Research Article
The digestibility of oat hay
- H. F. Walker
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- 27 March 2009, pp. 289-295
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1. Digestibility trials, using sheep, were carried out on five batches of oat hay grown during 2 years; nitrogen balance experiments were made simultaneously.
2. The oat hay was not readily consumed by the sheep; this necessitated calculating the digestibility data on an ‘as consumed’ and on an ‘as offered’ basis; it also prevented a majority of the sheep from obtaining their maintenance requirements of energy or from maintaining nitrogen equilibrium.
3. Statistical analysis of the data revealed a downward drift in digestibility in the succeeding periods of the 1955 trial.
4. While stage of maturity had little consistent effect on digestibility or on the amounts of digestible nutrients present, the percentage digestible crude protein did increase with advance in maturity.
5. The amounts of digestible nutrients present in oat hay indicated that it had a nutritive value between those of oat straw and medium-quality meadow hay.
6. The data suggest that the maximum yield of digestible nutrients is obtained when the oat hay is cut at the ‘late cheesy’ stage of maturity.
The effect of time of sowing on flowering and fertile tiller production in S. 48 timothy
- R. H. M. Langer, G. J. A. Ryle
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- 27 March 2009, pp. 145-150
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1. In a field experiment all plants of S. 48 timothy produced ears after being sown on or before 24 April; more than 90% of the plants still flowered if sown up to 19 May but fertility declined after later sowings, until only vegetative growth resulted in plants sown on or after 30 June.
2. In a pot experiment, during which the performance of individual tillers was recorded, all tillers arising after 23 July were found to remain vegetative. Ear-bearing capacity declined towards this date but was still high in tillers appearing as late as 2 July in plants sown in the middle of May.
3. Tillers on the main stem were more fertile and produced heavier ears than other tillers of the same age and order of succession on the plant.
4. Many plants sown late in the field produced ears which formed vegetative proliferations after the end of the summer.
5. The results are discussed in relation to the response of timothy to the changing environment, notably the length of day. It is suggested that timothy does not react to favourable photoperiods immediately upon germination and that failure to flower in plants sown after the middle of May does not necessarily imply any inadequacy of the environment to cause floral initiation, since it was possible for tillers appearing up to 2 July to produce ears, with few exceptions. Factors inherent in the organization of the plant are considered to be responsible for a decline of ear-boaring capacity from tiller to tiller, which occurred irrespective of changing environmental conditions.
The effect of moving colonies of honeybees to new sites on their subsequent foraging behaviour
- J. B. Free
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- 27 March 2009, pp. 1-9
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1. Groups of colonies have been moved to crops requiring pollination: group A, before any blossom appeared; group B, when 5–15% of the crop was in flower; and group C, when the crop was in full flower, and the amount which the colonies of the different groups visited the crop was determined. The results tend to show that colonies of group B visited the experimental crop more than colonies of group A, thus supporting recommendations that colonies should not be moved to a crop requiring pollination until it has started to flower, so that the bees will not have previously become conditioned to visiting other flower species in the locality.
2. When a colony is moved to a new site its foragers tend to visit species they have visited previously, and the amount of a particular pollen that a colony collects at a new site is sometimes related to the amount of it the colony collected before it was moved.
3. The conclusion of previous workers that different colonies utilize the local flora in different ways have been confirmed. Different colonies vary greatly both in the number and kind of species they visit and in the extent to which they visit the same species. Although the extent to which colonies visit certain species tends to be related to the extent they have visited them previously, exceptions often occur.
Comparisons between combine-drilling and broadcasting muriate of potash for spring barley
- F. V. Widdowson, A. Penny, R. J. B. Williams, G. W. Cooke
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- 27 March 2009, pp. 10-16
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1. Twelve experiments were carried out in Bedfordshire and Hertfordshire in 1955–57 to compare combine-drilling and broadcasting muriate of potash for barley. Ordinary mineral soils were used and only one contained more than 25% of calcium carbonate.
