1. The proportion of stained spermatozoa in a ram semen-nigrosin-eosin mixture has been found to increase with the time of exposure to the stain. Five minutes is considered to be a suitable interval for practical use.

2. The value obtained for the proportion of dead cells can be considerably affected by the selection of fields that are easy to count; fields should be chosen at random.

3. The variation between, counts on the same smear is much larger than that expected for binomial proportions. This may be due partly to the ‘clumping’ of the dead spermatozoa and partly to the difficulties of interpretation caused by the presence of many partially stained cells.

4. A significant difference was found between the estimates of the proportion dead obtained by the two experimental workers; this is thought to be due to a difference of interpretation of ‘stained’ and ‘unstained’.

5. Tables are given by which to determine the approximate accuracy of counts made on a range of numbers of spermatozoa, smears and subsamples, separate tables being necessary for ram, boar and bull semen.

1. Deep tillage, namely, ploughing to a depth exceeding 12 in., or subsoiling to a depth of about 18 in., increased crop yields on about half the fields in which an experiment was made. Unfortunately, it was not possible to recognize what was the difference in soil properties between the 50% of fields that responded appreciably to deep tillage and the remainder whose yields were either unaffected or sometimes reduced by deep tillage, though, as one would expect, sands were normally less responsive to deep tillage than the heavier soils.

2. On the clay soils, deep ploughing in autumn tended to give a surface soil that dried out up to several weeks earlier in the spring than land that was shallow ploughed. Subsoiling did not cause the surface soil to dry out in the same way. Only rarely did the subsoil brought up by deep ploughing give difficulty in working down to a seedbed, and probably in as high a proportion of fields the subsoil worked easier than the surface soil.

3. On the clays and loams, the response of potatoes to deep tillage was more marked on fields that were heavily manured than on those lightly manured.

4. Sugar beet normally gave a higher yield if its potash and phosphate was spread on the land before ploughing, even if this was in the autumn, than if it was applied in the seedbed. The exceptions to this result were for soils heavier than sandy loams if ploughing depths exceeding 12 in. were used, for the yield of beet was, on the average, depressed on these soils if the potash and phosphate was ploughed in compared with it being worked into the seedbed.

5. Deep ploughing tended to give better control of many perennial weeds, and often of annual weeds than shallow ploughing. It is suggested that much of this benefit could be obtained when ploughing to 9–10 in. deep if ploughs were used that cut a furrow considerably wider than the conventional 10½–11 in. furrow, so allowing more complete inversion of the furrow slice.

1. The efficiency with which Ayrshire calves digested the dry matter of fresh grass was measured over two trial periods extending from the third to the tenth week of age.

2. A statistical method for determining digestibility coefficients is outlined and its advantages over the conventional procedure, particularly for young growing animals, are discussed.

3. The mean coefficient of digestibility of the dry matter of the grass for four calves was 74·6%.

4. This digestive efficiency was attained immediately the grass was fed and did not vary throughout the experiment.

5. Simultaneous feeding of milk in the first trial period did not affect the digestion of grass.

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.

1. A spring top-dressing of 0·5 cwt.nitrogen/acre was applied to winter wheat as urea or ammonium nitrate in a single spray at 30 gal./acre or as solid fertilizer applied to the soil. A weed-killer, 2,4-dichlorophenoxyacetic acid, was applied in the nitrogen spray or separately in spray to plots that received solid fertilizer.

2. Uptake of nitrogen by the crop from solid fertilizer was about twice that from fertilizers applied in sprays. Solid fertilizer increased yield slightly more than did sprays.

3. Ammonium nitrate and urea had the same effects, both when applied in sprays and when applied as solid to the soil.

4. 2,4-D decreased the amount of weed slightly, but had no effect on yield of wheat.

5. The interactions between weed-killer and method of applying nitrogen were small; the response to nitrogen in dry weight of straw, including weeds, in one experiment, and of shoots in another experiment, was decreased by 2,4-D when nitrogen was applied in spray but not when it was applied as solid fertilizer.

Results are recorded of experiments over four years to study the effects of various rates of N fertilizer applied early (soon after each cut) and late (1 or 2 weeks before cutting) to grass-clover swards cut repeatedly for conservation.

