bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of cotton to nitrogen and water in a tropical environment. III. Fibre quality
Authors: Hearn A. B.
Published: March 2009

In two experiments three dates for time of last irrigation were combined factorially with four rates of application of nitrogen fertilizer and two varieties of cotton. Early termination of watering (when the crop had set 70 bolls/m2) combined with heavy application of nitrogen (168and225 kg/ha) decreased fibre strength, micronaire and yarn strength, particularly in 1973. In two other experiments three frequencies of watering were combined factorially with several rates of application of nitrogen. Frequent watering (weekly) combined with heavy application of nitrogen (168 kg/ha) decreased uniformity of fibre length, micronaire and yarn strength and appearance. In both experiments application of nitrogen increased fibre length. The responses of both varieties were similar except for effect of nitrogen on micronaire. Application of nitrogen decreased the micronaire of Deltapine 16 more than that of Acala 1517 BRI.

The response of the fibre properties to variation in crop nitrogen and water supplies are interpreted in terms of the effects of these factors on (i) the intrinsic fibre properties of bolls maturing at the same time, (ii) the change in the fibre properties of bolls maturing progressively later in the season, (iii) the proportion of total yield contributed by bolls maturing at different times and (iv) delay in harvest and consequent variation in exposure to weather prior to harvest. Yarn strength did not respond as much as fibre properties to the experimental treatments and in particular did not reflect the influence of weathering on fibre properties to the degree anticipated.
Net assimilation rate of cotton in relation to spacing
Authors: Bhatt J. G. , Shah R. C. , Sharma A. N.
Published: March 2009

The net assimilation rates (NAR) of three genotypes of cotton differing in their growth habit were studied under different spacings. The NARs of a very bushy type, G 67, and a comparatively less spreading type, IAN 560, were the same but that of a compact type, IAN 579, was twice as much when the leaf area index (LAI) was one. Though subsequently in G 67 and IAN 560 NAR under varying spacings either decreased less rapidly or remained steady, the decrease was nearly Hnear with increasing LAI. However, for IAN 579 dependence of NAR on LAI was generally positive indicating genotypic improvement. Under different spacings the leaf-density dependance of NAR appeared to have been decreased in IAN 560, but was nearly absent in IAN 579 with more efficiency towards increasing the yield of seed cotton.
The effect of herbage allowance on herbage intake and performance of lambs grazing perennial ryegrass and red clover swards
Authors: Gibb M. J. , Treacher T. T.
Published: March 2009

The effect of daily herbage allowance on herbage intakes and growth rates lambs grazing perennial ryegrass and red clover was investigated in two experiments. Herbage allowances defined as g herbage D.M./kg live weight (LW)/day were controlled by varying the areas of plots grazed for 2 days by groups of six lambs.

In the first experiment five herbage allowances in the range 20–120 g D.M./kg LW/day were offered on two areas of a perennial ryegrass (cv. S. 23) sward that received nitrogen fertilizer applications of 39 or 78 kg N/ha/28 days. In the second experiment five herbage allowances in the range 30–160 g D.M./kg LW/day were offered on perennial ryegrass (cv. S. 23) and red clover (cv. Hungaropoly) swards.

Asymptotic curves were fitted to describe the relationship between herbage allowance and daily intake of herbage. In Expt 1 nitrogen fertilizer rates did not affect the yield of herbage or animal performance. In Expt 2 intakes were higher on the clover sward than on the ryegrass sward at the higher herbage allowances.

The asymptotic curves to describe the relationship between herbage allowance and growth rate of lambs differed widely between periods. Growth rate of the lambs increased linearly with increase in digestible organic matter intake. Live-weight gain per unit of digestible organic matter intake was higher on the red clover than on the ryegrass.

The conclusion is drawn that if the herbage present to ground level is not more than three times the daily intake of the animals, intake of herbage of the animals may bo restricted.
The nutrition of the early weaned lamb. IV. Effects on growth rate, food utilization and body composition of changing from a low to a high protein diet
Authors: Ørskov E. R. , McDonald I. , Grubb D. A. , Pennie K.
Published: March 2009

About sixty male lambs were fed ad libitum from 6 weeks of age on low- or highprotein diets based on barley or barley and fishmeal and containing respectively 120 and 200 g crude protein/kg dry matter. Some lambs were changed from one diet to the other when they reached 28 kg live weight. All were slaughtered as they attained a predetermined series of live weights ranging from 20 to 75 kg.

Throughout the experiment, rates of live-weight gain were substantially higher with the high-protein (HP) than with the low-protein (LP) diet, but were highest after a change from low to high protein (LHP). The feed consumption of the LHP lambs did not exceed that of the HP lambs, but the former showed a substantial superiority in feed conversion ratio at the same live weight.

At similar empty body weights, the LP lambs contained more fat and less water in the empty body than the HP lambs. Although the percentage differences decreased at higher weights, differences were still apparent at 70 kg live weight.

The LHP lambs showed dramatic and rapid changes in body composition, particularly in water and fat content. By 40 kg live weight, their composition approached that of the HP lambs.

The ratio of water to protein was consistently lower for the LP lambs. The ratio of protein to ash also differed between LP and HP lambs. It was initially highest for the HP lambs, at about 40 kg live weight it was the same, and at 70 kg live weight it was highest for the LP lambs.

