101 Rhode Island Red × Light Sussex chickens have been made to conform to four differently shaped growth-curves from hatching to 24 weeks, by control of their plane of nutrition. The four treatments HH, LH, HL and LL allowed comparisons to be made between birds of the same age but different weights.

As the main concern has been to find the essential nature rather than the precise extent of the effects produced by different planes of nutrition, the treatment differences were made as extreme as possible without allowing the rations to become unbalanced.

The conclusions reached are as follows:

1. The treatments used have produced marked effects on the growth-curves of the birds, analysed on the basis of equal age. These effects have been shown to be statistically significant at all stages after 3 weeks.

2. In body-weight and form, two types of bird were produced. The HH and LH birds were similar, with greater relative proportions of the late developing parts and secondary sexual characteristics, and the small differences that existed between them were not significant at 24 weeks. Likewise, the LL and HL birds formed a comparable group, exhibiting a more infantile body form similar to that of the HH and LH birds at an earlier age. The difference

between the HL and LL birds, though generally not statistically significant, is greater than that between the LH and HH group.

3. The treatments produced a small but consistent effect on the external measurements of the birds when comparisons were made on the basis of equal weight. Nine measurements were recorded. In the case of four measurements, no treatment effect was noted. Four skeletal measurements demonstrated a consistent effect of treatment, the LL and HL measurements exceeding those of the HH and LH at equal live-weights. This result was reversed in the case of the only muscular measurement, thickness of leg musculature. Opposite results are therefore indicated for the muscle and skeletal tissues. This finding will receive further discussion when the dissection analysis results are discussed in a later paper.

4. The presence of definite growth-gradients from the body extremities towards the trunk is indicated by the external measurements.

5. The two sexes differ in their live-weights at equal age and in their bodily proportions both at similar ages and similar weights. The most marked sex-difference in external measurement is noted in the length of the mid-wing, and a possible functional explanation is advanced. In general, the sex-difference is greatest for the late maturing characters.

1. Studies were made of the composition of Giant sainfoin cut successively at different stages of growth in two seasons under contrasting conditions of weather and soil.

2. Cuts were taken at preflowering, early- and full-flowering stages of growth. Yields of both fresh material and dry matter substantiated the usual farming practice of taking two cuts at full flower in one season, and indicate that cutting sainfoin before it comes into bloom has a seriously depressing effect on productivity.

3. Like most green fodder crops, sainfoin has a lower content of crude protein and nitrogen-free extractives, and a higher content of crude fibre as the plant increases in maturity. The mineral content is somewhat variable, and in particular the potassium content appears to reflect the status of this element in the soil.

4. The ratio of leaf dry matter to total dry matter of the plant decreases with advancing maturity. The leaf composition is fairly constant, irrespective of stage of growth, number of cuts and season, the fibre content being remarkably constant in contrast with that of stem, where it increases with advancing maturity. Leaf is richer than stem in crude protein, ether extract and total mineral matter, particularly calcium. Thus changes which do occur in the composition of the plant are due to variations in stem composition and leaf-stem ratio.

5. Analyses of sainfoin hay, made under both experimental and commercial conditions, are discussed, and the range of variation in the main constituents of thirty-five commercial samples is commented upon.

6. The present investigations into the composition of sainfoin, both as green fodder and as hay, show figures that differ appreciably from those derived from earlier German work. Examination of the data available for the nutritive value of fresh and conserved sainfoin reveal anomalies which suggest that such data are not typical of the crop as grown in this country, and also suggest the need for more modern data.

The results are given of an investigation of the successful production, and of the chemical composition and feeding value, of maize silage made from early maturing varieties of hybrid maize grown for three consecutive years in the south of England. The maize was ensiled at a stage when the cob contributed approximately 50% of the total crop and the dry-matter content of the crop varied from 16·3 to 27·2%. The mean crude protein content of the dry matter of the silage was 9·5% (range 7·9–11·2%). Average weight losses in the silo were fresh matter 25%, dry matter 30%, crude protein 25%, and soluble carbohydrates 40%.

