bluuebunny/crossref_metadata_2025 huggingface dataset:
The analysis of the lactation curve into maximum yield and persistency
Authors: Sanders H. G.
Published: March 2009

An attempt has been made to analyse the lactation yield into its two components, maximum yield and persistency; the latter has been defined as the ratio of lactation to maximum yield, and has been measured by a S.F. calculated from , where R is the mean ratio for the month of calving concerned.

Whilst, when corrections for external factors are applied, maximum and persistence are equally constant throughout the cow's life, these factors cause wider individual fluctuations with persistency; maximum yield is subject to a more rigid limit and may be largely determined by the area of the mammary gland, but persistency seems to be chiefly a nutritional factor—that is to say, it depends on the success of the mammary gland in competing with the other tissues of the body for the available nutriment. This leads to the view that persistency is higher in the dairy type of cow; it also appears to be associated with high constitution, for very definite positive selection is apparent with persistency, as compared to marked negative selection for maximum—this is attributed to pathological attrition falling more heavily on cows with high initial yield and low persistency.
The effect of seed rate on the yield of potatoes
Authors: Boyd D. A. , Lessells W. J.
Published: March 2009

This paper, which forms part of a series of investigations on the potato crop, presents evidence obtained from experiments reported in the literature on the relation between seed rate and yield of maincrop potatoes. The available experiments are sufficient to indicate what is the average relationship between seed rate and yield, but are insufficient to demonstrate any clear differences between different parts of the country, soil types or even different varieties.

Using this average relationship, optimum seed rates are presented for a range of prices of seed and produce. These optimal rates are compared with estimates from surveys of the actual amounts planted by growers in different parts of the country.

Provided the optimum seed rate is attained the precise combination of seed size and spacing distance appears to be of minor importance; that is, a grower should aim to plant at the optimum seed rate regardless of seed size. There is, however, an upper limit of spacing between sets which should not be exceeded however large the seed may be.

The optimum rate of planting at 1952 prices of ‘A’ or ‘H’ certificate seed is estimated to be 16–17 cwt. in most of the main potato-growing areas of the country, though it may be a little higher where a grower has a market for once-grown seed. Surveys indicate, however, that the normal planting rate of certified seed is over a ton to the acre in these districts.

For a grower's own once-grown seed, on the other hand, for which the cost is not more than the price received for ware, the optimum seed rate is at least one ton per acre, whilst the average weight of seed actually planted is only about 17 cwt. per acre. It is estimated that the average loss per acre due to this failure to plant at the optimum seed rate amounts to 20–25s. per acre planted with certified seed and 10–15s. per acre for once-grown seed.
Studies on the environmental physiology of cattle in Tanganyika I. Preliminary observations on the seasonal diurnal variations in the rectal temperature of local Zebu cattle
Authors: Hutchison H. G. , Mabon R. M.
Published: March 2009

1. Ten local Zebu cows representative of Africanowned cattle in Central Tanganyika, maintained under good African husbandry conditions, were temperatured twice daily over a period of 134 days from 23 July to 3 December, whilst the general meteorological environment was recorded.

2. The period of observations was divided into four parts, during two of which differential planes of nutrition were maintained between two groups of animals, the first and last parts being control periods when the plane of nutrition was common to all animals.

3. The diurnal variation in rectal temperature wasapproximately 99·0–102·5° F., arange of 3·5° F., whilst the atmospheric shade temperature varied about 12° F., from 64 to 76° F. at commencement of observations, and from 71 to 83° F. at the warmest period of the observations.

4. The variation within morning rectal temperatures was greater than that within afternoon rectal temperatures.

5. The low rectal temperatures in the mornings reflected inadequate nutritional level to maintain body temperature, as they were significantly increased by a moderate supplementary ration.

6. Supplementary feeding did not affect the afternoon temperatures.

7. Daily mean rectal temperature of the cows in the morning was verysignificantly negatively correlated with atmospheric temperature.

8. Rectal temperatures of ten cows' temperatures at 2 hr. intervals from 07.00 to 21.00 hr., over a period of 7 days, was positively correlated with direct sun temperatures taken 4 hr. before rectal temperatures.

9. Rectal temperatures were positively correlated with the dew-point in the morning, but were unrelated with the lower dew-point in the afternoon.

10. It is suggested that afternoon temperaturing of experimental animals of local Zebu type under African husbandry conditions might be more informative for clinical purposes than the customary morning temperaturing, owing to the lower variation.

11. It is tentatively suggested that the thermoregulatory system of local Zebu cattle may be regarded as operating a micro-adjustment mechanism to compensate for immediate variations in micro-climate, superimposed on a macroadjustment mechanism to extend the limits of operation of the micro-adjustment in accordance with seasonal trends of the macro-climate.

