scispace - formally typeset
Search or ask a question

Showing papers in "The Journal of Agricultural Science in 1968"


Journal ArticleDOI
TL;DR: In spite of the entomophilic structure of the rape flower, which is very attractive to nectar- and pollen-gathering bees, the crop gives good yields without insect pollination.
Abstract: In spite of the entomophilic structure of the rape flower, which is very attractive to nectar- and pollen-gathering bees, the crop gives good yields without insect pollination.

76 citations


Journal ArticleDOI
TL;DR: The Woburn Market-Garden experiment was started in 1942 to investigate the development of a market-garden type soil from an ordinary agricultural soil on light land by applying organic manures regularly as discussed by the authors.
Abstract: The Woburn Market-Garden experiment was started in 1942 to investigate the development of a market-garden type soil from an ordinary agricultural soil on light land by applying organic manures regularly. The ‘organics’ used were farmyard manure, sewage sludge, and composts of these with straw and farm waste. The use of sewage sludge was discontinued in 1961 and the yields of the crops up till then were published by Mann & Patterson (1963).

68 citations


Journal ArticleDOI
J. M. Forbes1
TL;DR: The volume of the uterus increased steadily as pregnancy progressed, but rumen volume was not reciprocally depressed until the last 5 weeks of pregnancy, which was a particularly important factor in the depression of rumen capacity in pregnancy.
Abstract: SUMMARY Five non-pregnant ewes and seventeen ewes at various stages of pregnancy were fed on a medium quality hay for several weeks before being slaughtered and frozen. Each ewe was sawn into 5 cm cross-sections. The sections were photographed. The uterus was extracted from the sections and its volume measured. Volumes of reticulo-rumen contents, intestinal contents and abdominal fat were estimated from the photographs. Models of the uterus and rumen were constructed and examples of these and of the photographs are shown. The volume of the uterus increased steadily as pregnancy progressed, but rumen volume was not reciprocally depressed until the last 5 weeks of pregnancy. Volume of digesta was inversely related to volume of incompressible abdominal content (uterus and fat). Abdominal fat was a particularly important factor in the depression of rumen capacity in pregnancy when there was great competition for space in the abdomen.

59 citations


Journal ArticleDOI
TL;DR: In this article, both field and pot experiments were carried out to determine how copper deficiency can be corrected on some soils in north-east Scotland. And the results showed that such treatments have large residual effects and under field conditions are effective for at least 8 years.
Abstract: Field and pot experiments were carried out to determine how copper deficiency can be corrected on some soils in north-east Scotland. Spring-sown oats and barley are more susceptible to this deficiency than mixed herbage, while potatoes and swedes have not responded to Cu. The deficiency can be corrected by applying 10–20 lb CuSO4.5H2O per acre to the soil. Both field and pot experiments show that such treatments have large residual effects and under field conditions are effective for at least 8 years. A foliar spray supplying 1 lb CuSO4. 5H2O per acre is usually less effective than a soil dressing.Using soil undiluted with sand, the increase in grain yield produced by Cu treatment in pots was appreciably greater than in the field. The Cu content of mature oats and barley was practically unaffected by soil dressings but foliar spraying produced a considerable increase.Significant correlation coefficients have been obtained between soil Cu, extracted by 0·05 M EDTA, and the increase in grain yield produced by Cu applications in both field and pot experiments. In field experiments in north-east Scotland, cereal yields were not restricted by a deficiency if the EDTA-extractable Cu was above 1·1 ppm. With soil contents below 0–75 ppm Cu, the grain yields from spring-sown oats and barley were usually increased considerably; small responses were possible with contents between 0·75 and 1·1 ppm.

44 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of time of application of nitrogen and potassium on the growth, development and yield of the second early variety Craig's Royal was studied by the technique of growth analysis.
Abstract: The effect of time of application of nitrogen and potassium on the growth, development and yield of the second early variety Craig's Royal was studied by the technique of growth analysis. There was an indication that witholding nutrients led to the earlier initiation of tubers, but this was of no practical consequence and all treatments affected tuber bulking rate rather than the duration of bulking. Compared with early application, late application of nitrogen depressed tuber yield, although total drymatter yield was not affected. Late application of potassium, however, increased tuber yield; this was associated with an improvement in the recovery of applied potassium. Delaying the application of nitrogen also resulted in its more efficient recovery in the crop. Late application of potassium improved the recovery of early applied nitrogen and vice versa. Reasons are put forward to account for these effects.

