Based on the knowledge that alpaca (Lama pacos) have a lower fractional outflow rate of feed particles (particulate FOR) from their forestomach than sheep (San Martin 1987), the current study measured methane (CH4) production and other digestion parameters in these species in three successive experiments (1, 2 and 3): Experiment 1, lucerne hay fed indoors; Experiment 2, grazed on perennial ryegrass/white clover pasture (PRG/WC); and Experiment 3, grazed on birdsfoot trefoil (Lotus corniculatus) pasture (Lotus). Six male alpaca and six castrated Romney sheep were simultaneously and successively fed on the forages either ad libitum or at generous herbage allowances (grazing). CH4 production (g/day) (using the sulphur hexafluoride tracer technique), voluntary feed intake (VFI), diet quality, and protozoa counts and volatile fatty acid concentrations in samples of forestomach contents were determined. In addition, feed digestibility, energy and nitrogen (N) balances and microbial N supply from the forestomach (using purine derivatives excretion) were measured in Experiment 1.

Diets selected by alpaca were of lower quality than those selected by sheep, and the voluntary gross energy intakes (GEI, MJ) per kg of liveweight0·75 were consistently lower (P<0·001) for the alpaca than for the sheep (0·74 v. 1·36, 0·61 v. 1·32 and 0·77 v. 2·53 on lucerne hay, PRG/WC and Lotus, respectively). Alpaca and sheep did not differ (P>0·05) in their CH4 yields (% GEI) when fed on lucerne hay (5·1 v. 4·7), but alpaca had a higher CH4 yield when fed on PRG/WC (9·4 v. 7·5, P<0·05) and Lotus (6·4 v. 2·7, P<0·001). When grazing on Lotus, the sheep had very high protozoa counts in their forestomach contents, compared with those with the other forages and those in the alpaca. On lucerne hay and Lotus, but not on PRG/WC, the alpaca had higher (P<0·01) acetate/propionate ratio in their forestomach fluid than sheep. When fed on lucerne hay, alpaca and sheep did not differ (P>0·05) in diet N partition or microbial N yield, but alpaca had higher (P<0·05) neutral detergent fibre digestibility (0·478 v. 0·461) and lower (P<0·01) urinary energy losses (5·2 v. 5·8 % GEI) than sheep. It is suggested that differences between these species in forestomach particulate FOR might have been the underlying physiological mechanism responsible for the differences in CH4 yield, although the between-species differences in VFI and diet quality also had a major effect on it.

Calorimetric experiments were made with a complete extruded diet for ruminants, ‘Ruminant Diet A’ prepared by Messrs U.K. Compound Feeds Ltd. Twelve determinations of energy and nitrogen retention were made using sheep and it was found that the diet had a metabolizable energy value of 2–32 kcal/g organic matter, and the net availabilities of its metabolizable energy were 42–7 % for fattening and 68–0 % for maintenance. These values agreed well with those predicted from equations published by the Agricultural Research Council. On a dry basis the starch equivalent was 38–3 %.

1. In the course of a 2-year field trial (1959–60) conducted in mid-Wales, 525 cattle were entered by 317 co-operating farmers for treatment with p.m.s. in the induction of multiple-pregnancy. Most animals were commercial, non-pedigree cattle maintained in accord with local custom. The cattle were of mixed ages and included some milking cows as well as animals used in calf rearing.

2. The method of hormone treatment tested consists of a single subcutaneous injection of a freeze-dried preparation of p.m.s. administered in the follicular phase of the oestrous cycle. Most cows were injected 16 or 17 days after a previous oestrus and bred by a.i. at the heat period following injection.

3. Of the 525 cattle injected 416 provide comprehensive data on factors affecting ovulatory response; seventy cattle, which had a ‘silent heat’ after injection, provide additional but partial information. In thirty-nine cattle, it was not possible to obtain reliable evidence of response. Data on ovulation and pregnancy were obtained by examinations per rectum conducted during the early weeks of pregnancy.

4. Ovulation data relate to 416 cows which were injected, came in oestrus shortly afterwards and inseminated, then examined for evidence of fresh corporea lutea at the following mid-cycle stage. Five dosage levels of p.m.s. were employed (800, 1000, 1200, 1600 and 2000 i.u.). The normal process of ovulation did not appear adversely affected by any of the doses employed. 173 of the 416 cows (41·6%) produced more than one egg.

5. There is clear evidence of a dose-response relationship over the dosage range employed. The mean number of ovulations varies from 1·43 at 800 i.u. to 3·97 at 2000 i.u. The percentage of cattle shedding additional eggs rises from 33 at 800 i.u. to 56–6 at 2,000 i.u., but increasing dosage level leads to considerable variability in ovulatory response: range of ovulations at 800 i.u. is 1–5, and at 2000 i.u. is 1–25.

