The analysis of series of crop variety trials has a long history with the earliest approaches being based on ANOVA methods. Kempton (1984) discussed the inadequacies of this approach.. summarized the alternatives available at that time and noted that all of these approaches could be classified as multiplicative models. Recently, mixed model approaches have become popular for the analysis of series of variety trials. There are numerous reasons for their use, including the ease with which incomplete data (not all varieties in all trials) can be handled and the ability to appropriately model within-trial error variation. Currently, the most common mixed model approaches for series of variety trials are mixed model versions of the methods summarized by Kempton(1984). In the present paper a general formulation that encompasses all of these methods is described, then individual methods are considered in detail.
The nutritional and immunological importance of colostrum for the survival and development of the neonatal pig are reviewed. The pig is born with low body energy stores and devoid of serum immunoglobulins. Colostrum provides the piglet with both energy and maternal antibodies but its fat and protein composition is very variable. Colostrum is very digestible, and both colostral energy and nitrogen (N) are retained with a very high efficiency. Colostrum production by the sow assessed from the weight gain of the litter from birth to 24 h of age is very variable (from 1900 to 5300 g). There is no clear effect of litter size or parity, suggesting that colostrum production is a characteristic of the sow. Within a litter, colostrum consumption by the individual piglets varies considerably. It is independent of birth order, but related positively to birth weight and negatively to litter size. Other factors influencing colostrum consumption, including cold stress, premature birth and birth hypoxia, are discussed. Because of the epitheliochorial nature of the porcine placenta, the new-born piglet must acquire maternal immunoglobulin G (IgG) from ingested colostrum for passive immune protection until the immune system of the piglet becomes fully developed. Colostrum IgG concentrations in milk vary widely between individual sows both in initial concentration and in the rate at which concentrations decline during the first 24 h of life. The piglet can only absorb intact IgG prior to gut closure, which Occurs in the first 24 h of life and is induced by intakes of colostrum which are insufficient to maintain piglet live-weight. As a result, the amounts of intact IgG absorbed by the piglet vary widely. The effects of colostrum consumption on neonatal survival are discussed. Consumption of colostrum in amounts sufficient to meet the energy requirement of the piglet is a major determinant for survival. Since most neonatal losses occur in the first 2 days of life, before acquisition of a maternal IgG for immune protection becomes important for survival, piglet serum IgG concentration does not correlate well with early survival but is important in later resistance to disease challenge. It is concluded that colostrum production is a good marker for the maternal quality of the sow. Future research should focus on the ability of the sow to produce more colostrum and on the possible delayed effects of passive immunisation on the health and performance of piglet at weaning and later in life.
Up until the 1940s chemical disease control relied upon inorganic chemical preparations, frequently prepared by the user. Key areas of use were horticulture and vegetable production with key targets being diseases that caused easily recognized damage. After this era and as the damaging effects of more crop diseases became obvious by the use of chemical control, the crop protection industry expanded rapidly and research to discover new active materials began in earnest. As new areas of chemistry were introduced, each one aiming to offer advantages over the previous ones, chemical families were born with research-based companies frequently adopting patent-busting strategies in order to capitalize on the developing fungicides market. Systemic fungicides offered new opportunities in disease control. The rise in Research and Development (R & D) and the increase in the number and quantity of chemicals being applied led to the introduction of regulation in the 1950s, initially on a voluntary basis, but now strictly controlled by legal obligations. In the 1960s, the market switched from horticulture and vegetables to one in which the main agricultural crops dominated. The cereal market, initially based on barley, moved to the current dominant market of wheat. The costs of R & D have risen dramatically in recent years and have become dominated not by the discovery process per se but by the provision of all the extra data needed to obtain registration. These rising costs happened at a time when markets showed little growth and are currently showing some decline. This has resulted in an industry that is continually striving to cut costs, normally by mergers and take-overs. As a consequence, many plant disease problems are not now being targeted by the industry and special measures have been introduced to ensure adequate disease control is available for these minor markets. Plant disease control will remain a necessity and fungicides will remain as a key factor in such control, although it is predicted that integrated control using chemicals, biological controls and biotechnology approaches will begin to dominate.