12. Further data are being collected to clarify these tentative conclusions.
Changes in propionate and glucose metabolism during synchronization of oestrus in ewes
Authors: Wilson S.
Published: March 2009

Propionate and glucose metabolism were compared in two groups of Scottish Blackface ewes, one in which ewes had been fitted with vaginal pessaries impregnated with progesterone-analogue for the synchronization of oestrus and the other when ewes were in anoestrus. In ewes given the same amount of feed, the production rate of propionate increased significantly (P < 0·05) from 33 in anoestrous ewes to 44 gC/day in ewes with pessaries. The proportion of glucose-carbon apparently synthesized from propionate also increased significantly (P < 0·05) from 0·31 in anoestrous ewes to 0·44 in ewes with pessaries. The proportion of glucose-carbon apparently recycled was also significantly (P < 0·01) increased from 0·12 to 0·22. No changes were observed in glucose concentration, production rate or oxidation rate between the two groups of ewes.
The efficiency of pneumatic tyred tractors under farm conditions
Authors: Russell E. W. , Hine H. J. , Keen B. A.
Published: March 2009

1. Increasing the ballast on pneumatic tyres, up to a certain weight, improves the tractor performance as judged by its speed, fuel consumption and wheel slip. Further increases beyond this point continued to decrease the wheel slip without having any marked effect on its speed or fuel consumption. No certain evidence was obtained that too heavy a ballast decreased the tractor's efficiency.

2. The tyre load affects the maximum pull the tractor can exert while working reasonably efficiently, but this pull does not depend markedly on the speed of work. Wheel weights of about 12–13 cwt. seem to be the minimum required for optimum performance of the 36 or 28 in. tyres at pulls of 1800 lb. under fairly good ground conditions, and possibly a greater weight may be required by the 24 in. tyre.

3. If the tractor is ploughing it is usually running tilted, and this tilt transfers sufficient weight on to the furrow wheel for it to work efficiently under most conditions. Additional ballast is, however, often necessary for the lighter land-side wheel.

4. Tyre performance is much less dependent on inflation pressure than on ballast. Pressures below 10 lb./sq. in. were only of use in wet conditions when small amounts of additional ballast were not available. Pressures above 12 lb./sq. in. may allow excessive slip to take place and probably only need be used on the furrow wheel of a well-loaded tractor ploughing.
Growth rate and carcass quality in bacon pigs: A study of polynomial coefficients fitted to growth rate data
Authors: Donald H. P.
Published: March 2009

1. An examination of carcass reports from two groups of bacon pigs (comprising eleven litters and seventy-five pigs) was made to determine whether the variation in growth rate of normally reared pigs was associated with differences in carcass measurements. The method adopted was to fit orthogonal polynomials to the third degree to the last 10–11 fortnightly weighings converted to logarithms.

2. The residual standard deviation after fitting was about 2–4%. For present purposes, the fitting of second degree parabolae appeared adequate.
The effects of heat treatment and protein quantity on digestibility and utilization of milk substitutes by lambs
Authors: Penning P. D. , Penning Ines M. , Treacher T. T.
Published: March 2009

The effects of heat treatment, as measured by undenatured non-casein nitrogen (NCN gN/100 g total N), and of protein: energy ratio on the digestibility coefficients and utilization of milk substitutes by lambs were investigated.

Twenty-four Finnish Landrace × Dorset Horn lambs (12 males and 12 females) were given milk substitute diets in which approximately 20 or 30% of the gross energy was supplied by protein (PE20 and PE30). NCN levels were approximately 7, 12, 18 and 5, 11, 16 for diets PE20 and PE30 respectively.

All lambs were offered a daily allowance of milk substitutes containing 7·95 MJ of gross energy from 3 to 25 days of age, when they were slaughtered and the chemical composition of the empty body was measured. Gains in the chemical components were measured using the comparative slaughter technique.

For each unit increase in NCN value there was an increase in the apparent digestibility coefficients of dry matter (D.M.), crude protein (CP) and ash of 0·13, 0·13 and 0·93 percentage units, respectively. The apparent digestibility coefficients of all the dietary components, except lactose increased by 0·24 (d.m.), 0·24 (CP), 0·63 (fat), 0·75 (ash) and 0·32 (energy) percentage units and the metabolizability by 0·24 units for each 1% increase in PE.

Live-weight and empty body-weight gains increased with increasing PE and NCN. Lambs receiving diets PE20 had a daily live-weight gain 42 g less than those on diets PE30; increasing NCN from 5 to 18 gN/100 g total nitrogen, increased live-weight gain by 33 g/day.

Increasing PE and NCN increased water gain and nitrogen retention; increasing PE also increased ash retention and decreased fat gain.

Lambs on diets PE20 contained more fat and less protein, at the same empty body weight, than those receiving diets PE30.

Efficiencies of conversion of dry matter and energy to live-weight gain, and energy and N utilization all increased with increasing NCN, but increasing PE did not affect energy utilization and decreased N utilization.

Female lambs had lower growth rates than males (—14·5 g/day) and had a higher total fat gain (128 g).
The nature of the competition between cereal crops and annual weeds
Authors: Blackman G. E. , Templeman W. G.
Published: March 2009

In continuation of earlier work, a study has been made of the factors controlling the competition between spring-sown cereals and annual weeds. During the years 1934 and 1935 some eighteen replicated trials were carried out in widely different localities. In six experiments, observations involving some 20,000 counts were made on the cereal development. Competition between Brassica arvensis (yellow charlock) and spring barley primarily reduced the number of tillers and fertile shoots; competition on the other hand with Raphanus raphanistrum (white charlock) diminished in addition ear size. The presence of R. raphanistrum in spring oats may decrease panicle size to the same extent as shoot number. In four out of six experiments the addition of nitrogen to both the weedy and clean crop had similar effects, greatly increasing tiller production in barley and both panicle size and shoot number in oats.

