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.

1. This investigation into double scaup in hill sheep took the form of a series of field experiments combined with the gathering of incidental information.

The field experiments were designed to test the currently held view that double scaup is a ‘disease’ caused by mineral deficiencies (probably phosphorus) complicated by parasite infestation, which can be cured by the offering of, or treatment with, mineral mixtures combined with the use of anthelminthics.

2. The experiments involved the use of a proprietary mineral mixture containing feeding bone flour, lime salt and trace elements, freely offered in troughs. Phenothiazine, dicalcium phosphate and trace elements administered orally were also used. Vitamin D2 (calciferol) was introduced into the investigation following a suggestion by Innes (1934) that double scaup may be a form of rickets.

3. Statistical analysis of the weight records obtained from these experiments revealed no beneficial effect on weight gains from any of the treatments given. Field examination indicated that the treatments also had no effect upon the incidence of detectable double scaup in each of the flocks studied.

4. It was found that double scaup is not a condition affecting only poorer hill farms in the north of England and in southern Scotland, but is in fact an indication of the generalized thinning of the skeleton of vast numbers of young and apparently healthy sheep in these areas.

1. Data from twenty-four short-term trials on the nutrition of dairy heifers have been used in a study of the effects of management, method of estimation of live-weight gain, length of experimental period, covariance analysis and the use of monozygous twins upon experimental error.

2. The value of rigid adherence to a routine and allowing ample time for the animals to settle down before the trial have been demonstrated.

3. Error standard deviations were associated with length of experimental period, those for 42-day periods being about half those per 21-day periods, but were not appreciably correlated with initial live weight.

4. No advantage could be demonstrated for the use of monozygous twins, or covariance analysis with initial weight or rate of gain, indicating that genetic effects contributed little to the error in experiments lasting 3–6 weeks.

5. There was no significant difference between errors in live-weight gains calculated from the regression of live weight on time, from single initial and final weights, or from two initial and final live weights, indicating that deviations from linear regression are not solely in the nature of random day to day fluctuations in live weight.

The effects of air temperature (30–70° F.) and live weight upon the water consumption of dairy heifers from 350 to 550 lb. live weight have been studied together with the amount drunk in different periods of the day. The water consumption increased by 0·03–0·06 gal./° F. rise in temperature and by 0·0075 gal./lb. increase in live weight. Most of the water consumption occurred during meals.

1. Over four breeding seasons (1952–6) field trials, involving a total of 2504 treated and control ewes of nine breeds (Romney, Clun, Suffolk, Cheviot, Lincoln, Welsh Mountain, Ryeland, Southdown and Hampshire) were conducted in an attempt to increase flock fertility by injections of p.m.s. hormone. The hormone employed was in three forms of preparation: purified, freeze-dried and whole serum. Dosage levels from 250 to 1000 i.u. were injected subcutaneously.

2. There is no evidence that the treatment affected the ability of the ewe to conceive.

3. A significant increase in fertility was induced by treatment. The extent of the increase apparently depended on the dosage level and form of p.m.s. employed, and was found to be affected by the normal fertility status of the sheep undergoing treatment. At any given dosage level of p.m.s. the increases induced by treatment were greatest where flock fertility was very low.

4. When used at comparable dosage levels, whole serum tended to be more effective in inducing superfertility than freeze-dried or purified serum. Freezedried serum tended to be more effective than purified serum.

5. 1047 injected sheep that conceived to service at the treatment oestrus produced 1898 lambs (1·81 lambs per ewe); 997 control ewes that conceived at the same time produced 1506 (1·51 lambs per ewe).

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 effect of selection of dairy bulls on their daughters' 1st lactation yields has been investigated, using contemporary comparison information availreable for some 1273 bulls. It was shown that incomplete repeatability of individual records would introduce a negative bias into the regression of the increase in production of a bull's daughters with age on his contemporary comparison and this bias was calculated. The observed regressions on 1st lactation contemporary comparison were close to zero after correction for bias both for increase from 1st lactation yield to 2nd (— 0·08) and for the increase from 2nd lactation to 3rd (+ 0·09). Selection on 1st lactation yield should not, therefore, change the increase of yield with age, in agreement with results of other workers. The results are related to the problem of the heritability of the separate lactations.

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.

Section 1

1. A total of 189 ewes, of various breeds and crosses were used in slaughter experiments conducted in anoestrum during 1953–6. The ewes were of mixed ages, and included four lambs, aged 52–71 days.

