bluuebunny/crossref_metadata_2025 huggingface dataset:
The value of liquid digested sewage sludge. I. The effect of liquid sewage sludge on growth and composition of grass-clover swards in South-east England
Authors: Coker E. G.
Published: March 2009

During the period 1959-62 liquid digested sludge was applied to grass to supply nitrogen at rates similar to those normally recommended to farmers. The responses were compared to those produced by equivalent inorganic fertilizers.

Liquid digested sludge gave as large an increase in dry matter as equivalent fertilizers. At the low rate of application the mean dry matter increase was 15.2 lb./lb. of applied nitrogen, and at the high rate the mean response was 11.0 lb. dry matter per lb. of nitrogen.

On one site, all treatments reduced the clover percentage, the high rate more than the low rate. Sludge treatments reduced the clover percentages less than equivalent inorganic fertilizers.
Crop production and water-use. I. A model for estimating crop water-use with limited data
Authors: Wright E. , Carr M. K. V. , Hamer P. J. C.
Published: March 2009

An attempt was made to re-assess the results of irrigation experiments carried out in the UK during the last 30–40 years in order to develop functional relationships between crop yield and actual wateruse. It was first necessary to develop a model, based on relatively simple functions, which could be used to predict actual water-use (evaporation and transpiration). The derivation of this model, known as WATYIELD, is reported here, whilst its application and validation for sugarbeet and for potatoes are described in subsequent papers. Simple functions relate components of evaporation to the proportion of the incoming solar radiation intercepted by the crop canopy, reference crop evapotranspiration, the precipitation and irrigation amounts and the soil water deficit. Transpiration is also related to soil hydraulic characteristics, rooting density and potential evaporation rate.
Comparison of two varieties of Italian ryegrass (Lolium multiflorum) for milk production, when fed as silage and when grazed
Authors: Wilman D. , Walters R. J. K. , Baker D. H. , Williams S. P.
Published: March 2009

Two varieties of Italian ryegrass (Lolium multiflorum Lam.), Tribune and RvP, were cut in each of 2 years, ensiled and individually fed, ad libitum, to dairy cows. In one year, two rates of supplementary concentrate feeding were compared and, in the other year, two types of concentrate and a silage-only diet. Tribune silage was more digestible, in vitro, and was lower in neutral detergent fibre and fibrosity index than RvP silage. There was no difference between the varieties, however, in the cows’ intake of silage. On the silage-only diet, the cows fed Tribune produced a higher yield of milk solids than did those fed RvP; on the other diets, there was no significant difference between varieties in the yield or composition of milk.

The same two varieties were compared when grazed by herds of dairy cows in spring, summer and autumn of the first harvest year on six farms and in the second harvest year on four of the farms. Tribune persisted much better than RvP, in numbers of plants and tillers/m2 and in ground cover, and the herbage was more digestible than that of RvP. Milk yield/cow was c. 0·6 kg per day higher when grazing Tribune than when grazing RvP.
Predicting the emergence of potato sprouts
Authors: Firman D. M. , O'Brien P. J. , Allen E. J.
Published: March 2009

Sprout emergence in the potato variety Estima was investigated in controlled environment and field experiments. The effects of temperature, physiological age, planting date and soil moisture were examined in controlled environments and the results were compared with the emergence of physiologically young and old seed in field experiments with different soil types, planting dates and planting depths.

Elongation of sprouts could be described by a lag period of slow growth followed by a period of rapid linear growth. The lag period was shorter with increase in temperature up to 20 °C and sprout length at planting up to c. 10 mm. The lag period was slightly reduced by warming seed at 10 °C before planting, compared with planting seed directly from cold storage. The rate of linear growth increased with temperature up to 20 °C but was similar for young and old seed at different planting dates. The rate of growth was lower in dry soil than in soil near to field capacity, particularly at high temperatures.

The observed date of emergence in the field was usually later than predicted, particularly with shallow planting, but prediction was improved by accounting for soil moisture. The use of this model should give more accurate estimation of emergence for farm operations and crop growth models than existing equations.
Partitioning losses of nitrogen fertilizer between leaching and denitrification
Authors: Addiscott T. M. , Powlson D. S.
Published: March 2009

When 15N is used to trace the fate of N fertilizer applied in spring to winter wheat crops, some is not recovered in the crop or the soil and has to be presumed lost. In 13 experiments made from 1980 to 1983 on three widely differing soils, these losses ranged from 1 to 35%. We partitioned them between leaching and denitrification by using models to estimate the loss by leaching, talcing into account the N absorbed by the crops, and subtracting this loss from the total loss to obtain the apparent percentage loss by denitrification, LDN. An analysis of variance showed that LDN increased significantly with the quantity of N applied, so the study considered LDN values for a standard N application of 150 kg/ha subsequently. Regressions showed that LDN was better related to the wetness of the soil during the 3 weeks after fertilizer application than to the corresponding amount of rain, as would be expected for denitrification. Values of LDN could not, however, be satisfactorily related to soil temperature, probably because the range of temperatures was too narrow. The apparent losses by denitrification were, on average, nearly twice as large as those by leaching, but the ratio varied greatly between experiments.
The health and performance of the grazing animal in relation to fertilizer nitrogen usage. I. Calves
Authors: Hodgson J. , Spedding C. R. W.
Published: March 2009