In six experiments nitrogenous manuring raised the yield of the weedy crop (containing either B. arvensis, R. raphanistrum or Chrysanthemum segetum (corn marigold)) to or above the level of the clean crop; n i four the yield increases were greater in the weedy than in the weed-free crop. In one experiment doubling the amount of nitrogen applied to the weedy crop did not increase the yield of oats more than the single rate, although the final yield level was considerably below that of the weed-free oats. In four other experiments additional nitrogen did not raise the yield of the weedy crop; but in only one was the yield of the clean crop increased by nitrogenous manuring.
The practical application of age conversion factors to dairy cattle production (butterfat) records
Authors: Ward A. H. , Campbell J. T.
Published: March 2009

1. From an analysis of the records from 702 cattle of predominating Jersey type tested for at least six consecutive years under normal and average herd conditions in New Zealand, the authors have attempted a detailed study of the nature of the increase in production according to age.

2. They are unable to find any evidence supporting the theory that increase in production for dairy cattle operates as a percentage addition from early age to maturity.

3. The evidence secured from an analysis of 702 Jersey records of six consecutive lactations commencing at 2 years of age, strongly suggests that the increase in production according to age can be summarized neither by a percentage addition nor a constant addition alone, but is best represented by a regression formula of the nature X = aY + b, where X equals the maturity production and Y the immature production.

4. The strict regression formula will probably change according to the interpretation of “maturity equivalent”, but in general its application should lose little of the simplicity of the ratio form of conversion.
Nutritive value of pasture: XIV. The influence on yield and composition of a single heavy dressing of sulphate of ammonia compared with that of periodic small dressings throughout the season
Authors: Woodman H. E. , Evans R. E. , Oosthuizen P. M.
Published: March 2009

This paper deals with the final phase of the investigations described in the two papers immediately preceding it in the present issue of this Journal. These earlier papers may therefore be consulted for complete details concerning the general design and wider issues of the work as a whole (Woodman & Evans, 1938a, b).
Differences in carbohydrate fractions between Lolium perenne and two tropical grasses of similar dry-matter digestibility
Authors: McLeod M. N. , Minson D. J.
Published: March 2009

Four samples each of Lolium perenne, Chloris gayana and Setaria splendida grown under similar conditions and having similar in vivo dry-matter digestibilities with sheep were used in a comparison of the chemical composition of tropical and temperate grass. L. perenne had less lignin, crude fibre, neutral-detergent fibre, acid-detergent fibre and cellulose than the two tropical grasses but more neutral-detergent solubles. In vivo digestibilities of the cell-wall polysaccharides of the tropical grasses were not reduced by their higher lignin contents. The digestibilities of the cell wall were generally higher than the digestibilities for the dry matter and neutral-detergent solubles. It is suggested that the effect of lignin on the digestibility of cell-wall polysaccharides is dependent on the area of protection, and better predictions may be achieved if the cell wall is divided into two fractions, an unlignified fraction that is completely digested and a completely indigestible fraction containing all the lignin.

It is concluded that differences may be found in the carbohydrate composition of temperate and tropical grasses but that these differences may not cause differences in the overall in vivo digestibility of the dry matter.
Stocking rate trials in Ankole, Uganda: II. Botanical analysis and oesophageal fistula sampling of pastures grazed at different stocking rates
Authors: Harrington G. N. , Pratchett D.
Published: March 2009

Botanical analyses of trials grazed at 3·6, 2·4, 1·2, 0·8 and 0·6 ha/300 kg animal for 4 years are detailed. The two heaviest grazing pressures encouraged Brachiaria decumbens, a high quality grass, at the expense of Themeda triandra and Hyparrhenia filipendula. Rotational grazing allowed the weed grass Cymbopogon afronardus to regenerate after clearing more rapidly than did continuous grazing.

Bullocks with oesophageal fistulas sampled pastures grazed at 2·4, 1·2 and 0·6 ha/animal at 4-weekly intervals for 12 months. The 0·6 ha/animal treatment was repeated on pasture cleared of the weed grass Cymbopogon afronardus. Cattle growth rates, both long term and at the time of sampling, were recorded.

Cattle growth rates were greatest at 2·4 ha/animal but fistula sampling demonstrated that the diet was significantly lower in CP and higher in CF than the more heavily stocked treatments, which is contrary to the normal pattern. It is concluded that the differences in cattle growth rates at the different stocking rates were due to differences in dry-matter intake rather than the recorded differences in diet quality. The higher CP in the diet at the heavier stocking rates is ascribed to the increase of B. decumbens in the diet.

An unexplained ceiling to cattle growth rates of ca. 0·5 kg/day, and a calculated drymatter intake of < 2·1% body weight/day, in the presence of unlimited forage of 10% CP and 55% apparent digestibility, makes it more economic to stock for maximum production per ha than per animal.
Experiments on the spacing of sugar beet: III. Further statistical considerations
Authors: Hey G. B. , Kemsley W. F. F.
Published: March 2009

1. The distribution of the total weight of beet in small areas (2 yards by 1 yard) was examined and estimates made of the effects of missing beet on the final yield, and of the yield to be obtained with various percentage plants.