Triticale (x Triiicosecale Wittinack) is the intcrgcneric hybrid between the Cernale parent wheat (Triticum ssp.) and the male parent rye (Secale ssp.). The early work identifying and then producing primary and secondary triticales is described. Early wheat-rye hybrids were characterized by reproductive disorders and the cytology and meiotic characteristics have received much attention. Chromosome Constitution has been Studied particularly in relation to R-D substitution. Triticale has always been bred as a self-pollinating crop although outcossing can occur, and current cultivars are all nearly homozygous and homogenous lines. Hybrid breeding (using cytoplasmic male sterility) makes the optimum exploitation of heterosis possible and, with the aid of molecular markers, triticale germplasm is presently being investigated to establish genetically diverse heterotic groups. The first released spring and winter cultivars were generally characterized by good disease resistance, but low grain yield, shrivelled grain, high protein content, excessive height, lodging and preharvest sprouting. Breeding effort has increased yield, reduced shrivelling and improved test weight but at the expense of protein content, which is now comparable to wheat and rye. Plant height and lodging are also now comparable to wheat and rye. Progress in reducing preharvest sprouting by genetic selection is proving difficult and slow. Triticale may be suitable for grain production and for dual Purpose usage for Forage and grain.
White clover (Trifolium repens L.) and red clover (T. pratense L.) are the most important legumes of temperate pastures. The former is used largely in systems based around sheep or cattle grazing and is grown together with a companion grass. Breeding aims to optimize the white clover contribution to the sward. This means that yield per se is not the aim but rather to take full advantage of the benefits of white clover: in particular, nitrogen fixation, high protein content, digestibility, mineral content and high intake. The objective is an agronomically and, as far as possible, nutritionally balanced sward, thus persistence of white clover and yield stability over a number of years are key goals. A considerable focus of germplasm improvement has therefore been overcoming biotic and abiotic stresses to clover performance. The former include not only pests and diseases but also the impact of the ruminant animal and the competitive interaction with the companion grass, while abiotic stress could be loosely defined as 'winter hardiness' and 'summer survival' depending on the site. In recent years the focus of many breeding efforts has shifted to give more consideration to the effects of variation within white clover germplasm on animal performance and the environment. Beneficial effects on productivity have been known for many years, but recent studies of the impact of forage diets on meat and milk quality have opened up new opportunities for improvement. Diffuse pollution of nitrogen and phosphorus from agricultural sources is high on the environmental protection agenda of many governments. Breeding efforts are now being made to reduce the contribution of clovers to both direct (leaching) and indirect (through animal returns) pollution. In particular, recent insights into mechanisms affecting protein breakdown in the rumen and silo offer new prospects for breeding interventions to reduce environmental impacts. Molecular marker methods are being developed in white clover and the transfer and use of resources and information accumulating in the model legumes Medicago truncatula and Lotus juponicus is likely to be a major route by which the power of genomic approaches is translated into forage legume improvement. Hybrids of white clover and related species have been developed to introgress key traits; namely, drought tolerance, grazing tolerance of large leaf types and enhanced seed yield, for which only limited genetic variation is present within the white clover gene pool. Red clover is less persistent than white clover, is typically cut three or more times in a season and is used to make silage for winter feed. Although it is often grown with a companion grass, monocultures are common and yield per se as well as persistency and pest and disease resistance are major breeding aims. Fewer agronomic studies and less germplasm improvement have been carried out in this species and molecular studies are not Lis well advanced although, as with white clover, future developments are likely to benefit greatly from a close relationship to model legumes. Red clover brings considerable benefits in terms of animal production and meat and milk quality. These aspects, alongside approaches to reduce nitrogenous pollution from the silo, represent considerable opportunities for variety development.