1. An experiment was carried out in 1961 and 1962 to test the effect of the application of high levels of fertilizer N to S 23 ryegrass swards on the health and performance of grazing calves. A uniform application of 47 kg. P and 75 kg. K/ha. was used in each year. Nitro-chalk was applied at monthly intervals from February to September, at rates equivalent to 22.4 kg. (Nl) and 112 kg. (N3) per hectare in 1961; in 1962 an intermediate rate (N2) of 67.2 kg./ha./month was also used. The total quantities of N applied per hectare in 1961 were 185 and 1042 kg. and in 1962, 192, 576 and 961 kg.

2. Male calves, 2-6 months old when introduced to the experiment, grazed in rotation round a series of four paddocks on each treatment. In 1961 Friesian, Aberdeen Angus cross and Shorthorn twin calves were used; in 1962 all the calves were unrelated Friesians.
Variations in the time of onset of the breeding season in Clun ewes
Authors: Lees J. L.
Published: March 2009

Variations in the time of onset of the breeding season in Clun ewes have been studied during the four years 1962-65. Differences within seasons were studied in 1963 and 1964 by scattering the lambing over the first 7 months of the year. The date of first service then appears to be very highly dependent on the date of previous lambing. Time of previous weaning appears to be less important.

Very highly significant differences have been found between seasonal means and these differences have been shown to be significantly related to the mean ambient temperature during a limited period between mid-summer and the mean date for the resumption of cyclic activity in the ewes. The higher this temperature the later the onset of breeding activity. Over the years individual ewes have tended to breed consistently either early or late.
The relationship between seed yield and associated characters in meadow fescue (Festuca pratensis)
Authors: Lewis Joseph
Published: March 2009

A study was made of phenotypic correlations between seed yield and some other traits of determinable value in two bred varieties of meadow fescue. Seed yield and such characters as time of flowering, plant height and dry-matter production of spaced plants in October and at the time of anthesis were found to be closely associated.

The method of path coefficient analysis was used to study the interrelationships of seed yield and its components in the causal system: fertile tiller and floret numbers, percentage fertility and thousandseed weight. This analysis corroborates the result of simple correlations in showing the importance of fertile tiller numbers and fertility as major determinants of seed yield.
Effect of zinc supplementation on performance and zinc metabolism of lambs fed forage-based diets
Authors: Kegley E. B. , Spears J. W.
Published: March 2009

Experiments were conducted to determine the effects of zinc (Zn) supplementation on the performance and mineral metabolism of lambs fed forage-based diets containing 15–23 mg Zn/kg. In Expt 1, 20 lambs were fed a good-quality orchardgrass (21·4 mg Zn/kg) or a low-quality tall fescue (14·7 mg Zn/kg) hay and supplemental Zn (as ZnO) at 0 or 30 mg/day in a 2 x 2 factorial arrangement of treatments. Forage was fed ad libitum and all lambs received 92 g dry matter/day of a corn-based supplement which served as the carrier of the supplemental Zn. Lambs fed orchardgrass hay had a greater (P < 0·01) dry matter intake and average daily gain for the 42-day study. Zinc supplementation did not affect performance of lambs fed tall fescue but tended to improve performance in those fed orchardgrass hay. At the end of the 42-day growth phase, lambs were placed in metabolism crates for a 7-day total collection of urine and faeces. Supplemental Zn increased intake (P <0·01) and faecal excretion (P <0·01) of Zn. Absorbed Zn was greater (P < 0·05) for lambs fed supplemental Zn. There was a tendency for a forage × Zn interaction (P < 0·10) for urinary Zn excretion and retention. Urinary Zn excretion was highest in lambs fed tall fescue hay supplemented with Zn. In Expt 2, 24 lambs were fed diets consisting of ad libitum chopped tall fescue hay (23 mg Zn/kg) and 176 g/day of a corn and mineral supplement which served as the carrier of the Zn treatments. Treatments were no supplemental Zn or 30 mg/day supplemental Zn as ZnO, ZnSO4 or Zn methionine. Zinc oxide and ZnSO4 supplementation increased average daily gain (P < 0·10) and decreased feed/gain (P < 0·10) for the 56-day study when compared to control and Zn methionine-supplemented lambs.
Effects of poultry manure and mineral fertilizers on the yield of crops
Authors: Giardini L. , Pimpini F. , Borin M. , Gianquinto G.
Published: March 2009