The ash content of the LHP lambs remained virtually constant during the period of rapid growth and rapid deposition of water, protein and fat which took place immediately after the change of diet, and only showed compensatory increases after 35 kg live weight. This finding was supported by the pattern of changes in weight and specific gravity of the femur and tibia + fibula.

Use was made of separate relationships between live weight and body composition for the LP, HP and LHP lambs to estimate rates of accretion of crude protein, fat and water in the empty body. There was a particularly striking increase in the rate of accretion of water immediately following the change of diet. There was an increase in the water content of empty-body gain and a reduction in the ratio of gain in fat to gain in protein.

Derived estimates of the ratio of metabolizable energy intake above maintenance to the energy content of empty-body gain gave some suggestion of an improvement in efficiency of utilization of metabolizable energy for gain following the change from low to high protein. It is concluded however that the improvement in food conversion ratio following the change is attributable mostly to difference in the composition of gain.
Evaluation of the phosphorus status of some coconut-growing soils of Sri Lanka
Authors: Loganathan P. , Dayaratne P. M. N. , Shanmuganathan R. T.
Published: March 2009

The phosphorus status of 58 soil samples representing 15 soil series and four soil Orders (Ultisol, Entisol, Alfisol and Oxisol) in the major coconut-growing regions of Sri Lanka was evaluated by determining the available P extracted by the methods of Olsen, Bray & Kurtz No. 1, Bray & Kurtz No. 2 and NH4OAc (pH 4·8) and the various P forms. Total P in the soils ranged from 37 to 338 mg/kg with organic P and active P constituting only about 20 and 50% of the total P respectively. In general the sandy soils of the Entisols and Oxisols had lower total and organic P but higher active and available P than the rest. The relative abundance of the various inorganic P forms was generally in the decreasing order of inactive P, Fe-P, Al-P and Ca-P. Al-P and Ca-P were positively correlated with percentage sand and negatively correlated with percentage silt and percentage clay whereas total P and organic P had the opposite trend. Available P extracted by the four methods was very low in almost all soils except some of the sandy soils (Entisols) which had marginal to moderate P contents. They were positively correlated with Al-P, Ca-P, percentage sand and negatively correlated with percentages of silt, clay and organic carbon.

Phosphorus concentrations (0·074–0·116%) in the 14th leaf of coconut at the soil sites were all lower than the critical leaf-P concentration (0·120%). Leaf-P correlations with Bray & Kurtz No. 2-P and NH40Ac-P were significant (P < 0·05) and with Al-P and Ca-P were close to significant.

The study revealed that the coconut-growing soils of Sri Lanka were deficient in total as well as the active and available forms of P except perhaps some of the sandy soils of the Entisol. This was confirmed by coconut leaf P analysis.
Free amino-nitrogen exchange across the hindquarters of fed and fasted sheep and pigs
Authors: Chalmers Margaret I. , Grant I. , White F.
Published: March 2009

Free amino·N estimations were used to monitor the movement of free amino acids in blood passing through the hindquarters of sheep and growing pigs. The net uptakeor release of free amino·N was calculated from arterio-venous differences in the concentration of free amino·N measured in whole blood and plasma at short intervals of time.

In both species the net change was an apparent release of free amino·N into venous blood. The release increased on fasting. Net uptake of free amino·N from blood was occasionally found at single sampling times due to loss from the cell compartment in sheep and from the plasma compartment in pigs. The uptake measured in whole blood was always less than in a single compartment of blood. The greatest fluctuation in free amino·N concentration occurred in the cells of aorta blood.

It is concluded that both blood cells and plasma have independent roles in the net flux of free amino·N requiring determinations of amino acids in both whole blood and plasma to describe the exchange of blood free amino acids with tissue. A negative arteriovenous difference of free amino·N in blood across skeletal muscle is normal for healthy well-fed animals. Fasting increases the negativity.
A comparison of growing wheat continuously with growing wheat in a four-course rotation
Authors: Ridgman W. J. , Walters D. E.
Published: March 2009

The design and analysis of an experiment to compare the yield of wheat grown continuously with that of wheat grown in two phases of a four-course rotation is described and the results discussed. A method of analysis which avoids making assumptions about the covariance structure of the errors derived from repeated observations on the same plots, which could be appropriate to other sorts of rotation experiments, is given.

There were no differences between yields of the first and second wheat crops which followed oats after beans in a four-course rotation, but the average of these two crops was 0·75 t/ha greater than the yield of wheat grown continuously. The response to N was the same in the two systems of cropping. The only yield component affected by the system of cropping was grain mass.
An attempt to improve the yield and quality of direct-drilled winter wheat grown continuously
Authors: Holbrook J. R. , Osborne J. D. , Ridgman W. J.
Published: March 2009

Six field experiments on the effects of rate and time of application of nitrogen, three variety trials and one trial combining varieties with rates of application of nitrogen, all on winter wheat grown continuously and direct-drilled on a single farm, are described and the results discussed.

