Journal of Agricultural Science, Vol. 50, No. 2

Plates 8 and 9 have been incorrectly placed.

Plate 8 should face page 151 and Plate 9 should face page 197.

An account is given of a field experiment in the control of ground water-level in a Fen peat soil, together with its results on the yields of crops in a six-course rotation.

The seasonal variations in rainfall are presented in terms of potential evaporation and soil moisture deficit. The effect of the water-level on the moistness of the soil above it is indicated. Even in a wet summer, drying was perceptible within 18–20 in. of the ground water-level between successive falls of rain.

The fluctuations of the ground water-levels are discussed. Those of the high water-levels were chiefly due to individual incidences of rain causing rises short in duration, but sufficient in the case of water-levels within 20 in. of the surface to cause total waterlogging and surface ponding. Those of the deep water-levels were most influenced by evaporation, with steady and persistent falls during any rain-free period.

The deterioration of the physical condition of the soil over high water-levels is shown in the result of sieving tests. In 6 years the loss of tilth over waterlevels within 20 in. of the surface was very marked and was discernible over those as low as 30 in.

The possibilities of effectively using high ground water-levels occasionally in soils in good condition are shown by the results with celery and potatoes.

The phosphorus effects of several nitrophosphates were compared with those of superphosphate and dicalcium phosphate in field experiments in 1954 and 1955. In both years immediate effects were measured on radishes, and in 1954 residual effects were measured on a crop of ryegrass which was cut twice.

None of the nitrophosphates tested were more than one-third as efficient as superphosphate for radishes. The residual effects of nitrophosphate (relative to superphosphate) for grass were much larger than their corresponding immediate effects on radish; several materials were as good as superphosphate for increasing the yields of the second cut of grass. The immediate effects of nitrophosphates were much increased by preparing finely ground powders from commercial granulated products.

In both years dicalcium phosphate was equivalent to superphosphate and gave significantly higher yields of radish than any of the granulated nitro-phosphates. At the second cutting of grass in the 1954 experiment there were no significant differences between yields given by dicalcium phosphate and the nitrophosphates.

The solubilities of the phosphorus of nitrophosphates in solutions of citric acid, neutral ammonium citrate, and alkaline ammonium citrate, were of little value in estimating immediate effects of granulated products. It is suggested that physical properties of the granules affect the rate at which phosphate ions can diffuse and so complicate the interpretation of solubility tests.

1. Analysis of spring mating data in 1955 indicated that the fall in conception rate associated with the use of older semen was a serious problem.

2. The fall in conception rate in 1955 was more marked in bulls of below average conception rate than in those with above average conception rate.

3. Results for groups used in two successive years indicate that this decline is highly repeatable.

4. Bulls which have ‘good keeping quality’ semen can be selected on the records of a previous season. Where there is no previous record, it has been shown that an individual can be classified as a ‘good keeper’ or a ‘poor keeper’ by measuring the fructolysis index of the semen on the day after collection. If the fructolysis index is above some minimum figure (1·05 mg. fructose/hr./109 sperm has been adopted in this case for second-day semen), the bull can be used for delayed inseminations with good prospects of success.

5. The best method of classification would appear to be: (i) initial classification by fructolysis index; (ii) subsequent rejection of bulls of low fertility in this group after fertility records are available.

Semen samples of five Dexter bulls were mixed and the effects of mixture on the live/dead ratio, the percentage of abnormal cells and on motility and survival of motility as measured by impedance change frequency were studied. Altogether fifty-six samples and mixtures were examined. No effect of mixture on live/dead ratio nor on percentage abnormals was found, but mixtures of semen had a motility which was slightly nearer the value of the less active component of the mixture than that of the means of both components. No explanation for this effect is offered.

Hoof, formalized hoof, formalized casein, leather wastes and dried blood were compared with ammonium sulphate for vegetables in several field experiments which were continued for a number of years. Residual effects were measured in one experiment at Rothamsted.

For crops which had a high requirement for nitrogen, hoof and formalized casein tended to give somewhat lower yields than equivalent ammonium sulphate. Organic nitrogen fertilizers tended to be slightly superior to ammonium sulphate for less responsive crops, and also in experiments where the high rate of ammonium gave lower yields than the medium rate.

Crushed hoof and a formalized casein product gave similar yields of most crops. There were no marked gains from treating hoof with formalin; a coarse (5·7 mm.) sample of formalized casein did not give materially different yields from the ordinary fine (2 mm.) product.