In three controlled feeding trials with cows and heifers in milk, maize silage was found to be equal in nutritive value to a ration of mangolds and oat and tare silage when fed on an equal dry-matter basis. The silage was very palatable and a daily ration of 50 lb. was consumed.

It is concluded that although maize silage compares favourably with an average crop of cereal -legume silage in feeding value, its adoption on a wide scale cannot be recommended in view of the relatively low yield of dry matter per acre, the high costs of production and the appreciable silo

1. The experiments started in 1949 to determine the weight and chemical composition of the herbage dry matter eaten by two groups of dairy cows grazing under a rotational and a close-folding system of management have been continued in 1950.

2. Good-quality herbage was fed in adequate quantity to both groups for 20 weeks, in four fiveweekly periods allowing a double change-over system for the groups. The weights of protein, fibre, other extractives, lignin and minerals eaten daily by the close-folded group were determined. Difficulty in obtaining truly representative herbage samples from the rotational paddock made such detailed analyses for the rotationally grazed cattle not worth while.

3. The weight of dry matter eaten by the closefolded cows was remarkably constant, the mean was 26 lb./cow/day and the standard deviation ±2·7 lb. The weight eaten by the rotationally grazed cows was more difficult to measure and appeared to vary considerably, the average being 31 lb. dry matter/ cow/day, and the standard deviation ±3·1 lb. Reasons are suggested why this figure of 31 lb. may be at least 5% too high.

4. The relationship between the chemical composition of herbage as cut for sampling and the probable composition of the herbage as eaten by the grazing animal is discussed. Correction curves are given to convert the protein and fibre contents of herbage as cut in these experiments to values corresponding to those in the herbage as eaten.

5. An attempt has been made to provide a balance sheet, in terms of D.C.P. and S.E., of animal production against nutrient intake. A deficiency of both protein and energy existed during the first spring period in both 1949 and 1950 (according to presentday standards), and although the protein balance became positive later in the season, the energy provided by the grass eaten was still barely adequate.

6. Mineral balances calculated for the closefolded cows showed deficiencies of both calcium and phosphorus during the period of high milk yield, with the balances becoming positive later in the grazing season.

1. Lambs' tails at about a month old have been collected from two or three flocks of several different British breeds and crosses of sheep, and have been classified into ten grades according to the relative amounts of wool or hair extending from base to tip of the tail.

2. In general the relative amounts of wool and hair found on the tail of the lamb in the different breeds correspond with the quality of the wool of the adult fleeces of the breeds.

3. Considerable variability in tail grade was found between different individuals in the same flock, so that there is scope for selection in this respect to improve the quality of the wool especially on the britch.

4. It is suggested that as differences are more obvious on the tail at birth than in the adult fleece, selection for uniformity of fleece might be made at this time.

1. The method adopted for making three different grades of silage, from grass cut at different stages of maturity, is described.

2. A feeding trial is described including four groups of cattle fed on grades I–III silages and on swedes and straw respectively.

3. The live-weight gains made are recorded together with the rate of dry-matter intake.

4. A digestibility trial was carried out on the three grades of silage. The digestibility coefficients found are recorded.

5. It is shown that cattle fed solely on silage build up a bigger ‘gut fill’, to the extent of 40 lb. (± 11), than similar cattle fed on swedes and straw.

6. When an allowance had been made for a 40 lb. greater ‘gut fill’ in silage-fed cattle it was found that grades I and II silages produced a significantly greater rate of fattening than grade III silage and than swedes and straw.

7. It was found that the rate of total daily drymatter intake rose to a peak at the eighth week and then fell; it did not continue to rise beyond that point but the cattle continued to gain in live weight.

8. The efficiency of utilization of the dry matter of the rations fed increased during the latter part of the trial.

9. It is suggested that the increase in efficiency of utilization of the dry matter consumed may be attributed to an adaptation in the rumen microflora of the cattle which proceeded for up to 8 weeks after the cattle were put on to the experimental diets.

