Three experiments, carried out in 3 years (1972–5), which examined the effects of a wide range of rates of nitrogen fertilizer applied to seed crops of Home Guard on seed and progeny crop growth are reported. There was little effect of increasing rate of N application over the range 0–300 kg/ha on seed yield, and the results suggested that very low rates of nitrogen fertilizer (< 75 kg/ha) were required for maximum seed yield in mid-Wales. Increasing the rate of nitrogen fertilizer above 304 kg/ha delayed growth and decreased yield in seed crops. Although increasing the rate of nitrogen fertilizer in seed crops delayed senescence and increased the nitrogen concentration of tubers, there were few consistent effects on sprouting or growth of progeny crops.

Close negatively quadratic relationships were found between the dry-matter content of tubers and their size. The dry-matter content of all sizes of tubers increased during growth, but there were no effects of nitrogen on dry-matter content.

1. In a population of Hereford crossbred steers carcass conformation was measured by weighing wholesale joints cut in London and Home Counties fashion and dissecting a single rib sample joint. Correlations were calculated between weight of joints and certain linear carcass measurements.

2. Weights of individual joints in a group of good cuts were studied in relation to carcass composition estimated from sample joint dissection. Carcass fatness at constant carcass weight was correlated positively with some joints and negatively with others. A thigh width measurement was related to the weight of these joints in a similar fashion. This accounted for the low value of thigh width as an index of the proportion of good cuts.

3. The weights of joints, and many of the measurements, were highly correlated with carcass weight. When carcass weight was allowed for, partial correlations were too low to support the use of linear measurements to predict weight of joints in individual carcasses.

An experiment was carried out in which each of thirty-six ewes was offered one of six dietary treatments from the 30th to the 140th day of gestation. The treatments supplied two levels of metabolizable energy (ME) intake (128 and 116 kcal/kg W0.75/day) each at three patterns of protein intake, namely equal increments at 22 day intervals, equal decrements at the same intervals and a constant daily intake throughout. The protein intake patterns supplied a mean daily intake of digestible crude protein of 3·74 g/kg W0.75/day. Nitrogen balances were carried out on four ewes from each dietary treatment during the last 10 days of each 22 day period.

Thirteen ewes randomly distributed on all dietary treatments were barren. Mean rate of live-weight gain in the pregnant ewes was 123 g/day compared with 66 g/day in the non-pregnant ewes and was not significantly affected by treatments. Lamb birth weights adjusted to the basis of twins were 3·83, 4·02 and 3·56 kg for the increasing, constant and decreasing patterns of protein intake respectively.

Within patterns of protein intake there were no significant differences in nitrogen retention between pregnant and non-pregnant ewes until after 90 days of gestation. Thereafter retention increased in the pregnant ewes offered the constant and increasing patterns of crude protein and remained constant in the non-pregnant ewes. During the same period the retention of both pregnant and non-pregnant ewes on the decreasing pattern decreased.

The effects of both energy and protein intake on nitrogen retention in early and late pregnancy were assessed by multiple regression analysis. The results are discussed in relation to other recent findings.

Two potential new kale cultivars were compared with five control cultivars in 12 trials involving five sites in the north of England and the south of Scotland, 2 years, and a range of sowing and harvest dates.

The differences between cultivars were small for dry-matter and digestible organic-matter yield. Genotype-environment interactions were relatively large by comparison and hence only tentative estimates could be made of relative yield performance in a wider range of environments. However, the set of trials was satisfactory for determining the heights, dry-matter contents and digestible organic-matter contents of the cultivars despite the presence of statistically significant genotype-environment interactions.

Joint regression analyses revealed that the two cultivars with the lowest mean freshweight yields were also the least responsive to environmental change and that environments resulting in low digestible organic-matter contents were best for discriminating between cultivars.

The effect of three levels of N fertilizer on the ensiling characteristics of S. 24 perennial ryegrass and S. 37 cocksfoot have been examined during first growth in two growing seasons. The effects of sucrose supplementation, inoculation with Lactobacillus plantarum and wilting were also examined in certain cuts. All silages were made in the laboratory using a small scale vacuum silage technique.

The perennial ryegrass herbage was higher in water soluble carbohydrates than the cocksfoot, N fertilizers decreased soluble carbohydrates and dry-matter content in both species. Buffering capacity was not consistently different between grasses or between N levels.

