The Agricultural Research Council's system of feed evaluation provides a method of predicting the most profitable ration composition, given information about available feedingstuffs and the values of the parameters in the beef-feed production functions. Because these functions are non-linear, parametric estimation based on average data for a group of animals will give biased results. A method of determining unbiased estimators of the parameters is derived and the magnitude of the bias is shown to be small. Some simplifications of the ARC formulae are proposed.

Laboratory indices of P availability were compared for six soils. Phosphorus soluble in sodium bicarbonate, ammonium fluoride and citric acid solutions, and in water was determined. Maximum P adsorption capacity was calculated from data by a batch method obtained from equations using the Langmuir isotherm. Adsorbed P values were derived from the same equations. Measurements of P adsorption obtained by leaching soil samples with a phosphate solution yielded asymptotic curves which also allowed the maximum adsorption capacity to be calculated. Results obtained by the two methods were very similar. Leaching of soil samples by water was the basis for calculating maximum P desorption values; these agreed well with the adsorbed P values obtained from the Langmuir isotherm.

Phosphorus uptake by plants, determined in a greenhouse experiment, was correlated with the various data and parameters obtained in the laboratory; there were no significant correlations with the P values from extraction methods, but there were good correlations with some of the parameters from the equilibration and leaching experiments.

Maize seedlings (cultivars Bastion, Ace, Anko and Mirna) were raised for 15, 30 or 45 days in a glasshouse and planted in the field between early May and mid-June in 1989 and 1990, at 10 plants/m2. Samples of transplants and direct-seeded crops of the same cultivars were taken at regular intervals throughout the growing season for growth analyses. In both years, the 15-day-old transplants established more rapidly in the field than older transplants, and the patterns of leaf production of these young transplants were similar to those of direct-seeded maize. Transplants flowered earlier than direct-seeded maize from the same planting date. At most harvests, transplants showed significantly higher dry weights than their direct-seeded counterparts, and May-planted maize had significantly higher dry weights than June-planted crops, while cultivar effects were small. Final biomass yields were consistently higher in 1989 (17 t/ha) than in 1990 (11 t/ha). In both seasons, particularly in 1990, there was a trend for a lower harvest index in direct-seeded maize which reflected its immaturity at final harvest. The lowest harvest index (0·07) in 1990 was recorded for direct-seeded maize of the late cultivar, Mirna (June planting), the highest harvest index (0·65) for 30-day-old Mirna transplants (May-planted). A comparison of the experienced effective temperature sums during the vegetative, reproductive and grain-filling phases suggested that the transplant nursery period provides an advancement in thermal time which can affect grain-filling and crop maturity. Year to year variation in climate seems to be of primary importance for yield advantages of transplanted over direct-seeded maize.

Eight forage rape cultivars were grown in replicated trials in 1980, 1981 and 1982; the plots were either inoculated to promote early infection with powdery mildew (Erysiphe cruciferarum) or they received one application of fiuotrimazole (in 1980) or triadimefon (in 1981 and 1982) to control mildew.

Mildew infections first appeared during August and increased rapidly during September to give highly significant differences between cultivars for the percentage leaf area infected in October; cv. Lair had the least mildew and cvs Samo, Early Giant, Bishop and Winfred were most severely infected. Regression analyses were used to investigate the increase in mildew over time in 1980 and 1981. No clear pattern of disease development was evident in 1980, but in 1981 the increase in mildew was predominantly linear and in untreated plots the greatest increase occurred in cvs Winfred, Samo and Bishop and the least in cv. Lair. Mildew was reduced in each year (P < 0·001) on fungicide treated plots and the mean fresh weight yield increase of 4·61 t/ha from treated plots was attributed mainly to the control of E. cruciferarum.

Fungicide treatment had little effect on % organic matter (OM), % digestible organic matter (DOMD) or concentration of thiocyanate ion (SCN-); both % nitrogen (N) and concentration of S-methyl cysteine sulphoxide (SMCO) were reduced in fungicide-treated plots in 1981, and N was also reduced in 1982. The mean concentration of SCN- from treated and untreated plots over 3 years was least in cv. Samo (14·90 mg/100 g D.M.) and greatest in cv. Lair (22·15 mg/100 g D.M.). The response in yield and quality factors to fungicide treatment is discussed in relation to the control of powdery mildew and other, possibly phytotonic, effects.