2. The distribution of gaps over the field is found to be non-random. The percentage of gaps varies from block to block, but does not differ greatly between the spacings. Three methods were employed and gave consistent results.
The effect of soil characteristics on the zinc-copper interaction in the nutrition of wheat
Authors: Arora C. L. , Sekhon G. S.
Published: March 2009

A pot culture experiment was conducted on 11 soils differing in their physicochemical characteristics to study the occurrence of Zn-Cu interaction in relation to plant growth and Zn and Cu concentrations of wheat. The nature of the interaction was found to vary with the soils and the amounts of applied nutrients. The plant growth showed antagonistic interaction between Zn and Cu when one of the two elements was added in low amounts. However, when the two elements were applied in large amounts, their concentrations in the plants increased but the plant growth was adversely affected. The applied Zn generally failed to affect the uptake of native or low amounts of applied Cu whereas the applied Cu decreased the uptake of native zinc in five out of 11 soils.

The DTPA extractable amounts of Zn in experimental soils were not affected signicantly by Cu application and vice versa. The fact that the application of Zn or Cu may not affect or increase the uptake of each other may depend upon the soil characteristics and the rates of their application.
The relationship between yield and sprout length after storage in diploid and tetraploid potatoes
Authors: Maine M. J. De
Published: March 2009

An observed positive correlation between tuber sprout growth in store and yield and tuber weight was due to the association of short sprouts with small tubers (less than 75 g). Sprout growth in larger tubers appears to be unaffected by tuber weight.
The phosphorus requirement of lettuce
Authors: Smith R. , Scaife M. A.
Published: March 2009

The optimal intensity of P supply for lettuce was investigated in a pot experiment with five soils, six levels of P application (0, 15, 30, 60, 120, 240 ppm) and three times of harvest (2, 3 and 4 weeks after emergence). The P adsorption isotherm for each soil was measured in 0.01 M CaCl2.

All soils responded strongly to P application, the amounts required for maximum growth varying from 120 ppm on a sandy soil to 300 ppm on a moss peat. The differences in requirement were related to the P adsorption by the soil, and on all soils a solution P concentration of about 1 ppm resulted in maximum growth.

The Optimal leaf P concentration in young lettuce was about 0·6%.
Formic acid as a silage additive for wet crops of cocksfoot and lucerne
Authors: Wilson R. F. , Wilkins R. J.
Published: March 2009

Crops of lucerne and cocksfoot of high moisture content were ensiled without additive and with the addition of formic acid at up to 0·91% of the fresh crop weight in test-tube silos and in silos containing about one tonne of crop. Silages from the larger silos were fed to sheep for measurement of voluntary intake and digestibility.

Silages made without formic acid were badly preserved and contained large quantities of acetic acid, butyric acid and ammonia. The addition of formic acid reduced the production of acids and ammonia. With test-tube silos differences between the minimum pH measured during the storage period and the final pH after 155 days were not significant for silages made from both crops with addition of 0·45% or more of formic acid: these silages were considered to be stable.

Silages from the larger silos were generally not as well preserved as those from the test-tube silos, particularly at the higher levels of formic acid application. This difference was attributed to less effective application of additive to the larger silos and loss of formic acid in the effluent which was released from these silos but not from the test-tubes. Organic matter intake increased with increase in formic acid level, but organic matter digestibility was not significantly correlated with formic acid levels. Intake was closely related to the quantity of ammonia in the silage and it is argued that formic acid affected intake by influencing the pattern of fermentation in the silo rather than by a direct effect of formic acid itself.
A comparison of ryegrass populations from intensively managed permanent pastures and leys
Authors: Charles A. H.
Published: March 2009

Ryegrass populations collected from intensively used swards, both leys and permanent pastures, were compared under spaced plant and sward conditions.

On average, the bred ryegrasses were higher yielding, more resistant to crown rust, and more persistent under intensive conditions than the permanent pasture populations, but there was no significant difference in cold-resistance between these two groups.

The potential yield of dry matter of the best of the permanent pasture populations was similar to that of the highest-yielding leys. Several of even the most intensively used pastures were, however, dominated by ryegrass that was not nearly as high yielding as the best of the bred varieties. In addition to differences in yield of dry matter, there was a wide range in persistency, resistance to low temperature and crown rust (Puccinia coronata), as well as in mean date and variance of inflorescence emergence and in yield of digestible organic matter in dry matter (DOMD). Thus, no one type of ryegrass could be associated with permanent pastures, even when the sample was restricted to a narrow range of managements associated with intensive use.

Some of the highest-yielding swards were based on complex mixtures of ryegrass cultivars; this might give rise to difficulty in relating management to stage of maturity and in predicting the composition of the sward established.

A comparison of survivor material derived from S·23 leys revealed no difference in yield of dry matter or DOMD under sward conditions. Other data, however, showed that the populations differed in yield as spaced plants, rust resistance, cold-hardiness, persistency and date and variance of inflorescence emergence.