Herbage was cut at two stages of maturity in the first year. In the first cut (8 days before ear emergence), perennial ryegrass silages were well preserved irrespective of the amount of N applied to the grass. Cocksfoot silages were well preserved only when the lowest level of N fertilizer had been applied (50 kg/ha). Supplementation of cocksfoot with sucrose prior to ensiling markedly improved silage quality, but inoculation had no effect. In the second cut (26 days after ear emergence) the grasses were higher in drymatter content and showed a lower buffering capacity, but neither ryegrass nor cocksfoot silages were well preserved unless supplemented with sucrose prior to ensiling.

In the second year of the experiment only one cut was taken (9 days after ear emergence). As in the previous year, silages made from herbage at a late stage of growth were poorly preserved. Wilting prior to ensiling resulted in well-preserved silages.

It is concluded that the need for additives and wilting to ensure satisfactory preservation varies in relation to the variety of grass used and its stage of growth.

1. An experiment has been conducted with dairy cows to find the effect on milk production of feeding rations with a high dry-matter content—typical war-time rations.

2. It was found that where a ration high in dry matter is fed, the cow tends to refuse food, and a statistically significant fall in milk production results. The correlation between the refusal of food, calculated in terms of starch equivalent, and the fall in milk production was 0·959.

3. The factors causing this inability of the cow to consume sufficient food to meet her total nutrient requirements have been considered. It has been concluded that dry-matter consumption is not an adequate method of expressing the amount of food a cow will consume, and that the major factor influencing food consumption is the palatability of the individual foods making up the ration.

My thanks are due to Dr S. J. Rowland for chemical analysis of the individual foods used in the experiments.

An experiment was conducted to compare the relative performance of fourteen populations of Italian ryegrass at sward and three non-sward densities. The non-sward densities were 3 in sown rows, 6 in square planting and 3 in square planting.Seven of the populations were commercial cultivars and seven were 50:50 mixtures of two cultivars.

Pedigree analyses were conducted of the Portland, Manx Loghtan and Hebridean sheep. These breeds are kept in small flocks, usually with only one ram active. Total population, and number of flocks have grown since registration started in 1975. Gene flow among flocks arisesfrom transfers of rams and of ewes: about 70% of breeding rams and 40% of breeding ewes have been transferred. Between half and three-quarters of the 1984 lamb crop were measurably inbred. More ram lambs are registered than would be expected in commercial practice.

About a third of flocks supplied rams to other flocks showing that these breeds do not have a very hierarchical structure. There is, however, a tendency towards hierarchical structure in the Manx Loghtan. A high proportion of the animals registered as foundation stocks in the earlyyears of the Combined Flock Book were represented in the pedigrees of recent lamb crops, i.e. genetic conservation has, on the whole, been achieved.

A ryegrass silage with pH of 3·8 was prepared and part was neutralized to pH of 5·4 with sodium bicarbonate. Sheep were fed ad lib. in four treatments in which the two silage feeds were fed with either all the feed being consumed per os or with the introduction of silage (15 g D.M./kg LW0·75 per day) directly into the rumen through a fistula. Intake per os was significantly higher (P < 0·001) for the modified silage than for the original silage and was significantly lower (P < 0·001) for the treatments which included feeding per rumen rather than all the food being consumed per os. Feeding per rumen resulted in a small but significant (P < 0·05) increase in the total (per os + per rumen) intake of both types of silage. This increase in intake through feed being introduced directly into the rumen suggests that factors sensed in the oro-pharyngeal region which were by-passed with this treatment may have some limiting effect on the intake of both these silages. The effect of the introduction of feed directly into the rumen on intake per os was similar for the two silage feeds, despite much higher levels of consumption of the modified silage for both feeding methods. This suggests that the increase in intake brought about by partial neutralization was not mediated through this treatment affecting any oro-pharyngeal limitation on the intake of silage.

Volatile fatty acid concentrations in the rumen were higher for the modified silage treatments, but differences between silage treatments for molar proportions of volatile fatty acids, rumen pH and rates of cellulose digestion were non-significant. The initial digestion of cellulose was slower, the molar proportions of acetic acid were lower and of propionic acid higher for treatments which involved feeding per rumen rather than all the food being consumed per os. These observations are discussed in relation to the use of the intra-ruminal feeding techniques and to possible factors limiting the intake of highly acid silages.