6. Little affect was observed in ovulatory response according to the stage of p.m.s. administration. At low dosage levels, an interval of at least 2 days between injection and oestrus was necessary to allow response to occur. Among factors affecting response to a standard dose of p.m.s., lactation and state of normal ovarian activity appeared to have some importance. There was no evidence of an effect on cycle length. Treatment did not give rise to abnormal mating behaviour and the incidence of adverse side-effects following p.m.s. injection was negligible. The occurrence of large unovulated follicles occurred more frequently following treatment with 2000 i.u. than with lesser dosage levels. 59·1% of all ovulations occurred in the right ovary and 40·9% in the left. In examinations made prior to injection, the incidence of spontaneous double ovulations was 4·1%.

7. With the p.m.s. approach, it is found that one problem in cattle is that of silent heat, the condition where ovulation is not accompanied by the usual symptoms of oestrus. In 486 animals for which information was obtained, silent heat occurred in 70 (14·4%). There is some tendency for the condition to occur more frequently where low dosage levels are used or where p.m.s. is administered very late in the oestrous cycle. Lactation appears to affect the incidence of the defect. The lowest incidence (4·8%) occurs in ‘dry’ cows and the highest (22·7%) in cattle rearing three to four calves. Superovulation occurred less frequently at silent heat than at normal oestrus. There is no evidence that p.m.s. injection is the direct cause of the condition. It appears that time of ovulation in animals showing silent heat is comparable with that for cattle showing the normal symptoms.

8. Of the 416 cattle put to a.i. shortly after p.m.s. administration, 317 (76·2%) were pregnant when examined some 6 weeks after first insemination. This compares closely with the normal 30–60 day non-return figure for the mid-Wales area (78·5%). Cattle conceived as readily after injection with 2000 i.u. as after treatment with 800 i.u. Even where animals shed many eggs (e.g. more than six) the conception percentage (84·0) was high. It is clear that this form of therapy does not adversely affect the processes of ovulation, fertilization and implantation. There is some suggestion that p.m.s. aided conception in repeat-breeder cattle. Examinations in the mid-cycle stage following a.i. did not adversely affect conception.

9. Data on the number of eggs surviving (as foetuses) in the 6th week after mating, in relation to the initial number of ovulations, clearly show a heavy loss in eggs in early pregnancy. 41·6% of cattle shed additional eggs but only 23·1% possessed multiples in early pregnancy.

10. Reduction to a single foetus seemed particularly liable to occur in cattle producing two eggs-only. Of sixty-seven double-ovulating animals that conceived, thirty-two possessed twins at the 6th week (47·7%). The survival of both eggs in such cows was better when one egg was shed by each ovary (61·5%) than where both ovulations occurred in the one ovary (28·6%). Analysis of data on egg survival according to factors such as age, breed, time of treatment did not reveal differences.

11. Trans-uterine migration of eggs was rarely (1 case in 197 examinations) noted. The ability of a single uterine horn to sustain more than two foetuses was limited. In cattle where three to six eggs were shed by an ovary, the survival of twins in the associated uterine horn was observed in a majority (57%) of cases. Where many eggs (ten to fifteen) were shed by an ovary, twins were rarely sustained by the associated uterine horn.

12. A steady increase in the percentage of cows carrying multiples (at 6 weeks) was noted over the dosage range employed. 20·8% of cows injected with 800 i.u. carried multiples, the figures for doses of 1000, 1200 1600, and 2000 i.u. being 25·2, 31·3, 41·7 and 42·7, respectively. Multiples in the form of triplets and quadruplets occurred more frequently at the higher dosage levels than at 800–1000 i.u. of all cows with multiples considered, 36·5% possessed more than two foetuses at examination in the 6th week.

13. Pregnancy diagnosis examinations were conducted over a period ranging from 35 to 101 days after mating, with most falling in the period 41–44 days. It appeared that the most appropriate time for diagnosing multiples was at the end of the 6th week of pregnancy. The need to conduct diagnosis at a specific time after mating, and the fact that the examination may lead to total litter loss in many animals, makes the procedure unsuitable for any widespread practice. Partial litter loss (loss of one foetus) was observed in 12·5% of cows carrying twins at 6 weeks and in 20·0% of those with triplets.

14. In nineteen cows, each possessing either three or four foetuses, an attempt was made in the 6th week of pregnancy to control litter size to two. This was by rupture of excess amniotic vesicles by manipulation per rectum. Two of those so treated eventually produced calves, the others either aborting or returning in oestrus soon after the control procedure. The method is unsuitable for farm application for reason of the delay in returning to normal breeding after such cases of failure of pregnancy.

15. A substantial proportion (32·5%) of those cows which were subjected to pregnancy diagnosis lost the conceptus a short time afterwards. Foetal loss in cows with twins was greater (43–46%) where foetuses were both in the one horn than where distributed between both horns (31%). The various factors which were possibly involved in foetal loss are discussed. Evidence was obtained that total foetal loss occurred more frequently in animals shedding many eggs than in those shedding few.

16. Information is recorded for 147 injected cattle which produced single calves following conception at the oestrus immediately following hormone treatment. Additional data on single calvings are provided by 200 untreated cattle which were studied in the area of the trial. These data show birth weight of single calves to be 78·6 lb., and the incidence of calf mortality, retention of foetal membranes and difficult calvings to be 4·9, and 6·0%, respectively. The mean duration of the gestation period was 283·4 days.