There was no indication of ryegrass yield decreasing with the age of the ley from which the plants were derived.
The yield and composition of the milk of Finnish Landrace × Blackface ewes: II. Ewes and lambs grazed on pasture
Authors: Peart J. N. , Edwards R. A. , Donaldson Elizabeth
Published: March 2009

The milk production of 14 Finnish Landrace × Blackface ewes suckling either single, twin or triplet lambs was recorded while they were wholly maintained on a high-quality grazed pasture. Intravenous administration of oxytocin followed by hand milking was used to estimate milk production within 4 days of parturition and then at weekly intervals during a 12-week lactation period. At each milking the milk from each ewe was retained for analysis. Herbage samples for analysis were cut by hand shears at weekly intervals at a height simulating the harvesting by the sheep. In vitro analysis showed a decline in the digestible organic matter in the herbage from approximately 75% in the early stages, to around 67% at the end of lactation. The percentage crude protein in the dry matter of the herbage was variable but tended to increase towards the end of the lactation period. The estimated mean total milk production values were 125, 176 and 193 kg for single-, twin- and triplet-suckled groups of ewes, respectively. Almost all of the difference in total yield between the groups of multiplesuckled ewes occurred in the first 4 weeks of lactation. Analysis of variance showed no significant differences between suckling groups in the concentration of any of the milk constituents. Regression analysis showed significant evidence for differences between the linear and quadratic components of the regressions on stage of lactation for the suckling groups only in respect of daily milk yield, energy and protein production. The concentration of constituents other than lactose was higher in colostral milk but the differences were statistically significant only in respect of energy, total solids and fat. The lactose content of ordinary milk was significantly higher than that of colostral milk. The mean daily live-weight gains of the single- and twin-suckled lambs were significantly greater than that of the triplet-suckled group.
Thiomolybdates and the copper–molybdenum–sulphur interaction in ruminant nutrition
Authors: Dick A. T. , Dewey D. W. , Gawthorne J. M.
Published: March 2009

In 1945 we reported (Dick & Bull, 1945) the first observations on the effects of molybdenum in the diet of ruminants in limiting the accumulation of copper in their tissues.

Further observations (Dick, 1952) indicated that there was a third factor which materially altered the control by molybdenum of copper accumulation and this factor, present in lucerne hay, was identified as inorganic sulphate (Dick, 1953a). It was also shown that sulphate regulated molybdenum excretion (Dick, 1953b) in the urine and hence the level of molybdenum in circulating blood (Dick, 1953c).
Changes induced by cowpea green manure and farmyard manure in the timing of phenological events in maize (Zea mays)
Authors: Aggarwal G. C. , Sekhon N. K.
Published: March 2009

The effect of cowpea green manure (CGM) and farmyard manure (FYM) on phenological events in maize grown with different rates of nitrogen (N) was evaluated at Ludhiana, India in 1988–89 as part of a long-term experiment on sandy loam. Tasselling (T), anthesis (A), silking (S), maturity (M) and appearance of leaves were recorded in 1988 and 1989 from plots of maize manured with cowpea and FYM and grown at 0, 75 and 125 kg N/ha. Time to phenological events was calculated in terms of calendar days and growing degree units (GDU).

Phenological events in maize were significantly advanced by CGM, FYM and N. The occurrence of T, A and S with CGM was earlier by 60·5, 84·5 and 114·5 GDU, respectively, than without it and the end of each of the growth stages T, A and S was advanced by 81·0, 99·0 and 78·5 GDU, respectively. Maturity was earlier than in the control by 65·0 GDU. Leaf emergence occurred earlier after organic manuring. Farmyard manure advanced development less than CGM. Changes in phenological events due to N followed the same pattern of changes as those found with organic manures. Time from sowing to onset of T, A, S and M, and the interval between T, A, S and M were significantly correlated with yield and yield-related characters. Desirable changes in the timing of phenological events are thus one of the factors contributing to the improvement in productivity caused by organic manures. Calendar day was found to be as accurate an index as GDU for evaluation of the effect of cultural practices on phenological events.
The effects of soil type on the early growth of lettuce
Authors: Costigan P. A.
Published: March 2009

Large and consistent differences in growth rate of lettuce on different soils were recorded in two consecutive experiments in which lettuce cv. Avondefiance was grown for about 4 weeks in miniplots of 13 different soils. The miniplots were 20 cm in diameter and 20 cm deep and were buried flush with the soil surface at a single site. Each soil received the recommended amount of fertilizer and only seedlings emerging on a particular day were allowed to grow on. The relative performance of the different soils was very similar in each of the experiments with the plants in the best soil being 2·2–3·3 times heavier than those on the worst soil by the end of the experiments. The relative growth rates (RGR) of the plants were positively correlated with % P in the plants (accounting for 44–68% of the variation in RGR) and in turn with the availability of P in the soil. There was also a negative effect of soil organic matter on RGR, acting independently of % P, so that a multiple regression with % P and organic matter accounted for 65% of the variance of RGR in Expt 1 and 75% in Expt 2. Soil solution phosphorus appeared to be a useful measure for assessing phosphorus availability as plant growth was reduced only when concentrations fell below about 1 μg/ml.
Optimum sowing date and nitrogen fertilizer rate for rice varieties under intermediate deepwater conditions (15–50 cm)
Authors: Sharma A. R. , Reddy M. D.
Published: March 2009