Experiments at the Experimental Station of the Agricultural University of Padova, Italy (45° 21′ N, 11° 58′ E) during 1985–89 evaluated poultry manure as a fertilizer. Two levels of fertilization (medium and high), using different mixtures of poultry manure and mineral fertilizers were compared with a non-fertilized control. The fertilization treatments were repeated each year on the same plots. All the crops tested responded strongly to fertilization, giving the following increases in yield (expressed as a percentage of the maximum yields): 30% for potato (Solanum tuberosum L.), 19% for sugarbeet (Beta vulgaris L. var. saccharifera L.), 82% for onion (Allium cepa L.), 85% for tomato (Lycopersicon esculentum Mill.) and 64% for spinach (Spinacia oleracea L.). The most effective fertilization formula varied with crop and year of cultivation. All the tested fertilization treatments had a similar effect on potato and onion, whereas the highest yields of tomato and spinach were obtained with a mixed fertilization at the highest rate of nutrients.
Radiographic pregnancy diagnosis in sheep
Authors: Wenham G. , Robinson J. J.
Published: March 2009

During the period 1968–71, 417 ewes of various breeds were radiographed for pregnancy diagnosis during the period 60–95 days of gestation.

Pregnancy per se was diagnosed by observing the presence or absence of a definite uterine outline with accuracies of 77, 97 and 100% of the period 60–70, 71–80 and 81 + days of gestation. During the periods 60–70, 71–80, 81–90 and 91 + days of gestation foetal numbers were diagnosed with an accuracy of 88, 94, 99 and 99 % respectively. Breed, size of ewe and number of foetuses carried did not affect the accuracy of diagnosis.
The amino acid composition of barley grain protein during development and germination
Authors: Smith D. B.
Published: March 2009

The amino acid composition of barley grain was studied during the maturation of the grain and during germination of the mature grain. Samples of the variety Proctor, grown at two nitrogen levels in each of the years 1969 and 1970, were analysed together with one sample of Sultan grown in 1970. It was found that during maturation the proportions of glutamic acid and proline increased and that the levels of these amino acids were highest in those samples with the highest total protein content. During ripening the proportions of lysine, alanine, aspartic acid, threonine and glycine decreased. On germination the proportions of glutamic acid and proline rapidly decreased whilst aspartic acid, lysine, alanine and glycine increased.

The nutritive value of ripe barley grain is limited by its low lysine content. Whilst the germination process increases the level of lysine it is suggested that this does not increase the nutritional value of the grain due to the low level of cystine in the germinated grain.
The effect of plant density on tiller growth and morphology in barley
Authors: Kirby E. J. M. , Faris D. G.
Published: March 2009

A detailed study was made of the tillering of barley plants grown at densities which ranged from 50 to 1600 plants m–2. Throughout the season the initiation of tiller buds and their growth in length and leaf number were followed, and measurements were made of leaf sheath and lamina length and lamina width. A proportion of tillers died and their positions and times of death are given.

Three phases of tillering were recognized. The first, tiller bud initiation, was little affected directly by density. During the second phase, buds did not grow or did grow and emerge from the subtending leaf sheath. If they grew, there was no difference in growth rate of tillers at different densities. At the higher densities fewer buds developed, and the morphology of those tillers which did grow was affected by density. This suggests that the growth of the tiller bud may be controlled by levels of endogenous gibberellin, while in the final stage, growth after emergence from the subtending leaf sheath, competition for light appears to be the factor which determines whether a tiller survives to produce an ear. The data are discussed in relation to the practical importance of tillering.
The effect of feeding maize and lucerne silages on blood composition in dairy cows
Authors: Little W. , Manston R.
Published: March 2009

Maize or lucerne silages were fed to two groups of cows in a large dairy herd. Metabolic profile tests carried out during the trial showed that abnormal blood chemistry such as might lead to production disease did not occur in either group.

The results of feed analysis and digestibility trials showed that the two silages provided equal quantities of digestible energy but that the lucerne silage provided more digestible protein than the maize silage. Blood glucose concentrations were similar in both groups of cows but serum urea and albumin concentrations were significantly higher in the cows fed lucerne silage than in those fed maize silage. There was also evidence that lucerne silage provided slightly less available phosphorus but more calcium than the maize silage.

It is concluded that maize silage, as used in these experiments, showed no tendency to lead to production disease, and furthermore the metabolic profile test provided additional information to feed analysis in making this assessment.
The non-protein nitrogen composition of grass silage:III. The composition of spoilt silages
Authors: Hughes A. D.
Published: March 2009

The nitrogenous composition of the water soluble, non-protein nitrogen fractions of three samples of high-pH-spoilt silage and one sample of overheated silage were examined in detail. The amino acid nitrogen content of the high-pH-spoilt silages declined with increasing extent of spoilage, due to a selective degradation of the amino acids. Losses of amino acids were associated with proportionate increases in the amount of volatile basic nitrogen. Lower aliphatic amines were not present and it was therefore concluded that the ultimate end product of nitrogen metabolism in high-pH-spoilt silages was ammonia. Only low concentrations of putrefaction products, such as putroscine, cadaverine and histamine were present.