2. On average of all the experiments in each year 0·25 cwt. K2O/acre drilled with the seed gave higher yields than 0·5 cwt. K2O/acre broadcast and worked into the seedbed. The average extra yields of barley from combine-drilling, as compared with broadcasting, were 1·2 cwt./acre when 0·25 cwt. K2O/acre was applied and 2·0 cwt./acre of grain when twice as much K2O was given. In twenty-one of the total of twenty-four comparisons drilling gave higher yields than broadcasting and in onethird of these comparisons the effects were significant. Combine-drilling gave higher average yields of straw than broadcasting.
3. The average level of response was not great, the low and high rates of combine-drilled muriate of potash increasing yields by 13 and 16%, respectively. Only a small proportion of the applied potassium was taken up by the crops; apparent recoveries by grain plus straw averaged 11% of the light-drilled dressing and 8% of the heavy dressing.
4. The level of response to potassium varied from year to year, but was much greater on average in the 1955 experiments than in 1956 and 1957. There was no close relationship between the degree of response and values for dilute hydrochloric-acidsoluble potassium or exchangeable potassium in the soils used.
Effect of rate and method of application of ammonium sulphate on irrigated wheat sown on three different dates
- A. Wahhab
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- 27 March 2009, pp. 296-298
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An experiment on irrigated wheat was laid out in a split-plot design in which six levels of N, three dates of sowing and two times and methods of application were tried. The data were subjected to pooled analysis and it was noticed that years, dates of sowing, manures and the interaction of manures and dates of sowing were highly significant, while the time and method of application of the fertilizer and all other interactions were non-significant. Graphs have been presented depicting the law of diminishing returns. Optimum levels of N have also been given. Application of the fertilizer by placement to normal and late sown crops is much better than its application by broadcasting.
Studies of the chemical composition of kales and rapes III. The minor elements
- D. J. C. Jones
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- 27 March 2009, pp. 151-155
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1. Four varieties of marrow stem kale, three of thousand headed kale, Hungry Gap Kale, Rape-Kale and five other rape varieties were sampled at two centres in mid-Wales and separate leaf and stem samples analysed for manganese, molybdenum and boron. Similar samples of four varieties of marrow stem kale, two of thousand headed kale, Hungry Gap Kale, Rape-Kale and two other varieties of rape were taken from two further centres and prepared with the most stringent precautions to prevent contamination. Iron, copper, zinc and lead were determined in these samples.
Genotype-environment interactions in the wintering of lambs
- J. W. B. King, J. H. Watson, G. B. Young
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- 27 March 2009, pp. 156-171
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An experiment to investigate the differential response of lambs of various breeds and crosses to different planes of nutrition is described.
Two groups of twin lambs were used comprising Blackfaces and their crosses ( x Lincoln, Wiltshire and Border Leicester rams) and Welsh and their osses ( x Suffolk and Wiltshire rams).
From October to January, each cross was divided between high and low planes of nutrition. Approximately half of the twin pairs were split and the remaining pairs distributed between the environments. Significant differences were found between the crosses and twin pairs of the same cross for body weight, body measurements and wool production but not for various blood characters. For almost all characters studied, plane differences were found. There was, however, only one significant (P < 1%) cross-plane interaction—for non-protein nitrogen concentration in the blood.
At the end of January, each plane was subdivided to produce high-high, high-low, low-high and low-low groups. The lambs remained in these groups until May. As before, differences between crosses were found for body weights and measurements, and wool characters but not for most blood characters. The majority of characters were affected by plane of nutrition. Cross-plane interactions were not found except in antibody response to Erisipelothrix rhusiopathia vaccine (P < 5%).
At the end of May the high-high group were slaughtered and the remaining three groups fattened on grass until each reached the same average weight as the high-high group. Carcass measurements showed that all the crosses shared a striking ability to recover from previous poor nutritional treatments. One significant (P < 5%) interaction of cross and plane was found in weight of cannon bone.
The most characteristic feature of the results has been the similarity of response of the different genotypes to the different nutritional environments. The few interactions found to be statistically significant by conventional methods are difficult to interpret because of the many tests of significance carried out in the analyses.