One leather product made by simple roasting was inferior to ammonium sulphate and to hoof. Other leather wastes processed by alkalis did not behave very differently from crushed hoof or from ammonium sulphate. Dried blood was tested in a few experiments, there were no significant differences between yields given by blood and by ammonium sulphate.

In experiments on a light soil, spring cabbages planted in autumn were very sensitive to the time of applying nitrogen fertilizer; there were much larger gains in yield from ammonium sulphate applied half at planting and half in spring, than from either ammonium sulphate or organic nitrogen fertilizers applied wholly at planting.

1. An experiment is described in which the effect of the level of nutrition, as determined by stocking rate and the use of supplementary concentrates, on milk yield and efficiency of production was studied.

2. Three levels of nutrition were used: Treatment (A)—one milking cow per acre plus 1 lb. of concentrate mixture for each 5 lb. of milk produced. Treatment (B)—one milking cow per acre—no concentrates. Treatment (C)—one milking cow per sixtenths of an acre—no concentrates.

3. Fifteen sets of identical twins were used per year over an experimental period of 3 years. The groups were rotationally grazed with a daily shift to a fresh pasture on a 14-day rotation. Ninety complete lactations were available for analyses.

4. The A cows produced 45% and the B cows 16% more f.c.m. than the C cows. Per unit area, however, the C treatment produced 30% more than the B.

5. Significant differences in milk composition were established, but these were of much smaller magnitude than those in milk yield.

The effect of short leys and arable cropping on the yields of the following arable crops has been tested since 1937 at Woburn Experimental Farm, Bedfordshire. The leys were a 3-year grazed ley and 3 years of lucerne cut for hay and the arable cropping was potatoes, winter cereal and either a 1-year ley or a third tillage crop. The effects of these crop sequences were measured by test crops of potatoes and barley, uniformly treated except that 15 tons farmyard manure was applied on one-half of each plot for potatoes.

Without farmyard manure, the yield of potatoes after the grazed ley was higher than after three tillage crops by an average of about 3 tons per acre; after lucerne it was about 2 tons per acre more than after the tillage crops and after the 1 -year ley under 1 ton per acre more. With farmyard manure the benefit from leys was less (about 2 tons per acre for both lucerne and the grazed ley). The average effect of the farmyard manure was about 2·8 tons except after the grazed ley, where the increase was only 1·6 tons per acre.

Effects of the previous cropping on the yield of barley were small in the early years of the experiment, but in the last 5 years the yield after ley and lucerne has exceeded that after the tillage crops by about 15%.

Part of the difference in potato yield between the ley and arable sequences can be attributed to the differential incidence of potato-root eelworm, which has reached a high level of infestation on some of the arable plots. Much of the remainder may be ascribed to the low level of basal manuring which has affected the yield of all plots, but particularly those under tillage crops. How far the observed differences can be explained by these considerations remains a matter for speculation, but may to some extent be clarified when further results are obtained from a revised scheme of cropping and manuring.

A conservation experiment is described in which a comparison of the nutrient losses and quality of sodium metabisulphite silage and molassed silage is made. The loss of dry matter in molassed silage is shown to be 3·5% higher than in metabisulphite silage.

The lactic-acid content of metabisulphite silage is found to be some 40% less than that of molassed silage.

The results obtained are discussed in relation to published work on conservation by metabisulphite and to the practical application of the method.

1. Ten experiments on spring barley (mainly Proctor) and four on spring wheat (mainly Atle) in 1954–6 compared 0·25 and 0·5 cwt. N/acre (as ammonium sulphate) when drilled with the seed, with dressings broadcast before sowing. Tests were also made of ‘Nitro-Chalk’ dressings given in mid-May. In heavier split applications seedbed dressings were supplemented by top-dressings of 0·5 cwt. N/acre.

2. Barley gave much larger average responses than wheat. For barley combine-drilling 0·25 or 0·5 cwt. N/acre gave consistently larger yields than broadcasting the same nitrogen dressing on the seedbed; for wheat combine-drilling gave slightly higher yields at the high rate of dressing only.

3. For both crops 0·5 cwt./acre of N drilled with the seed was almost sufficient for maximum yields, but where only 0·25 cwt. N was applied at sowing a mid-May top-dressing of 0·5 cwt. N/acre gave higher yields.

