The relationship between germination rate within a carrot seed lot and subsequent seedling performance was studied in four seed lots of different viability. Seedling performance was assessed using slope tests conducted under controlled conditions and in the field following fluid drilling under a range of environmental conditions. Germination rate within a seed lot was positively related to vigour measured by slope tests, percentage emergence and seedling weight, and was negatively related to the spread of emergence times (In variance days) and the coefficient of variation (c.v.) of seedling weights. Sowing seeds selected as fast germinating resulted in greater seedling emergence percentages over a range of environmental conditions than when sowing seeds selected as slowly germinating.

The present paper contains the results of investigations on silver-leaf disease which are a continuation of those previously described by one of us (1,2) in earlier numbers of this periodical.

Some time ago it was thought desirable to duplicate as far as possible in different localities the experiments conducted on this disease. Hence most of the experiments described in this paper have been carried out both at Cambridge and at the John Innes Horticultural Institution, Merton.

In tests with seedlings in the glasshouse, significant differences in susceptibility to downy mildew, caused by Peronospora farinosa f. sp. betae, were observed between individual stocks of sugar beet. The resistance of a particular stock in glasshouse tests was not always a reliable guide to its resistance in the field. There were also serious discrepancies between the results of tests with seedlings and those with mature plants in the field, suggesting that the resistance of certain stocks, relative to one another, may vary with increasing age of the host plant. This contention was supported by evidence from a field experiment in which the susceptibility of several sugar-beet stocks was compared throughout the growing season. It also appears that changes in environmental conditions affected resistance to downy mildew more in some stocks than in others.

Progenies of selected plants that had not shown severe symptoms of downy mildew, after exposure to natural inoculation with P. farinosafor more than 3 months in the field, were much more resistant than the parent stocks. This showed that a single generation of selection under suitable conditions can significantly improve the resistance of sugar-beet breeding stocks to downy mildew.

An inbred sugar-beet line of American origin showed exceptional resistance to downy mildew in experiments under glass and in the field. Inoculated plants of this line usually showed no symptoms of the disease and P. farinosa did not produce conidia on them. These results show that sources of extreme resistance are present in cultivated sugar beet and suggest that an excellent control of downy mildew in Britain may eventually be achieved through the use of resistant varieties.

1. Three contrasting varieties of spring oats were grown at six centres in England and Wales for three seasons, at two levels of manuring. They were harvested at two stages of ripeness, and both straw and grain were analysed for all treatments.

2. Varietal differences in composition between samples of straw grown under similar conditions and harvested at comparable stages of ripeness were negligible. In this respect there was no relationship between quality of straw and that of grain.

3. Differences in composition attributable to environment were very large. Crude protein content ranged from 1·9 to 7·6%, and crops grown under cool and wet conditions always yielded a better quality straw than those grown under the warmer and drier conditions in the south of England.

4. The chemical composition of oat straw changed very little between the early ‘binder-ripe’ stage and the fully ripe ‘combine’ stage, although physically it tended to become more brittle and less attractive in appearance. The grain also showed little change in composition between the two times of harvesting.

5. A spring dressing of 2 cwt. per acre of nitrochalk increased the protein content of the straw very considerably, but the response varied widely with conditions. The average increase at all centres over three years was 20%.

6. Under cool and moist conditions the composition of oat straw was comparable with that of meadow hay.

Some interesting contributions to this subject have appeared during the past three years. They contain somewhat discordant ideas and it has therefore been concluded that the present time is suitable for a brief review of the whole matter and for the publication of further experimental results. A striking susceptibility to environmental change is evinced by both the awn and the lateral floret, and it is part of the purpose of this paper to describe the nature of the fluctuations involved and to indicate the extent to which they militate against the reliable determination of genetic ratios.

In two feeding experiments the effects of different sources of protein on nitrogen utilization were studied. Three protein sources were examined in both experiments; (a) soya-bean oil meal; (b) lucerne hay or vetch oat hay, and (c) a mixture of soyabean oil meal and hay. The first experiment was carried out with nine adult rams and the second with twelve growing rams.