The effects of nitrogen upon three stiff-strawed winter wheat varieties
- F. V. Widdowson
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- 27 March 2009, pp. 17-24
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Eleven winter wheat experiments were carried out from 1955–57, to compare the effects of nitrogen on three stiff-strawed varieties of winter wheat, Heine 7, Hybrid 46 and Minister. In 1955 the experiments tested ‘Nitro-Chalk’ top-dressings at rates supplying 0·45, 0·90 and 1·35 cwt. N/acre. In addition, drilled dressings supplying 0·15 cwt. N/acre were supplemented with either 0·30 or 0·75 cwt. N/acre as a top-dressing.
In the 1956 and 1957 experiments ‘Nitro-Chalk’ top-dressings were applied at 0·60 and 1·20 cwt. N/acre. In addition, divided dressings were compared by supplementing 0·15 cwt. N/acre by combine-drill with 0·45 cwt. N top-dressing.
Significant increases in yield were obtained from the first increment of nitrogen in twenty-three of the thirty-three available comparisons. There were significant additional gains from the second increment of nitrogen in only seven of the same comparisons. Responses to nitrogen varied considerably between seasons. Large and consistent responses were obtained at all centres in 1955 and dressings supplying 0·9 cwt. N/acre were well worthwhile. In 1956 responses were generally smaller and dressings in excess of 0·6 cwt. N/acre could only be justified at two centres. Mean responses in 1957 were lower than those obtained in either of the previous season and 0·6 cwt. N/acre was sufficient for maximum yields at three of the four centres.
There was little advantage in dividing dressings of nitrogen between autumn and spring in any of the experiments and none of the differences reached significance. On average, higher yields were obtained by retaining the whole of the nitrogen until the spring, than by applying part of the dressing in autumn by combine-drill.
Comparisons between the varieties show that Hybrid 46 was the only variety which was able to take consistent advantage of the heaviest rates of manuring. In each year Hybrid 46 produced the highest percentage increase in yield and Minister the lowest. In addition Hybrid 46 contained the highest percentage of nitrogen in the grain when averaged over each level of manuring. The percentage recovery of nitrogen was calculated for each year and each variety. Comparisons of this data show that Hybrid 46 converted more of the fertilizer nitrogen into grain or crude protein than either of the other two varieties. The experiments provide evidence that there are considerable variations in the efficiency with which present-day winter wheat varieties can utilize nitrogen, and that varieties with both high fertilizer efficiency and high unmanured yields are likely to increase the level of crop production.
Studies on the cutting management of grass-clover swards. I. The effect of varying the closeness of cutting on the yields from an established grass-clover sward
- D. Reid
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- 27 March 2009, pp. 299-312
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1. A 3-year experiment is described in which perennial rye-grass/white clover swards were cut to within either 1 in. of 2–2½ in. of ground level when the herbage had reached either the ‘grazing’ or the ‘silage’ stage of growth. Superimposed on the cutting treatments were several fertilizer treatments which involved application of varying amounts of nitrogen at different dates over the season.
2. Throughout the experiment cutting to within 1 in. of ground level gave greater dry-matter and crude-protein yields of mixed herbage and of clover than cutting to within 2–2½ in. of ground level, the increase in dry-matter yield ranging from 39 to 49%.
3. The response of clover to these ‘height of cutting’ treatments developed more slowly than the response of the sward as a whole, and was modified in the later stages by the particular fertilizer nitrogen treatment applied.
4. It is suggested that the greater herbage yields obtained from close- than from lax-cut swards resulted from the differential effects of the two cutting treatments on stem and leaf formation in the grasses, but the need for further investigation is stressed.
5. Discrepancies between the effects of the ‘height of cutting’ treatments in this experiment and those reported by other workers are indicated, and it is shown that these discrepancies probably result from the varying cutting frequencies adopted.
6. Cutting the sward at varying stages of growth and increasing the rate of fertilizer nitrogen application had very similar effects on mixed herbage and clover yields in this experiment to those reported previously by other workers.