The composition of the non-protein nitrogen fraction of the overheated silage was unusual in that the ammonia nitrogen content was high and associated with the complete destruction of certain amino acids. The free amino acid nitrogen content was low but this was partially compensated for by a very high ‘peptide’ nitrogen content. There was no evidence of putrefaction products in this silage.
A study of growth in calves:II. Relative growth in muscles
Authors: Butterfield R. M. , Johnson E. R.
Published: March 2009

The growth patterns of impetus groups of muscles were mostly not significantly affected by rate of growth of the musculature. One small group – the low/average impetus muscles – had a significantly lower ‘b’ value in the calves fed at a high plane. It appears that under differences of feeding encountered commercially, no changes of practical importance in the relative growth of muscles are likely to be produced which are attributable to rate of growth of the musculature.
A study of growth in calves:III. Energy and nitrogen efficiencies of growth of carcass tissues
Authors: Pryor W. J. , Johnson E. R.
Published: March 2009

The gross energy and nitrogen contents of muscle, fat, and connective tissue of calves were determined, and from these data and feed analyses the gross energetic (GEE) and nitrogen efficiency (GNE) of growth, and the gross efficiencies of accretion since birth (GEA, GNA) were calculated.

The percentage range of actual efficiency values for calves were GEE 55·3–7·7, GEA 18·1–1·4, GNE 58·1–22·8, and GNA 28·1–7·3. Within each treatment group these values were higher in the heavier calves. An hypothesis for the apparent temporary rise in these values in the heavier calves is that a compensatory mechanism acts in calves on low energy and possibly low N intake to enable them better to utilize their food. The results were obtained in calves whose diet was comprised of a reconstituted milk of low-solid content which led to low growth rates.
Studies on the digestibility and utilization of the nitrogen of irradiated rumen bacteria by rats
Authors: Mason V. C. , Palmer R.
Published: March 2009

Rumen bacteria were isolated from the rumen contents of eight Friesian cattle that had been fed a barley-soyabean diet. These preparations were freeze-dried, irradiated with 1 Mrad and analysed for various nitrogenous components.

In nitrogen utilization studies involving both young and adult rats it was observed that the ‘true’ digestibility of the bacterial nitrogen was about 80%, while the net protein utilization (NPU) value was approximately 57.

It was concluded that about 20% of the bacterial nitrogen, mainly incorporated in the cell wall, was not absorbed by the rat. On the other hand, about 71% of the absorbed nitrogen was utilized by the growing rat for tissue synthesis.

Irradiation with 1 Mrad killed virtually all the rumen bacteria without adversely influencing the nutritional value of the bacterial protein.
Within-animal variances for flow rates of metabolites in an open-compartment model with continuous isotope infusion in sheep
Authors: Smith Helen K. , Milne J. A. , Mayes R. W.
Published: March 2009

Flow rates of metabolites in an open-compartment model can be calculated from specific activity measurements taken at equilibrium during continuous infusion of an isotope. The within-animal variance gives an estimate of the precision of the flow rate.

The Jack-knife method of calculating within-animal variances is described. It was evaluated using simulated data, and shown to be superior to a simpler method, the Single Section method.

The increase in experimental accuracy caused by increasing the number of specific activity samples per animal depends on the ratio of between- to within-animal variance components (B/W). For three experiments with sheep, 23 of the 30 values B/W for the different flow rates ranged from 0·25 to 1·5. For this range between six and 12 samples per animal are needed.
Further observations on the utility of N2-fixing micro-organisms in the phyllosphere of cereals
Authors: Samanta R. , Sen S. P.
Published: March 2009

The utility of spraying some Na-fixing micro-organisms on rice (cv. Masuri and IR-26) and wheat (cv. Sonalika) leaves grown both in N2-less sand culture and under field conditions was examined. All the growth variables studied, including dry weight, chlorophyll content and N content of plants, were enhanced appreciably in N-less sand culture and under field conditions. The yield of rice cv. IR-26 per unit area was more than doubled or nearly so with Pseudomonas azotocolUgans, Ps. azotogensis, Klebsiella pneumoniae KUPBR2, K. pneumoniae KUP4, KUP6D, KUP7D, Azospirillum brasilense, Xanthobacter fiavus and K. rubiacearum. When rice cv. Masuri was used the grain weight was doubled by A. brasilense, Ps. azotocolUgans, Ps. azotogensis, KUPBR2, and KUP6D. Grain N content was increased appreciably in mostcases. The organisms also reduced acetylene to ethylene in the phyllosphere. In wheat cv. Sonalika grown in N-less sand culture, KUP4, KUPBR2, Ps. azotocolligans, A. brasilense, X. flavus, and KUP6D each doubled the N content of plants. Under field conditions Ps. azotocolligans gave the highest grain yield although grain yield was doubled by a large number of strains. N content of grains was also increased appreciably, the best result being given by KUP4.
Crop production and water-use. III. The development and validation of a water-use model for potatoes
Authors: Hamer P. J. C. , Carr M. K. V. , Wright E.
Published: March 2009

As a prerequisite for developing crop-yield/water-use functions for potatoes using the results of historical irrigation experiments, it was necessary to develop a water-use model which could operate with a limited data set. The general form of this model has been reported by Wright et al. (1994), and its application to the sugarbeet crop by Hamer et al. (1994). In this paper the development and validation of the model for potatoes is described.