Extensive research has been conducted on temperate cereal development since the inception of the Journal of Agricultural Science, Cambridge in 1905. This review presents an overview of the orderly and predictable development of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). It begins with the concept of building canopies by the formation, growth and senescence of phytomers (the unit comprised of the leaf, axillary bud, node and internode). Morphological naming schemes for uniquely identifying each plant part are then extended to uniquely name each phytomer unit. The role of the phyllochron (rate of leaf appearance) in synchronizing cereal development and phytomer formation is discussed, as is the use of phenology to predict the timing of the formation, growth and senescence of individual components. The complete developmental sequence of the winter wheat shoot apex correlated with growth stages is extended to spring barley. This overview discusses the abiotic factors controlling cereal development, with special attention given to key questions regarding the critical role of temperature. The review concludes with some cautious glances forward to the exciting possibilities for better understanding of mechanisms controlling the phyllochron and phenology being gained from advances in functional genomics and Molecular biology.
Heritable variation is at the heart of the process of evolution. However, variation is restricted in breeding for uniform crop populations using the pedigree line approach. Pedigree lines are successful in agriculture because synthetic inputs are used to raise fertility and control weeds, pests and diseases. An alternative method promoted for exploring the value of variation and evolutionary fitness in crops is to create composite cross populations. Composite cross populations are formed by assembling seed stocks with diverse evolutionary origins, recombination of these stocks by hybridization, the bulking of F, progeny, and subsequent natural selection for mass sorting of the progeny in successive natural cropping environments. Composite cross populations can provide dynamic gene pools, which in turn provide a means of conserving germplasm resources: they can also allow selection of heterogeneous crop varieties. The value of composite cross populations in achieving these aims is dependent on the outcome of mass trials by artificial and natural selection acting upon the heterogeneous mixture. There is evidence to suggest that composite cross populations may be an efficient way of providing heterogeneous crops and of selecting superior pure lines for low input systems characterized by unpredictable stress conditions.
Grass is a complex crop and its value for agriculture must be assessed in terms of the quantity and quality of downstream livestock products (milk, meat and wool). In addition to being a natural low-cost feed for ruminants, grassland protects soil and water resources and enhances the landscape. Temperate grasslands support a major share of the world's milk and beef production but now there is increasing emphasis on sustainability in livestock farming systems rather than maximizing outputs. The economic sustainability of livestock producers in many developed temperate regions is increasingly linked to production from fewer animals giving a higher quality product. A key element in the efficiency of all grassland systems is to optimize the protein/energy balance of forage and value it in a similar way to other livestock feeds. Grasses are rich in energy comprising structural and non-structural carbohydrates while forage legumes are rich in protein. The main forage legumes used in Europe are white and red clover, and lucerne, which form an essential part of sustainable farming systems because of their high nutritive value and ability to fix nitrogen. The productivity of grasslands containing legumes generally reflects the amount of N fixation, which is 65-280 kg/ha/year in W. Europe. Animal production from white clover-based pastures in Europe can be 0.8 that obtained from grass pastures fertilized with 400 kg N/ha/year, and that from lucerne and red clover can be equivalent to animal production from such pastures. [PUBLICATION ABSTRACT
The UK rural economy is increasingly driven by consumption-based demands rather than by productive land use. Such demands have been an influence on rural land use for many hundreds of years, but a range of factors, including greater wealth and mobility, have reinforced a long-standing trend for the rural economy to be consumption driven. A number of recent economic analyses and more anecdotal sources are used to furnish evidence of the importance of new consumption demands. It is argued that such demands may impact directly on land markets through land purchase for amenity, etc. and indirectly through bringing affluent people into closer proximity to diversified business opportunities. It is argued that these new economic realities are the dominant drivers of economic change and that their recognition might suggest new approaches to the support of strategies to deliver more sustainable rural development.