41 citations


Journal ArticleDOI
TL;DR: The data suggest that though these ewes drew on body reserves for milk production, this process could not sustain milk yields, and the data suggest this difference was due to a reduced intake of milk by the lambs suckling the eWes in group I during the weaning process.
Abstract: Data collected from mid-pregnancy until the 5th week of lactation were used to select three nearly uniform groups each of nine ewes suckling single lambs. After 4 weeks of lactation, experimental treatments were applied to these selected groups as follows: Group I. Both ewes and lambs fed ad lib. throughout. Group II. Ewes fed ad lib. throughout. Lambs offered one-third the quantity of solid food being consumed by group I lambs. Group III. Food intake of ewes restricted to 9·2 g D.o.M./kg, based on their mid-pregnancy live weights. Lambs fed ad lib. throughout. The effects of these treatments were assessed in terms of milk production, food intakes and live-weight changes of ewes, and the solid food intake and growth rates of lambs. Mean total milk production of ewes of groups I and II remained similar until the 8th lactation week, but during the 8–12 week period milk production of the ewes in group II was 6·17 kg greater than that of ewes in group I. The data suggest this difference was due to a reduced intake of milk by the lambs suckling the ewes in group I during the weaning process. From week 4 the milk yield of group III ewes declined rapidly and though these ewes drew on body reserves for milk production, this process could not sustain milk yields. The average daily live-weight gains of lambs of groups I and III were both significantly greater than that of group II, and the gain of group I lambs was significantly greater than that of group III. All groups of ewes made similar live-weight gains during early lactation and after 4 weeks each group had attained a mean value of about 60 kg. Groups I and II continued to gain weight and during week 12 their respective mean weights were 67 and 65 kg. This difference was not statistically significant. The mean live weight of group III ewes declined rapidly after week 4, reaching a minimum value of 41·5 kg. The mean daily intake of dry matter by ewes of all groups reached a maximum value of about 2·9 kg/ewe in lactation week 3 and declined to about 2·6 kg in week 4. Intakes by ewes in groups I and II were almost identical throughout. During the period of restricted feeding the mean daily intake of group III ewes was 0·58 kg dry matter/ewe. During week 5 the mean daily intakes of solid food dry matter by lambs of groups I, II and III were 44, 32 and 158 g respectively. These increased to 1230, 418 and 1537 g respectively during week 12.

39 citations


Journal ArticleDOI
TL;DR: In this paper, the cumulative K-yield of ryegrass was very significantly related to the K-intensity of the uncropped soil; the ‘16-week’ yield was slightly better related than the '60-week' yield.
Abstract: Summary Thirty-four soils from the Rothamsted Experiments were exhaustively cropped with ryegrass in the glasshouse. The concentration and yield of potassium in ryegrass tops and the potassium intensity in the soil were measured every 4 weeks, after harvesting the grass. The change in K-intensity of soils, rich in potassium, with exhaustion differed from that of ‘poor’ soils. This change was related to the rate of change of the cumulative K-yield. The rate of change of soil K-intensity demarcated periods of intense and limited exhaustion and partial recovery of the soil during cropping. The cumulative K-yield of ryegrass was very significantly related to the K-intensity of the uncropped soil; the ‘16-week’ yield was slightly better related than the ‘60-week’ yield. For Park Grass soils, the relationship was improved by allowing for variations in soil pH. The K-intensity of all soils, with or without manuring, decreased to nearly 10-3 (M)½ in (AR)0 units after 16 weeks cropping, although large differences in K-yield persisted until much later. K-buffer capacity per unit clay content of the soil, measured by a laboratory method, was inversely related to the K-intensity of the uncropped soil. The K-buffer capacities of soils rich in potassium, measured in laboratory and glasshouse experiments, were significantly related, but were unrelated for ‘poor’ soils. The K-buffer capacity (laboratory method) of Rothamsted soils with different manurial treatments was only very approximately related to the cumulative K-yield. Less K was taken up from all Rothamsted soils given nitrogen fertilizer in the field and their K intensities were also smaller than the corresponding soils without ‘N’. Field liming of acid soils decreased their K-intensity and increased their K-buffer capacity, presumably because more potassium was removed by the field crop. A rapid method is suggested for measuring potassium intensities of soils.

38 citations


Journal ArticleDOI
TL;DR: Culture studies were conducted with eggs recovered from cattle following super-ovulation treatment, finding that transfer of eggs to pseudo-pregnant rabbits led to continued cleavage in 71 of 138 attempts and culture of eggs in vitro met with limited success.
Abstract: Culture studies were conducted with eggs recovered from cattle following super-ovulation treatment. Transfer of eggs to pseudo-pregnant rabbits led to continued cleavage in 71 of 138 attempts. Culture of eggs in vitro met with limited success in 58 of 189 attempts. The maximum cleavage stage reached in the in vivo studies was 64 cells; in the in vitro work it was 24 cells.

