly, than the other diets. 5 . The times spent daily eating and ruminating both increased as the proportion of roughage in the diet was increased, but in relation to the amount of dry matter eaten, eating times were lowest with diets containing 20 or 40 % roughage. Time spent ruminating per kg straw eaten decreased with increasing straw content of the diet. Rumen contraction rate during eating was greatest when dry-matter intake was greatest, but during rumination it was similar with all three levels of roughage. 6. Before and after feeding, the amount of digesta and digesta dry matter in the rumen increased as the proportion of roughage in the diet increased. After feeding, there was a highly significant linear relationship between the amount of digesta in the rumen and the digestibility of the diet. 7.In a second experiment, similar diets containing o or 50 yo roughage were given to two cows for 5 or 24 h daily. The 24 h intake expressed as a percentage of 5 h intake was 148 % for the 0% roughage diet, but only 105 yo when the diet contained 50% roughage. 8.The results of these experiments are interpreted as indicating a declining importance of physical factors in the regulation of the intake by cows of a range of diets of increasing digestibility.

SummaryA single injection of 100 i.u. ACTH given to milking cows had no statistically significant effect on the yield or composition of the milk. A long-acting preparation of ACTH, when given to cows in single doses of 200 and 400 i.u., depressed milk yield and raised the butterfat content of the milk. There was no significant change in the SNF content of the milk but the SNF content of the milk serum was increased. Three injections of 300 i.u. of long-acting ACTH given at 24-h intervals reduced yields of milk, fat and SNF and increased the fat and SNF contents of the milk.Small but generally consistent changes occurred in the butterfat characteristics of the milk of all groups treated with ACTH. There was a decrease in the iodine number and refractive index and a rise in the softening point of the fat in all the experiments. The Reichert value of the butterfat was lowered by single or multiple injections of the long-acting preparation. The carotene content of the butterfat was lowered by injections of the long-acting ACTH preparation but the vitamin A content was unaffected.

No abstract

I . Rats given diets containing freshly-irradiated wheat showed significantly lower mean antibody titres to four different antigens, decreased numbers of antibody-forming cells in the spleen and rosette-forming lymphocytes as compared to rats given either unirradiated wheat or irradiated wheat stored for a period of 12 weeks.2. The immune response in rats given go g protein/kg diet was essentially similar to that seen in animals given 180 g protein/kg diet.Irradiation has been recommended as one of the methods for disinfestation and prolonged storage of food grains (WHO, 1970). A large number of investigations have so far been carried out which relate to the 'wholesomeness' of irradiated foods. These have included somatic, cytotoxic and mutagenic evaluation. Before the safety of consuming irradiated foods can be fully established, it is essential to determine that when such foods are included in habitual diets, they do not in any way seriously modify vital physiological functions.Immunological competence is an important host defence mechanism and alterations in this mechanism may be expected to adversely affect resistance to infection. A variety of factors like malnutrition and chemicals are known to modify the immune status (Scrimshaw, Taylor & Gordon, 1968;Bluestein & Green, 1970; Nikolaev, Ponomareva, Geller, Rozgan & Garipova, 1972; Gopalan & Srikantia, 1973). Also, there is experimental evidence which suggests that several macromolecular dietary components exhibit distinct antigenicity in germ-free animals (Sell, 1964; Wostmann, Pleasants & Bealmear, 197 I). It has been recently reported from this Institute that in children, rats and mice given freshlyirradiated wheat there were evidences of cytotoxicity and mutagenicity, and such changes were not seen when irradiated wheat was stored for 12 weeks before feeding (Bhaskaram & Sadasivan, 1975; Vijayalaxmi & Sadasivan, 1975; Vijayalaxmi & Visweswara Rao, 1975; Vijayalaxmi, I 976). The present study was designed to investigate the immune response in rats given irradiated wheat as the main ingredient of high(180 g/kg)-and marginal(90 g/kg)-protein diets. (In poor habitual Indian diets, approximately 80% of the energy is derived from cereals such as wheat or rice or both, and hence in the present study wheat was incorporated at 700 g/kg diet.) MATERIALS A N D METHODSIn the first study, forty weanling rats of the Wistar strain from the Institute's colony were divided into four groups of five males and five females each. They were maintained on one of the following four diets (protein content (gjkg) in parentheses) : unirradiated wheat (I 80), unirradiated wheat (go), freshly-irradiated wheat (180) and freshly-irradiated wheat (90). The details of the irradiation procedures have been described previously (Vijayalaxmi & Sadasivan, 1975). The composition of the diets is given in Table I . All rats were immunized 12 weeks after they were started on the experimental diet. At intervals of I week, for a period of three successive weeks, two soluble antigens (tetanus a...

SUMMARY1. Eight British Friesian and eight Jersey calves were fed fresh milk during the period from 3 days to 40 days of age, at two levels of feeding.2. Energy and nitrogen balances were measured twice for each calf.3. Fasting heat production (FHP) (MJ/day), which was measured on these occasions, was related to live weight (kg) by FHP = 0·435 W0·75. There was no significant difference in FHP/kg0·75 between the breeds but previous level of feeding and the duration of fast had significant effects.4. The data for heat production, metabolizable energy (ME) intake and energy retention were interpreted to provide estimates of ‘true’ net energy required for maintenance of 0·23–0·27 MJ/kg0·75 daily.5. Pooled values for ME required for maintenance and for the net efficiency of utilization of ME above maintenance were 0·39 or 0·42 MJ ME/kg0·75 daily, and 0·67 or 0·72 determined by simple or multiple regression techniques respectively; there were no significant differences between the breeds. Pooled values for the partial net efficiencies of utilization of ME for the synthesis of protein and fat were 0·54 and 0·79 respectively.6. ME required above maintenance was estimated to be 11·3 and 13·6 MJ ME/kg of live-weight gain for the lower and higher rates of gain respectively.7. A small experiment revealed no major differences between diets of milk alone or milk plus solid food, with regard to maintenance requirement or net efficiency of utilization of ME by calves.