The canopy was modelled in terms of intercepted incoming solar radiation using functions based on thermal time and time. Four phases of growth were identified: emergence, expansion, plateau and senescence. An empirical drought factor was included to allow for the effects of water stress on canopy development during the expansion phase. Root development was described using a two-phase model: linear and maximum depth (both time dependent).

Independent data from various sources were then used to validate the model in terms of its capacity to predict crop canopy development, with and without drought stress, soil water extraction at different depths and soil water deficits during the season. The study confirmed the validity of the model for predicting the water-use of potatoes.
Nature and availability of residual phosphorus in longterm fertilized pasture soils in New Zealand
Authors: Condron L. M. , Goh K. M.
Published: March 2009

The nature and availability of phosphorus in long-term fertilized pasture soils was investigated in a series of field trials, which included liming, N fertilizer and cultivation and involved monitoring plant P uptake and changes in topsoil (0–7·5 cm) P fractions for 2 years (1982–83). Liming increased soil organic P mineralization. This was indicated by significant decreases in extractable organic P and concomitant increases in microbial biomass P in the limed soils, although these changes in soil P had no significant effect on pasture yield and P uptake. On the other hand, N fertilizer increased pasture yield and P uptake but had little effect on the amounts of P in the different soil P fractions. In the cultivated soils, increases in plant-available inorganic P were attributed to the release of P during decomposition of plant residues, while the maintenance of fallow conditions decreased amounts of microbial P in these soils.
Effects of applied plant growth substances on pod set in broad beans (Vicia faba var. major)
Authors: Rylott P. D. , Smith M. L.
Published: March 2009

The effects on flower drop and pod set of applications of either the auxin 4-choloroindole, the cytokinin 6-benzylaminopurine (BAP) or gibberellic acid (GA3) to every flower, 1 day before or 1 day after tripping, were studied in broad bean plants grown in a glasshouse in 1988. Control plants shed most of their flowers; pods that did set originated primarily from flowers at proximal positions on the raceme. Most pods set on the lower part of the reproductive portion of the control plants. Chloroindole and GA3 application before tripping had no significant effect on pod-set pattern. However, GA3 applied after tripping significantly enhanced pod set at proximal flowers by 21% but inter-raceme pod set was not significantly altered. Chloroindole applied after tripping significantly increased pod set, particularly at proximal flower positions on the raceme; this treatment increased inter-raceme pod set but the increase was significant only for the basal four racemes and racemes 11, 12 and 13. Application of BAP before or after tripping resulted in almost complete pod set on all racemes; but greater flower drop was observed on the uppermost five racemes of plants treated after tripping than on corresponding racemes of plants treated before tripping. The effects of BAP, chloroindole or GA3 treatment were not due to changes in the synchrony of flower opening. An adequate supply of a cytokinin appeared to be necessary at or before pollination to initiate changes in reproductive organs to prepare them to become net attractors of assimilates from other plant parts. Auxin and gibberellin were only effective in promoting fruit set 24 h after tripping. An adequate supply of auxin, and perhaps of gibberellin, in balance with cytokinin appears to be required after pollination to maintain the flow of adequate assimilates to enable further pod development and for maturation to proceed.
Effect of trenbolone acetate on urea metabolism in cattle fed low-protein roughage diets
Authors: Hunter R. A. , Magner T.
Published: March 2009

In two experiments using cattle implanted with 0 or 300 mg trenbolone acetate and fed restricted diets of low-protein roughage, urea synthesis was measured by plasma dilution of a single intravenous injection of [14C]urea. Urea flow to the gut was calculated as the difference between synthesis and urinary urea output. Because rumen ammonia concentrations were only c. 1 mg/1, it was assumed that urea transfer from the gut to blood was negligible.

In the first experiment, fistulated heifers treated with trenbolone acetate synthesized significantly (P < 0·05) less urea (0·8 v. 1·2 g/h) and had a tendency to excrete less (P = 0·08) urea in urine (0·04 v. 0·14 g/h) and to have a lower (P = 0·07) flow of urea into the gut (0·8 v. 1·1 g/h) than untreated animals. They also had significantly (P < 0·01) lower rumen digestion rates, determined from disappearance of feed dry matter from nylon bags suspended in the rumen for 48 h.

In the second experiment, steers treated with trenbolone acetate synthesized significantly (P < 0·05) less urea (1·0 v. 1·9 g/h) and had a significantly (P < 0·05) lower flow of urea into the gut (0·9 v. 1·8 g/h) than untreated steers.