36 citations


Journal ArticleDOI
TL;DR: There were no consistent effects on the numbers of pigs born apart from the first litter in which L(e) sows produced significantly larger litters at birth, and the higher energy intakes in pregnancy and lactation led to very similar increases in the weights of the piglets.
Abstract: SUMMARY Fifty-two Large White gilts, arranged in thirteen groups of four litter sisters, were allocated at mating to one of four treatment groups. These treatments, arranged as a 2 × 2 factorial, allowed daily energy intakes in pregnancy of 8·3 Meal (H(e)) or 5·2 Meal (L(e)) and of average daily intake during lactation of 20 Meal (h(e)) or 13·8 Meal (m(e)). Daily intakes of protein, minerals and vitamins were similar for all treatments. There were no consistent differences in health or breeding regularity between the treatments. The H(e) sows had a net gain in pregnancy 22 kg greater than the L(e) sows. Feeding the higher level in lactation (h(e) resulted in a reduced sow weight loss during lactation of 20, 12 and 10 kg in the first, second and third parities respectively, as compared with the m(e) sows. There were no consistent effects on the numbers of pigs born apart from the first litter in which L(e) sows produced significantly larger litters at birth. The higher energy intakes in pregnancy and lactation led to very similar increases in the weights of the piglets, of the order of 0.1 kg at birth, 0.4 kg at 3 weeks of age, and 1.1 kg at 8 weeks of age. Sowsgiven the same overall energy intake throughout their reproductive life (H(e) m(e), L(e) h(e)) at the end of the third litter had similar live weights and had produced a similar total weight of weaned pigs. The practical implications of these results are discussed.

33 citations


Journal ArticleDOI
TL;DR: The intake of long roughage, particularly straw, by the cow, when offered in conjunction with a separate supply of the concentrate mix, was very low and led to serious falls in milk butterfat content, apart from the depressed butterfat levels on the two long Roughage treatments the health and condition of the cows remained good.
Abstract: Twelve Friesian heifers were given four dietary treatments from 2 months before first calving to the end of the first lactation. Two of the treatments involved the ad libitum feeding of a complete diet consisting of a basal concentrate meal of rolled barley with supplements, incorporated into a mixture with either hay or barley straw both coarsely ground and included at a level of 25 % of the complete mix. In the other two treatments either the hay or the straw was given ad libitum in the long form and the concentrate mix fed ad libitum from a separate self-feeder.Full records were kept of the intake of food and water, the output and quality of the milk and of live weight. Detailed measurements were made of various aspects of rumen function using one cow on each treatment fitted with a cannula. Rumen samples were also obtained from non-fistulated cows by stomach tube.The intake of long roughage, particularly straw, by the cow, when offered in conjunction with a separate supply of the concentrate mix, was very low and led to serious falls in milk butterfat content. Where the roughage was incorporated into the complete diet normal butterfat levels were maintained. However, apart from the depressed butterfat levels on the two long roughage treatments the health and condition of the cows remained good.The very low intake of long straw was associated with a smaller volume of liquid in the rumen, a reduced rate of flow of liquid leaving the rumen, a lower proportion of acetic and butyric acids and a greater proportion of propionic acid in the rumen liquor and finally with a higher blood glucose content. The inclusion of milled roughage resulted in values within the normal range for volume of liquid in the rumen, flow rate of liquid from the rumen, V.F.A. proportions in the rumen liquor and blood glucose.The intake of both food and water over the productive cycle showed a consistent pattern for all cows. Food intake reached its lowest point around calving followed by a sharp rise to a peak in the 4th month after calving and then a gradual but increasing decline. Water intake followed a similar pattern but the fluctuation was greater and the peak consumption occurred in the 3rd month of lactation. Water intake was more closely associated with D.M. intake than with milk output.The efficiency of utilization of the complete diets containing the milled roughages is discussed in relation to comparable data from cattle fed conventionally.

32 citations


Journal ArticleDOI
TL;DR: Evidence on cleavage stages attained, and on the location of eggs in the Fallopian tubes and uterus, suggests that a majority of eggs were capable of normal development.
Abstract: SUMMARY Eighty-nine cattle were treated to induce high superovulation with 3000 i.u. PMSG on day 16 of the cycle and slaughtered shortly after breeding and injection of 2000 i.u. HCG. In the 79 cattle that came in oestrus, the mean number of ovulations was 9.0. The percentage of follicles ovulating and the mean ovulation rate increased markedly as the interval between PMSG and oestrus increased from 2 to 5 days. Seventy-one percent of eggs shed were recovered; 68% of eggs recovered were cleaved. Evidence on cleavage stages attained, and on the location of eggs in the Fallopian tubes and uterus, suggests that a majority of eggs were capable of normal development.

Journal ArticleDOI
TL;DR: Yield and growth analysis has been applied to the results of an experiment comparing early and late sown peas and it is suggested that the relationship between leaf area and pod growth rate is complicated by the existence of other sources of materials for pod growth such as stored products in the roots and stems, and photosynthesis by the fruit itself.
Abstract: Yield and growth analysis have been applied to the results of an experiment comparing early and late sown peas. Yield analysis showed that in this experiment late sown peas had: (i) fewer podding nodes per main stem, (ii) fewer pods per podding node, and (iii) a slower rate of increase in pod weight. The physiological origins of these differences are discussed. The first component is determined by the stage at which node production is terminated by the death of the apical bud. The second is determined by morphogenetic factors at the apical meristem early in in the life of the plant, when (in the variety DSP) either a single or a double flowered raceme is initiated, and also during the harvesting period when some pods are lost from the lower-most flowering nodes. The differences in the third component, the rate of increase in pod weight, could not be explained by conventional growth analysis. Pod growth rate was not a simple function of leaf area index. It is suggested that the relationship between leaf area and pod growth rate is complicated by the existence of other sources of materials for pod growth such as stored products in the roots and stems, and photosynthesis by the fruit itself.