1. In an experiment conducted at the Hannah Institute the effects of irrigation and fertilizer nitrogen treatments on four sward types were studied for 3 years. The swards were S 23 perennial rye-grass with S 100 white clover, S 23 rye-grass alone, S 37 cocksfoot with S 100 white clover, and S 37 cocksfoot alone.

2. The irrigation treatments were—a control (no water) treatment, and two treatments which were irrigated to planned deficit levels of 2 or 0·5 in. below field capacity.

During the introduction of a new crop, it is important to study and select for resistance to pests to ensure preservation of possible natural protection in the plant material. One accession of Barbarea verna (Mill.) Asch. and one of Barbarea vulgaris R. Br. was exposed to female pollen beetles, Meligethes aeneus Fab. (Coleoptera: Nitidulidae) in a greenhouse experiment. The experiment was initiated to reveal the extent to which the plant material is accepted as a host plant to this important Brassicaceae pest. The two species, B. verna and B. vulgaris, were used for oviposition by 26% and 21% of the females, respectively. The amount of oviposition and feeding injury on either of the two species throughout the experiment did not indicate any difference in acceptance of the species by the pollen beetle. For both species a majority of the egg-laying females oviposited only once during the 5-day period and laid less than 3 eggs per clutch. The females present on the Barbarea spp. were not more disposed to accept the species as the days passed and the mean clutch size did not increase with time since previous oviposition. Females laying eggs used large and small buds of B. verna to the same extent for feeding. On B. vulgaris there was a tendency for more frequent use of large buds for feeding than small. Acceptance for oviposition by the pollen beetle on the two accessions of Barbarea is low in this experiment. Injury caused was limited to a level probably tolerated by the plant material without causing economic damage. As the oogenesis of the pollen beetle is reduced by exposure to low-quality host plants the potential natural protection would endure despite an increasing occurrence of the species.

Polyhalite is a multi-nutrient mineral ore containing potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S). Historically, it has enjoyed minor use as a fertilizer, but the opening of a new mine in the UK will make larger quantities available. Therefore, an examination of the performance of crops fertilized with polyhalite, or selected commercial alternatives, was pertinent and is reported here.

Four field trials were carried out between 2013 and 2016 to investigate the response of winter barley (Hordeum vulgare L.) and forage maize (Zea mays L.) to different application rates of polyhalite, potassium chloride (muriate of potash, MOP) and potassium sulphate (sulphate of potash, SOP) fertilizers. Potassium and S nutrition were the focus of these trials as they limit field production more often than Mg and Ca.

Polyhalite was found to be an effective source of both K and S for crop production. In three out of four trials, application of polyhalite resulted in similar or greater K offtake compared with both MOP and SOP; MOP application resulted in greater K offtake in one trial. In three out of four trials, application of polyhalite resulted in similar or better S offtake compared with both MOP and SOP; SOP application resulted in greater S offtake in one trial. Polyhalite and MOP treatments produced similar total dry weight in all four trials, but were slightly inferior to SOP treatment.

Factorial experiments were carried out on spring- and winter-sown oat crops in Ireland in 2016–2019 to identify plant responses in yield formation and grain filling procedures. Two cultivars (Husky and Keely), three seed rates (250, 350 and 450 seeds/m2), six applied nitrogen (N) rates (40, 70, 100, 130, 160 and 190 kg N/ha) with a plant growth regulator (PGR) were examined in spring and winter sowings, using the same cultivars at five rates of applied N (80, 110, 140, 170 and 200 kg N/ha). The applied N rate and seed rate significantly (P < 0.05) modified the yield components determining grains/m2 in spring- and winter-sown crops with increases in panicle number of key importance. Increases were also observed in the proportion of primary grain by weight (0.9–1.6%) and number (0.7–1.4%) ratios in spring-sown crops in response to applied N rate, with winter-sown crops exhibiting a more consistent pattern of grain fill. Seed rate and PGR application had minor effects on yield components and panicle conformation. Grain fill procedures played an important role in the maximization of grain yield under seasonal conditions. Significant positive correlations were observed between the number of aborted grain sites and yield under drought conditions (0.22), with negative associations observed in near-optimal conditions (−0.22 to −0.41). Agronomic effects on grain site abortion were minimal in comparison with seasonal effects. In seasons characterized by cool, consistent conditions, grain yield was maximized by the utilization of all available grain sites. Where assimilate shortages were encountered during grain fill the abortion of grains sites was positively associated with grain yield.