The fertility of a number of ejaculates from normal dairy bulls in regular service is found to be positively correlated to the light-reflecting capacity, NE, of the spermatozoa in the ejaculates.

The partitions of phosphorus and aneurin were determined in the colostrum and in the transitional and mature milk of Ayrshire cows with the following results:

1. The ratio of nitrogen to phosphorus was 11:1 in the first mammary secretion but dropped to a minimum value of 4·5:1 a week later. Thereafter the ratio increased throughout lactation attaining a value of 7·2:1 at the fortieth week. The first colostrum was very rich in both phosphorus and nitrogen.

2. Phosphatase titre in colostrum was 154 units in the first post-partum secretion but decreased to 10 during the first five days of lactation. The titre fluctuated slightly during the next few days and increased gradually thereafter, attaining 189 units in the 38th week of lactation.

3. Phosphatase was correlated positively with inorganic-P (r= +0·83) and negatively with both ester-P (r= −0·94) and lipid-P (r= −0·70), all P fractions being expressed as percentages of total P. The percentage of phosphorus present as casein was initially 19–21%, but was only 14% in late lactation.

4. The first colostrum contained 74 μg. aneurin/100 ml. skim milk. This value became 35 in midlactation and only 28 in late lactation. The corresponding figures for cocarboxylase were 20, 5·7 and 2·3 μg./100 ml. respectively, and for protein-bound aneurin 14, 3·2 and 1·7 respectively. Both cocarboxylase and protein-bound aneurin were negatively correlated with phosphatase.

A comparison is made of the herbage production and animal output, as measured by live-weight gain, of temporary pastures sown to ultra-simple seeds mixtures with those sown to a more complex generalpurpose mixture.

Herbage production was somewhat higher in the simple-mixture series on account of the inclusion of a lucerne-meadow fescue mixture. In total seasonal output, as reflected by live-weight gain of fattening stock, only small differences occurred.

It is suggested that the value of simple mixtures lies in their ability to provide seasonality of grazing and a more even output of animal products throughout the season. This is not always possible when, using general-purpose competitive mixtures.

The object of the present investigation, was to compare the supplemental value of the microbial proteins in dried brewers' yeast with the animal proteins in white-fish meal when incorporated in a barley meal-fine bran diet containing a little lucerne meal and suitably adjusted as regards minerals. The investigation was carried out both by the nitrogen-balance method and by the statistically controlled growth method, using the individual-feeding technique. The main problem was to find the minimum percentage of yeast that had to be included in the cereal diet so as to sustain the same rate of growth and economy of food conversion, and to enable retention of nitrogen to take place at the same rate, as is obtained on a standard diet containing 7% of white-fish meal, the total digestible nutrients in all diets being kept approximately constant.

In the first nitrogen-balance trial a comparison was made between the standard diet containing 7% of white-fish meal and a similar basal diet supplemented with 15% of dried brewers' yeast. The percentage crude protein in the yeast diet was 15·39 as compared with 15·12 in the standard treatment, the total digestible crude protein being 12·34 and 12·29, respectively. The supply of total digestible nutrients was almost alike on both treatments.

After about 6 weeks on experiment, the two hogs on the yeast diet became subject to vomiting at rather frequent intervals, although they were always eager for their food and their faeces remained normal. It is unlikely that vomiting was caused by the presence in the yeast of any toxic substance and the possibility that it was due to the presence of live yeast cells is also remote for reasons given. The most likely hypothesis is that it was due to the animals ‘bolting’ their food with great avidity, since the pigs found the yeast diet to be highly palatable and they always appeared to be hungry.

The two hogs on the yeast diet made average daily live-weight gains of 0·85 and 0·80 lb., the figures over a corresponding period for the hogs on the standard treatment being 0·67 and 0·71 lb. Economy of food conversion was also better on the yeast treatment. The average daily retention of nitrogen was also higher on the yeast treatment the figures being 9·28 and 9·01 g. as compared with 8·07 and 8·90 g. on the standard diet. It is evident therefore that when yeast is incorporated in a cereal diet so as to bring the digestible crude protein content to the same level as in the standard treatment containing white-fish meal, maximum storage of nitrogen takes place, even with young pigs.