Journal ArticleDOI
TL;DR: The evidence indicates that ewes in lean body condition have a higher efficiency of food conversion to milk and that in situations of continuous undernourishment a high state of body condition is undesirable during lactation.
Abstract: SUMMARY Approximately 15 weeks before parturition, forty-eight pregnant Blackface ewes were divided into three similar groups. During the 15–6 weeks prepartum period the ewes were fed to increase the live weights and body condition scores of ewes in each of groups A and B and to decrease those of ewes in group C. At 6 weeks prepartum mean differences of approximately 11 kg live weight and two grades of body condition had been created. Food was rationed to the ewes in all groups per kg live weight based on their weights 6 weeks prepartum, to provide the theoretical requirements of Blackface ewes bearing twin lambs. All groups of ewes made similar live-weight gains in late pregnancy and the mean birth weights of the lambs were also similar. Blood plasma F.F.A. values confirmed that the ewes were similarly nourished in late pregnancy regardless of live weight or body condition. During lactation the ewes were fed 9·2 g D.O.M./kg based on their immediate post-partum live weights, plus an allowance for a predicted level of milk production. Ewes in groups A and C were fed 0·5 and ewes in group B, 0·25 g D.O.M. per g of predicted milk production. The ration was increased after the 1st and 2nd weeks of lactation, then maintained at a constant level for the remainder of lactation. Milk production of the ewes was measured using a lamb suckling technique during a 10-week lactation. The mean daily milk production of ewes in groups A and C were similar and the yield of each of these groups was substantially greater than that of group B ewes. The mean total milk production of ewes suckling twin lambs in groups A, B and C was 127, 108 and 142 kg respectively, and of ewes suckling single lambs 104, 81 and 91 kg respectively. The mean live-weight changes of ewes in groups A and C were similar during lactation. Except for group A ewes suckling single lambs, which maintained their mean live weight, all ewes lost weight in early lactation and consistent gains were not made until late lactation. Greatest live-weight loss occurred in group B ewes and extended further into lactation. Changes in body condition followed a similar course to live weight changes. The mean daily live-weight gain of twin lambs in groups A, B and C was 279, 275 and 284 g respectively, and of single lambs, 318, 300 and 319 g respectively. The evidence indicates that ewes in lean body condition have a higher efficiency of food conversion to milk and that in situations of continuous undernourishment a high state of body condition is undesirable during lactation.

Journal ArticleDOI
TL;DR: The strains confirmed the usually accepted levels of oil and of the principal mineral components, except that modern beans appear to be richer in phosphorus.
Abstract: Studies were made of the proximate and mineral compositions of modern strains of both spring· and winter-sown beans. The majority of the winter beans were of the Throws M.S. variety, of the spring beans Minors. On the dry-matter basis spring beans averaged 31·4% crude.protein, winter beans 26·5%—a highly significant difference. The true protein values showed a parallel trend. Winter beans averaged 9% crude fibre, spring beans 8%, again a highly significant difference. The strains confirmed the usually accepted levels of oil and of the principal mineral components, except that modern beans appear to be richer in phosphorus.

Journal ArticleDOI
TL;DR: Competition had differential effects upon the plant weight/ tillering relationship and it is possible that the resultant morphological changes would influence the re-growth quality of the species.
Abstract: SUMMARY Timothy [S. 50], meadow fescue [S. 53], perennial ryegrass [S. 23], Italian ryegrass [S. 22] and cocksfoot [S. 143] were grown together in all possible pair combinations at two levels of fertility, in a pot experiment. Dry weight of herbage and tiller counts were determined at 136 and 198 days from sowing. The data were analysed for competitive effects by the application of the diallel analysis technique of Durrant (1965). The competitive effects were largely compensatory in type with dominant species such as Italian ryegrass and perennial ryegrass increasing in mixtures, relative to their pure stand values, more than species such as timothy and meadow fescue declined. This resulted in a tendency for the mixture means to exceed their mid-constituent values. The competitive effects on the reciprocal differences were seen to be predominantly of the alpha type; that is, there was a constant increase or decrease in one or more species when grown with others. The alpha values were found to be correlated with the unmixed species values so that ƀ, the mean effect, wasappropriately calculated from alpha. The over-all value of ƀ was –1.216, which means that for each gram difference in weight between the species when grown by themselves there was 2.452 g increase in difference between the species when grown in mixtures, the larger species increasing and/or the smaller species decreasing. There were significant differences in ƀ values between harvests, the ƀ competitive effects being approximately twice as large in the more mature plants. Although the alpha competitive effects increased in magnitude with time the species order remained relatively constant, and in terms of competitive ability the species could be placed in the ascending order, meadow fescue, timothy, cocksfoot, perennial ryegrass and Italian ryegrass. Tiller number showed a similar pattern, but the ƀ values were smaller, and not significant. Nevertheless competition had differential effects upon the plant weight/ tillering relationship and it is possible that the resultant morphological changes would influence the re-growth quality of the species. The conclusions derived from the analysis of reciprocal differences in this work is compared with earlier examples.

