1. A method is described suitable for the estimation of the milk yield of sheep under natural grazing conditions.

2. The yields obtained from Welsh Mountain sheep in two environments are shown.

3. A close but diminishing relationship is shown to exist between the milk yield of the ewe and the growth of the lamb. Evidence is given of the effect of milk yield at later stages.

4. The estimation of the ewe's milk yield from the weight of the young lamb is discussed. These estimates are used in conjunction with actual milk records in the present study.

5. The ewe's milk yield is shown to be significantly related to nutrition, body weight, udder size and the lamb's birth weight.

6. The relation of milk yield to weight gain during lactation, fleece weight and fleece type were mainly non-significant.

7. From the limited data available, it seems that milk yield has a fairly high repeatability and heritability.

Davies (1941) has estimated that there are nearly 1,300,000 acres of hill land in England and Wales upon which the white bent or wire grass (Nardus stricta) is predominant, or constitutes a high proportion of the ground cover. From this estimate, which is probably a conservative one, it follows that approximately 24% of the rough grazings of this country are wholly or largely Nardus pastures. The opinion that Nardus is of almost negligible grazing value is widely held. Smith (1918) has said that no stock will graze it by preference, although he admits that a certain amount of the foliage is eaten in early summer. Pearsall (1950), Fenton (1936) and Stapledon (1937) have expressed very similar views. Wallace (1917) regarded this grass in a more favourable light and, while he certainly did not rank it with the best moorland grazing plants, stressed its value in winter. The truth is that these opinions are based almost wholly on observation and are supported by very little evidence on nutritive value. Analyses on conventional lines have been made by Kinch (1884), Evans (1927), Fagan & Watkins (1934) and Thomas & Dougall (1948). Thomas & Trinder (1947) have made a detailed examination of the ash. Digestibility data appear to be nonexistent; without such data any worth-while estimate of nutritive value is almost impossible. In view of the existence of very large areas on which little other than Nardus is available for the sustenance of hill sheep, it would seem desirable to attempt such an estimate. It was therefore decided to carry out digestibility trials in which the grass, cut at two stages of growth, was fed to sheep of a hill breed.

1. One of the biggest difficulties in the measurement of the feed, intake of grazing animals by the indirect method using indigestible ‘markers” is to determine the optimum frequency for dosing and for taking faeces samples in order to achieve greatest accuracy while yet retaining realistic free-grazing conditions of husbandry.

2. Results of earlier studies of the rate of excretion of individual doses of marker by grazing sheep are used to illustrate the probable outcome of various schedules of dosing.

3. It appears that if marker doses were administered and faeces samples were taken twice daily at alternate intervals of 9 and 15 hr. approximately, the mean marker concentration of these samples would yield an essentially unbiased estimate of the general level of marker in the faeces. Since there is no satisfactory evidence that animals fail to excrete all the marker administered, it should be possible then to derive estimates of mean faeces output with an error probably of the order of + 10%.

4. This technique was tested in two stall-feeding trials and and one free-grazing trial with a total of seventeen sheep.

5. The unweighted mean of the estimates of faeces dry-matter output for the seventeen individual sheep periods was about 100 ± 8%.

6. Alternative methods of bulking the faeces samples so as to yield estimates of group mean faeces output are considered, but the possibility of introducing a serious bias by the bulking process is pointed out.

1. An analysis has been made of milk records from 3109 cattle of the six main dairy breeds in England and Wales.

2. The correlation between measurements on separate lactations declined as the time interval between the lactations increased. The average correlation was 0·38 for 70 days' milk yield and 0·48 and 0·55 respectively for milk yield and fat content in the 305-day lactation.

3. The heritabilities of the three measurements measured by daughter-dam regression were found for heifer lactations to be 0·36, 0·43 and 0·43 respectively. On second lactations, they were 0·09, 0·24 and 0·42.

4. As a consequence of the low heritability of the second lactation yield, the average yield of the first four lactations proved to have no more value as a prediction of a cow's breeding merit for yield than did her heifer yield.

5. In agreement with other workers, we found that 70-days yield was an excellent guide to the total lactation (r ~ 0·80), and that it could be used as a guide to early selection.

6. There was some indication that the correlation between yield and fat content in the same lactation was more strongly negative in heifers and in the Channel Island breeds. The overall genetic correlation on first lactations was found to be − 0·66 ± 0·20, rather more strongly negative than has been found previously.

The concentrations of potassium in the whole blood of representative samples of sixteen British breeds of sheep have been studied.

The proportion of sheep with a high level of potassium in the whole blood (high potassium or HK type) was found to differ significantly between breeds. It ranged from 0% in the English Leicester to 73% in the Rough Fell.

There were significant differences between breeds in the mean concentration of potassium in the whole blood of both the LK and HK sheep.

1. It has been shown that under a given feeding régime the concentration of blood urea in the sheep is constant.

2. Changes in the diet lead to different levels of blood-urea concentration which can be correlated with different rumen-ammonia concentrations; the change in blood-urea concentration follows increases or decreases in rumen ammonia after a delay period of 4–8 hr.