The objective was to establish a multivariate model using two complementary multivariate statistical techniques, factor analysis and multiple stepwise regression to predict carcase characteristics, carcase cuts, internal fat, viscera and loin eye area from body measurements of goats Boer mestizos. Thirty-two goats were used, with initial average weights of 3.3 ± 0.61 kg and final average weights of 16 ± 2.5 kg. Before slaughter and after 16 h of fasting, body weight was measured along with the biometric measurements (BMs) of each animal: body length, withers height, croup height, chest width, croup width, croup perimeter, thoracic perimeter, leg length and thigh circumference. The half carcases were sectioned in six anatomical regions that made up the commercial cuts: neck, palette, rib, handsaw, loin and ham. BMs showed a high correlation with a few exceptions; most of the correlations are above 50%. What also happens with the Carcass weight and cuts were also correlated above 50% with BMs. The data presented an index for the Kaiser–Meyer–Olkin test of 0.80, demonstrating the adequacy of the factor analysis. Through factor analysis, it was possible to observe that the first two factors extracted accumulated 75.47% of the total variance of the studied characteristics. Moderate to high and positive correlations of morphological characteristics with body weight, carcase characteristics and primary carcase cuts suggested the adequacy of morphological characteristics as criteria for early selection of crossbred Boer goats for their body weight and carcase characteristics without slaughter.

Understanding and representing the transformation of agricultural production systems has attracted increasing interest due to its importance for identifying drivers of changes and coping mechanisms in response to global challenges. These challenges are all the most pressing in North African countries exposed to a dramatic reduction in rainfall and increasing temperatures that affect sustainability in more than half of this semi-arid territory. This paper describes an improved way to understand such transformations through a cross-cutting analysis of crop–livestock system indicators over a period of 10 years in one community in Southern Tunisia. Our methodology is divided into four steps: (i) systems identification, (ii) indicator-based assessment of system crop–livestock sustainability, (iii) hierarchical clustering to identify sustainable intensification (SI)-based farm types and, finally, (iv) analysis of trajectories of these farm types. Results showed that the sustainability of the systems studied increasingly depends on diversification rather than intensification, which dominated in the 2000s. However, diversification has not necessarily improved socio-economic viability. Over the 10-year period, results revealed a dramatic increase of almost 50% in the population of small-scale farms whose viability depends on a range of on- and off-farm activities to meet the short-term needs that correspond to a buffer strategy. Additionally, the dominant SI processes were shown to be mostly based on diversification to livestock activities with both milking and fattening. Our holistic and timeline approach to system transformation makes it possible to account for sustainability between (systems) generations, which will be highly needed in future discussions about sustainability.

Muscle metabolism was studied in pregnant sheep over the final 4 weeks of pregnancy, between January and March 1985 and between December and March 1986, to investigate the effect of (i) chronic cold exposure, induced by shearing pregnant ewes 8 weeks before lambing and (ii) undernutrition in shorn and unshorn ewes. This was achieved by measuring hind-limb tissue metabolism using a combination of isotopic and arterio–venous difference techniques.

The rates of blood flow, oxygen uptake, carbon dioxide production and calculated heat production were all significantly higher across the hind-limb tissues in shorn than in unshorn ewes. The increase in hind-limb energy metabolism in the shorn group was such that 65% of the difference in wholebody heat production between shorn and unshorn groups could be attributed to muscle tissue. Following underfeeding, all of the difference in whole-body heat production between the two groups was completely attributable to muscle tissue.