Journal ArticleDOI
TL;DR: The changes in phosphate availability that occurred when fertilizer phosphate was incorporated in moist uncropped soil were examined by storing fertilized soil in the open for periods up to 3 years before a final test crop was grown.
Abstract: The changes in phosphate availability that occurred when fertilizer phosphate was incorporated in moist uncropped soil were examined by storing fertilized soil in the open for periods up to 3 years before a final test crop was grown. Superphosphate was the standard source as it was fully available initially and therefore provided a measure of the rate of immobilization of phosphate on the four soils used. The extent to which this rate was modified by slower rates of dissolution of non-water-soluble sources was examined, using dicalcium phosphate (powder and granular), basic slag and ground North African rock phosphate (GNAP).Powdered dicalcium phosphate and basic slag in general behaved similarly to superphosphate, indicating very rapid dissolution. The only exception was a slightly lower rate of dissolution of slag on the calcareous soil. Other than in the very acid soil, the rate of dissolution of GNAP was slow so that the available phosphate was not similar to the superphosphate treatment until after at least the second year. On the calcareous soil GNAP was practically inert. Granular dicalcium phosphate was the only consistent slow-release source. It gave available phosphate levels which were initially lower, but subsequently higher, than those from superphosphate. In the absence of a crop, cumulative assessments of phosphate availability were not possible.The pertinence of these results to the problem of maintaining a high soil phosphate status is discussed.

Journal ArticleDOI
TL;DR: The results showed that calcium metabolism is regulated in the digestive tract, and the fact that the lactation calcium requirements increase at the same time as the amounts of digestible calcium and the calcium balance corroborates this statement.
Abstract: Statistical analyses were carried out on the data obtained under strictly controlled conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg. The authors have calculated and studied the correlations between faecal and urinary calcium losses, calcium excretion in the milk, digestible calcium, and calcium balance, and the 75 other nutritive factors which were analysed for each of the 55 above-mentioned experimental diets. The results showed that calcium metabolism is regulated in the digestive tract, and the fact that the lactation calcium requirements increase at the same time as the amounts of digestible calcium and the calcium balance corroborates this statement. But except for this endogenous factor of resorption, the fate of the dietary calcium does not depend on the ingested amounts but on the nature itself of the components of the diets and their proportions in the diets. Cereals, and especially barley, have from this point of view a particular beneficial effect. These factors act on the absorption of calcium and thus directly on the balance, since the daily urinary excretion of calcium is generally small and independent. It has also been demonstrated that the balance is not inevitably negative in cows with a daily milk production of 11–20kg, and that a careful composition of the rations should enable one to equilibrate it. The other nutritive factors do not work on calcium utilization, but a close parallel exists between digestibility, urinary excretion and balance of both calcium and magnesium.

Journal ArticleDOI
TL;DR: It was concluded that the pathogen showed continuous variation in virulence and that it would be difficult and of little value to attempt to define races, and it is suggested that selection for resistance under conditions which favour the expression of variation can lead to the production of resistant populations which retain their Resistance under conditions in which the parental stocks showed no worthwhile resistance.
Abstract: Summary Variations in the host–parasite relationship of bacterial blight of cotton, caused by Xanthomonas malvacearum, E. F. Smith (Dowson), axe elucidated in terms of the three main components of variation, namely, genetic variation in the host, genetic variation in the parasite and variations in environment. Although the relative resistance shown by host varieties differed both with the culture of the pathogen used for inoculation and with the environmental conditions, over-riding patterns of host resistance could be detected, showing that certain varieties maintained their resistance over a wide range of conditions. It was found that phage type in X. malvacearum was not related to virulence. Moreover, none of the cultures of the pathogen which had been isolated from different sources, could be shown to be identical when inoculated into a range of host varieties under a range of environmental conditions. It was concluded that the pathogen showed continuous variation in virulence and that it would be difficult and of little value to attempt to define races. Some success was achieved in relating observed variations in the host–parasite relationship to easily measured components of the environment, by using multiple regression analyses. It is suggested that this might provide a means of characterizing the complex variations observed and that the host–parasite relationship could be regarded as a dynamic system, in which disease expression is a function of the interactions of environmental factors and two polygenic systems, that of the host and that of the parasite. Intrapopulation variances were also studied in the host varieties. A population which showed little variation for resistance under one set of conditions might show considerable variation in a different environment or when inoculated with a different culture. It is suggested that selection for resistance under conditions which favour the expression of variation can lead, by repeated selection and inbreeding, to the production of resistant populations which retain their resistance under conditions in which the parental stocks showed no worthwhile resistance. These conclusions are discussed in relation to problems in resistance breeding and genetics.