The results were consistent with an hypothesized sequence of events resulting from treatment with trenbolone acetate. The sequence proposed was a decrease in the rate of tissue protein breakdown, a decrease in the rate of urea synthesis from de-amination of amino acids, a decrease in the amount of urea recycled to the rumen, a decreased rumen digestion rate and thus a decrease in feed intake.
Growth and development in beef cattle. 1. Direct and residual effects of plane of nutrition during early life on components of gain and food efficiency
Authors: Patterson D. C. , Steen R. W. J. , Kilpatrick D. J.
Published: March 2009

Low, medium and high planes of nutrition were imposed on Friesian calves from 1 to 13 weeks of age (Period 1) and factorially arranged with low and high planes of nutrition in the 13–25 week period (Period 2). In the final (residual) period, from 25 weeks to slaughter, all animals were given the same high plane diet comprising 3·5 kg of concentrates and grass silage ad libitum. The different planes of nutrition were achieved by offering restricted allowances of milk replacer or concentrates with grass silage ad libitum. Representative animals were slaughtered at 1, 13 and 25 weeks of age while the remaining animals were slaughtered at mean liveweights of 503 and 553 kg. Over 2 years, a total of 120 Friesian steers were taken through to the final slaughter point, with 60 additional animals being slaughtered at interim stages. The animals were housed in non-bedded accommodation throughout the study and the calves were born in January of each year. The ME intake of the low plane animals in Period 1 was 0·55 that of the high plane animals and produced liveweight (LW), empty body (EBW), carcass (CW), non-carcass (NCW) and alimentary tract (ALW) weight gains which were 0·60, 0·46, 0·47, 0·44 and 0·55 of the gains of the high plane animals. In Period 2 the low plane animals had ME intakes which were 0·69 of the high plane animals and produced proportional gains of 0·57, 0·48, 0·45, 0·51 and 0·56 respectively. Previously restricted animals had higher rates of gain subsequently and the indices for weight compensation by the final slaughter point in LW, EBW, CW, NCW and ALW for the low plane treatments in Period 1 were 0·72, 0·82, 0·89, 0·73 and 0·97 while indices for low v. high in Period 2 were 0·82, 0·82, 0·79, 0·86 and 0·95. With lower plane animals, food intakes/liveweight0·75 were significantly higher during the compensating period. Calves which had been restricted in either of the early periods had significantly improved food conversion efficiency during the compensating period but lifetime food efficiency was not affected by plane of nutrition in early life.
Simulating winter wheat shoot apex phenology
Authors: McMaster G. S. , Wilhelm W. W. , Morgan J. A.
Published: March 2009

Simulation models are heuristic tools for integrating diverse processes and help to increase our understanding of complex processes and systems. Models that predict crop development can serve as decision-support tools in crop management. This paper describes a phenology simulation model for the winter wheat shoot apex and reports validation and sensitivity analysis results.

The complete developmental sequence of the winter wheat shoot apex is quantitatively outlined and correlated with commonly recognised phenological growth stages. The phyllochron is used to measure the thermal time between most phenological growth stages, thereby increasing the flexibility over the growing degree-day (GDD) and photothermal approaches. Nineteen site-years covering a range of climatic conditions, cultural practices and cultivars across the Central Great Plains, USA, are used to validate the model.

Validation results show that the predicted phyllochron (108 GDD) agrees well with the observed phyllochron (107 GDD) for ten cultivars. Mean seedling emergence is predicted to within 2 days in almost all of the 19 site-years. The ability of the model to predict growth stages accurately increased successively from jointing to heading to maturity. Maturity is generally predicted to within 5 days of the observed day.

After validation, recalibration of the phyllochron estimates between growth stages are provided, and corrections for mesic and xeric conditions are suggested. Further validation of the entire developmental sequence of the shoot apex is recommended.
Effects of sowing winter barley on different dates in autumn on the severity of take-all (Gaeumannomyces graminis var. tritici) in those and the subsequent crops
Authors: Jenkyn J. F. , Gutteridge R. J. , Todd A. D.
Published: March 2009

Experiments on winter barley at Rothamsted, testing different sowing dates, were sampled in 1987–89 to measure effects on take-all caused by the fungus Gaeumannomyces graminis var. tritici. The experiments used the same plots in each year, and in 1988 and 1989 the randomization was restricted so that sowing dates were balanced for sowing dates in the previous year.

The site had been used to grow barley since at least 1979 (spring barley from 1979 until 1985), and take-all was much more severe than expected. It was usually most severe in the earliest-sown plots and decreased almost linearly as sowing was delayed. There was also evidence that the sowing dates of the preceding crop had a continuing, residual effect. In the two years that the effects of previous sowing dates were tested, there was usually least take-all in plots where the crop followed one sown very early or very late in the previous year, and most where it followed one sown at the end of September or in early October. These effects probably reflect differences in amounts of inoculum and in the rate of development of take-all decline.
Determination of optimum tuber planting density in the potato varieties Pentland Squire, Cara, Estima, Maris Piper and King Edward
Authors: Wurr D. C. E. , Fellows J. R. , Allen E. J.
Published: March 2009

Thirty-two experiments examining the effects of the weight and within-row spacing of potato seed tubers on graded tuber yields of five varieties were conducted on eight sites from 1980 to 1985. A complex analysis technique was used to combine these data and estimate the optimum tuber planting densities for different ratios of seed cost to small (40–60 mm) and large (60–80 mm) ware value. The same technique could be applied to any other combination of seed cost, ware size and ware value.