N fertilizer proved essential for high yields of dry matter and protein per acre. It reduced the amount of clover, but it is clear that clovers are not as productive as grasses adequately manured, and that any N excreted by clovers into the soil is far from enough to enable associated grasses to make full growth.

The amount of N fertilizer applied proved more important than the time of its application. Early N gave higher yields of dry matter but rather lower percentages of crude protein in the herbage than late N dressings.

To increase yields substantially and at the same time to maintain the protein content of the herbage on a par with a grass-clover ley it seems necessary to apply a minimum of 4 cwt. ‘Nitro -Chalk’/acre as an early dressing before each cut. An additional 2 or 3 cwt. ‘Nitro-Chalk’/acre may be applied from one to two weeks before cutting if even higher crude protein values are required.

Experiments on the milking qualities of New Zealand Romney ewes, maintained at liberal standards of grazing and at different planes of nutrition under stall-feeding conditions, were described in four earlier papers published in this Journal (Barnicoat, Logan & Grant, 1949).

In the meantime several other original papers in this field have appeared: Coop (1950) studied the effect of certain factors including milk intake on the growth and development of lambs of various breeds of sheep in the South Island of New Zealand; Barnicoat (1952) discussed some practical applications of the work; Owen (1953), employing a modified technique for measuring milk yields of Welsh hill ewes, found that the correlations between lamb gains and estimated milk yields were of a similar order to those established elsewhere under easier conditions of farming; Thomson & Thomson (1953) carried out experiments with Cheviot ewes fed indoors, and their results support the viewpoint that adequate nutrition in the final stages of pregnancy is of paramount importance; and Gill & Thomson (1953) discussed the significance of milk yield of ewes under farming conditions in Great Britain which contrast widely with conditions pertaining to the district in which the experiments described in this series of papers were conducted.

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.

Experiments are described which give some basic information on the rate and pattern of marker excretion by sheep on pastures ranging in digestibility from 70 to 80% and on hay of barely 50% digestibility.

The faeces output of individual sheep varied from 100 g. to more than 400 g. daily, and the estimated feed intake from below 400 to over 1,900 g. daily.

Despite these wide ranges a typical pattern for the passage of single doses of markers was quite consistently repeated in the trials on pastures:

1. Markers first appeared in the faeces 5–8 hr. after dosing.

2. Concentrations rose rapidly to peak values about 10–18 hr. after dosing.

3. Concentrations fell thereafter by about 50% each 6–10 hr. until 60–70 hr. after dosing when marker content could no longer reliably be determined by the methods used.

Factors affecting the basic pattern

1. The overall quality of the feed was of prime importance, in that peak concentrations occurred progressively later on poorer pastures and on hay.

2. For any given feed a high level of (estimated) feed intake was often associated with earlier appearance of marker in the faeces, an earlier peak of concentration, and slightly faster fall in marker concentration.

3. There was evidence that the time of administration might slightly affect rate of passage, presumably through its relation to grazing periods, for doses given at or near times of greatest feed intake were passed rather more rapidly.

4. It did not appear that there was any considerable retention of either marker within the tract beyond 72–96 hr. after dosing.

The influence of the maternal environment on the size of lambs from birth to 8 months has been studied by reciprocally crossing the large Border Leicester and the small Welsh Mountain breeds of sheep and by transferring fertilized eggs between ewes of these breeds.

Ewes which lambed later in the spring gained more weight during the last 6 weeks of pregnancy than did the earlier-lambing ewes. The birth weight of the lambs was not, however, affected by either the date of lambing or the ewes' gain in weight during the last six weeks of pregnancy.

Significant breed differences in gestation length were recorded; these were 144·7 days for the Border Leicester and 147·1 days for the Welsh Mountain. Border Leicester ewes carrying pure-bred Welsh lambs had an average gestation of 149·6 days, while Welsh Mountain ewes carrying pure-bred Border Leicester lambs had an average gestation of 146·0 days. From the births of ‘transferred’ lambs, it appeared that the genetically smaller lamb was a cause of a longer gestation period. On the other hand, within groups, both live weight and length of ‘cannon bone’ of the lambs at birth increased when the gestation period was longer.