Journal ArticleDOI
TL;DR: The observed relationship between herbage digestibility and herbage intake may reflect the greater sensitivity of young ruminants than adult stock to changes in the digestibility of the diet, and the reduced importance of the chemostatic control of food intake, except at very high levels of digestibility, in young rapidly growing animals.
Abstract: Nitro-chalk was applied to S.23 ryegrass swards, at approximately monthly intervals, at two contrasting levels in 1961 and three levels in 1962. Steer calves, 3–6 months old, grazed in rotation round a series of four paddocks on each treatment. Paddocks were trimmed and fertilizer applied after each grazing. The herbage intakes of the calves were determined on three occasions in 1961 and four occasions in 1962. Faecal output was estimated by chromic oxide dilution. In vitro digestibility determinations were carried out on samples of herbage clipped from the swards.There was a close linear relationship between the digestibility of the herbage and the amount eaten, over the full range of digestibility encountered (68–82%). Regression equations calculated within seasons and fertilizer levels, and within years, did not differ significantly. The regressions of faecal output on herbage digestibility were not significantly different from zero.The observed relationship between herbage digestibility and herbage intake may reflect (a) the greater sensitivity of young ruminants than adult stock to changes in the digestibility of the diet, and (b) the reduced importance of the chemostatic control of food intake, except at very high levels of digestibility, in young rapidly growing animals.

Journal ArticleDOI
TL;DR: A method is proposed which would allow meaningful grazing experiments to be carried out employing only one stocking rate, thus considerably reducing the expense of this type of experimentation.
Abstract: SUMMARY Experiments designed to assess differences between treatments in pasture productivity as measured by the production of animals are complicated by the stocking rates chosen. The paper attempts toderive a simple model relating production per animal and production per unit area to stocking rate for meat animals, based on biological considerations. A method is proposed which would allow meaningful grazing experiments to be carried out employing only one stocking rate, thus considerably reducing the expense of this type of experimentation. The model is applied to some recent data obtained by Hodgson (1966) and Appleton (1967, personal communication).

Journal ArticleDOI
TL;DR: In an 8-year field experiment, Potasium sulphate and to a lesser extent magnesium sulphate increased yields of all crops both when applied alone and together as mentioned in this paper, although K/Mg interactions did not affect yields they considerably affected the ratio of concentrations of these elements in the dry matter of the crops.
Abstract: In an 8-year field experiment, potassium sulphate and to a lesser extent magnesium sulphate increased yields of all crops both when applied alone and together. Although K/Mg interactions did not affect yields they considerably affected the ratio of concentrations of these elements in the dry matter of the crops. Sodium chloride increased yields of kale but not of barley harvested at ear-emergence.Percentage yield response to potasium followed the orderPotatoes (218%) < clover = barley < sugar beet < kato; < ryegress (17%).Magnesium increased yields from 3 to 10%, most with potatoes.Changes in exchangeable magnesium in the soil reflected differences between applied magnesium and crop uptakes. Changes in exchangeable potassium were less than expected, probably because non-exchangeable potassium was released on plots without added potassium and ‘fixed’ in non-exchangeable forms on plots where much fertilizer potassium had been given.Increase in the incidence of magnesium deficiency symptoms reported recently in South. East England are attributed to the local liming materials containing only small amounts of magnesium and to less F.V.M being applied to crops than previously.

Journal ArticleDOI
TL;DR: In this article, the correlation between faecal and urinary losses of magnesium, magnesium in milk, digestible magnesium, and magnesium balance and the other nutritive factors of the 55 above-mentioned experimental diets have been calculated.
Abstract: Statistical analyses were carried out on the data obtained under very strict conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2 to 6 months earlier and whose daily milk production ranged from 11 to 20 kg.The correlation between faecal and urinary losses of magnesium, magnesium in milk, digestible magnesium, and magnesium balance and the other nutritive factors of the 55 above-mentioned experimental diets have been calculated.The magnesium absorption is enhanced by increasing magnesium and calcium intake, while nitrogen and, to a lesser extent, fat, giving higher faecal losses, have an opposite effect. There is no influence at this level of lactating requirements.The urinary losses of magnesium are not related to the magnesium intake and digestibility, and the balance is thus directly proportional to the digestible amounts. But this balance is decreased when the diet contains more dry matter or energy, to the benefit of urine in dry cows. We were not able to determine whether this balance reduction also benefits the milk production in the lactating cows.Our results demonstrate that the faecal endogenous losses of magnesium can be highly variable.The balance of magnesium is frequently but not inevitably negative in cows with a daily milk production of 11–20 kg.