2. Ewes received P.M.S. in different combinations with progesterone to induce co-incident oestrus and ovulation. Progesterone was employed in three forms, as a solution in oil, as a micro-crystalline suspension and as fused pellet implants. One hundred ewes were injected with the oil solutions, eighty-five with the suspensions and four received the pellet form of the hormone.

3. The percentage of ewes that came in oestrus (oestrous response) was higher in those treated for a 5-day period than in those treated for a 3-day period with progesterone in oil P.M.S. being administered 2 days after the final progesterone injection. The oestrous response in ewes receiving progesterone over a 13-day period was no higher than in those treated over 5 days.

4. 172 ewes' tracts were examined for ovulations. In those sheep (excluding the four young lambs) which came in oestrus, all had ovulated. Ovulation was apparently inhibited in some ewes which received progesterone in suspension form. The ovulation rate following treatment with 700 i.u. whole serum P.M.S. was higher than that where 750 i.u. purified serum was employed.

5. Forty-one of the ewes which came in oestrus were slaughtered 41–120 hr. after estimated onset of oestrus. Seventy-six of the ninety-two ova shed by these animals were recovered. 81·3% of recovered ova were cleaved. Of thirty-four ewes slaughtered 61–120 hr. after oestrus, thirty-two (94·1%) yielded one or more apparently normal fertilized ova. There was no evidence that fertility in the Suffolk rams employed in matings decreased to the point where it might affect conception in out-of-season breeding.

1. In the 1954–5 and 1955–6 breeding seasons, 117 ewes of the Border Leicester, Welsh Mountain and Suffolk breeds were used in order to investigate the effects of PMS treatments on (a) the length of the dioestrous cycle, (b) the number of ovulations per ewe, (c) the proportion of eggs which were cleaved, uncleaved or abnormal when recovered, and (d) the ability of fertilized superovulated eggs to develop normally.

2. In the 1954 and 1955 anoestrous periods, ninety-four 2-tooth and mature ewes of mixed breeds were used in order to investigate (a) the proportion of ewes which could be induced to ovulate and exhibit oestrus as a result of treatment with progesterone and PMS, (b) the proportion of the mated ewes which had cleaved, uncleaved or abnormal eggs, and (c) the ability of fertilized eggs shed during anoestrum to develop normally up to the 21st day of pregnancy.

3. Dioestrous cycles in untreated ewes were significantly shorter for Welsh Mountain than for Border Leicester ewes, and their length was not affected by the year in which they were measured. The first and second cycles of the breeding season tended to be shorter than the third cycle.

4. The length of the dioestrous cycle was shortened by treatment of both Border Leicester and Welsh Mountain ewes with PMS. The average extent of this reduction was 0·6 days, and the effect was significant.

1. Fifty-five kids of the East African dwarf goat were used in the experiment. The kidding percentage was 107·8%, and the twinning percentage 12·7%; the proportion of twin births increased in the latter stages of the experiment, related to the longer period the late-kidding dams had spent on the rising plane of nutrition.

2. The percentage of female kids to total kids born was 56·4%, male kids 43·6%. The mean birth weight of female kids was 4·5 lb., compared to 5·2 lb. for male kids.

3. The sex difference in live-weight increase increased markedly after 16 weeks of age. The growth of females slowed down to approximately ½ lb. per head per week, whereas that of males continued to increase at the rate of approximately 1 lb. per head per week. H-plane female kids reached 33 lb. at 31 weeks, H-plane males achieved the same weight at 20 weeks of age.

4. The effect of plane of nutrition on the live weights of experimental kids of both sexes was statistically significant as from the third week of age. H-plane kids reached 33 lb. live weight at approximately 26 weeks of age, L-plane kids at about 48 weeks.

5. The kids initially placed on a L-plane of nutrition exhibited a marked resilience when switched to the H-plane. The live-weight gains after switching were for females as great as, and for males greater than, the gains made by kids on a H-plane of nutrition throughout the growing period.

This recuperative capacity of animals changed from L to H levels of diet, at or before the point of inflexion of the growth curve, has now been clearly established for all types of farm livestock examined, the pig, the sheep, the chicken and the goat. Both sexes exhibited this capacity to recover from initial low-plane feeding.

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.

1. A detailed analysis was made of the rumination behaviour of one caged sheep on four combinations of diet, ranging from 100% hay to 100% concentrate meal.

2. When hay was fed there was no relationship between the quantity of it ingested and the amount of rumination, which averaged 8 hr. daily. When concentrates were fed alone rumination time fell to 2½ hr. per day and much of this was ‘pseudorumination’.

3. Evidence is produced to show that the number of chews and not the time chewing is the accurate way of measuring rumination quantitatively. This particular sheep made an average of 39,000 rumination chews per day when hay was fed.