The maternal environment affected foetal growth when the genotype for size of the foetus was different from that of the mother. The mean live weight and ‘cannon-bone’ length of cross-bred lambs born to Border Leicester ewes were 1·08 lb. and 0·37 cm. greater at birth than those of cross-bred lambs born to Welsh ewes. Comparable figures for the maternal influence from the results of transferring eggs from one breed to the other were 1·96 lb. and 0·33 cm. On the other hand, within breeds, there was no effect on the size of the lambs at birth of variations in the size of the ewes. The length of the ‘cannon bone’, which grows relatively rapidly during the early stages of growth (an early-maturing part of the body), was less influenced by the maternal environment than the late-maturing live weight.

Mature ewes produced larger lambs at birth than young ewes. The mean differences at birth in weights and in lengths of ‘cannon bone’ of the lambs born to young and mature ewes were 1·38 lb. and 0·31 cm. respectively.

From these and other experiments, the conclusions were drawn that: (i) the maternal influence on the size of young at birth is greater, in the larger species which have longer gestation periods, than the effect of the genotype of the young; (ii) the maternal organism competes with the foetus for nutrients, thus limiting the size of the young at birth; and (iii) the maternal organism may also influence pre-natal foetal growth by means of some internal secretion or metabolic substance.

The amount of milk consumed by the lambs had a marked effect on their live weight gains during the first half but not during the second half of lactation. Variations in milk consumption by the lambs did not affect the growth in length of their ‘cannon bones’. The influence of the post-natal maternal environment is largely exerted through the milk yield of the ewe and causes of variation in this milk yield were reflected in the post-natal maternal influence estimated in these experiments.

The total milk yield of ewes was affected by their date of lambing, that of late-lambing ewes being less than the yields of ewes which lambed earlier in the season.

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.

The non-protein nitrogenous (NPN) fraction of grassland herbage given a range of repeated nitrogenous fertilizer treatments has been examined. The herbage was intended for conservation and the treatments were 0, 2, 4, and 6 cwt. ‘Nitro-Chalk’ per acre per cut, applied early, after cutting, and late, 10–14 days before cutting.

1. The experiment described confirmed earlier findings that a folding management across wormfree pasture was capable of preventing infection of the lamb by all species except Strongyloides papillosus.

2. The growth and productivity of lambs infected at five different levels were compared with those of ‘worm-free’ controls grazing with them.

3. Live-weight gain of the total infected group was significantly depressed; within the infected group only level 5 differed significantly from the control group.

4. Loss of productivity was, in this experiment, associated with egg counts between 30 and 57 e.p.g.

5. The problem of definig a ‘tolerance’ level below which no appreciable damage occurs is discussed in relation to the results obtained.

1. Carcasses of twenty-one fat cattle (from six cows, ten steers and five heifers, aged from 12 months to 12 years and representing seven breeds) have been dissected into nine joints, and the fatty and muscular tissue from each joint dissected and analysed for fat. The iodine number of each sample of fat has been determined.

2. The fat in fatty tissues ranged from 28·3 to 96·7%, and in muscular tissues from 1·3 to 14·2%. Iodine numbers of fat from fatty tissues ranged from 34·0 to 69·0 and those of fat from muscular tissues from 45·9 to 73·2.

3. By an analysis of covariance it has been possible to reduce these data to two families of regression lines—those for fatty tissue and those for muscular tissue.

4. The equations for fatty tissue have the following generalized form:

I.N. = AFT + CFT + JFT + b1F/FT,

where AFT = 55·6 ± 1·7 and is a general constant,

CFT is a series of constants for the various carcasses and ranges from +12·6 to −6·7,

JFT is a series of constants for the various joints and ranges from +6·6 to −10·3,

b1 is a general constant with the value −0·052(± 0·025),

F/FT is the percentage of fat in any given sample of fatty tissue, and I.N. is its iodine number.

5. A similar set of equations has been deduced for muscular tissue. Here, however, the relation between iodine number and percentage of fat is a rectangular hyperbola. Consequently, the inverse (Z) of the percentage of fat (in order to get a straight-line relationship) has been used.

1. Two hundred and ninety-one samples of semen from seventy-four dairy bulls in use at seven artificial insemination centres and one bull-rearing centre were tested and graded according to the type of metabolic response under the experimental conditions described by Melrose & Terner (1953).