In the second nitrogen-balance trial the amount of yeast in the diet was reduced to 12% so as to investigate whether this amount would also support maximum retention of nitrogen and maximum growth. The percentage of digestible crude protein in the diet was 12·56 on the standard treatment and 11·29 on the yeast treatment, the total digestible nutrients being 64·47 and 64·18%, respectively. Over the 63 days that the pigs were in the metabolism crates the two hogs on the standard treatment made slightly higher live-weight gains and retained rather more protein in their tissues, the average retention of nitrogen being 9·43 g. on the standard diet and 8·3 g. on the yeast diet.

It appeared from these results that a cereal diet supplemented with dried brewers' yeast so as to bring the crude protein content to 14·18% (15·95% on the basis of dry matter) does not supply quite enough protein to support maximum retention of nitrogen. In the first experiment, however, when the yeast diet contained 15·39% of crude protein (17·37% on the basis of dry matter) the results were fully equal to the standard treatment containing 15·12% of crude protein (17·21% on the basis of dry matter). These conclusions were tested further by means of a growth trial with ten individually-fedpigs on each treatment.

In the growth trial the ten pigs on treatment A received a supplement of 9% of dried brewers' yeast, those on treatment B were on the standard diet containing 7% of white-fish meal and those on treatment C received a supplement of 12% yeast. The percentage of crude protein on the mean moisture basis was 14·62 in treatment A, 16·15 in treatment B and 15·4% in treatment C. It was concluded from the results of this growth trial that when approximately one-third of the total crude protein in the diet comes from either dried brewers' yeast or white-fish meal, complete supplementation of the proteins in the basal diet of barley meal and fine bran occurs, so as to enable maximum retention of nitrogen or maximum growth to take place without wastage of aminoacids. The results for treatment A suggest that the proteins in yeast may even be superior in supplemental value to the proteins in white-fish meal.

The deductions made from both methods of experimentation are therefore in close agreement and the results show that a basal diet of 2 parts of barley meal and 1 part of fine bran with a little lucerne meal and minerals when supplemented with dried brewers' yeast so as to bring the crude protein content of the mixture to about 15·5% enables the young pig to store the maximum amount of protein in its tissues and to grow at a maximum rate in conformity with the net energy content of the diet. The distribution of essential amino -acids in the proteins of yeast and in the proteins of whitefish meal, when based on equal weight of crude protein, is not significantly different, any differences being slightly in favour of the yeast proteins.

A comparison is also made between the results obtained with dried brewers' yeast and those obtained with extracted decorticated ground-nut meal used in previous trials.

In continuation of our work on the relative supplemental value of animal and vegetable protein concentrates (Woodman & Evans, 1951), a study has been made of the proteins in extracted soya-bean meal. It is probable that vegetable protein concentrates may vary among themselves in nutritive value and that the proteins of ground-nut meal, which were the subject of investigation in our previous experiments, could not for this reason be regarded as representative of vegetable proteins in general. The same basal diet, composed of roughly 2 parts of barley meal and 1 part of fine bran, together with a little lucerne meal and minerals, was again used in the present investigation.

1. The availability of the calcium in three grassland species, all legumes, has been investigated, with the rat as experimental animal.

2. Two procedures involving determination of the calcium balance, (a) by analysis of feed, faeces and urine, and (b) by a slaughter technique, were used.

3. The foregoing methods gave results, for any one species, which were without significant difference. It is considered that the slaughter technique would be the less laborious when any large number of determinations has to be made.

4. The calcium in both lucerne and late-flowering red clover was available to a significantly greater degree than that in wild white clover. In all three species calcium availability was high.