The rust diseases have plagued cereal cultivation from the early days of domestication. Biblical accounts report on the plight of Hebrews resulting from severe rust epidemics, while the ancient Greeks and Romans made offerings to the corn god, Robigus in attempts to defeat these devastating diseases (McIntosh et al. 1995). Man's approaches to fighting plant disease have changed since the time of the Romans, but still the fight continues. While we may have won many battles, the war is not yet over.
Few methods exist for estimating quantitatively the diet composition of free-ranging herbivores. The current study examined whether long-chain fatty alcohols (alcohols) or long-chain fatty acids (acids) could be used along with n-alkanes to allow reliable diet composition estimates to be made in herbivores consuming complex diets. Twelve Scottish Blackface wether sheep housed in metabolism crates were fed four different mixtures of three plant species (three animals per mixture) for a seven-period experiment. Concentrations of cuticular wax n-alkanes, alcohols and acids were estimated in samples of individual plant species, and the faeces from animals that consumed mixtures of these species. These concentrations were then used to calculate the dietary proportions of each species by a least-squares optimization procedure. To explore the differences between the estimation methods (individual markers and their combinations), the mean squares of errors (EMS) between the actual and predicted proportions of plant species were calculated. In three out of the four mixtures, alcohols had the lowest discrepancies (lowest EMS values), followed by n-alkanes and then acids. Acids yielded the lowest discrepancy in one mixture and the highest in the others. It is concluded that, for this particular set of mixtures, alcohols had great potential to estimate composition of complex diets. However, the estimation using acids was less good and n-alkanes were of intermediate potential. Estimation from the combination of the three marker classes was always better than using the poorest individual marker.
Seed yield and seed quality determine much of the value of rice (Oryza sativa L.) crops to the producers. The effects of genotype and environment on seed yield and quality were investigated using 12 rice genotypes grown during 3 years (2000-2003) at four different sowing dates in India, where detailed environmental data were collected. Yield, seed weight, proportion of seed setting and quality in terms of potential seed longevity, proportion of discoloured seeds, seed leachate conductivity and percentage germination were evaluated. The results were subjected to analysis of variance and the influence of environmental factors was evaluated by correlation analysis. Analysis of variance suggested that proportion of seed setting, seed leachate conductivity, potential seed longevity, percentage seed germination and proportion of seed discoloration were influenced more by environmental effects than by genotypic effects. In contrast, yield, panicle number, seed weight, and proportion of high-density grains were influenced more by genotypic than by environmental effects. The significant interaction effects of genotype and environment for all characteristics were attributed to differential resistance of genotypes to lodging (caused by increased plant height, low radiation and excessive rain at the time of grain filling) and were associated with fewer particles harvested, lower seed setting and lower seed weight. Correlation analysis suggested that warm weather conditions with high solar radiation and without excessive rains during grain filling stage gave the best rice seed yield with high quality.
For the determination of soil organic carbon (OC) concentrations, the availability of a fast, low-cost analysis method is required. The aim of the present Study was to evaluate the possibilities of near infrared reflectance spectroscopy (NIRS) to build a spectral database and to develop calibrations for the prediction of organic carbon concentrations in grassland soils. NIRS spectra of 1626 soil samples from different grasslands (both agricultural and natural) were collected between 1100 and 2500 nm. NIRS calibrations were developed with modified partial least square regression and tested with independent validation samples. The best equations were obtained with the first derivative of the spectra without scatter corrections. For the global calibration, containing the samples of all origins.. the standard errors of calibration (SEC) and of prediction (SEP) were respectively 3.70 g OC/kg dry soil (R-2=0-89) and 3.95 g OC/kg dry soil (R-2=0-88). The ratio of the standard deviation of the reference validation data to the SEP (RPD), indicating the performance of the calibration, was 2.9. Dividing the samples into groups according to their practice (agricultural or natural grassland), improved SEP by 5.8 and 7.7%, respectively. Dividing the samples into texture groups (clay, silt, sand) improved SEP for agricultural grassland by, on average, 7.4% and for natural grassland by 16.2%.