Nonesterified fatty acid (NEFA) oxidation by muscle accounted for 46% of the difference in whole-body NEFA oxidation rate between fed shorn and unshorn groups. Underfeeding significantly increased the mean arterial plasma concentration of NEFA in shorn and unshorn ewes and the rate of NEFA oxidation across the hind-limb tissues in shorn ewes. The difference in whole-body NEFA oxidation between shorn and unshorn groups could, therefore, be completely accounted for by muscle. No significant differences in the arterial plasma concentrations of glucose, lactate or 3-hydroxybutyrate were recorded between shorn and unshorn ewes, although the rate of glucose uptake across the hind-limb tissued was significantly higher in the shorn group. Calculation of the maximum potential contribution of these substrates to hind-limb metabolism demonstrated that NEFA were the predominant energy source in all experimental conditions studied in all ewes. When data from fed and underfed shorn ewes were pooled, regression analysis revealed a significant negative correlation between the arterial plasma concentrations of glucose and 3-hydroxybutyrate, and significant positive relationships between the arterial concentrations of both glucose and 3-hydroxybutyrate and their rate of uptake across the hind-limb tissues. These relationsips were not observed in unshorn ewes.

It is concluded that the muscle mass plays a major role in the nonshivering thermogenic adaptation to chronic cold exposure in shorn pregnant sheep and that NEFA are the major substrate utilized for oxidative metabolism in this tissue.

1. The percentage of intramuscular fat (and its iodine number), of moisture (fat-free), and of total, myofibrillar, sarcoplasmic, stroma and non-protein nitrogens in lumbar 1. dorsi muscles, and their ultimate pH, fibre diameter, cross-sectional area and weight (both absolutely and as a percentage of the total musculature) were determined at bacon weight in two male and two female litter-mate pigs from each of four pure-bred sows mated with one boar of the same breed. Such data were obtained for pigs of Large White, Landrace and Welsh breeds.

This study compared ¾ Hereford–¼ Brahman calves with Hereford calves under Imperial Valley conditions. The calves produced in four successive crops were all paternal half sibs.

The cross-bred calves outgained the Hereford calves in the summer both on pasture and in the feedlot; the reverse was true for feedlot gains during the fall and winter, the period of non-stressful weather in the Imperial Valley for British type cattle. Possible causes for the breed by season interaction are discussed.

For several years observations have been made on the composition of rain-water, collected by Mr H. Welt, at Uithuizermeeden, a village in the northern part of the Province of Groningen. These observations were made as a part of a research on nitrification in a light clay-soil, by the method of drainage-plots such as are well known from the Rothamsted investigations. The results of these researches appeared in a Dutch journal. In the meantime it seems desirable to publish the results relating to the composition of rain-water.

The current study evaluated responses of early lactation Iranian Holstein cows to feeding roasted whole soybeans (SB) plus cottonseed meal (CSM), raw SB plus CSM and soybean meal (SBM) plus cottonseed (CS) in diets with lucerne hay and maize silage as the primary forage source. Treatments consisted of a total mixed ration that included 387 g forage/kg, supplemented with: (1) 120 g roasted SB/kg and 82 g CSM/kg, (2) 120 g raw SB/kg and 82 g CSM/kg, or (3) 120 g SBM/kg and 82 g CS/kg on a dry matter (DM) basis. Diets were offered to 14 multiparous Holstein cows (body weight=617·0 kg, days in milk=16·9) that were assigned randomly to one of three experimental diets for a 45-day trial. Dry matter intake (DMI) was significantly higher for the roasted SB plus CSM diet than for the raw SB plus CSM diet but the difference between the SB plus CSM diets and SBM plus CS was not significant. Yields of milk and 35 g fat-corrected milk (FCM)/kg and milk fat were significantly higher for the roasted SB plus CSM diet than for raw SB plus CSM and also for the SB plus CSM diets than for SBM plus CS. Milk protein concentration was significantly increased by about 2·0 g/kg by the SBM plus CS diet, but milk protein yield was the same for cows fed SBM plus CS, roasted SB plus CSM and raw SB plus CSM diets. Rumen ammonia N, plasma urea N (PUN) and milk urea N (MUN) concentrations were lower when the roasted SB plus CSM diet was fed. Ruminal pH and plasma glucose and β-hydroxybutyrate concentrations were not affected by dietary treatments. Plasma concentrations of essential amino acids (EAA), except Leu and Phe, were higher in cows fed the roasted SB plus CSM diet than in those fed raw SB plus CSM. The cows fed the SBM plus CS diet had the same concentrations of EAA, except Phe, as cows fed SB plus CSM diets. For diets based on lucerne hay and maize silage as the primary forage source, roasting of SB provides additional benefits over raw SB.