The optimum tuber planting density decreased with increasing seed-tuber weight. Differences in optimum planting density between varieties were much greater with small (35 g) than with large (105 g) seed tubers and decreased as the cost of seed increased relative to the value of ware. As large ware became worth more than small ware the influence of increasing seed cost on the optimum density was reduced. As the value of large ware increased, net returns increased and the effect of seed cost on net returns was reduced. Mean tuber size decreased with increasing stem density at harvest and at the same stem density was lower in varieties producing more daughter tubers/stem. Changes of mean tuber size (μ) and the spread of yield across size grades (σ) with time were well described by parallel curves in different varieties. It is suggested that in future it may not be necessary to determine optimum tuber planting densities by complex experiments involving several seed-tuber weights and spacings. Instead μ and σ could be estimated from simple experiments and tuber spacings determined by comparison with control varieties.
Nutrient cycling and losses based on a mass-balance model in grazed pastures receiving long-term superphosphate applications in New Zealand: 1. Phosphorus
Authors: Nguyen M. L. , Goh K. M.
Published: March 2009

Phosphorus (P) cycling and losses in irrigated, sheep-grazed pastures receiving superphosphate (SP) applications for 35 years at annual rates of 0, 188 and 376 kg/ha were studied using a massbalance approach which accounted both for P inputs to and outputs from the soil-plant-animal system. Total recoveries of applied P in the soil-plant-animal systems in the 188 and 376 kg SP/ha treatments were 94 and 83% respectively. Approximately 52–53% of the applied P was recovered in the soil within the major plant rooting zone (0–300 mm soil depth). These data suggest that P leaching losses from SP fertilizer, plant litter, root residue and sheep faeces were unlikely to occur beyond the major plant rooting zone. However, the transfer of excretal P to stock camps and the transport of P from SP fertilizer, plant litter and sheep faeces via the irrigation water along the border from the top to the bottom of the irrigated border strip accounted for less than 6% of the applied P. Superphosphate applications resulted in the accumulation of both soil inorganic and organic P fractions to a depth of 225 mm. The accumulation of soil inorganic P was most pronounced when SP was applied annually at the rate of 376 kg/ha, which was in excess of pasture P requirements.
Ettatum
Authors: Laredo M. A. , Simpson G. D. , Minson D. J. , Orpin C. G.
Published: March 2009

An omission occurred in the title, which should have read as follows:

The potential for using n-alkanes in tropical forages as a marker for the determination of dry matter intake by grazing ruminants
Effects of plant density and fertilization on the yield and quality of flue-cured tobacco in the Kenana area of the Sudan
Authors: Farah S. M.
Published: March 2009

In one experiment, variety Kutsaga 51 was grown at inter- and intra-row spacings of 60, 80 and 100 cm. Both yield and quality of leaf were improved as plant density per unit area increased. The greatest yield and highest quality were obtained from the 60 x 60 and 80 x 60 cm spacings while the lowest yield and quality were obtained from the 100 x 100 and 100 x 80 cm spacings.

In a second experiment the same variety was subjected to three levels of N and four levels of K. Higher doses of N or K were not necessarily effective in increasing the yield or improving the quality of leaf; on the contrary rates higher than 42/ha reduced both yield and quality of the leaf. Progressively higher doses of K did not offset the ill effects of excessive N.

Yield of leaf was primarily a function of leaves per unit area in the plant density experiment and number of leaves per plant in the fertilizer experiment.
Influence of growth temperature on anatomy andin vitrodigestibility of maize tissues
Authors: Cone J. W. , Engels F. M.
Published: March 2009

Tissues of maize grown under different temperature regimes showed remarkable differences in anatomical and chemical properties andin vitrodigestibility. A high temperature regime (12 h at 30 °C and 12 h at 24 °C) resulted in decreased cell wall thickness, cell diameter and cell wall yield, doubled lignin content and decreasedin vitrodigestibility, compared with plants grown under a low temperature regime (12 h at 18 °C and 12 h at 12 °C). A reduction in intensity of staining for lignin was observed in plants grown at 30/24 °C. Cell wall digestibility was thought to be limited by an indigestible cell wall layer between the secondary walls of adjacent cells. The use of lignin staining was of limited value for predicting cell wall digestibility. High temperatures probably affect physiological processes leading to lignin formation and deposition.
Excretion of purine derivatives by ruminants. Effect of microbial nucleic acid infusion on purine derivative excretion by steers
Authors: Verbic J. , Chen X. B. , MacLeod N. A. , Ørskov E. R.
Published: March 2009

Two steers totally nourished by intragastric infusion of volatile fatty acids and casein were given an abomasal infusion of a microbial protein preparation (Pruteen) at eight rates with a purine input ranging from 0 to 170 mmol/day over 11 successive 5-day periods. The urinary excretion of purine derivatives relative to the purine input was measured. Negligible amounts of xanthine plus hypoxanthine were present in the urine. The relative contributions of allantoin and uric acid to the total excretion were not affected by the rate of purine infusion. Total purine derivative excretion (uric acid and allantoin) was linearly correlated with purine input. Recovery in the urine of the infused purines was 0·77. It is suggested that utilization of exogenous purines may only occur in the intestinal mucosa and that the remaining purines may be completely converted, before entering the liver, to uric acid and allantoin, which are subsequently eliminated by the renal and extrarenal routes. The differences between cattle and sheep in excretion of purine derivatives, and the implications of these differences for the use of purine excretion values in order to estimate microbial protein supply to the ruminant, are discussed.
Solubility of mineral elements present in ruminant feeds
Authors: Ibrahim M. N. M. , Van Der Kamp A. , Zemmelink G. , Tamminga S.
Published: March 2009