2. Conception rates of bulls were obtained from the breeding records based on not less than 150 first inseminations. Since the mean conception rates of centres varied, the fertility of each bull was assessed in relation to the mean conception rate of the centre at which the bull was standing. Bulls were considered of ‘high’ fertility when their conception rates were above, and of ‘low’ fertility when their conception rates were below a dividing line 5% below the mean conception rate of the centre.

3. A highly significant relationship (P < 0·001) was found between the groups of the metabolic responses and the fertility levels of the bulls. The practical application of the test in the assessment of the potential fertility of individual bulls is discussed.

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 rate at which organic matter added to soils decomposes under temperate conditions seems to have been little studied. It depends, as Russell (1950) remarks, on the soil aeration, the calcium supply, and the temperature, and tends, in an arable soil, to an equilibrium value depending on the crop rotation practised for a given soil under given climatic conditions. And while this equilibrium value is lowest for a rotation containing a high proportion of wide-spaced intertilled crops or cultivated fallows, it increases with crops of small grains or grass. The results at Rothamsted, Broadbalk Field, as judged by the nitrogen content, show that this equilibrium value with no organic additions has remained almost constant from 1865 to 1945 and similarly, at a higher level, where 14 tons of farmyard manure are applied annually, has remained constant from 1914 to 1945.

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.

The results of over 400 field experiments testing different kinds of phosphate fertilizers are summarized and are discussed with special reference to the reactions of the soils used. The classifications were:‘very acid’ soils—pH below 5·5, ‘acid soils’— pH 5·6 to 6·5, neutral soils—pH over 6·5. All comparisons are made in terms of fertilizers supplying the same amounts of total phosphorus.

In war-time experiments Gafsa and Morocco rock phosphates were about two-thirds as efficient as superphosphate for swedes and turnips grown on very acid soils. In 1951–3 experiments on very acid and acid soils Gafsa phosphate was practically equivalent to superphosphate for swedes, but for potatoes it was as effective as only one-third as much phosphorus supplied as superphosphate; on neutral soils Gafsa phosphate was useless. For establishing grassland on acid soils Gafsa and Morocco phosphate were equivalent to about onethird as much phosphorus supplied as high-soluble basic slag. Rock phosphates were somewhat more effective for promoting growth of established grassland but they remained inferior to high-soluble basic slags and to superphosphate. Curacao rock phosphate was roughly equivalent to Gafsa phosphate for swedes and grass. Florida pebble phosphate was much less effective and was judged unsuitable for direct application. Mixtures of rock phosphate with superphosphate were not more efficient than equivalent amounts of the separate components used correctly.

Silicophosphate was practically as effective as superphosphate for swedes grown on very acid and acid soils; it was less efficient on neutral soils. For potatoes silicophosphate was nearly as effective as superphosphate on very acid soils; it was much less efficient on acid and neutral soils. Silicophosphate was roughly equivalent to high-soluble basic slag for grassland.

Mixtures of superphosphate with lime, serpentine, and low-grade basic slag were prepared, most of the water-soluble phosphorus being converted to insoluble forms. In experiments on swedes and potatoes these basic superphosphates were not superior to untreated superphosphate. For establishing grassland on very acid soils, the mixtures were slightly superior to ordinary superphosphate.

Dicalcium phosphate was practically equivalent to superphosphate for swedes on all groups of soils. For potatoes dicalcium phosphate was more efficient than superphosphate on very acid soils, on less acid and neutral soils it was inferior to superphosphate.

1. This paper reports a study of the behaviour of five strains of ryegrass (Devon Eaver, Irish S. 24 and New Zealand certified mother perennial ryegrass and H.I) under three different conditions of spacing and two types of management. Strain performances are compared on the basis of green and dry-weight data of total herbage, and green weight of sown strain contributions under the three techniques of evaluation.

2. Under both managements, the total annual production per unit area was greatest from broadcast and least from single-plant areas. Some individual cut yields were, however, greater than those from broadcast plots, with the drill-row production intermediate.

3. Yield differences between the four perennial ryegrasses were greatest as spaced plants and least in broadcast plots. Single plants and broadcast plots of H. 1 were outstanding compared with the perennial strains. Under neither management were there significant interactions between strains and sowing method in 1952, though such interactions were detected in both cases during 1953.

4. The relative yield performance of strains under similar spacing conditions were almost identical under both managements.