In an intermediate deepwater situation (15–50 cm) at Cuttack, India, three improved high-yielding rice varieties, Utkalprabha (semi-tall), CR 292–8051 (intermediate tall) and Gayatri (semi-dwarf) were sown on 20 May, 30 May and 10 June in 1988 and 1989 with an application of either 0, 20 or 40 kg N/ha at sowing. Tall varieties performed better than the dwarf type but grain yield decreased with delay in sowing. The early-sown crops (20–30 May) germinated with pre-monsoon rains and were established well before water accumulated in the field from mid-June onwards. The late-sown crops (10 June), despite good initial germination, could not withstand immediate waterlogging. The tall variety, Utkalprabha, elongated faster with rising water level and escaped complete submergence; whereas the semi-dwarf Gayatri failed to withstand such extreme excess water stress. Application of N fertilizer up to 40 kg/ha proved beneficial to the crops sown by the end of May. However, with crops sown on 10 June, the application of N could not compensate for the loss in yield due to an inadequate initial crop stand. Therefore, early sowing of tall varieties by the end of May along with a basal application of N fertilizer is recommended for higher productivity of rice under excess water conditions.
Growth and metabolism studies in growing pigs given diets containing a low glucosinolate rapeseed meal
Authors: Rowan T. G. , Lawrence T. L. J.
Published: March 2009

Two growth and two metabolism experiments were made in which a low gluoosinate rapeseed meal (var. Tower; TRSM) was compared with soya-bean meal (SBM) as the sole protein-rich material in simple diets containing barley and a vitamin and mineral supplement only.

In the first growth experiment 108 pigs were fed individually and restrictedly SBM and TRSM diets so that digestible energy (DE) and crude-protein intakes were similar. The DE used to promote a unit of growth or a unit of carcass weight was significantly less for the SBM, than for the TRSM, diet. In the second experiment 48 pigs were given, in groups of four, diets similar to those in Expt 1. There were no significant differences in growth rate or in serum thyroxine concentrations, but a significantly higher degree of thyroid hypertrophy was induced in pigs given the TRSM diet.

The two metabolism experiments compared the same diets used in the first growth experiment. Apparent digestibility of dry matter, nitrogen and gross energy, and retention of nitrogen relative to intake, were significantly greater for the SBM diet than for the two RSM diets. The addition of synthetic lysine to the TRSM diet significantly improved the apparent digestibility and retention of nitrogen. Pooled DE values (MJ/kg dry matter) calculated for SBM, TRSM and barley were 13·72 (S.E. 0·318), 13·97 (S.E. 0·211) and 14·01 (S.E. 0·080) respectively.
Effects of defoliation and time of harvest on tuber dry-matter percentage of Pentland Crown Potatoes
Authors: Wilcockson S. J.
Published: March 2009

Two experiments are reported which investigated the effects of time and method of crop defoliation and of extending the interval between defoliation and harvest on the relationship between dry-matter percentage and tuber size in Pentland Crown potatoes.

Differences in average tuber dry-matter content between seasons and treatments were large, but the relationship between tuber dry-matter percentage and tuber size was always negatively quadratic. The dry-matter content of tubers of all sizes invariably decreased after defoliation, by about 0·6 % on average for each week that harvest was delayed in 1983 and 0·3 % in 1984. The largest decrease was from 22·7 to 16·7 % over the 10-week period following mechanical defoliation in mid-August 1983. In 1984, chemical defoliation in mid-August gave a smaller decrease than the mechanical method (0·25 and 0·38%/week) but their effects were similar when carried out in mid-September. Water uptake was the main factor responsible for the decrease because evidence showed that fresh weights of tubers increased proportionally following defoliation whilst dry weights remained virtually constant.

Natural senescence was late in both seasons experiments so that the crops foliage was still mostly alive when defoliation occurred, even in September and early October. Thus, the relatively large effects of late defoliation may have been greater than might be expected where haulm senescence is already well advanced by this time and water uptake has almost ceased. Nevertheless, the decline in dry-matter percentage which may occur between defoliation and harvest can be extremely important where potatoes for processing are concerned. It could make them unacceptable for particular outlets and should be considered when defoliation and harvesting programmes are planned.
Effects of underfeeding and of fish meal supplementation on forage digestion in sheep
Authors: Kabré P. , Doreau M. , Michalet-Doreau B.
Published: March 2009