The results of N balance experiments showed clearly the superiority of the hay ration over the soya-bean meal ration. N retention when the mixed ration was given was greater than on hay alone. No parallel trend was found between the protein digestibility of any of the diets and its efficiency for N retention.

With adult sheep a negative correlation between the extent of N retention and blood urea concentration was found; this agreed with our earlier findings. No such negative correlation was found with growing animals.

The highest concentrations of the various forms of soluble N compounds such as soluble a-amino N, diffusible N and diffusible peptide N were found in the rumen liquor taken from the sheep kept on the hay diet. The lowest amounts were observed when the soya-bean oil meal diet was given and intermediate amounts with the mixed diet. These trend sappeared to be related to the NPN (non-protein nitrogen) content of the diet, but the amounts of soluble N compounds present in rumen liquor were not directly correlated with the extent of N retention.

Concentrations of VFA present in rumen liquor depended primarily on the carbohydrate composition in the diet. The type of protein ingested exerted some influence, particularly on the concentrations of caproic and iso-caproic acid. The ratios of concentrations of the individual fatty acids in blood to the concentrations of the same acids in rumen liquor were found to increase with lengthening of the fatty acid chain.

The examination of 108 first year seeds hays showed the average crude protein content to be 9·0 ― and the average crude fibre content 25·7 ―. The crude protein content varied from 5·0 to 13·5 ― and was directly associated with the clover content.

Figures obtained on hays cut in the second and third years of the ley suggest that the protein content falls, and the crude fibre content rises, with increasing age of ley.

The composition and digestibility of twenty first year hays were determined and the average figures quoted for hays of high, medium and low clover content. The starch equivalent values of these hays were high and moderately constant, varying from 33·3 to 41·2, average 36·8. The protein equivalent values varied from 1·8 to 8·4 ―, average 5·1 ―.

The composition and digestibility of four samples of second year seeds hay, two samples of third year hay, one sample of second cut hay in its first year and one sample of lucerne and cocksfoot hay were also determined.

Alternate 2·4 m wide strips of a mixture of birdsfoot trefoil (Lotus corniculatus L.) with white clover (Trifolium repens L.) (BW), and of red clover (Trifolium pratense L.) (RC) were offered in the proportions (by area) of 0·80[ratio ]0·20, 0·67[ratio ]0·33, 0·33[ratio ]0·67 and 0·20[ratio ]0·80 to yearling heifers in groups of three for periods of 3 days over four replicates in time, balanced for effects of previous treatments. Observations on the distribution of grazing activity and biting rate were made over 3 h periods each evening, and on the morning of Day 2. Biting rates were consistently higher on BW than RC (52·3 v. 46·3±0·59 bites/min, P<0·001). Initially the animals showed a strong tendency to concentrate grazing on the sward of smaller proportional area, but the selection coefficient (log θ) changed from positive to negative with time as herbage on minority strips was depleted. These results are discussed in the context of concepts of partial grazing preference.

An analysis of yield data from 31 tea clones grown in replicated trials at four locations revealed the presence of significant genotype-environment interactions. Joint regression analysisshowed that a significant proportion of these interactions could be attributed to differences in the linear response of each genotype (clone) to the range of environments. However, estimates of the deviations from regression were also significant, indicating the presence of some unpredictable variation.

The response of each individual clone was estimated by computing the regression coefficient of individual yield on environmental mean yield at each location. The clones used in this study had regression values ranging from 0·19 to 2·08, indicating considerable genotypic difference in response to environmental change. Genetic variation in adaptation was also found to be present. Clones of the Assam type were found to possess general adaptation whereas the one clone of Indo-Chinese origin was specifically adapted to low-yielding environments.

Some known features of several tea clones are explained on the basis of the linear regression model and a more scientific basis is provided for the recommendations of clones for differentdistricts. The implications of genotype-environment interactions in practical tea breeding and selection are also discussed.

Red blood cell electrolyte levels and haemoglobin types have been determined in flocks of Peppin Merino sheep genetically different for clean fleece weight and crimp frequency. The flocks selected for high clean fleece weight or low crimp frequency had significantly higher mean erythrocyte potassium levels than did those flocks selected for low clean fleece weight or high crimp frequency, this difference was apparent in both haemoglobin AB and BB types. Erythrocyte potassium concentration was not correlated with either clean fleece weight or crimp frequency within flocks. The high clean fleece weight flock had a significantly higher gene frequency for high potassium than did the low clean fleece weight flock, while the high crimp frequency flock had a lower haemoglobin B gene frequency than the low crimp frequency flock.