High-temperature-adapted strains RAU 1, RAU 2 and RAU 3 of Azospirillum brasilense C 7 were isolated from stepwise transfer to higher temperature (30 to 42 °C). One of the strains (RAU 1) showed more growth, greater nitrogenase and hydrogenase activities at 30 and 42 °C than parental and other temperature-adapted strains. This strain also showed growth and more nitrogenase activity from pH 6·5 to 8·0. Strain RAU 1 showed cross-resistance to penicillin (300/µg/ml) but not to streptomycin, kanamycin, viomycin and polymixin B at 30 and 42 °C. It was demonstrated in field plots in calcareous soil that seed inoculation with RAU 1 enhanced mineral uptake of cheena. Inoculation with RAU 1 led to a significant increase in associative nitrogen fixation, dry weight of roots, grain and straw yield of cheena compared with the uninoculated control with or without applied N, but the effect of seed inoculation with high-temperature-adapted strains was variable with different genotypes of cheena.

1. Percentages of fat, solids not fat and protein were determined in over 700 samples of mixed milk from 15 herds during 1925–26. In the case of fat content, nine herds produced one or more samples below 3 per cent., one herd recording 25 per cent, of samples below this limit. With regard to solids not fat, twelve herds produced milk containing less than 8·5 per cent, on one or more occasions, the highest percentage of deficient samples recorded being 40.

2. Frequency distributions of fat, solids not fat and protein percentages in the samples analysed, are given, together with standard deviations, and mean percentages with probable errors for these three constituents.

3. Correlation tables of fat with solids not fat, and protein with solids not fat have been prepared, and graphs illustrating the variations are given.

Two experiments, each involving five potato cultivars, investigated the effects of date of planting and harvesting of the seed crop, and of two seed storage temperature sequences, on date of dormancy break, sprout growth and subsequent field growth. The seed storage sequences in each case involved early or late accumulation of temperature to produce a physiological age of 600 day-degrees > 4 °C.

The effects of seed crop husbandry on most variables were small, with the exception of date of dormancy break, which occurred earliest when the seed crop was planted and harvested early. Effects of temperature sequence were more pronounced, although cultivars differed significantly in degree of response. Late temperature accumulation gave a larger number of sprouts per tuber, the length of the longest sprout was increased, as was the total sprout length per tuber. Emergence was more rapid, ground cover was initially greater and the number of mainstems per plant was greater with late temperature accumulation. Secondary stem production was more prolific and the total number of stems per plant greater when temperature accumulation was early. The number of tubers per plant reflected the total number of stems, and individual tuber size generally decreased as numbers increased, with the result that storage temperature treatment affected graded yields in some varieties.

The field growth of the crops from the late temperature accumulation treatment was in many ways suggestive of greater physiological age than the early temperature accumulation treatment, although the number of day-degrees accumulated was the same in each case. It is possible that the number of day-degrees underestimates physiological age as the period of accumulation is delayed.

Part of the variation among butterfat yields in dairy cows arises from genetic differences among the animals. The proportion which this bears to the total variance is known as heritability. In the ‘narrow’ sense it is defined (Lush, 1940), as the proportion of the total variance that is due to additive gene effects; the ‘broad’ sense definition includes genetic variation arising from non-additive gene effects as well as that due to additive effects. Since related animals have a proportion of their genes in common the covariance among their production records can be used for estimating genetic variation and hence heritability. This paper discusses three groups of related animals most frequently used for this purpose, twins, daughter-dam pairs and paternal half-sibs, and presents the results of analysing production records of artificially bred heifers in New Zealand, including evidence of the magnitude of the sampling errors of the heritability estimates.

Birthooat fibre types were investigated in Barki, Merino and their crosses. The halo hair grade was high in the Barki breed, in the Merino a wide range of grades occurred but the majority was low. A trend of a decrease in halo-hair grade and an increase in non-hairy birthcoats occurred with the increase of Merino proportion in the crosses. An anterior reduction in halo-hair density was encountered in all groups under study.

Fibre type arrays were all coarse in Barki and ¼ Merino, the ¾ Merino had 50% fine arrays and 75% of the Merino arrays were fine. A trend towards a maternal influence on the birthcoat was observed in the ⅜ Merino and ⅝ Merino; more fine arrays were encountered in lambs born to dams with more Merino proportion.

Within saddle and ravine arrays, CT/Pre-CT ratio was highly significantly correlated with the pre-natal check as indicated by Merino proportion.