The experiments showed that worthwhile yield responses could be obtained to very high rates of N application and that percentage protein in the grain increased linearly with amount of N supplied even to the highest rate (350 kg N/ha) applied. The effects of time of application were variable but there was a suggestion that applying the nitrogen in two doses in the spring gave more yield than a single dose, in one experiment. Applying some N in the autumn gave no more yield than applying it all in the spring.

The variety trials gave results reasonably consistent with those of the National Institute of Agricultural Botany but the variety x nitrogen trial showed clear differences between varieties in response to nitrogen; the oldest variety, Maris Huntsman, showed a maximum at about 240 kg N/ha whereas none of the new varieties had reached their maximum by 270 kg N/ha.

It is argued that field trials devoted to improving crop yields for a particular farm are worthwhile if site x treatment interaction is large and season x treatment interaction is small.
Microbiological and chemical changes in the rumen during the stepwise adaptation of sheep to high concentrate diets
Authors: Mackie R. I. , Gilchrist Frances M. C. , Robberts Anna M. , Hannah P. E. , Schwartz Helen M.
Published: March 2009

A stepwise adaptation was carried out on eight sheep through diets containing 10, 24, 44, 60 to a final diet containing 71% maize meal and molasses. The numbers of protozoa in the rumen increased in proportion to amount of readily fermentable carbohydrate fed, up to and including the 60% grain and molasses diet, while the numbers of total culturable bacteria remained essentially constant. However, the proportions of amylolytic and lactate-utilizing bacteria increased, and there was an orderly shift from acid-sensitive to more acid-tolerant species, particularly amongst the lactate-utilizers in response to the gradual decrease in the ruminal pH. Up to this stage the protozoa probably controlled the rate of fermentation by engulfing starch grains and bacteria and were thus able to maintain the pH of the rumen above 5·5. Lactic acid appeared only transiently and the peak values tended to diminish as adptation progressed.

The first day the final diet was fed the ruminal pH decreased to 5·4 or below for several hours. Within 7 days the number of protozoa had decreased by 50–80% and the number of total culturable bacteria increased sharply. Conditions in the rumen became unstable: peak values of D- and L- laotic acid increased by ca. 0·5 HIM, the acetate/propionate ratio decreased to ca. 2 and peak glucose concentration increased t o 3·2–9·5 mM. One animal refused all food for 1 day. Acid-tolerant species of lactate-utilizing bacteria multiplied rapidly in response to the increased production of ruminal lactic acid and the ratio of amylolytics to lactate-utilizers decreased from a mean of 10·7 to 3·6. This controlled the increase in lactic acid and the decrease in ruminal pH, allowing the ciliate protozoa to proliferate and regain control of the fermentation.

The types of cellulolytic bacteria did not change during the experiment. Despite their acid sensitivity, the number of cellulolytic bacteria per gram of ingesta was of the same order after 54 days on the 71% grain and molasses diet (0·5–13·3 × 107) as on the initial high roughage diet (3·2–7·6 × 107).

Three sheep which bloated showed no marked chemical or microbiological differences from the non-bloating animals.
Studies on the breeding season of Icelandic ewes and ewe lambs
Authors: Dýrmundsson Ø. R.
Published: March 2009

The paper reports on a study, conducted in four successive seasons, of sexual development and breeding activity in females of the Iceland breed, the only breed of sheep kept in the country. The ewe lambs normally attained puberty in their first year of life, on average at 7 months of age, with marked individual variation in both age and body weight at first oestrus. Ewe lambs always showed oestrus on average slightly later than mature ewes (2–9 years), the mean date of onset of the breeding season of the latter being 8 December, however, with considerable individual variation. Furthermore, ewe lambs had a shorter breeding season (1–4 months) than ewes (4–6 months) and they appeared to experience more silent heats resulting in less regular cyclic activity. There seemed to be a minor increase in the duration of the oestrous cycle with age and ewe lambs clearly exhibited shorter oestrus (heat) than ewes. With seasonal breeding activity ranging from November to May the mid-breeding season occurs some 4–7 weeks after the shortest day.
Coating and modified atmosphere effects on potato tuber greening
Authors: Banks N. H.
Published: March 2009

Coating and modified atmosphere treatments reduced light-induced greening of King Edward potatoes. Although ‘Pro-long’ coating and 5% O2 treatments gave more complete inhibition of greening in some tubers, the variability of response was greater and the mean response less than for treatment with 15% CO2, 21% O2. The pattern of greening in the different treatments suggested the presence of O2 gradients within the tuber flesh. Coating caused small internal atmosphere changes, with CO2 content being negatively correlated with chlorophyll content. Larger changes achieved by modifying the external atmosphere of such tubers increased greening suppression. However, the magnitude of response to coating and to the low O2 treatment varied with maturity and growing conditions. The success of coating for inhibition of greening in potatoes will depend upon the physiological variability of the tubers to which it is applied.
Virus infection: a host dependent reaction reversible phenomenon
Authors: Ghosh S. K.
Published: March 2009

Rice necrosis mosaic virus infection induced different reactions on monocotyledonous and dicotyledonous plants under field conditions. Under identical conditions virus infection reduced the grain yield of rice by inhibiting plant growth, whereas in dicotyledonous plants likeLudwigiaand four fibre crops (including jute infection with sap from rice necrosis mosaic virus-infected rice plants, but not with sap from healthy plants) markedly increased yield, plant height, leaf size, stem diameter, seed weight and number of seeds per capsule.
Optimizing seed rate and stem density for seed potato production
Authors: Sekhon H. S. , Singh M.
Published: March 2009