Eight feeds were treated with seven solvents and the proportion of seven mineral elements (Ca, Mg, P, Na, K, Cu, Zn) released was assessed. Six of the feeds were from Sri Lanka (Panicum maximum ecotype Guinea A, Glyricidia maculata, Artocarpus heterophyllus, untreated and urea-treated rice straw, and rice bran) and two from the Netherlands (maize silage and wheat straw). The solvents were water, tris buffer, rumen fluid from a cow deprived of (RF -) or fed (RF +) mineral supplements, neutral detergent solution with (NDS +) or without (NDS -) EDTA, and acid detergent solution (ADS).

Both the type of feed and the solvent significantly influenced (P < 0·01) the amount of dry matter loss and the proportion of minerals released. Maize silage released over 80% of its minerals, except Cu, in water and tris buffer, probably because of the low pH (3·7) during ensiling. The other feeds differed widely in their ability to release minerals. In general, P, Na and K. were more soluble in water than Ca, Mg and Zn.

Mineral concentration in RF influenced not only the amount of minerals released, but also the extent of sorption by the feed. The latter effect was more pronounced in feeds with low mineral concentration, maize silage being no exception.

Treatment with NDS+ and ADS removed all minerals except Cu. With all feeds, 12–34% and 5–34% of the Cu remained in the ND and AD residues, respectively, indicating its association with the cell wall. Results of the NDS- treatment showed that some of the Ca and Mg may be associated with the cell wall.

Comparison of the feeds across the different solvents tested indicated that, in terms of absolute quantity of mineral released, G. maculata could be a good source of Ca, Mg, K and Cu, and that rice bran is a good source of P and Zn. The variety of rice straw tested released high amounts of Na. A. heterophyllus is rich in available Ca.
Recovery and germination rates of seeds of Mediterranean medics and clovers offered to sheep at a single meal or continuously
Authors: Thomson E. F. , Rihawi S. , Cocks P. S. , Osman A. E. , Russi L.
Published: March 2009

Measurements were made of the recovery and germination rates of seed of eight species of annual medic (Medicago spp.) and three of clover (Trifolium spp.) after ingestion by sheep. Recovery of medic seed was measured as the number of seeds collected from faeces after feeding, in addition to a basal diet, either (i) 200 g of pods at a single meal, or (ii) a quantity of pods estimated to contain 30000 seeds at a single meal or (iii) 200 g of pods daily for 21 days. Only the first method was applied to the clovers.

There were large differences (P < 0·001) in seed recovery between species, from < 2% to nearly 20% in medics, and up to 59% in T. campestre, which has low single-seed mass. Although there was a curvilinear decrease in seed recovery as single-seed mass increased (r2 = 0·80), the high recovery of M. rotata, a fairly large-seeded species, suggests that there are important differences between species, irrespective of seed size.

When 200 g of medic pods was offered to sheep at a single meal, mean seed recovery was slightly lower than when 200 g of medic pods was offered daily for 21 days. Seed recovery of medics was much higher (P < 0·001) when 30000 seeds were offered at one meal.

Germination rate before ingestion was 1·9–6·5% (P < 0·001) for hard-seeded medics and 2·7–9·7% (P < 0·001) for clovers with low single-seed mass; passage through the digestive tract increased (P < 0·001) germination rate in both medics and clovers.
Effect of hedgerow species in alley cropping systems on surface soil physical properties of an Oxic Paleustalf in south-western Nigeria
Authors: Hulugalle N. R. , Kang B. T.
Published: March 2009

Effects of hedgerow species on surface soil physical properties were studied in an on-going trial established since 1981 on an Oxic Paleustalf in southwestern Nigeria. The experimental treatments wereLeucaena leucocephala, Gliricidia sepium, Alchornea cordifoliaandAcioa barteriihedgerows planted at 4 m interhedgerow spacings and a control (no hedgerows). Plots were sequentia-ly cropped with maize (Zea mays) and cowpea (Vigna unguiculata). Soil physical properties, i.e. particle size distribution, bulk density, apparent pore size distribution and water infiltration, were monitored during the dry season in January and the main growing season in June 1989. Soil temperature was monitored at approximately monthly intervals from February to June 1989. Soil properties of alleycropped plots were superior to those of the control. Soil compaction was highest in the control and lowest withL. leucocephala. Between the hedgerow species, within-season increases in soil compaction were largest withA. cordifolia. Lowest soil temperatures were observed withL. leucocephalaandA. barterii. Frequency, quantity and quality of prunings produced by the hedgerow species appeared to have a major beneficial effect on soil physical properties.