7. Where the total amount of fertilizer nitrogen applied over the season was small (4 cwt. ‘Nitro-Chalk’/acre) delaying the first dressing until after the first or second cut reduced the dry-matter and crude-protein yields of mixed herbage, and had little effect on those of clover. A similar delay where greater total amounts of fertilizer nitrogen were used (8–12 cwt. ‘Nitro-Chalk’/acre) reduced the dry-matter yields of mixed herbage, and slightly increased the dry-matter and crude-protein yields of clover. Under these heavy nitrogen treatments the crude-protein yields of mixed herbage decreased only where the delay involved a reduction in the total amount of fertilizer nitrogen applied over the season.
8. Although delaying the first dressing of the season reduced mixed herbage yields at all fertilizer nitrogen levels, it resulted in a more uniform distribution of production over the season. The practical significance of this is discussed.
Effect of frequency of cutting on the yield and composition of some fodder grasses in Nigeria (Pennisetum purpureum Schum.)
- V. A. Oyenuga
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- 27 March 2009, pp. 25-33
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1. The influence of frequency of cutting on the yield and chemical composition of Pennisetum purpureum Schum under the environmental conditions obtaining in south-western Nigeria was studied in 1953–54. The cutting frequencies adopted being seventeen, eight, six and four times sampling a year, which permitted the plants to grow for intervals of 3, 6, 8 and 12 weeks, respectively, before cutting.
2. When elephant grass was sampled four times a year, at an interval of 12 weeks, a yield of 52·9 tons of green fodder per acre was obtained for the 11-month period (24 June 1953 to 27 May 1954). This yield was 1·8 times more than the green fodder produced from plots sampled seventeen times a year, at 3-weekly intervals, and 1-4 times more than that obtained from each of those sampled six times a year (intervals of 8-weeks) and eight times a year (6-weekly intervals), respectively. These yields, which are probably the highest ever recorded for any grass species grown in unfertilized soils in Nigeria, are also higher than the yields reported under similar conditions and treatments in other tropical countries.
3. The percentage dry matter similarly increased with the length of cutting intervals. Differences in yields of dry matter between the various treatments are more pronounced than similar differences for green fodder yields. The dry-matter yields obtained from either the 6-weekly or the 8-weekly cutting intervals were significantly higher than those obtained from the 3-weekly cut samples, while those from the 12-weekly cut samples were significantly superior to each of the other cutting treatments. The difference in yield between the 8- and the 6-weekly cut samples, however, was not statistically significant.
4. A progressive reduction in yields of dry matter and of green fodder was shown with successive cuttings, particularly in the case of the more frequently cut grasses; the yields obtained during the 1964 seasons were lower than those of 1953. It is possible that the application of fertilizers might arrest this diminution in growth and yield.
5. It was shown that when the grass was allowed to grow for a period longer than 3 weeks, the stems of Pennisetum purpureum Schum tend to mature more rapidly than the leaves. This fact might be responsible for the rapid deterioration in nutrient content, so characteristic of tropical fodders.
6. The percentage crude protein and of silicafree ash fell as cutting intervals increased; the percentage dry matter, crude fibre and nitrogenfree extract rose directly with length of cutting intervals. It was shown that it is best to cut elephant grass every 3 weeks of growth in order to obtain the highest yield of protein and of silicafree ash per acre; this grass should, however, be cut every 12 weeks to obtain the maximum yield of total nutrients and carbohydrates. It does not appear profitable to cut or graze elephant grass at 6- or 8-weekly intervals for either of the above purposes.
7. While green fodder yields were directly, drymatter yields were inversely, related to the degree of monthly precipitation. Generally, periods of high rainfall were followed by high yields of green fodder and low yields of dry matter, those of low rainfall by low green fodder and high dry-matter yields. The percentage crude protein and of silicafree ash of dry matter, fluctuated directly with rainfall; the percentage nitrogen-free extract and of crude fibre showed an inverse relationship with rainfall fluctuations.
It is these latter constituents rather than the former which thus reflect the dry-matter content of the herbage.
Semen and testis characteristics and sexual behaviour of boars
- J. L. Hancock
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- 27 March 2009, pp. 313-326
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Two procedures were followed to train boars to mount a dummy sow for semen collections. Of thirty-nine boars which were introduced to the dummy sow with no previous training twelve were trained successfully. Of eight boars which were first allowed daily mating with an oestrous sow in the pen housing the dummy sow, seven were trained successfully.