3. Fluctuations in blood-urea concentration in the sheep are not primarily due to changes in the overall nitrogen intake.

4. It is suggested that these findings might form the basis of a supplementary test in assessing the value of the protein in a foodstuff for ruminants.

Between 1953 and 1955 a series of field experiments have been carried out in Great Britain to assess the effect of sowing date on the extent and the rate of emergence of a number of varieties of maize.

The range of sowing dates was from late March till May. Records were kept of the soil temperatures, these will be reported later, and in certain experiments the water content of the soil was maintained at field capacity. In all experiments a northern flint variety and a southern dent variety were sown, in the first year only flint × dent hybrids were also grown.

There was an increase in final emergence with the later sowing dates. The northern flint varieties were superior to the southern dent varieties, while the flint × dent hybrids occupied an intermediate position. The lower final emergence of the southern dent variety was most marked at the earlier sowing dates.

Differences between varieties in the speed of emergence, taken as the number of days from sowing until half of the surviving seedlings had emerged, was observed at several centres. The open-pollinated varieties usually emerged more slowly than the flint × dent hybrids. There was a very marked difference between early- and late-sowing dates in speed of emergence.

It was possible in the second year to compare seed of high quality with that of low quality as determined by the ‘cold test’ of germination capacity. The lowquality seed gave greatly reduced final emergence, the experiments stressing the need for the adoption of a standard ‘cold test’ for maize seed, especially of that intended for sowing in north-western Europe.

The high final emergence of the northern flint varieties suggest that a gene source for resistance to soil pathogen attack is readily available. The possibilities in north-western Europe for expansion of growing grain maize would be greatly strengthened by development of varieties capable of growth at low temperatures. The experiments suggest that until such varieties are available little advantage in time of emergence will be gained by sowing maize before late April in Britain.

The effects of inbreeding of the sow and plane of nutrition after mating on litter size at 28 days were investigated.

Outbred Large White sows were mated at first heat after weaning to inbred boars, and inbred sows to outbred boars, so that both groups of sows carried the same type of embryo. The sows were then placed at random on either high or low planes of nutrition until slaughter 28 days later, when their corpora lutea and number of embryos were counted.

Litter size was significantly higher in outbred than in inbred sows by 2·52 ± 0·93 pigs. This resulted from 2·89 ± 0·94 more ova shed and 0·37 ± 0·93 more embryos dying. The general conclusion is that inbreeding of the sow reduces early litter size mainly by depressing ovulation rate.

The different planes of nutrition produced negligible differences in within-litter mortality and, therefore, on litter size, but resulted in a marked difference in conception rate. All animals on the high plane were pregnant, whereas on the low plane 25% were empty, this difference being highly significant.

Age of the sow, but not her weight, was found to be significantly correlated with number of corpora lutea (r = 0·39). The latter had a correlation with litter size of 0·55 and with mortality of 0·45. The correlation between litter size and mortality was −0·50.

Parity increased and inbreeding reduced the length of the uterus which was not, however, significantly correlated with litter size.

The paper describes the results of over 300 factorial experiments carried out in each factory area in the years 1934–49 for the Sugar Beet Research and Education Committee of the Ministry of Agriculture as a result of co-operation between Rothamsted workers and the agriculturists and fieldmen attached to the beet factories. All the experiments tested the effects of levels of nitrogen, phosphate and potash, and rather more than half tested the effect of salt also.

Except on fen soils, nitrogen gave substantial responses in all factory areas, especially in the presence of high levels of potash or salt. Large variations in response from season to season were closely associated with the rainfall of the preceding winter months, responses being greater after wet winters than dry ones.

In spite of some selection of sites in favour of greater responses, the average net returns from phosphate were relatively small.

The effect of potash was closely linked with the amount of nitrogen applied; in the presence of nitrogen, dressings well above the level of 1·2 cwt. K2O per acre tested in the experiments are likely to give a useful net return. Soils derived from the Chalky Boulder Clay seem to be exceptional in showing no response. Apart from this, there were only small variations in responses to nitrogen and potash between factory areas. The application of 5 cwt. salt gave substantial responses in almost all parts of the country, whether or not potash was also applied; on the other hand, responses to potash were usually small when salt was also applied.

Whilst there was a general relationship between soil analysis for phosphate and potash (citric acid method) and crop response, adjustments to the optimal dressings according to soil analysis were not of sufficient reliability to be of much practical value.

Information on how growers actually manure their crops is available from the Survey of Fertilizer Practice, carried out by the Provincial Soil Chemists of the N.A.A.S., in collaboration with Rothamsted. These data indicate that, taking into account the nutrients in farmyard manure, the average amounts of nitrogen and potash applied are not far from the optimal amounts suggested by experiment, whilst phosphate dressings are on the average at least double requirements. This may be due in part to the fact that few compounds are available with a low ratio of phosphate to other nutrients.

Except in one or two factory areas the use of salt on sugar beet is still very limited.