Previous investigations (e.g. Bates, 1935; Singh, 1952; Bremner & Taha, 1966; Sharpe & Dent, 1968) established that increase in the size of potato seed planted and decrease in inter-sett spaoing increased the number of stems and of tubers, resulting in yield advantage generally, but reduced tuber size in the produce. The use of large seed and of close spacing are, therefore, generally preferred for growing a seed crop. However, their use involves higher seed rates, especially when the two are combined. At high seed rates the improvement in yield with increased seed rate may not be commensurate with the extra investment in seed, beoause of the associated increase in inter-sprout and inter-tuber competition. The severity of the competition may be intensified when some factor, for example water, limits tuber growth (Singh, 1952). As the number of stems is not a simple multiple of seed weight, because of the phenomenon of ‘apical dominance’ in potato tubers, it may be desirable to plant small seed or ‘chats’ closely, without increasing seed rate unduly, to optimize stem density without sacrificing net yield (total yield –seed planted). To investigate this, a seed size and spacing experiment was conducted under irrigated conditions in the autumn crop season.
The effects of frequency of defoliation on the yield response of a perennial ryegrass sward to a wide range of nitrogen application rates
Authors: Reid D.
Published: March 2009

In a 3-year experiment on a sward of S. 23 perennial ryegrass 21 rates of nitrogen fertilizer ranging from 0 to 897 kg/ha were applied annually on plots cut three, five or ten times per year. The cutting dates within each frequency were decided on the basis of herbage growth stage. Four-parameter exponential curves fitted to the herbage yield data show that the pattern of response to nitrogen application in the five cuts per year treatment was markedly similar to that reported for a previous experiment (Reid, 1970). Alterations in the cutting frequency affected the pattern of dry-matter yield response to nitrogen, but not that of crude-protein yield response. The combined effects of cutting frequency and nitrogen rate are illustrated by response surfaces fitted to the dry-matter yield results using an extension of the equation for the curves fitted to the individual frequency results. These surfaces show that as the number of cuts per year was increased the total yield and the response to nitrogen decreased, but the response was maintained to an increasingly high nitrogen rate. The practical implications of the results are discussed in relation to intensive grazing managements for dairy cows.
The digestion of spring and autumn harvested perennial ryegrass by sheep
Authors: Beever D. E. , Terry R. A. , Cammell S. B. , Wallace Annie S.
Published: March 2009

S. 24 perennial ryegrass harvested in June, and subsequently in September from the same sward was conserved by rapid freezing. The digestion of the carbohydrate and protein components of the two diets was investigated, using sheep fitted with re-entrant cannulae at the proximal duodenum and terminal ileum and consuming daily 950 g of herbage dry matter.

The higher content of soluble carbohydrate and the lower content of protein in the spring-cut herbage compared with the autumn cut, led to a more efficient fermentation in the rumen with a higher yield of volatile fatty acids per mole of substrate degraded, a proportionately higher yield of propionic acid and a substantially greater net gain of protein between mouth and duodenum on the spring cut herbage. Consequently, the quantity and composition of the amino acids entering the small intestine, or being absorbed therein, were not significantly different, despite the higher protein content noted on the autumn herbage.

The total energy absorbed was markedly higher for the spring herbage (11·2 MJ/kg D.M.) compared with the autumn herbage (9·5) and the energy absorbed as protein from the two diets comprised 20 and 26% of total energy absorbed respectively.

The possible causal mechanisms within the rumen, and the subsequent effect of these on nutrient supply are discussed in relation to the well-established higher efficiency of use of metabolizable energy (ME) of spring-cut herbage compared with autumn cut herbage of similar apparent energy digestibility.
Dry deposition of atmospheric ammonia at Rothamsted in 1976 and 1977
Authors: Rodgers G. A.
Published: March 2009

Soils at Rothamsted receive approximately 4 kg NH3-N/ha/year through dry deposition of atmospheric ammonia. The value is low compared with other nitrogen input processes and reflects the low concentrations of ammonia in the atmosphere. Rainfall is a major factor limiting dry deposition as it removes large amounts of ammonia from the atmosphere. Dry deposition of ammonia is a relatively unimportant source of combined soil nitrogen compared with other natural and artificial sources.
Effects of variety and date of harvest on the tuber dry-matter percentage of potatoes
Authors: Wurr D. C. E. , Bean J. N. , Allen E. J.
Published: March 2009

Using data from four field experiments, comparisons were made between the drymatter percentages of several varieties harvested at different times during the growing season.

There were negative quadratic relationships between tuber dry-matter percentage and tuber size in all varieties except Pentland Marble. The dry-matter percentage of particular tuber sizes varied according to the variety and the time of harvest. Failure to recognize the importance of tuber size and the time of harvest may easily distort differences in dry-matter percentage between varieties.