Three successive field experiments (2000/01-2002/03) assessed the effect of wheat cultivar (Consort.. Hereward and Shamrock) and fungicide (epoxiconazole and azoxystrobin) applied at and after flag leaf emergence on the nitrogen in the above-ground crop (Total N) and grain (Grain N), net nitrogen remobilization from non-grain tissues (Remobilized N). grain dry matter (Grain Dill), and nitrogen utilization efficiency (NUtE(g) = Grain DM/Total N). Ordinary logistic curves were fitted to the accumulation of Grain N, Grain DM and Remobilized N against thermal time after anthesis and used to simultaneously derive fits for Total N and NUtE(g). When disease was controlled, Consort achieved the greatest Grain DM, Total N, Grain N and NUtEg; in each case due mostly to longer durations, rather than quicker rates, of accumulation. Fungicide application increased final Grain Dill.. Grant N, Total N and Remobilized N, also mostly through effects on duration rather than rate of accumulation. Completely senesced leaf laminas retained less nitrogen when fungicide had been applied compared with leaf laminas previously infected severely with brown rust (Puccinia recondita) and Septoria tritici, or with just S. tritici. Late movement of nitrogen out of fungicide-treated laminas contributed to extended duration of both nitrogen remobilization and grain N filling, and meant that increases in NUtE(g) could occur without simultaneous reductions in grain N concentration.
Diets for broiler chickens (n=90) were supplemented with chromium (CrCl3, 6H(2)O), either alone (0(.)2 mg/kg diet) or in a combination with ascorbic acid (0(.)2 mg Cr and 50 mg ascorbic acid/kg diet). The objectives of file study were to ascertain if ascorbic acid had any additive effect oil the actions of chromium and whether chromium supplementation could alleviate the nutritional stress in the birds imposed by a reduced energy intake. The birds were fed at the recommended (Bureau of Indian Standards 1992) and at a lower plane of energy. Live-weight gain and diet Utilization were higher (P < 0(.)01) when the normal energy diet supplemented with chromium wits fed. Food intake (35 days) was higher (P < 0(.)001) in the birds fed with the low energy diet. There was an increase (P < 0(.)01) in metabolizability due to the supplementation of chromium. The metabolizability of crude protein and total carbohydrate increased (P < 0(.)05) when chromium and ascorbic acid were supplemented together. Chromium intake was higher (P < 0(.)001) in the supplemented birds, especially in those fed with the low energy diet (P < 0(.)05) though its retention was higher (P < 0(.)05) when the normal energy diet was given. Chromium in combination with ascorbic acid also enhanced (P < 0(.)01) chromium retention. Blood glucose (P < 0(.)001) and plasma cholesterol (P < 0(.)05) were lower in the supplemented birds and blood glucose was reduced further when ascorbic acid Was supplemented together with chromium (P < 0(.)01). Plasma protein increased (P < 0(.)05) in the supplemented chickens. However, variation in the dietary energy concentration did not exert any significant effect oil these blood parameters. Plasma chromium was higher (P < 0(.)05) in the supplemented birds, though chromium had little effect in this regard with ascorbic acid. Plasma copper increased (P < 0(.)05) when chromium was supplemented alone and increased further (P < 0(.)05) when chromium and ascorbic acid were supplemented together. Deposition of chromium in the breast and thighs increased (P < 0(.)05) due to supplementation. Protein content and total accretion of protein in the carcass were higher (P < 0(.)05) when chromium was supplemented alone and with ascorbic acid. The supplemented birds had less (P < 0(.)01) Fat per 100 g of carcass irrespective of the dietary energy concentration. Weight of the hot carcass increased (P < 0(.)05) due to chromium supplementation although dietary energy concentration did not affect this particular parameter. It was concluded that inorganic chromium supplementation (0(.)2 mg chromium/kg diet) might effectively enhance the growth performance, diet utilization and carcass characteristics in broiler chickens. Addition of ascorbic acid might also be beneficial in this regard. However, dietary energy concentration was more critical and to yield the maximum benefit of Cr supplementation in broiler chickens, ail optimum level was essential.