Measurements of semen characteristics were made on twenty-five fertile boars including nine boars (morphological characteristics only) in use at commercial insemination centres.
The mean ejaculate volume of thirty-four ‘first’ ejaculates was 173·7 ml. (range 85–275 ml.). The mean volume of the fluid fraction was 109·3 ml. (range 15·220 ml.). For second ejaculates these values were 156·9 ml. (range 80·220 ml.) and 93·2 ml. (range 25·165 ml.).
The mean sperm concentration in thirty-five ‘first’ ejaculates was 284·5 x 106/ml. (range 11 × 106/ml. to 925 × 106/ml.). The mean concentration for ten second ejaculates was 224·4 × 106/ml. (range 18 × 106 to 295 × 106/ml.).
In samples collected in successive 20 ml. fractions the highest concentration was found in the first 20–40 ml. In some boars the spermatozoa were distributed more uniformly throughout the ejaculate than in others.
The mean number of spermatozoa per first ejaculate was 28·26 × 109 (range 0·77 × 109 to 80·0 × 109). The mean for second ejaculates was 15·88 × 109 (range 0·76 × 109 to 44·17 × 109). The mean initial pH of thirty-four first ejaculates was 7·22 (range 6·85–7·9); for second ejaculates it was 7·54 (range 7·22–8·0).
There was a marked increase of pH with time after collection when semen was stored in open vessels; this did not occur when semen was stored in filled stoppered vessels.
The mean pH of the sperm fraction in six ejaculates was 7·06 (range 6·8–7·4); the mean pH for post-sperm fractions of the same ejaculates was 7·36 (range 7·0–7·6).
The freezing points of three ejaculates were –0·54, –0·55 and –0·56° C.
The mean methylene blue reduction time for seven ejaculates was 5·0 min. (range 2·5–6·5 min.). The reducing power of boar semen was virtually unaffected when all the spermatozoa were killed by freezing.
Motility of boar semen was lost rapidly when it was examined under a cover-glass; motility was restored by aeration (removal and replacement of the cover-glass).
The mean percentages of nine morphological classes of spermatozoa in ejaculated semen of fertile boars were as follows: Malformed heads, 3·0; malformed middle-pieces, 2·7; bent tails, 4·5; coiled tails, 0·9; headless, 0·3; tailless, 0·3; broken necks, 0·1; neck beads, 11·8; middle-piece beads, 17·18.
The decline in the concentration of spermatozoa in successive fractions of an ejaculate was associated with a decline in the frequency of middle-piece beads.
The semen of one sterile boar showed a mean frquency of 77% malformed middle-pieces.
The mean percentages of the above classes in samples from the vasa deferentia of nineteen fertile boars were: malformed heads, 5·7; malformed middle-pieces, 5·1; bent tails, 3·6; coiled tails, 0·06; headless, 0·6; tailless, 0·3; broken necks, 0·1; neck beads, 17·4; middle-piece beads, 59·2.
The average percentages in samples from vasa deferentia of four sterile boars were: malformed heads, 11·9; malformed middle-pieces, 30·7; bent tails, 9·1; coiled tails, 0·5; headless, 0·4; tailless, 0·5; fractured necks, 0·9; neck beads, 24·2; middlepiece beads, 30·0.
The mean testis and epididymis weights were 359·2 and 84·7 g. Expressed as percentages of body weight the weights were 0·285 and 0·068. The mean within pair differences in weights were 48·9 g. (between testes) and 8·5 g. (between epididymides).
The macroscopic and microscopic histological features of the testes are described. Tubular atrophy associated with impaction was found to be a common feature of this sample of boar testes. There was no clear relationship of the histological features of the testes either to semen characteristics or to fertility. It is shown that fertile boars may show grossly pathological testes characteristics. The cause of the observed pathological changes was not identified. The findings are discussed.