There were significant positive correlations between the number of tubers produced by each variety on 25 June and four different variables representing the dry-matter percentage of tubers harvested on 10 September. Varietal maturity, assessed as persistence of the foliage, was not significantly correlated with any tuber dry-matter percentage variable in September.
The amino acid, collagen and mineral composition of preruminant calves
Authors: Williams A. P.
Published: March 2009

The amino acid, mineral and collagen composition of certain different components of the bodies of preruminant calves was determined. The amino acid composition (g/kg crude protein) of the empty bodies of preruminant calves was: hydroxyproline, 40; aspartic acid, 81; threonine, 40; serine, 44; glutamic acid, 129; proline, 81; glycine, 113; alanine, 71; cystine, 13; valine, 39; methionine, 17; isoleucine, 28; leucine, 69; tyrosine, 25; phenylalanine, 36; lysine, 64; histidine, 25; arginine, 70; tryptophan, 8. The hydroxyproline, proline and glycine contents were much higher than in bovine muscle because about one-third of the total protein of the calves was collagen, a protein particularly rich in these amino acids. The collagen content of the individual body components varied considerably as did their amino acid contents. There were also some marked differences in the contents of some of the major constituents and minerals in the individual components. In particular the internal organs and blood (component (6)) contained significantly lower concentrations of crude protein, ash, Ca, Mg and P but significantly higher concentrations of Cu and Fe.
Efficiency of fallow as a store for fertilizer nitrogen in a semi-arid region
Authors: Seligman N. G. , Feigenbaum Sala , Benjamin R. W. , Feinerman Dvora
Published: March 2009

Fertilizer nitrogen recovery under fallow and under a wheat crop (Triticum aestivumL., cv. Miriam) grown on a deep loessial silty loam (Calcixerollic Xerochrept), was studied with15N labelled KNO3. The labelled nitrogen was applied (at a rate of 180kg/ha) to 30 cm diameter microplots enclosed in hard plastic tubes that protruded 5 cm above the soil surface. In the 1st year of the experiment there was a long dry spell during the main part of the growing season and plant dry-matter yields were low. The 2nd year was wet, with heavy rain early in the season. About one-third of the fertilizer N applied to the fallow was lost from the top 60 cm layer in the 1st year. Most of the fertilizer N remaining in the soil as mineral N at the end of the first season was lost in the 2nd year. The possible reasons for such low N-conservation efficiency are discussed.
The reaction of lettuce (Lactuca sativaL.) cultivars to cucumber mosaic virus
Authors: Walkey D. G. A. , Ward C. M. , Phelps K.
Published: March 2009

All 53 lettuce cultivars inoculated with cucumber mosaic virus became infected. Leaf mosaic symptoms were generally mild and unreliable for distinguishing degrees of resistance between cultivars. Yield reduction was the most satisfactory criterion for evaluating resistance, with reductions in individual cultivars ranging from 8 to 50%.
The effect of artificial light, hormones, and rams on the reproductive performance of Finn-cross ewes during the seasonal anoestrus in Israel
Authors: Amir D. , Gacitua H.
Published: March 2009

Adult Finn-cross ewes, pregnant from September matings, were kept under natural (control) or artificial photoperiod (experimental). The artificial photoperiod consisted of an abrupt increase in daylength to 18 h for 30 days in November, followed by a step wise decrease of 30 min every 10 days until May.

The ewes of the two groups were either exposed daily to rams after lambing in January-February or after weaning in March, or were kept isolated from the males until mating in April. Time of mating in the latter animals was determined by measuring the intra-vaginal electrical impedance. Hormone treatment for oestrus induction was given after weaning to a portion of the control and experimental ewes. The ovarian activity of the animals was determined by examining their plasma progesterone changes.

Daily teasing of the ewes from lambing to weaning and/or treatment with artificially decreasing daylength did not influence the ovarian activity during this period. All the ewes which were examined for ovulation, from both the control and experimental groups, ovulated 40–60 days after lambing, and 96% of the animals of the two groups which were not treated with hormones for oestrus induction exhibited spontaneous oestrus in March–May.

The lambing–first ovulation and the lambing–first spontaneous oestrus intervals were longer in the light-treated than in the control ewes, and in the animals kept isolated from the rams until mating than in those exposed to the males after lambing or weaning.

A conception rate of 70–100% and a high rate of cycle activity were obtained during the two consecutive years of the experiment in both control and experimental animals, treated or not with hormones and exposed or not to rams. In view of these results, no conclusions could be drawn about the effectiveness of the artificial photoperiod, ram effect and hormone treatment, alone or in combination, in inducing cycling activity and to increase the fertility of Finn-cross ewes during the seasonal anoestrus in Israel.
Some effects of rate of application of nitrogenous fertilizer to wheat grown continuously compared with wheat in a four-course rotation
Authors: Ridgman W. J. , Walters D. E. , Wedgwood R. B. , Müller-Wilmes U.
Published: March 2009

An experiment comparing continuous winter wheat with the two wheat crops in a rotation of beans, oats, wheat, wheat, with four rates of application of N fertilizer, is described and the results discussed.