It was suggested, from the birthcoat studies, that ⅝ Merino might be the best combination in the Merino crosses as far as the fibre type arrays were concerned.

Less coarse arrays were encountered in the birthcoat due to selection against kemp in rams used for breeding.

Observations were made of the ages at first appearance of each pair of permanent incisors (‘eruption age’), and the time from first appearance to full eruption of each pair (‘eruption period’), for Large East African Zebu cattle (Boran). For females the eruption ages were found to be 108·5±9·9 weeks, 137·2±12·9, 165·7±15·8, and 200·9±18·2 for incisor pairs one to four respectively; for steers the figures were 104·3±7·9, 130·3±10·6, 154·6±13·2, and 180·9±14·0; and for bulls 103·3±8·6, 127·6±11·2, 151·0±12·9, and 181·2±15·7. Females were significantly different from steers (P < 0.01), but steers not significantly different from bulls, for all four incisor pairs.

The distributions of eruption ages for each sex and pair can be considered as Normal for statistical purposes. There is a tendency for eruption to be asymmetrical after the first pair, with the right tooth preceding the left.

Correlations of eruption ages between adjacent pairs are of the order of 0·80 for all pairs and sexes; they decrease progressively as pairs intervene to 0·55 for the first and fourth pairs. Partial correlations approach zero when any intermediate pair is held constant. These results indicate that the whole eruption process is highly interdependent.

Evaluation of age grouping and estimations from the presence of incisors showed that this technique, although limited on its own, is still the best developmental trait for ageing. A steer with one incisor pair present had a probability of 0·108 of being the same age or older than one with two pairs. The ages of steers with one and two incisor pairs present were 115·7±12·05 and 140·7±14·27 weeks respectively.

Heritabilities of eruption age, for the various incisor pairs, varied between 0·91±0·33 and 0·43±0·25 for females, and 0·87±0·37 and 0·11±0·59 for steers.

Sources of environmental variation examined were variation between and within years, both of which were of the same order and a very small proportion of the total variation. The maternal environment had a small effect, probably specifically associated with milk consumption, which had a correlation of —0·22 for females and —0·12 for steers (P < 0.01) with the eruption age of the first incisor pair.

Eruption periods for females were 5·1±2·8 weeks, 5·7±3·8, 6·8±4·5, and 8·8±5·6 for pairs one to four respectively; for steers 4·6±2·6, 4·9±2·9, 5·6±3·8, 7·2±5·3; and for bulls 4·9±2·2, 4·8±2·7, 5·7±3·8, 6·0±3·3. Females were significantly slower than steers (P < 0·05) for the first three incisor pairs only, while steers did not differ significantly from bulls for any pair.

The distribution of eruption periods was positively skewed, and the correlations between pairs ranged between 0·0 and 0·35. Correlations of eruption ages and periods within incisor pairs lay between 0·50 and 0·95.

Variation of eruption periods was not significant within years, but was between years, and arose almost entirely from the first two experimental years. The majority of the heritabilities approached zero.

Growth rate differences probably accounted for the differences in eruption periods between the four incisor pairs and the three sexes. The cause of asymmetry of eruption was not the source of the variation in eruption times within incisor pairs, the first tooth consistently having a greater eruption time.

Seed shape (SS) affects the yield and appearance of soybean seeds significantly. However, little detailed information has been reported about the quantitative trait loci (QTL) affecting SS, especially SS components such as seed length (SL), seed width (SW) and seed thickness (ST), and their mutual ratios of length-to-weight (SLW), length-to-thickness (SLT) and weight-to-thickness (SWT). The aim of the present study was to identify QTL underlying SS components using 129 recombinant inbred lines derived from a cross between Dongnong46 and L-100. Phenotypic data were collected from this population after it was grown across nine environments. A total of 213 simple sequence repeat markers were used to construct the genetic linkage map, which covered approximately 3623·39 cM, with an average distance of 17·01 cM between markers. Five QTL were identified as being associated with SL, five with SW, three with ST, four with SLW, two with SLT and three with SWT. These QTL could explain 1·46–22·16% of the phenotypic variation in SS component traits. Three QTL were identified in more than six tested environments three for SL, two for SW, one for ST, two for SLW and one for SLT. These QTL have great potential value for marker-assistant selection of SS in soybean seeds.