4. At most centres May top-dressings of ‘Nitro-Chalk’ gave lower yields than equivalent ammonium sulphate drilled with the seed. Yields were often reduced by lodging on plots which received seedbed dressings plus top-dressing or the heavier rates of top-dressing alone; these treatments also reduced the quality of the grain. Combine-drilled or broadcast seedbed dressings did not cause serious lodging or reduce grain quality.

5. 0·25 or 0·5 cwt. N/acre broadcast on the seedbed or combine-drilled had little effect on the percentage of nitrogen in the grain; equivalent topdressings in mid-May consistently increased nitrogen content. Seedbed dressings plus top-dressings supplying heavier total quantities of nitrogen continued to increase nitrogen percentage in grain without giving any increase in yield.

The ovaries from 251 cattle with known histories were dissected, and this work was linked with clinical and histopathological studies. In almost 20% of the cattle, resorption of corpora albicantia appeared to have taken place, beginning usually, after the fourth pregnancy. In 10% of cattle more corpora albicantia were found than corresponded with the normal pregnancies. Most such cases appeared to be associated with unrecognized ‘temporary pregnancies’, but normal pregnancy associated with two corpora lutea, as in the camel, may occur, though rarely. A scheme with correction factors, for allocating random samples to age categories, has been prepared. In 110 cattle, or 44%, miniature as well as full-sized corpora albicantia were recovered. Evidence from their histories is brought forward that the miniature corpora correspond to ‘temporary pregnancies’ of perhaps 2–5 months duration. This is cross-checked and confirmed, both from the histories of 112 cows yielding no miniature corpora, and also by correlation with the histopathological findings from the genitalia.

In many animal production experiments, carcass weight is used as the sole criterion for the effectiveness of the treatments and of the nutritional status of the animals involved. In these experiments some knowledge of the carcass components would be desirable in order to assess any effects on the various tissues. Determination of these components has hitherto been costly and time consuming. Accordingly, these disadvantages have lead to a search for simple indices of carcass composition which can be readily applied even in relatively large-scale experiments. Until recently, however, no research worker has specified a relationship between carcass weight and carcass composition which would justify the use of carcass weight alone. There are, of course, many indications which suggest that such a relationship would exist, at least, for the main tissues of the carcass.

Though there has been a considerable amount of recent research on the early weaning of calves, few scientific papers have been published. Preliminary studies at the Rowett Institute have indicated that early weaned calves show greater thriftiness and increased liveweight gains when small quantities of antibiotics are included in the diet (Preston, 1955). Pilot trials carried out at Cockle Park in 1955/6 suggested that there is little difference between the performance of abruptly and gradually weaned calves (Quayle, 1956a). This present study has been carried out to verify these observations, and includes some comments on nutritional scouring.

1. Good quality cod-liver oil, produced by modern methods and containing anti-oxidants, is a highly satisfactory ingredient of the diet of young chicks whether fed fresh or stored as an ingredient of mixed mash for from 2½ to 3½ months before use at the recommended rate of 1 pint/cwt.

2. Chicks so fed had slightly better food conversion ratios and a better appearance, and slightly lower liver vitamin A levels, than those birds receiving a comparable amount of vitamin A in powdered form.

3. Chicks so fed had better food conversion ratios and appearance, a higher liveweight gain, and slightly higher liver vitamin A reserves than those receiving a powdered vitamin preparation at the recommended rate of use of 0·05 lb./cwt.

4. It may be concluded that both this form of codliver oil and the powdered preparation are reliable sources of vitamin A as such.

5. Chicks hatched in early December grew better and maintained their vitamin A reserves for longer than comparable chicks hatched in early March.

1. Fresh, good quality cod-liver oil, containing an antioxidant, was incorporated at varying levels of up to 5% in the rations of pigs throughout the whole period from weaning (at 56 days) to bacon weight (at 196 days), without any evidence of detrimental effect.

2. Cod-liver oil did not at any level produce discoloration of the body fat, fishiness or other taint, or any other adverse effect upon carcass quality as judged subjectively and by routine measurements. Increasing levels of cod-liver oil increased the iodine number of the body fat, but this was not accompanied by any visual softening.

3. Although the experiment was not designed to assess the effect of high levels of cod-liver oil upon productive efficiency, it was, nevertheless, found that improvement in food conversion accompanied increases in the amount of cod-liver oil fed.