The wheat following wheat in the rotation consistently outyielded the wheat following oats, but the continuous wheat yielded on average less. Response to N fertilizer was not affected by sequence of cropping and since there was practically no response to the highest increment of N, it is clear that additional N could not have brought the yield of the continuous wheat up to the level of the wheat in rotation.
Effects of restricted water on feed intake, nutrient utilization and nitrogen metabolism in Zebu cattle
Authors: Ikhatua U. J. , Ehoche O. W. , Umoh J. E.
Published: March 2009

Eighteen growing cattle with a mean live weight of 180 kg were used to study the influence of restricted water on feed intake, nutrient utilization and nitrogen metabolism in Zebu cattle in the Sudano–Sahelian ecological zone of Nigeria.

Feed intake and water consumption were negatively correlated (r= 0·63). As the amount of water intake was reduced from 15·8 to 11·91/day, the mean feed intake increased from 5·6 to 6·8 kg D.M./day; water to feed ratios decreased from 2·83 to 1·75 and average daily live-weight gain as well as apparent feed utilization efficiency improved significantly from free-choice water to 50% of free-choice water treatments respectively.

Apparent digestibility coefficients of almost all the nutrients from the 75 and 50% of free-choice water treatments indicated progressively higher (though not significant) values than those of the free-choice water treatment. Nitrogen metabolism did not indicate any difference in the nitrogen intake in any of the three treatments; however, nitrogen balance and nitrogen retained as a percentage of nitrogen intake were significantly (P< 0·05) higher on the 50% of free-choice water treatment.

The survival ability of these Zebu breeds of cattle under water stress during the acute water scarcity of the protracted dry period of the Sudan–Sahelian zone of Nigeria could probably be attributed to increased recycling of nitrogen as well as a reduction in nitrogen loss during the period.
Radiation absorption, growth and yield of cereals
Authors: Gallagher J. N. , Biscoe P. V.
Published: March 2009

Analysis of measurements of absorbed radiation and leaf area indices of wheat and barley crops showed that throughout most of growth the fraction of absorbed solar radiation could be described by a simple exponential equation.

For several of these crops grown under a wide range of weather and husbandry at Sutton Bonington and Rothamsted, 2-weekly values of crop growth rate (C) were closely related to radiation absorbed until ear emergence and about 3·0 g of dry matter (D.M.) were produced by each MJ of photosynthetically active radiation (PAR) absorbed. Final crop weight was closelyrelated to total PAR absorbed during growth (SA); on average about 2·2 g D.M. were produced per MJ absorbed, equivalent to a growth efficiency (Eg) of approximately 3·9%. Unfertilized and drought-stressed crops had a smallerEg.

The fraction of total crop D.M. harvested as grain (harvest index) varied more for wheat than for barley. Calculations of a maximum realizable grain yield made using the largest values ofEgandSAfor the crops measured and assuming a harvestindex of 0.53 (achieved in an experimental crop) showed a grain D.M. yield of 10·3 t D.M./ha to be possible. To achieve such a yield would require full crop cover from the beginning of April until the end of July in a typical English growing season.
The effect of protected lipids on nutrient intakes, blood and rumen metabolites and milk secretion in dairy cows during early lactation
Authors: Bines J. A. , Brumby P. E. , Storry J. E. , Fulford Rosemary J. , Braithwaite G. D.
Published: March 2009

supplements of protected soya-bean–tallow were incorporated at 0, 1·7, 3·0 or 5·0 kg/day into a hay–concentrate diet and fedad libitumto Friesian cows during the first 13 weeks of lactation.

Intakes of supplement during weeks 1–6 were 0,1·34, 2·25 and 3·18 kg/day and during weeks 7–13, 0, 1·64, 3·10 and 4·24 kg/day on each of the respective treatments.

As the lipid supplement increased there was a reduced intake of hay and concentrates, giving rise to reduced intakes of total, protein, and particularly ‘carbohydrate’ (non-protein, non-fatty-acid) energy. Apparent digestibilities, particularly of fibre, decreased as fatty-acid intake increased. After correcting for endogenous losses, true digestibilities of organic matter, carbohydrate, protein, non-fatty-acid lipid, total energy, calcium, magnesium and phosphorus were unaffected by the amount of supplement given, whereas fibre digestibility was reduced by increasing the supplement. Fatty acid digestibility was little affected up to an intake of 1·4 kg/day but above this there was a sharp reduction.

Yields of milk, milk energy, protein, fat and lactose were increased at low lipid supplementation but reduced at the highest supplementation when amounts of protein and carbohydrate digested were lowest.

Lipid supplementation reduced concentrations of rumen total volatile fatty acids in association with reduced, proportions of butyrate and. increased proportions of propionat. Plasma β-hydroxybutyrate and magnesium were reduced and plasma free fatty acids increased in cows given lipid supplemented diets.

There were no differences between treatments in plasma glucose, lactate or calcium nor in live-weight changes.
Studies on the nutritive value of silage with particular reference to the effects of energy and nitrogen supplementation in growing heifers
Authors: Griffiths T. W. , Spillane T. A. , Bath I. H.
Published: March 2009

Four digestibility and balance experiments were carried out in which 33 growing heifers were fed basal diets of low dry matter silage offeredad libitum, supplemented with various levels of barley and/or groundnut meal or urea.

Voluntary intake of the silages was low although apparent digestibility of D.M. was high (66–75%). There was a significant linear negative relationship between the intake of D.M. as supplement and silage D.M. intake.