Grain yield and incidence of take-all were measured in barley grown continuously and in successive barleys after two crops (oats, beans) not susceptible to the take-all fungus. Without fertilizer N, first barley crops after beans yielded about 1 t/ha more than second barleys and 2 t/ha more than third; growing more barleys did not further lessen yield. With increasing amounts of fertilizer N yields of barleys after barley nearly equalled yields of barley after beans. Take-all increased to a maximum in third barleys and was decreased by N, but it was not possible to separate the effects of take-all andsoil and fertilizer N on yield.

Three nitric phosphate fertilizers with 30, 60 and 70% of their phosphorus in watersoluble form were evaluated relative to superphosphate and rock phosphate on neutral to alkaline soils. The test crops were wheat, paddy and berseem. Linear grain yield and dry-matter yield responses were obtained up to 100 kg P2O5/ha for wheat and berseem, respectively. Quadratic response functions were fitted to paddy grain yield. Yields of the various crops were well related to the water solubility of the P fraction in different sources. Availability coefficient ratios were calculated for each fertilizer. These indicated that the minimum water solubility of the phosphorus fraction in nitric phosphates required for high crop yields is dependent on the nature of the crop, on soil characteristics and on the method of application which together determine the shape of the response curve. Band placement of sources with higher water solubility of their P fraction (70% or more) resulted in fertilizer efficiency similar to wholly water-soluble sources. Nitric phosphates of 30 and 50% water-solubility were inferior to water-soluble sources when applied broadcast. However, where curvilinear responses were obtained, low water-solubility sources (30 or 50% water-solubility) performed better at higher than at lower rates of application.

The concentration of nitrogen (N) within the emerging, youngest fully expanded and the youngest dead leaf laminae were examined in the grasses Lolium perenne, Agrostis stolonifera, Holcus lanatus and Poa trivialis in Devon, UK, in 1986 and 1987. Lamina growth, appearance interval and lamina utilization were also examined in each species. Marked tillers were measured in situ over 14–21 day periods in a continuously grazed permanent pasture under steady state management on plots receiving either zero (ON) or 400 kg nitrogen (400N) fertilizer/ha per annum. The concentration of N tended to be greatest in the distal half and least in the basal part of each lamina in each species. Total mass showed an opposite trend due in part to the shape of the lamina. Less than 40 % of the lamina N was lost through grazing either in the ON or 400N plots in the four species, except once in H. lanatus when more was lost. In absolute terms, because L. perenne and H. lanatus maintained larger and longer laminae than either A. stolonifera or P. trivialis, they lost more N through grazing. The four grass species recycled N from the senescing lamina with the same apparent efficiency; this meant that differences in lamina N concentration and carbon: nitrogen ratios were present in the dead laminae of the four species. L. perenne achieved the highest tissue growth rate per unit of N in the lamina in the ON plot, not only in comparison with the three other grasses but also compared with the 400N plot. This high N-use efficiency in L. perenne was not translated into an ability to either expand or maintain its population in the ON plot. L. perenne had a lower leaf appearance rate than the other species in both the 400N and ON plots, but this inherent characteristic of the species was particularly pronounced in the ON plot. A slower leaf appearance rate would limit the potential tillering capacity of L. perenne compared with the other species. A reduced tillering capacity, exacerbated by N deficiency, was probably the principal factor limiting the ability of L. perenne to exploit available niches in the ON pasture.

In France, many dairy farms plan the allocation of animal wastes to the fields of the farm at the beginning of every year. This decision is complex, because many factors must be taken into account at the field and farm scales, including increasingly constraining environmental regulations. To evaluate the environmental impact of waste allocation strategies, these strategies have to be translated into consistent decisions. The objective of the current study was to reproduce the decisions made by farmers, in a wide range of contexts. For this purpose, a linear programming model that could help in generating yearly waste allocations was developed. The model, called Fumigene, takes into account the farmer's preferences and environmental, agronomic and feasibility constraints. It was applied on two case farms and the simulated waste allocations were compared to those chosen by the farmers over periods of 3 and 4 years, respectively. The evaluation showed that the waste allocations generated by the model were consistent with the strategies of the farmers. Fumigene was then used in investigating the impact of taking into account the phosphorus (P) fertilization constraints instead of only the nitrogen constraints. In the case studied, balancing P fertilization over 5 years led to small changes in waste allocation. Balancing P fertilization every year caused bigger changes and led to export of a part of the wastes. In a general way, Fumigene can be coupled with environmental evaluation tools to compare the impacts of different waste allocation strategies.