Nitrogen metabolism in the lactating sow
- G. A. Lodge
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- 27 March 2009, pp. 172-176
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1. Each of three litter sister sows was fed one of three levels of crude protein in the diet during two 8-day periods in the fourth and seventh weeks of lactation. The three protein levels were 11, 15 and 19% of the diet on an air-dry basis. The scale of feeding was varied to maintain each sow at constant weight throughout the 8-week lactation period.
2. During two 3-day collection periods following 5-day preliminary periods, intake of nitrogen from the diet and outputs of nitrogen in faeces, urine and milk were measured.
3. The sow receiving the medium level of protein in the diet was in positive nitrogen balance during both collection periods.
4. The major effect of increasing the protein level of the diet was an increase in the output of urinary nitrogen. Neither milk yield nor output of protein in the milk appeared to be affected over the limited period studied.
5. Apparent digestibility of dietary protein was 75% on the low level and 85% on the medium and high levels of intake.
Metabolism of nitrogen during long-term incubation of soil treated with fresh and rotted organic materials
- A. H. Cornfield
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- 27 March 2009, pp. 327-329
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The metabolism of nitrogen during incubation, at 28° C. for 184 days, of a soil treated with 1% by weight of five different bulky organic manures and 0·5% calcium carbonate was studied.
1. Ammonia and nitrite could not be detected at any sampling date with any treatment, hence nitrate levels in treated soils compared with that in the control soil indicated the extent of mineralization or fixation of nitrogen.
2. A good straw compost (carbon/nitrogen ratio, C/N, 20·6) was the only material which showed mineralization of nitrogen over practically the whole of the incubation period.
3. Rotted farmyard manure (C/N 15–6) caused a small, whilst fresh grass (C/N 22·6), caused a fair amount of nitrogen fixation in the early stages, but there was a small overall mineralization of nitrogen by the final sampling.
4. A poor straw compost (C/N 42·5) and straw (C/N 147·0) both caused considerable fixation of nitrogen in the early stages. With continuing incubation the bulk of the nitrogen fixed by the poor compost, but only a small portion of that fixed by the straw, was released.
The metabolic changes which occur in sheep transferred to lush spring grass I. Changes in blood and rumen constituents
- E. F. Annison, D. Lewis, D. B. Lindsay
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- 27 March 2009, pp. 34-41
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1. Changes are observed in the concentrations of a wide range of substances found in blood and rumen contents when sheep are first turned out to lush spring grass.
2. With some metabolites (e.g. rumen α-amino nitrogen, blood VFA) the increase is only temporary, and the animal (or its rumen microbial population) quickly adapts to the changed conditions. With other metabolites (e.g. rumen VFA) there is a sustained increase over a period of at least three weeks on grass.
3. It is possible that the nature of the previous diet may determine the magnitude of the metabolic changes occurring.
4. The overall nature of these changes should be taken into account in assessing the aetiology of the metabolic diseases occurring in ruminants under similar conditions.
The energy requirements of lactating sows and the influence of level of food intake upon milk production and reproductive performance
- G. A. Lodge
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- 27 March 2009, pp. 177-191
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1. A theoretical feeding scale, designed to supply the full nutritional requirements of the lactating sow and prevent weight loss (allowing approximately 8 lb. meal per sow and 0·8 lb. per piglet), was tested against a much lower but commonly recommended level (2 lb. meal per sow and 1 lb. per piglet). The meal (barley meal, 40%; ground oats 25%; middlings, 20%; white fish meal, 7·5%;, groundnut meal, 2·5%; dried grass meal, 3·8%; ground limestone, 0·3%; common salt, 0·3%; vitamins A, D and B2 supplement, 0·6%) contained approximately 16·25% crude protein and had a digestible energy value of approximately 1300 Cal./lb. During pregnancies all sows were fed equal amounts of a meal containing approximately 13·0% crude protein.
2. Four pairs of Wessex Saddleback litter sisters were divided between the two treatments and records taken over three lactations of food consumptions, sow body weights, milk yields, milk compositions, litter growth rates, creep-feed consumptions and reproductive performances. Litter sizes were standardized between pairs of sows within the first 10 days after farrowing.