5. The possible significance of the high faecal calcium found in rats receiving wild white clover has been discussed.

6. It was concluded that the extension of availability studies to a wider range of grassland species and of their ash-components would be desirable.

1. The methods employed by some of the earlier workers for separating analytical samples from heather, show little uniformity and are, in general, poorly defined. No procedure capable of separating the relatively large weights of material necessary for digestibility studies has hitherto been devised.

2. Analytical samples prepared by (a) a method used by Thomas, and (b) a method suggested by Braid were compared. The results obtained were very similar, but the latter method was recommended as being the better denned.

3. Two methods of preparing large samples for digestibility studies, one adapted for winter heather and the other for use in spring and summer, have been used. Both of these methods, when applied to winter heather, give samples which compare well with a sample obtained by the method of Braid.

4. Samples separated in summer by method 5 were compared with samples of material similar to that observed to be eaten by sheep. It was found that the former were of appreciably lower crude protein content and contained slightly more lignin than the latter.

5. No evidence of an adverse effect on digestibility by oven-drying for 24–48 hr. at 38° C. was obtained.

1. Since the pigmentation of the skin cannot be assessed by visual examination of the hair or hide, a simple and convenient method of grading the cutaneous pigmentation of cattle based on the microscopic examination of skin sections has been described.

2. The degree of cutaneous pigmentation of the skin of twenty body regions of three Ayrshire cows, two Ayrshire bull calves, two Sudanese Zebu bulls, one Sudanese Zebu cow and one Jamaican Zebu cow have been assessed by this method.

3. The skin of the Zebu cattle was found to be much more heavily pigmented than that of the Ayrshire cattle.

4. The dorsal and lateral regions of both the Zebu and the Ayrshire cattle were more pigmented than the ventral and leg regions.

1. Various portions of barley plants were made available for chemical tests from manurial experiments which were designed to test the effects of K treatment (broadcast and placed with the seed) on grain yield.

2. The experiments were located at three centres differing in soil characters and K status. Centre A was severely deficient in K; centre B was moderately deficient and at centre C, K was adequate.

3. A comparison was made between the results of the following tissue test methods for K, Mg, Ca, P and Mn: (a) diffusion method, using young leaf, mid-stem leaf, and internode respectively; (b) Waring blendor, and (c) ash analysis. Mn was not determined by the blendor method.

4. The coefficients of variation for the quick tests compared favourably with those of ash analysis for K, Mg, Ca, P and Mn respectively. Variations in results in tissue tests for Ca were, however, significantly greater than those of ash analysis, at centre A (second sampling).

5. Correlation coefficients between results of ash analysis and the tissue test methods for K, Mg, Ca, P and Mn were positive and significant for totals, treatment and treatment × sites, except for Mn in young leaf by diffusion method. The error term for P was also significant for the quick methods, thus decreasing the value of the correlations for this nutrient.

6. Correlation coefficients of yields with ash analyses, Waring blendor and diffusion method (mid-stem leaf) analyses respectively were significant and positive for K and negative for Mg, Ca, P and Mn. This confirms an interaction of K with the other nutrients.

7. Minimum K levels, determined 5 weeks after seeding, above which no further increase in yields may be expected at the three centres, were: by diffusion method, using young leaf, mid-stem leaf and internode, 700, 500 and 600 μg. extracted per. g fresh weight respectively; by Waring blendor using ‘tops’, 2000 μg. extracted per g. fresh weight; by ash analysis of tops 1·5% K in dry matter. There is evidence that these critical levels fall later in the season, especially in mid-stem leaves, presumably through translocation of K to the ears.

8. Minimum levels of K required for optimum yields are above those associated with the onset of deficiency symptoms of the element. Thus chemical methods only can determine suboptimal levels of nutrients in relation to final yields.

1. Samples of sheep and cow urine have been analysed microbiologically for seventeen aminoacids.

2. Over 90% of the total amino-nitrogen in hydrolysed urine was due to glycine.

3. Bound glycine was present not only as hippuric acid but also in other forms as yet uninvestigated.