A study of the commercial growing of different varieties of Bacillus thuringiensis (Bt) cotton compares the performance of growing official and unofficial hybrid varieties of Bt cotton and conventional (non-Bt) hybrids in Gujarat by 622 farmers. Results suggest that the official Bt varieties (MECH 12 and MECH 162) significantly outperform the unofficial varieties. However, unofficial, locally produced Bt hybrids can also perform significantly better than non-Bt hybrids, although second generation (F-2) Bt seed appears to have no yield advantage compared to non-Bt hybrids but can save on insecticide use. Although hybrid vigour is reduced, or even lost, with F-2 seed the Bt gene still confers some advantage. The F-2 seed is regarded as 'GM' by the farmers (and is sold as such), even though its yield performance is little better than the non-GM hybrids. The results help to explain why there is so much confusion arising from GM cotton release in India.
The challenge that faces agriculture at the start of the 21st Centuary is to provide security of food production in a sustainable way. Achieving this task is difficult enough, but against a background of climate change, it becomes a moving target. However, one certainty is that soil factors that limit crop growth must be taken into account as new strategies for crop management are developed. To achieve this, it is necessary to measure the physical and nutritional status of the root environment in the field. Before considering measurement methods, our understanding of how the plant interacts with its soil environment is reviewed, so that it is clear what needs to be measured. Soil strength due to soil drying is identified as an important stress that limits agricultural productivity. The scope to measure Soil factors that directly affect plant growth is reviewed. While in situ sensors are better developed, progress in the development of remote sensors of soil properties are also reviewed. A robust approach is needed to interpret soil measurements at the field scale and here geostatistics has much to offer. The present review takes a forward look and explores how our understanding of plant responses to soil conditions, the newly emerging sensing technologies and geostatistical tools can be drawn together to develop robust tools for Soil and crop management. This is not intended to be an exhaustive review. Instead, file authors focus on those aspects that they consider to be most important and where the greatest progress is being made.
Changes in the seed coat morphology of 12 annual legumes were studied using environmental scanning electron microscopy (ESEM). The seeds of Biserrula pelecinus L. cv. Casbah, Ornithopus sativus cv. Cadiz, Trifolium clypeatum L., T. spumosum L., T. subterraneum L. cv. Bacchus Marsh, Trigonella balansae Boiss. & Reuter., Trigonella monspeliaca L. and Vicia sativa subsp. amphicarpa Dorthes (morthes.) were examined by ESEM after exposure to field conditions for 6 months, while those of Medicago polymorpha L. cv. Circle Valley, Trifolium clypeatum L., T. glanduliferum Boiss., T. lappaceum L., T. spumosum L., and T. subterraneum L. cv. Dalkeith, were examined after 2 years' exposure. The entry of water into seeds was followed by covering various parts of the seed coat with petroleum jelly and soaking the treated seeds in dyes. As the seeds softened over time, more and larger fractures appeared on the seed coat. Water entered the seed either through fractures, over the seed coat as a whole or through the lens. It is hypothesized that the formation of fractures occurs after physicochemical changes in the seed coat, probably associated with changes in the amount and nature of seed coat lipids. The newly matured whole seeds of M. polymorpha cv. Circle Valley, T. clypeatum, T. glanduliferum, T. lappaceum, T. spumosum, and T. subterraneum cv. Dalkeith were analysed for lipid content in 1997. The seed coats of T. subterraneum cv. Dalkeith and T. spumosum were separated from the cotyledons and examined in detail for lipid content. The lipid content of whole seeds ranged from 48 (T. lappaceum) to 167 mg/g (T. subterraneum cv. Dalkeith). Total lipid of the whole seeds of T. subterraneum cv. Dalkeith and T. glanduliferum declined by about 9 mg/g over 2 years, while in T. spumosum it declined by about 17 mg/g. In contrast, the major fatty acids in the seed coat declined by 0.67 mg/g over the 2 years. Change in seed coat lipids showed a marked similarity to changes in hardseededness for both T. subterraneum cv. Dalkeith and T. spumosum. The results strongly suggest that seed softening is associated with loss of lipids in the seed coat, because lipids have physical characteristics that are altered at temperatures experienced in the field.