The effects of severe food restriction and of protein supplementation on the apparent digestibility of a forage were studied on 12 wethers in 1992 at INRA, Theix. Ruminal digestion of the forage cell walls was studied in a second experiment carried out on four ewes fitted with rumen and duodenal cannulas, receiving the same diets as the wethers. The animals were fed on two different hay-based diets: hay only (58 or 25 g/kg BW0·75 per day) or hay supplemented with fish meal (48 or 20 g hay with 6·5 and 3·0 g fish meal respectively per kg BW0·75). The effects of fish meal supplementation on apparent digestibility of the hay cell walls were small, + 1·8 and + 2·3 units for neutral detergent fibre (NDF) and acid detergent fibre (ADF) respectively. In contrast, NDF and ADF digestibility was respectively 4·0 and 4·7 units higher at low than at high intake. Rumen fluid volume decreased by 2·4 1 with decreasing intake, while water concentration in rumen content increased slightly from 89·8 to 91·8%. The mean retention time of the hay particles in the foreguts increased concomitantly from 39·5 to 55·1 h. This was achieved by a higher retention time to a similar extent in both slow and fast compartments. The calculated in situ degradability of NDF and ADF increased respectively by 12·1 and 13·1 units with decreasing intake. This reflected the lower fractional outflow rate recorded at low intake. If a fractional outflow rate value of 4·1%/h (as measured in high intake diets) was applied to all dietary treatments, NDF and ADF in situ degradability would be greater at low than at high intake (31·7 v. 26·6% for NDF; 27·9 v. 22·1 % for ADF), indicating a higher microbial activity in restricted diets. Interactions between intake and fish meal supply were detected for in situ degradation parameters, indicating principally a reduction of the cell wall undegraded fraction in supplemented diets when intake declined. Ruminal fermentation was modified by the dietary treatments, the acetate: propionate ratio being higher at low intake. Fish meal increased concentrations of ammonia and of isoacids in rumen liquid. The relationship between apparent digestibility and in situ degradability of plant particles is discussed.
Effects of nitrogen applied through new carriers on yield and quality of sugarcane
Authors: Yadav R. L. , Kumar R. , Verma R. S.
Published: March 2009

In a field experiment at Lucknow in 1985/87 and 1986/88, the ‘new’ N carriers urea super granules (USG), neem-cake-coated urea (NCU) and dicyandiamide-treated urea (DCD) and the traditional source of N, prilled urea (PU), were used to supply 150 kgN/ha to the plant crop (first crop after planting) of the cultivar Col 148. The ratoon crop was fertilized at 0 and 150 kgN/ha with PU over all the plant crop treatments. In both plant and ratoon crops, N application increased cane yields but decreased quality: differences in yield resulting from use of the new carriers were not significant, though the fertilizers tended to increase the final plant population density. Uptake and recovery of N were significantly greater using USG, NCU and DCD than using PU. The direct effect of N was 184 kg cane/kg of N applied to the ratoon crop but residual and cumulative effects of N applied to the plant crop on yield and quality of the ratoon crop were small. Adequate direct application of N is therefore suggested for increasing the yields of ratoon cane.
Stimulation of root growth and soil nitrogen uptake by foliar application of urea to wheat and sunflower
Authors: Sen S. , Chalk P. M.
Published: March 2009

Wheat and sunflower plants were grown in a temperature-controlled glasshouse in Melbourne, Australia (37° 50′ S, 145° 00′ E), from 9 August to 2 October 1991, in cylinders containing two soils (Walpeup loamy sand (LS) and Gombalin clay loam (CL)) of low and moderate N status, respectively. Nitrogen fertilizer was applied by immersion of leaves in 0·18 M urea solution (10·5 atom%15N).

Plants were N-deficient in the Walpeup LS but not in the Gombalin CL soils. Both species had higher root: shoot ratios, and higher proportions of foliar-absorbed N were transferred to the roots, in the Walpeup LS plants. Plant N derived from the fertilizer and root or shoot dry matter were significantly correlated only when plants were N-deficient.

In the Walpeup LS soil, N-fertilized wheat harvested 33 days after sowing (DAS) took up significantly less soil N compared with unfertilized plants, whereas significantly more soil N was taken up by N-fertilized sunflower compared with unfertilized plants harvested at 54 DAS. The fertilizerinduced response in uptake of soil N was directly related to the observed response in production of root biomass for both species. The different responses were related to the severity of the N deficiency and the limited effectiveness of foliar applications of urea in ameliorating the deficiency.
The effects of radiation and nitrogen on number of grains in wheat
Authors: Abbate P. E. , Andrade F. H. , Culot J. P.
Published: March 2009

The possible interacting effects of shading and N supply on number of grains ofTriticum aestivumL. (cv. Buck Ñandú) were investigated at Balcarce, Argentina, during the 1988/89 and 1989/90 growing seasons. Shading was imposed fromc.13 days before anthesis to 6 days after, and four rates of N fertilization were supplied within each shading treatment around the date of terminal spikelet formation. Water and other nutrients were not limiting.

Total grain yield was strongly correlated with grain number/m2, regardless of shading or N supply. At the highest N rates, grain number and dry weight of spikes at anthesis were linearly related to a photothermal quotient, i.e. the ratio of intercepted photosynthetically active radiation (PAR) to mean temperature minus 4·5 °C, during the period from 20 days before anthesis to 10 days after. The response of grain number to the photothermal quotient was interpreted in terms of the supply of assimilates to the spike at anthesis, which determined flower survival. The response of dry weight of spikes to photothermal quotient was interpreted in terms of crop growth rate since there was a linear relationship between crop growth rate and intercepted radiation. The lowest N rates reduced the number of grains/m2, at any given photothermal quotient. Since the reduction in grain number also occurred at any given dry weight of spikes, it cannot be explained by a reduced supply of assimilates to the spikes. Grain number responded directly to the supply of N to the spike, probably through the survival of differentiated flowers. The relationship between spike growth rate and crop growth rate was not affected by N supply. Crop growth rate was reduced by reduced N supply, because less radiation was intercepted and because radiation-use efficiency was lowered. These results indicate that current models for determining yield and number of grains/m2, based on crop growth, are not adequate when N is deficient.
Sugarbeet seedling growth from germination to first leaf stage
Authors: Durr C. , Boiffin J.
Published: March 2009