An assessment was made of the relative merits in the short term of KH2PO4and pig slurry as sources of orthophosphate. This involved a comparison of these two sources of P with regard to (1) adsorption of P by the soil from solution, (2) maintenance of the solid-phase P in labile form and (3) rate of release of the solid-phase P into solution.

The adsorption isotherms made with two soils revealed that the amount of orthophosphate adsorbed from pig slurry was much higher than that from KH2PO4 at all levels of application. Conversely, in order to raise the orthophosphate concentration in the soil solution to a given level, much larger applications of orthophosphate would be required as pig slurry than that in the form of KH2PO4. Therefore, the risk of direct orthophosphate-P pollution of ground water from pig slurry is likely to be even less than that from soluble P fertilizers.

Determinations of exchangeable-P in treated soils after different times from treatment showed that a larger fraction of the solid-phase P derived from slurry orthophosphate remains in an exchangeable form than that from KH2PO4.

The rate of desorption of solid-phase P into solution measured using an anion exchange resin was higher in the KH2PO4-treated soil than that in the slurry-treated soil at different times from addition of equal amounts of orthophosphate-P.

The results show clearly a more rapid and greater uptake of ammonium than of nitrate nitrogen by perennial rye grass grown in a sand-bentonite medium of pH 7·61. The extent to which the extra uptake with added ammonia was reflected in increased yields was dependent upon the age of the grass.

Except in the very early stages the percentage nitrogen content of the herbage was higher where nitrate nitrogen was applied than where ammonium nitrogen was applied. This indicates that any nitrate absorbed by the plant was less, efficient in increasing yields than was ammonium nitrogen.

The percentage P205 content of the grass was higher where the nitrogen was applied in the ammoniacal form than where it was applied as nitrate, and it appears that this greater P205 uptake with ammonium nitrogen resulted in increased growth.

The biological and useful yield of Phaseolus vulgariscv. ‘Banja’ and cv. ‘Diacol Nima’ were compared when sown at populations, in row spacings, equivalent to 5–4–32–3 plants m~2, at four levels of fertility achieved by the use of zero, five, ten and 20 cwt ae-1 respectively of a fertilizer mixture containing by weight 2:2:1 calcium ammonium nitrate, single superphosphate and muriate of potash. Yield and its components were determined at final harvest. The two cultivars behaved generally similarly. Crop Index, while highest in the plants with no fertilizer, was more or less constant for each cultivar over a wide range of biological yields in those plants receiving fertilizer. Yield is determined to the extent of 85–7% and 86–1% respectively for 'Diacol Nima’ and ‘Banja’ by the product of pods/plant and plants surviving to harvest. High densities, although giving the highest grain yields, are wasteful of seed in that the percentage of plants surviving to contribute to yield is much reduced.

The interaction between Phytophthora infestans and potato viruses X (PVX) and Y (PVY) was studied in the potato cultivar Kufri Chandramukhi. Prior infection by PVX and PVY reduced the susceptibility of the plants to P. infestans. The reduction in susceptibility was more marked when leaflets were inoculated with P. infestans 72 h after inoculation with PVY. The same type of reaction was observed in whole plants when the interval between PVY and P. infestans inoculation was 30 days. No significant differences were observed when the sequence of inoculation was reversed.

The control of eyespot (Pseudocercosporella herpotrichoides (Fron) Deighton) is most effective after application of carbendazim (Hampel & Lücher, 1973; Taylor & Waterhouse, 1975) or prochloraz (Marshall & Ayres, 1986) at growth stages (GS) 30–31 (Zadoks, Chang & Konzak, 1974), although some control occurred after applying prochloraz with carbendazim at GS 37–49 (Marshall & Ayres, 1986). Growers in the U.K. are advised to apply eyespot fungicides only when severe disease is expected. This forecast is usually made at GS 30, and spraying is recommended when two or more leaf sheaths have been penetrated on at least 20% of shoots (Anon. 1985). However, subsequent weather conditions may result in severe eyespot developing when no spray was recommended, or may not favour eyespot and result in fungicide being wasted.