Journal ArticleDOI
TL;DR: Differences between breeds in faecal output and in the digestibility of the diet were significant and were correlated with the quantity of green feed available.
Abstract: Two flocks of Merino wethers ranging in age from 3 to 87 months grazed a poor (L) or high (H) quality pasture for 3 months. The flocks were then combined, and intake was estimated while the sheep grazed four different pastures in succession. In a second experiment, flocks of Merino, Border Leicester, Southdown and Dorset Horn ewes of varying ages grazed in succession six pastures on which intakes were estimated and live weights recorded. The digestibility of the diet selected, as estimated from the faecal nitrogen concentration, declined with age by 0·053 units per month in Exp. (2) and curvilinearly in Exp. (1). In both experiments faecal output of sheep of similar breed receiving similar treatments increased with age to approximately 3 years and declined thereafter. In neither experiment was there a significant allometric relationship between intake and live weight.The intake of the L group was consistently greater than that of the H group when both groups grazed together. The differences were correlated with the quantity of green feed available. The faecal output of Dorset Horns, Merinos, Southdowns and Border Leicesters at 28·7 months of age was calculated to be 451, 402, 346 and 588 g per day respectively in Exp. (2). Mean digestibility of the diet selected estimated by the faecal nitrogen procedure was 65·1, 63·0, 64·7 and 64·5 units at 28·7 months for the Dorset Horns, Merinos, Southdowns and Border Leicesters respectively. Differences between breeds in faecal output and in the digestibility of the diet were significant.

Journal ArticleDOI
TL;DR: The content of fat in the body fell progressively from October to May and then increased; initially fat was withdrawn only from the soft tissues but by April and May the fat contents of both skeleton and soft tissues were exceedingly low.
Abstract: Groups of ewes kept under hill conditions were killed at intervals during October to July 1965–66. Supplementary feed was given between February and May. The carcasses were divided into soft tissue, uterus and its contents and skeletal fractions. Each fraction was dissolved in HNO 3 and its fat and mineral content measured. The sheep were heavier in November and lighter in May during lactation than at other times. The content of fat in the body fell progressively from October to May and then increased; initially fat was withdrawn only from the soft tissues but by April and May the fat contents of both skeleton and soft tissues were exceedingly low. The weight of fatfree soft tissue remained relatively constant but was heaviest in July. Fat-free skeleton fraction was lighter in January than in April. The contents of the predominantly intracellular ions, P, Mg and K in the soft tissue fell between November and January, remained constant between January and May and then increased. There was an increase in Na towards the end of pregnancy followed by a marked fall after parturition. The contents of Ca and P in the skeleton fell between November and January and during lactation between April and July. There was a marked increase between February and April when supplementary feeding was given. Evidence that Mg was selectively removed from the skeleton was obtained in November and January, two sheep having Ca:Mg ratios in skeleton greater than 100. Na and K contents of the skeleton were greatest at the end of pregnancy in April. For the lambs between 6 and 23 kg live weight, each kg of live-weight gain contained 8·8 g Ca, 5·0 g P, 0·27 g Mg, 0·83 g Na and 1·85 g K.

Journal ArticleDOI
TL;DR: Results of 132 maize fertilizer experiments (NP and NPK) carried out over 3 years in Western Tanzania have been grouped to give sixteen "response areas" as mentioned in this paper, where responses to N and P were very large in the southwestern half of the research zone, where rainfall is fairly well distributed.
Abstract: Results of 132 maize fertilizer experiments (NP and NPK) carried out over 3 years in Western Tanzania have been grouped to give sixteen ‘response areas’. Responses to N and P were very large in the south-western half of the research zone, where rainfall is fairly well distributed. On granitic soils around Lake Victoria, responses were mainly to N alone. In the drier areas, notably Shinyanga district, responses to both N and P were on average very small. No significant positive responses to K were found, except for one trial in Karagwe district.It was found that all observed responses to N and P could be accounted for in terms of a generalized two-factor Mitscherlich-Baule yield equation, with constant curvature terms, cn and cv.Using this equation it is possible to define ‘maximum economic requirements’ of the nutrients N and P for various maize and fertilizer prices and potential yields. The difference between this maximum requirement and the amounts of these nutrients supplied by the soil (given by the Mitscherlich-Baule parameters bn and bp',)represents the optimum rate of fertilizer application, where profit per acre is at a maximum.Empirical equations are presented for estimating b from soil analysis results for areas not adequately covered by these experiments, but such estimates may not always be accurate.