The objective of the study was to determine the in vivo relationship between the long-term administration of recombinant bovine somatotropin (rbST), circulating levels of IGF-I and insulin, mammary blood flow and other variables relevant to milk synthesis, in crossbred, Holstein cattle. Ten first-lactation, non-pregnant, crossbred, Holstein dairy cattle were divided into two groups of five animals each; an experimental group and a control group. Animals in each group were fed with rice straw, treated with 5 kg urea dissolved in 100 litres water per 100 kg dry rice straw as the source of roughage. Four consecutive study periods were carried out in each group. These consisted of a pretreatment period (45 days postpartum before lactation peak) and three treatment periods during early lactation (105 days postpartum), mid-lactation (165 days postpartum) and late lactation (225 days postpartum). During the treatment periods, animals that had completed 60 days of lactation were injected subcutaneously at fortnightly intervals with 500 mg of recombinant bovine somato-tropin (rbST) (POSILAC, Monsanto, USA) in the experimental group, while animals in the control group were injected subcutaneously at fortnightly intervals with 800 mg of sterile sesame oil, without rbST, as a placebo. During the pretreatment period, there were no significant differences in plasma concentrations of IGF-I, insulin and other parameters between the control group and the experimental group. During the treatment periods, the increase in the concentration of plasma IGF-I in rbST treated animals was significantly higher than in the control animals throughout the lactation period. Plasma glucose, protein and triglyceride concentrations in each group remained stable throughout the study. The total daily dry matter intakes were not significantly different between the groups. Milk yield increased by 20 % with rbST treatment and it was 22 % greater than that of the control animals receiving placebo in early lactation. Milk yield of rbST treated animals rose to a peak in early lactation and then gradually declined. In late lactation, milk yield of rbST-treated animals decreased by 19 % as compared with early lactation. Udder plasma flow and udder blood flow markedly increased with rbST treatment and there were no significant changes in the control animals. The ratio of udder blood flow to the rate of milk production increased in mid- and late lactation in controls and the rbST treated animals. These findings suggest that the short persistency of lactation in rbST treated animals was similar to that in the control animals receiving placebo. Changes in milk production during the progress of lactation in rbST treated animals might not be controlled systemically only but also locally within the mammary gland. The lack of effect of higher plasma IGF-I levels on persistency of lactation in rbST treated animals, may be due to changes in the pattern of IGF-I binding proteins and paracrine production inhibiting IGF-I action.
Flax fibre for industrial purposes differs from that for linen production, although the agronomic factors that influence fibre development and which factors are most important for industrial fibre production have still to be defined. A description of variations in the performance of fibre flax varieties is also necessary as current guidance relates to the European market rather than the UK. Field trials were sown in 2002 and 2003 at the Henfacs Research Centre in north Wales, investigating 29 and 26 varieties, respectively, of European fibre flax and dual-purpose flax varieties. In 2002 a nitrogen treatment was included in the trial with two treatments, 40 kg/ha and 80 kg/ha. Varieties were evaluated for 20 agronomic and fibre production variables, and the differences between the varieties were analysed using analysis of variance (ANOVA) and principal components analysis (PCA). The higher nitrogen rate was found to increase crop lodging, although some varieties were found to be more susceptible than others. Environment had a strong influence on crop success, with some varieties showing more year to year stability than others. PCA allowed those varieties that were the highest yielding, highest fibre producers and showed the best stability across the 2 years to be identified. Understanding the agronomic results presented and discussed here is important if fibre flax production is to become economically viable in the UK.