Apparent digestibility of crude fibre in the silages was high (74–83%). It was depressed significantly by addition of barley but not by addition of groundnut. There was a highly significant linear relationship between the digestibility of D.M. and G.B. in the mixed silage concentrate diets used.

Metabolizable energy (M.E.) values for the silages varied from 2·04 to 2·52 Mcal/kg (8·5–10·5 MJ/kg) D.M. Supplementation with barley at approximately 1% of live weight, increased M.E. values of the mixed diets to 2·57–2·85 Mcal/kg (10·8–11·9 MJ/kg) D.M. Additional N had little effect on these values.

Nitrogen retention was significantly increased in all experiments by barley supplementation. It was further significantly increased by groundnut in three experiments and by urea in one experiment.

Multiple regression analysis showed that N retention was significantly related to both M.E. intake and intake of absorbed N, and to M.E. intake and intake of supplementary N.

Apparent availabilities of Ca and Mg in silage based diets were low and the availability of Na varied with Na intake. Supplementation with either energy or nitrogen increased apparent availability and retention of Mg but did not exert consistent effects on availability or retention of Ca or Na.

There was a highly significant linear relationship between ingested and digested Na but not for Ca or Mg. There was a highly significant linear relationship between absorbed and retained Ca and Mg, but not for Na.

Animals fed second cut silages had rather low blood glucose levels and higher than normal levels of blood ketones.
Intra-varietal variability and response to single plant selection inGossypium hirsutumL.: II. Genotypic variability
Authors: Thomson N. J.
Published: March 2009

Progenies of randomly chosen plants from spaced plant populations of four American and one African variety ofGossypium hirsutumL. were grown in replicated single-plant plots at Kimberley Research Station in 1967–68 (all varieties) and 1968–9 (two varieties only) to estimate intra-varietal parameters of genetic variability.

Estimates of broad-sense heritability were usually similar when derived from components of variance on either a one- or two-season analysis basis or by parentprogeny regression Heritabilities were in general lowest for lint yield and boll number and highest for lint percentage. Mean value of heritability for lint yield and boll number, considered consistent enough on a varietal and seasonal basis to allow averaging, was about 0·15. Components of variance estimates of heritability on a single environment basis for other attributes ranged as follows: boll weight from 0·05 to 0·56, lint percentage from 0·29 to 0·80, mature height from 0·00 to 0·51, micronaire value from 0·20 to 0·63 and Pressley strength index from 0·05 to 0·56.

Genetic coefficients of variation showed an opposite trend to that for heritability: lint yield and boll-number values were large and lint percentage, micronaire value, and Pressley strength indices small. Expected responses to selection for the top 2·5 % of the population for lint yield and boll number at around 10% were usually higher than for other attributes.

Genotypic and phenotypic correlations were mostly similar but correlations often deviated widely between varieties. Positive lint yield correlations with micronaire value and negative lint yield correlations with Pressley strength index were recorded; these are often undesirable associations for breeding.

The association between the period of maintenance under Ord conditions and variability shown phenotypically in the original populations was not evident from the quantitative inheritance studies. Residual variability following breeding was considered as accounting for the larger portion of the genetic variability.
Experimental errors in laying experiments
Authors: Hale R. W.
Published: March 2009

To amplify published information on the size of errors in annual egg records, results are presented for fourteen laying experiments and one flock under uniform management at the Agricultural Research Institute of Northern Ireland, Hillsborough. It is concluded that in laying experiments on a semi-intensive plant the egg records are seldom affected to any serious extent by differences between pens that are treated similarly. Non-random allocation of pullets to the laying pens does not appear to have seriously affected the results on which this conclusion is based. It is pointed out that the distribution of egg records from a high producing flock is likely to be extremely skew and leptokurtic.
Studies of the composition of sainfoin
Authors: Baker C. J. L. , Heimberg M. , Alderman G. , Eden A.
Published: March 2009

1. Studies were made of the composition of Giant sainfoin cut successively at different stages of growth in two seasons under contrasting conditions of weather and soil.

2. Cuts were taken at preflowering, early- and full-flowering stages of growth. Yields of both fresh material and dry matter substantiated the usual farming practice of taking two cuts at full flower in one season, and indicate that cutting sainfoin before it comes into bloom has a seriously depressing effect on productivity.

3. Like most green fodder crops, sainfoin has a lower content of crude protein and nitrogen-free extractives, and a higher content of crude fibre as the plant increases in maturity. The mineral content is somewhat variable, and in particular the potassium content appears to reflect the status of this element in the soil.

4. The ratio of leaf dry matter to total dry matter of the plant decreases with advancing maturity. The leaf composition is fairly constant, irrespective of stage of growth, number of cuts and season, the fibre content being remarkably constant in contrast with that of stem, where it increases with advancing maturity. Leaf is richer than stem in crude protein, ether extract and total mineral matter, particularly calcium. Thus changes which do occur in the composition of the plant are due to variations in stem composition and leaf-stem ratio.

5. Analyses of sainfoin hay, made under both experimental and commercial conditions, are discussed, and the range of variation in the main constituents of thirty-five commercial samples is commented upon.