Journal ArticleDOI
TL;DR: In this paper, two experiments designed to provide data for the estimation of functional relationships, which may be used to determine economically optimum plant populations and planting patterns in Desire'e potatoes, are described.
Abstract: Two experiments designed to provide data for the estimation of functional relationships, which may be used to determine economically optimum plant populations and planting patterns in Desire'e potatoes, are described. Functional relationships between the number of main stems per acre and yield per acre were estimated from the results of experiment (i). Experiment (ii) investigated the relationship between stem number per tuber and seed tuber weight. ‘Square root’ functions estimated for seed yield and ware yield from the results of Exp. (i) were used to calculate a total Financial Returns curve. This returns curve, together with the Cobb-Douglas function estimated from the results of Exp. (ii), was used to calculate the stem numbers per acre, which would give maximum returns per acre and economically optimum returns in different cost/price situations.

Journal ArticleDOI
TL;DR: Nitrogen balance and digestibility studies confirmed the results of the production trials and there were no significant differences in the digestibility of dry matter or nitrogen between wet and dry feeding or between extreme temperatures of the feed.
Abstract: Experiments wore carried out to compare wet and dry feeding for bacon pigs and to study the effect of temperature of feed on the utilization of wet feed. There was no significant difference in growth rate between wet and dry feeding; food conversion ratios tended to be lower on wet feeding and were significantly lower in one experiment. There were no significant differences in growth rate or food conversion between wet feed given at 5 °C, 13 °C or 35 °C. None of the treatments had any significant effect on carcass characteristics. Nitrogen balance and digestibility studies confirmed the results of the production trials. There were no significant differences in the digestibility of dry matter or nitrogen between wet and dry feeding or between extreme temperatures of the feed.

Journal ArticleDOI
TL;DR: The intestine does not appear to play any major role in the formation of the high concentration of cholesterol ‘linolenate’ found in bovine plasma and the process of lipid digestion in the cow appears to be similar to that found in sheep.
Abstract: SUMMARY Samples of prefemoral, thoracic and intestinal duct lymph have been collected under acute conditions from three cows grazing pasture and the lipid composition compared with that of plasma. The concentration of lipids in peripheral lymph was 16–36% of that found in plasma; the fatty acid compositions of peripheral lymph lipids were similar to those of plasma. Of the fatty acids present in intestinal and thoracic lymph 86 and 76% were esterified as triglycerides, 10 and 13% as phospholipids and 3 and 5% as cholesterol esters, respectively. Saturated and mono-unsaturated fatty acids were preferentially esterified as triglycerides whereas di- and tri-unsaturated acids were associated more with phospholipids. The content of di- and tri-unsaturated fatty acids was greater in the triglycerides and phospholipids derived from the intestine than in those found in plasma. The di- and tri-unsaturated fatty acids in intestinal and thoracic lymph were transported mainly in the form of triglycerides (45–62%) and phospholipids (21–33%). Cholesterol esters were quantitatively of minor importance in the transport of these fatty acids in lymph. The intestine does not appear to play any major role in the formation of the high concentration of cholesterol ‘linolenate’ found in bovine plasma. The process of lipid digestion in the cow appears to be similar to that found in sheep.

Journal ArticleDOI
TL;DR: Four barley varieties were grown in a greenhouse with varying levels of nitrogen fertilizer in two experiments and relative potential yields of genotypes can be estimated under similarly controlled conditions.
Abstract: Four barley varieties were grown in a greenhouse with varying levels of nitrogen fertilizer in two experiments. One experiment was sown in late September and received supplementary light, the other in March without supplementary light.Varietal responses to nitrogen were essentially the same in both experiments. At low levels, differences in yield and protein content between varieties were small and inconsistent; at high levels, differences were pronounced and consistent. Betzes and Hannchen were highest in yield and lowest in protein, Palliser was intermediate in both, and Compana was lowest in yield and highest in protein. The results correspond with the known behaviourof these varieties under field conditions in Canada, except that Betzes yields more than Hannchen.We suggest that relative potential yields of genotypes can be estimated under similarly controlled conditions.

Journal ArticleDOI
TL;DR: The micro-Kjeldahl technique and paper electrophoresis were used to measure the total protein and γ-globulin concentrations in the sera of 423 2-day-old Finnish Landrace, Scottish Blackface, Merino and Merino × Cheviot lambs, and the totalprotein concentrations inThe sera and colostra of their mothers.
Abstract: The micro-Kjeldahl technique and paper electrophoresis were used to measure the total protein and γ-globulin concentrations in the sera of 423 2-day-old Finnish Landrace, Scottish Blackface, Merino and Merino × Cheviot lambs, and the total protein concentrations in the sera and colostra of their mothers. The concentrations were higher in Finnish lambs than in lambs of other breeds. The interbreed variations between single lambs were not significant, but the variations between lambs from larger litters were highly significant, because the concentrations in Finnish twins and triplets were as high as in single lambs, whereas the concentrations in Blackface and Merino × Cheviot lambs were negatively correlated with litter size. The differences between the breeds were attributable to the particularly high protein concentrations in the colostra from the Finnish ewes, to the small size of their lambs, and, probably, to a higher rate of production of colostrum by Finnish than by other ewes. There was some evidence of a positive correlation between the lengths of the gestation periods and the γ-globulin concentrations of the lambs.