4. The duration of the intervals between boli was constant at 15% of total rumination time, but the rate of chewing varied from 83–99 chews per minute, being slower during the midnight to noon half of the 24 hr., when most rumination occurred.

5. Rumination periods last from under 1 min. up to about 2 hr.

6. Tiring during a rumination period was reflected by an increase in the intervals between boli but the number of chews per bolus remained unchanged.

7. The first bolus of each period of rumination was chewed less than those following. This sheep averaged fifteen periods of rumination per day, a daily total of 500 boli were regurgitated. There were 2500 chews per period and seventy-eight chews per bolus.

1. Two series of observations are described on the habits of grade and zebu steers in an environment where maximum daily temperatures did not exceed 74° F.

2. No signs of heat stress were found in either group and the steers used were able to adopt a reasonable pattern of behaviour and graze throughout the day like cattle in other temperate regions.

3. Under wet conditions the zebus reacted to the cold much more than did the grades and did so by standing instead of Iying down.

4. There were considerable differences in the amounts of water drunk and it is suggested that these differences may result from the steers' efforts to maintain a homothermic state.

A series of seven experiments were carried out between May and September 1954 at the Grassland Research Institute as part of a co-operative study of bloat, which the Agricultural Research Council had helped to organize.

Hereford colour-marked steers were grazed or fed on legume-dominant herbage in an endeavour to produce pasture bloat. Observations were made to determine patterns of animal behaviour and bloat incidence. Heart rates were determined both before and during the experiments and jugular blood samples were taken for determination of cholin-esterase levels. Herbage samples were analysed botanically in order to determine the type of material eaten, and chemically for nitrogen content. Other herbage samples were placed in cold storage.

In the seven experiments (375 cattle feeding or grazing days) only twenty-seven cases of mild bloat and five cases of moderate bloat were recorded. This is surprising, because pains had been taken to provide feed that would by all normal standards be regarded as likely to induce bloat in cattle.

1. The results of an experiment to study the effect of continuous application of ammonium sulphate, with and without f.y.m. in an alluvium clay soil for a period of 10 years on the yield of paddy and soil, have been reviewed.

2. The grain yield was increased significantly by ammonium sulphate in all the years except in the last two. The increases in straw yield were significant in all years.

On consolidating the results, it was found that both the grain and straw yields were significantly increased by the effect of ammonium sulphate. The grain yield was not increased by the effect of f.y.m., but the straw yield was increased by this significantly at 5% level.

3. The straw:grain ratio increased with the increasing doses of nitrogen.

4. The maximum grain yield was obtained by the combination of ammonium sulphate at the rate of 30 lb. N plus f.y.m. at 100 md. per acre. This combination was significantly better than f.y.m. alone, but was not significantly better than ammonium sulphate at 30 lb. N. On economical consideration at the prevailing market price level, the dose 30 lb. N of ammonium sulphate applied alone is the most suitable.

5. No deleterious effect on the yield of paddy or change in the composition, hardness and percentage aggregation in soil have been observed after a 10-year period of continuous application of ammonium sulphate in the same paddy soil.

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. Field trials with gibberellic acid on grass, wheat, potatoes, turnips, carrots, peas, runner beans, lettuce, celery, blackcurrants, kale and maize are described. The effects on plant growth and crop yield were determined.

2. The experiments on grassland were carried out between July 1953 and June 1956, and included trials at four different centres. They all gave essentially similar results.

3. 2 oz. per acre of gibberellic acid sprayed at 100 gal. per acre stimulated the growth of all components of the swards. The stimulation was most clearly seen in spring and autumn when the natural growth rate was slow. At these times gibberellic acid was able to produce a grazeable growth of grass more rapidly than nitrogenous fertilizers. The stimulation of growth was accompanied by yellowing of the grass, but recovery to a normal green colour was speeded up by applying a nitrogenous fertilizer at the same time as the gibberellic acid spray.

4. The dry-matter yields at the first cut following a treatment with gibberellic acid were increased by 0·6–10·8 cwt. per acre. The crude protein yields were also increased by the treatment, but to a relatively smaller degree, and the protein content of the grass was reduced by between ½ and 2%. The contents of phosphorus, potassium, sodium, calcium, barium, magnesium, manganese, copper, aluminium and tin were not altered.

In both ruminant and non-ruminant digestion, the nutritive ratio of a feed is shown to be very significantly related to the crude-protein content of that feed.

This confirms that there is a relationship between the total crude protein and digestible protein in a ruminant feed, and strongly suggests that there should also be a relationship between these two components in non-ruminant feeds.