6. The present investigations into the composition of sainfoin, both as green fodder and as hay, show figures that differ appreciably from those derived from earlier German work. Examination of the data available for the nutritive value of fresh and conserved sainfoin reveal anomalies which suggest that such data are not typical of the crop as grown in this country, and also suggest the need for more modern data.
Report on an experiment to compare the fattening values, for beef cattle, of silages made from grass cut at different stages of growth
Authors: Dodsworth T. L. , Campbell W. H. McK.
Published: March 2009

1. The method adopted for making three different grades of silage, from grass cut at different stages of maturity, is described.

2. A feeding trial is described including four groups of cattle fed on grades I–III silages and on swedes and straw respectively.

3. The live-weight gains made are recorded together with the rate of dry-matter intake.

4. A digestibility trial was carried out on the three grades of silage. The digestibility coefficients found are recorded.

5. It is shown that cattle fed solely on silage build up a bigger ‘gut fill’, to the extent of 40 lb. (± 11), than similar cattle fed on swedes and straw.

6. When an allowance had been made for a 40 lb. greater ‘gut fill’ in silage-fed cattle it was found that grades I and II silages produced a significantly greater rate of fattening than grade III silage and than swedes and straw.

7. It was found that the rate of total daily drymatter intake rose to a peak at the eighth week and then fell; it did not continue to rise beyond that point but the cattle continued to gain in live weight.

8. The efficiency of utilization of the dry matter of the rations fed increased during the latter part of the trial.

9. It is suggested that the increase in efficiency of utilization of the dry matter consumed may be attributed to an adaptation in the rumen microflora of the cattle which proceeded for up to 8 weeks after the cattle were put on to the experimental diets.
The partition of phosphorus and aneurin in relation to phosphatase in the colostrum and milk of the cow
Authors: Chanda R. , Owen E. C.
Published: March 2009

The partitions of phosphorus and aneurin were determined in the colostrum and in the transitional and mature milk of Ayrshire cows with the following results:

1. The ratio of nitrogen to phosphorus was 11:1 in the first mammary secretion but dropped to a minimum value of 4·5:1 a week later. Thereafter the ratio increased throughout lactation attaining a value of 7·2:1 at the fortieth week. The first colostrum was very rich in both phosphorus and nitrogen.

2. Phosphatase titre in colostrum was 154 units in the first post-partum secretion but decreased to 10 during the first five days of lactation. The titre fluctuated slightly during the next few days and increased gradually thereafter, attaining 189 units in the 38th week of lactation.

3. Phosphatase was correlated positively with inorganic-P (r= +0·83) and negatively with both ester-P (r= −0·94) and lipid-P (r= −0·70), all P fractions being expressed as percentages of total P. The percentage of phosphorus present as casein was initially 19–21%, but was only 14% in late lactation.

4. The first colostrum contained 74 μg. aneurin/100 ml. skim milk. This value became 35 in midlactation and only 28 in late lactation. The corresponding figures for cocarboxylase were 20, 5·7 and 2·3 μg./100 ml. respectively, and for protein-bound aneurin 14, 3·2 and 1·7 respectively. Both cocarboxylase and protein-bound aneurin were negatively correlated with phosphatase.
The potassium status of barley in relation to yields of grain
Authors: Nicholas D. J. D.
Published: March 2009

1. Various portions of barley plants were made available for chemical tests from manurial experiments which were designed to test the effects of K treatment (broadcast and placed with the seed) on grain yield.

2. The experiments were located at three centres differing in soil characters and K status. Centre A was severely deficient in K; centre B was moderately deficient and at centre C, K was adequate.

3. A comparison was made between the results of the following tissue test methods for K, Mg, Ca, P and Mn: (a) diffusion method, using young leaf, mid-stem leaf, and internode respectively; (b) Waring blendor, and (c) ash analysis. Mn was not determined by the blendor method.

4. The coefficients of variation for the quick tests compared favourably with those of ash analysis for K, Mg, Ca, P and Mn respectively. Variations in results in tissue tests for Ca were, however, significantly greater than those of ash analysis, at centre A (second sampling).

5. Correlation coefficients between results of ash analysis and the tissue test methods for K, Mg, Ca, P and Mn were positive and significant for totals, treatment and treatment × sites, except for Mn in young leaf by diffusion method. The error term for P was also significant for the quick methods, thus decreasing the value of the correlations for this nutrient.

6. Correlation coefficients of yields with ash analyses, Waring blendor and diffusion method (mid-stem leaf) analyses respectively were significant and positive for K and negative for Mg, Ca, P and Mn. This confirms an interaction of K with the other nutrients.

7. Minimum K levels, determined 5 weeks after seeding, above which no further increase in yields may be expected at the three centres, were: by diffusion method, using young leaf, mid-stem leaf and internode, 700, 500 and 600 μg. extracted per. g fresh weight respectively; by Waring blendor using ‘tops’, 2000 μg. extracted per g. fresh weight; by ash analysis of tops 1·5% K in dry matter. There is evidence that these critical levels fall later in the season, especially in mid-stem leaves, presumably through translocation of K to the ears.

8. Minimum levels of K required for optimum yields are above those associated with the onset of deficiency symptoms of the element. Thus chemical methods only can determine suboptimal levels of nutrients in relation to final yields.