Two experiments with growing pigs grouped in pens and three with growing pigs kept in metabolism crates were undertaken in order to determine young growing pigs'dietary requirement for phosphorus of vegetable origin, the relative potency and true digestibility of that source and the effect of dietary Ca concentration on its utilization. Much of the P was contained in wheat offal, and of this 900 g/kg total P was phytin-P.

In the first two experiments the responses to vegetable P were measured by pig live-weight gain, gain: feed ratio, several conventional carcass measurements and the weight, length and density, and the ash, Ca and P contents of the fourth left metacarpal, and also by the alkaline phosphatase activity of blood serum. No significant differences were found between treatments in terms of body-weight gain, gain: feed ratio, or the commercially important carcass characteristics. The requirement of pork pigs for P was measured by bone and serum enzyme characteristics when all the dietary P was of plant origin, apart from 0·3 g P/kg from casein. Under the conditions of this experiment this P requirement appeared to be met when the diet contained 5–6 g P/kg. The potency of vegetable P in Expts 1 and 2 and of wheat offal P in Expt 3 relative to feed grade dicalcium phosphate was 0·77, equivalent to a net retention of 0·4–0·5 as a proportion of that consumed estimated from growth and digestibility measurements. A true digestibility coefficient of 0·53±0·01 for wheat offal P was obtained in Expts 4 and 5. The effect of variation in dietary N and energy, associated with variation in dietary offal concentration, on the reliability of the potency estimates is discussed.

Increasing dietary Ca concentration caused a slight decrease in the digestion of wheat offal-P. The soaking of wheat offal in water for an average of 11 h before feeding increased P digestion in one of two experiments. In vitro evidence indicated that soaking initiated the hydrolysis of insoluble P compounds.

The present investigation was carried out to estimate the effects of genotype and sex on growth and laying performance and assess the variations in plasma constituents in the tested genotypes and their relations with productive traits after four generations of selection. Data of growth and laying performance on 1440 females and males of Japanese quail were taken from the three quail genotypes: maternal (MG), long shank length (LSG28) and control (CG) genotypes. Genotype significantly affected all studied growth productive traits, favouring selected genotypes. The LSG28 surpassed MG in total protein, albumin (Alb), globulin (Glob), triglycerides and Alb/Glob ratio and lowered both cholesterol and total lipids (TL). Sex significantly favoured females, which had higher body weight, longer shank length at 35 days of age and higher body weight gain during the period from 1 to 35 days of age. Females showed significantly higher concentrations of both Alb and TL than males. The MG exceeded LSG28 in fertility and hatchability per cent. Correlations for both growth and productive traits with plasma constituents revealed inconsistent trends in either magnitude or direction. Four generations of selection resulted in substantial phenotypic improvements in most growth and productive traits, as well as plasma constituents studied in LSG28, and favoured MG in maturity, days needed to produce the first ten eggs, higher egg production per cent and heavier egg mass.

An experiment is described in which sixty-four individually-fed pigs were used to investigate the effects of dietary protein status and administration of aureomycin on growth, efficiency of feed utilization and carcass conformation.

The main features of the results obtained were:

1. Pigs fed a ‘standard’ protein diet showed superior performance in terms of growth and economy of feed utilization in comparison with a ‘substandard’ ration. Appreciable differences in carcass quality including reduction in backfat and total body fat, concomitant with an increase in the lean meat content also resulted from variation in ration protein content. These results have been discussed in terms of the possible significance of both dietary crude protein status and amino acid content.

2. The administration of aureomycin at a ‘nutritional’ level had no apparent effect on any of the indices of pig productivity subject to analysis.