The growth of sugarbeet (Beta vulgaris L.) seedlings was investigated under laboratory conditions in 1990 and 1991. Three phases were identified during heterotrophic growth in the dark, based on the changes in dry weight, carbon and nitrogen contents. The perispermic reserves were first transferred to the young seedling. All the components of the seedling (cotyledons, hypocotyl, radicle) began to elongate and their dry weights increased. The seedling separated from the seed at the end of this first period, 4 days after imbibition had started at 20 °C. During the second period, there was a major redistribution of material between organs, mainly from cotyledons to the hypocotyl. The different organs elongated rapidly. From the start of the third period, 6 days after sowing at 20 °C, the organs began to lose weight and gradually ceased to elongate. The dry weights of the whole seedlings and of each organ were proportional to the initial seed weights. The elongations and changes in dry weights obtained at different temperatures coincided when time was expressed as thermal time using a base temperature of 3·5 °C. The growth of the seedling after illumination depended on the heterotrophic growth duration. If emergence occurred after 100 °Cd, the relative growth rate of the seedling decreased. In field conditions, plant variability at the end of sugarbeet establishment is due not only to variations in seed weights but also to environmental conditions that control emergence delay.
Edge effects on yield, yield components and other physiological characteristics in cereals and oilseed crops
Authors: Hadjichristodoulou A.
Published: March 2009

The edge effect (calculated as the mean of the two outer rows as a percentage of the mean of the four central rows of 6-row plots) was measured in ten comparative trials conducted in Cyprus during 1987–90, with two cultivars each of rapeseed, safflower and sunflower, and one cultivar each of barley and durum wheat. Grain, straw and total biological yields obtained from the outer rows were usually higher than those obtained from the central rows by 1–384%. In one trial with sunflower, the grain yield of the outer rows was only 64% of that of the central rows, which could not be explained, considering all the other data. Differences in edge effects between species and trials were significant. Grain yield estimated from the central rows was on average 53% of that estimated from whole plots, and this varied with species and season. Therefore, in comparative trials, the outer rows should be removed before harvesting. There was no significant edge effect on the oil content of the oilseed crops. Edge effects on harvest index, volume weight, 1000-grain weight and nitrogen content were generally smaller than those on yield, and on average ranged from 100 to 113, thus the values computed from the outer rows were only 0–13% higher than from the central rows.
Proceedings of the Twenty-Sixth Meeting of the Agricultural Research Modellers' Group
Authors: France J.
Published: March 2009

This group, which is concerned with the applications of mathematics to agricultural science, is sponsored by the Biotechnology and Biological Sciences Research Council. It was formed in 1970, and has since met at approximately yearly intervals in London for one-day meetings. The twenty-sixth meeting of the group, chaired by Professor R. J. Wilkins of the Institute of Grassland and Environmental Research, North Wyke, was held in the Wellcome Meeting Room at the Royal Society, 6 Carlton House Terrace, London on Friday, 7 April 1995, when the following papers were read.
Effect of species composition and sward structure on dietary quality in cattle and sheep grazing South African sourveld
Authors: O'Reagain P. J. , Owen-Smith R. N.
Published: March 2009

The effect of sward structure and species composition on dietary quality in cattle and sheep grazing a mesic, low quality grassland (sourveld) in South Africa was investigated over the 1990/91 and 1991/92 grazing seasons. Species composition had no measurable effect on dietary quality in either cattle or sheep but this variable could affect quality over grazing periods longer than those used in the study. In contrast, sward structure, and in particular sward greenness, had a major effect on dietary quality in both animals. Dietaryin vitrodigestibility (IVD) was positively correlated (P< 0·001) with sward greenness but negatively correlated (P< 0·05) with herbage mass and sward height. Dietary IVD in sheep was consistently higher (P< 0·001) then in cattle but both species reacted in a similar manner to changes in sward structure and season. Dietary quality declined over the grazing season, with IVD being highest in spring (> 60%) and lowest in winter (< 45%). Marked intra-seasonal fluctuations in quality also occurred in response to sward structure and apparent variation in soil moisture. Fire also appeared to have a significant effect on quality, with IVD being higher (P< 0·001) in the first year following the burn than in the subsequent year. It is suggested that on sourveld, dietary quality in the growing season is determined by a combination of environmental and management factors. Conversely, in the dormant season, dietary quality is largely determined by environmental factors beyond the control of the grazier.
Designs for controlling interplot competition in variety trials
Authors: David O. , Kempton R. A. , Nevison I. M.
Published: March 2009

Interplot competition in crop variety trials leads to biased estimates of variety differences. Modified alpha designs are proposed which aim to control competition by restricting the randomization so that adjacent varieties show similar competition effects. The designs are available in the computer program Alpha +.