The metabolic changes which occur in sheep transferred to lush spring pastures II. Changes in the acid-base balance of the whole animal
- E. F. Annison, D. Lewis, D. B. Lindsay
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- 27 March 2009, pp. 42-45
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1. Acid-base changes were observed in the blood of some sheep after turning them out to lush spring grass.
2. These changes were observed in animals previously fed a diet of hay plus concentrates. No changes were found in animals previously fed hay alone.
3. Reasons are given for believing the acidosis observed was a consequence of feeding on lush pasture, and not a consequence of the exercise and excitement involved in rounding up sheep for sampling.
The in vitro digestion of roughage dry matter
- D. M. Walker
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- 27 March 2009, pp. 192-197
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1. An in vitro apparatus is described for measuring the percentage dry-matter digestibility of roughages.
2. Samples of hay, dried herbage, oat hay and oat straw were tested in vitro and the values obtained compared with in vivo results obtained with sheep.
A note on the use of molassed wood pulp as a substitute for farm roughages in experimental rations for dairy cattle
- J. A. F. Rook, R. C. Campling
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- 27 March 2009, pp. 330-332
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In recent investigations at this Institute, attempts have been made to devise for dairy cows a ration extremely low in magnesium to be used in fundamental studies of magnesium metabolism. All common farm roughages are moderately rich in magnesium, and wood pulp, which is low in this element, has been tested as a roughage for use in these experimental rations. American workers (Titus, 1926; Mead & Goss, 1935; Byers, Stanbus, Nelson, Brown, Davis & Gardiner, 1955; Matrone, Ramsey & Wise, 1957; Smith, McLaren, Anderson, Welch & Campbell, 1957; Ellis & Pfander, 1958; Williams, Musgrave, Schul & MacVicar, 1958) have previously used wood pulp as a substitute for roughage in the development of purified rations for cattle and sheep, and it was fed extensively as a substitute farm feedingstuff in Norway during the war years (1940–44)(Edin, Helleday & Nordfelt, 1941; Hvidsten, 1946). This note records some observations on the feeding of wood pulp, often as the sole roughage, to both dry and milking cows.
The design of equipment for producing accurate control of artificial aerial environments at low cost
- G. C. Evans
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- 27 March 2009, pp. 198-208
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An account is given of the considerations which have been found in practice to govern the design of a small cabinet for growing plants under closely controlled conditions of atmospheric environment. Starting with questions of size, shape and material, the connexion between size of chamber and type of illumination is considered, followed by general policy on air supply. The main outlines of design having been laid down in this way, the various environmental factors to be controlled are reviewed. These include: (a) composition of the air, with particular reference to carbon dioxide; (b) light intensity. Various possible sources are reviewed, and the difficulties of imitating natural conditions of illumination are discussed, together with methods of measuring the illumination and checking for stability; (c) temperature. The degree of control needed for various purposes is considered, particularly in connexion with control of humidity, followed by systems of control, and the most advantageous arrangements for them. The cycle of operations of a control system is considered in some detail, and division of the system into a small relay-operated heater and a background heating or cooling system is advocated; (d) humidity. A similar division between background and relay-operated humidifiers is also advisable, and methods of achieving this are outlined. Dew-point control is shown to be most suitable for the background humidity, while a hot wick of low thermal capacity suffices for the relay-operated device. Finally, the principal uses of such cabinets are dealt with: (a) as adjuncts to field experimentation; (b) for work on plant pathology; (c) for producing standard plant material at any time of year; and rough estimates of running costs are given.
Liquid nitrogenous fertilizers
- H. R. Jameson
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- 27 March 2009, pp. 333-338
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The results show that liquid fertilizers generally gave lower yields of dry matter than conventional solid fertilizers in four experiments on grassland. In seven trials, on autumn wheat, spring wheat, sugar beet and kale, the efficiencies of the two forms of fertilizer were similar.
Liquid fertilizers containing ammonia must be injected into the soil and this needs special equipment, more complicated, particularly where anhydrous ammonia is to be used, than the distributors used for solid fertilizers. Running the injector over established grassland sometimes resulted in considerable damage to the sward. When used to top-dress winter wheat across the line of drilling some plants were killed.