3. The high killing percentages noted over-all, have been discussed in relation to dietary energy and fibre levels.

The root and shoot characteristics of triticale grown in either a monoculture sequence of winter triticale (WT) and spring triticale or in rotation with sugar beet and faba bean (Norfolk rotation) were studied. Grain yield, root and shoot biomass as well as root morphometric parameters, were determined in a long-term field trial carried out in Poland. Spring triticale had lower root biomass and shorter root length than WT as observed at a soil depth of 5–20 cm and was related to the 0·1–0·5 mm root diameter fraction. Grain yields were affected by both crop rotation (Norfolk>monoculture) and the type of triticale grown (winter>spring). Straw yield was lower for the Norfolk rotation (7·16 t/ha) than for monoculture (8·47 t/ha). Consequently, the harvest index (HI) was higher in the Norfolk rotation (0·421 v. 0·324). In conclusion, when grown in monoculture, triticale showed lower biomass production and HI compared with triticale grown in a rotation with other non-cereal crops. These differences could be caused not only by deterioration in the physical, biological and/or chemical properties of the soil resulting from the use of a monoculture rotation, but also by the beneficial effects of the organic amendments applied and the legumes grown in the Norfolk rotation.

Fourteen experiments which studied effects of date of planting in July, date of harvesting and seed rate on seed tuber yields (10–51 mm) of several potato varieties were carried out in four seasons in East Anglia. Seed tuber yields of c. 30 t/ha in Estima, Wilja and Maris Piper and 20 t/ha in Record were produced from the early planting and in all varieties c. 20 t/ha were produced from planting in late July. For maximum seed yield in all varieties, seed rates of 1·5–2 t/ha were sufficient for most harvests from both dates of planting but for the earliest harvest of the late-July planting, seed rates of only 1–1·5 t/ha were required. The value of seed crops was assessed as the number of ware hectares that could be replanted from the seed yield of one hectare graded 10–51 mm. In all varieties, the number of seed-size tubers and replantable hectares increased with increasing seed rate over most of the range, but numbers were close to the maximum at the early harvests. With delay in harvesting, the number of seed tubers and replantable hectares decreased in many experiments, especially from low seed rates, as more tubers exceeded the upper seed size limit. Maximum numbers of replantable hectares of 15, 15, 20 and 25 were found in Record, Estima, Wilja and Maris Piper, respectively.

The monetary value of seed crops of Record and Maris Piper was calculated using (i) a fixed price per tonne of seed and (ii) cost of seed per replantable ware hectare. Sale values from the latter were substantially higher than from the former at early harvests in Record and at all harvests in Maris Piper. In Record, differences in sale value between the two pricing methods decreased with delay in harvesting as yields increased while number of replantable hectares varied little. The results showed that high multiplication rates and monetary returns can be obtained from short-season seed potato crops which may follow crops harvested earlier in the same season. The implications for potato production in the UK are discussed.

Protein turnover is an energy-consuming process that is essential for ensuring the maintenance of living organisms. Gold standard methods for whole-body protein turnover (WBPT) measurement have inherent drawbacks precluding their generalization for large farm animals and use during long periods. Here, we proposed a non-invasive proxy for the WBPT over a long period of time and in a large number of beef cattle. The proxy is based on the rate at which urine-N and plasma proteins are progressively depleted in terms of 15N after a slight decrease in the isotopic N composition of the diet (i.e. diet switch). We aimed to test the ability of this proxy to adequately discriminate the WBPT of 36 growing-fattening young bulls assigned to different dietary treatments known to impact the WBPT rate, with different protein contents (normal v. high) and amino acid profiles (balanced v. unbalanced in methionine). The 15N depletion rate found in plasma proteins represented their fractional synthesis rate, whereas the slow depletion rate found in urine was interpreted as a proxy of the WBPT. The proxy tested in urine suggested different WBPT values between the normal- and high-protein diets but not between the balanced and unbalanced methionine diets. In contrast, the proxy tested in plasma indicated that both dietary conditions affected the fractional synthesis rate of plasma proteins. We considered that the rate at which urine is progressively 15N-depleted following an isotopic diet switch could be proposed as a non-invasive proxy of the WBPT rate in large farm animals.

The determination of livestock growth patterns is important for meat or milk production systems, and nonlinear models are used to summarize and interpret the information. The aim of this study was to more accurately estimate growth curve parameters in buffalo cows by evaluating and selecting nonlinear mixed models that employ different types of residuals and include or not contemporary groups (CG) as a covariate. Weight records from 720 animals obtained over a period of 60 months were used. The growth curves were fit using nonlinear mixed-effects models. The Bertalanffy, Gompertz and Logistic models were evaluated. Modelling residuals using four structures (constant, combined, exponential and proportional) and the inclusion or not of CG in the models were also evaluated. The Akaike information criterion (AIC) and Bayesian information criterion (BIC) were used to select the model. In addition to estimating the parameters of the nonlinear growth models and their correlations, the instantaneous growth rate and inflection point were obtained. The Bertalanffy model with a combined residual structure and CG exhibited the lowest AIC and BIC values. Asymptotic weight (A) estimates ranged from 621.8 to 742.1 kg, and the maturity rate (k) ranged from 0.068 to 0.115 kg/month. The correlation between A and k ranged from −0.32 to −0.82 among the models evaluated. The selection criteria indicated that the Bertalanffy model was the most suitable for growth curve analysis in buffaloes.

Five experiments in harvest years 1980–2 tested the effects of straw inoculum and fungicides on leaf blotch (Rhynchosporium secalis), growth and yield of winter barley. Inoculating plots with rhynchosporium-infected straw increased the rate of disease development and greatly decreased seedling growth but inoculating plots with wheat straw or sterilized barley straw had no effect. In 1982, plots inoculated with infected straw gave less grain than uninoculated plots, but in all years fungicide sprays applied in winter or early spring had mostly small effects on grain yield that were only poorly related to their effects on leaf blotch and seedling growth.

In 1939, Pinous & Waddington reported tetraploid early cleavage stages of the rabbit after colchicine treatment of fertilized eggs in vitro. Chang (1944) inseminated rabbit does with sperm suspended in 1/1000 colchicine in 0·9% NaCl and noted a few abnormal young in the resulting litters. No chromosome counts were made, but Chang considered the possibility that colchicine had entered the egg and caused polyploidy. Using the same technique as Chang, Swedish workers have claimed the production of two adult triploid rabbits and one adult triploid pig (Häggqvist & Bane, 1950a, b, c, 1951; Melander, 1950, 1951). This Swedish work has been criticized (Beatty, 1951; Beatty & Fischberg, 1950; Becker, 1952–3; Hertwig, 1951; Nachtsheim, 1950; Rostand, 1951; Venge, 1953). Nevertheless, the technique is ingenious and the claim of great interest. The present note records preliminary attempts to extend the technique to cattle and to confirm the results in rabbits.

The nutritive value of uromol, a heated product of urea and molasses, was compared with raw urea–molasses and groundnut meal in three metabolic trials on buffalo calves. The non-protein nitrogen (NPN) as urea or uromol contributed about 65, 48 and 30% of the nitrogen in the experimental concentrate mixtures, replacing partially or completely the groundnut meal of the control diets. The results showed that at 65% nitrogen replacement, the crude fibre and cellulose digestibilities and the nitrogen retention of the uromol diet was similar to that of the control but was significantly (P < 0·05) higher than the urea–molasses diet. At 48% nitrogen replacement the nitrogen retention in the uromol-fed animals was still significantly (P < 0·05) higher than the urea–molasses fed group. At 30% nitrogen replacement, the differences between the control, urea–molasses and uromol groups were not significant.

In vivo rumen studies with the diets containing 50% NPN replacement showed lower but sustained ammonia-N with uromol than the urea–molasses diet. The total volatile fatty acids (TVFA) in rumen fluid, though initially higher in the control and uromol groups, were not significantly different from the urea–molasses group. Abomasal studies with diets containing 65% N as urea or uromol indicated a higher total nitrogen content in the abomasal fluid of the control and uromol-fed animals than the urea-fed animals. The 24 h abomasal passage of total-N/100 g nitrogen consumed was 95·5, 93·5 and 77·9 g in control, uromol and urea groups, respectively. The TCA-precipitatable-N (TCA-N) was also higher in the first two groups. These studies suggest that uromol is safer and has a better feeding value than urea–molasses at high rates of nitrogen replacement.