17. The outcome of multiple calving was observed in forty-four cattle (thirty-five sets of twins, eight sets of triplets and one set of quintuplets). As a result of earlier examinations, farmers were usually alert to the fact that cows were carrying twins. Herd owners were encouraged to provide such cows with an additional 2 cwt. of a suitable concentrate feed during the final 2 months of pregnancy. Although a number of herd owners followed the recommended feeding programme, in a number of instances the most appropriate pre-calving preparation was not given. The outcome of calvings in relation to the level of additional feeding is considered under three headings, high, moderate and low plane.

18. Given good feeding (high plane) the outcome of twin calvings was satisfactory. Results suggest that the problems often associated with twins (low-weight calves, high rate of mortality, retained foetal membranes, loss of conditon and poor subsequent breeding of the dam) may largely be overcome by an adequate ‘steaming-up’ policy. In cows adequately prepared, birth weight ranging from 59 to 89 lb. were recorded (mean 73·9 lb.) Mean gestation was a little less (280·6 days) than for singles. The incidence of retained foetal membranes (18·2%) was greater than that for single-bearing cows, but did not constitute a serious problem in any animal.

19. Less satisfactory results were noted in cows not given adequate preparation for twins. Where triplets were carried, the outcome for cow and calves, regardless of the feeding attention given, was unsatisfactory. Triplet-bearing cows calved earlier, and the incidence of retained foetal membranes, difficult calvings and calf deaths was much above that noted for the twin-bearing animals. The single set of quintuplets was born prematurely, all calves being dead.

20. Problems in the field application of the p.m.s. technique are considered in the light of the results obtained in the trial and from discussion with farmers in the area of work.

21. Information was obtained on the incidence of natural twins in 3826 calvings in the mid-Wales area. The figure of 2·82% compares closely with that noted in other surveys in the United Kingdom. Literature on the incidence is reviewed.

22. It is clear, from the results obtained in this trial, that the technical problems facing commercial usage of p.m.s. are too numerous to allow any practical recommendation to be made. While none seems to be of such a nature as to make the eventual development of a twinning technique unlikely, there is little hope of immediate solution to many of them. The lines of work which may lead to more satisfactory results are discussed in the final section of the paper.

Liming is often recommended to minimize the plant uptake of potentially toxic elements from sludgeamended soils. In outdoor experiments conducted during 1989–91 in a rural location, near Brentwood (UK), wheat, carrots and spinach were grown on soils from a wide range of sites previously amended with heavy applications of sewage sludge. The objective of these studies was to examine the effect of liming on the accumulation of sludge-borne metals in the crop plants. The results showed that liming the soils to pH 7 prior to sowing significantly reduced metal concentrations in carrots and spinach, although the reduction appeared to be greater for Cd, Ni and Zn than for Cu and Pb. The wheat crop was grown on soils which had been limed 2 years previously, and the average pH of these soils was 6·5 compared to a pH value of 5·95 in the unlimed soils. This comparatively small pH difference between limed and unlimed soils (6·50–5·95) generally had little influence on metal contents in wheat.

These results suggested that maintaining the soil at pH 7 is better than pH 6·5 for minimizing the accumulation of potentially toxic elements from soils which have received relatively high levels of sludge application over many years. The data for winter wheat suggested either that metal uptake into the grain was not sensitive to differences in soil pH or that a relatively small residual effect of past liming was not high enough to reduce metal uptake.

Ammonia volatilization from stored slurry or surface-applied slurry in the field is strongly affected by pH. Thus a simple, iterative model was developed to predict pH changes in slurry. Concentrations of NH4+/NH3, CO2/HCO3-/CO32- and volatile fatty acids were input data to the model. The model was validated by titrating 17 slurry samples collected from four cattle farms, seven pig farms and three biogas plants. Predictions of pH agreed well for 14 slurries with titration data in the pH interval from 4 to 10. Simulations indicated that microbial degradation of VFA to methane and carbon dioxide resulted in a pH increase if the carbon dioxide produced was lost to the atmosphere. There was little change in pH if the produced carbon dioxide dissolved in the slurry.

The growth and development of single plants of oil seed rape, variety Zollerngold, are described quantitatively and particular attention paid to the sequence and pattern of flower and pod production on the different inflorescences. The period of flower opening over the whole plant spanned an average of 26 days and more than 75% of the pods which were retained to maturity were formed from flowers which opened within 14 days of anthesis. Most of these flowers were found on the terminal raceme and on the basal and middle regions of the axillary inflorescences arising from the uppermost three nodes.

1. Construction and details of operation of a respiration chamber suitable for studies on the laying hen are described.

2. Calorimetric data on the utilization of food energy from balanced rations and from glucose are given.

3. The net energy of balanced rations for maintenance and production is 83·7% of the metabolizable energy. The figure for glucose is considerably higher.

4. The maintenance requirement of the 2 kg. laying hen is 88·9 kcal. metabolizable energy/kg./day.

5. Some comments are given on the significance of protein metabolism in relation to the use of indirect calorimetry for avian species.

The seed-coat of all white-flowered varieties of Vicia faba and segregants tested was free of tannin. In two field trials, the whole grain of white-flowered varieties wassignificantly higher in in vitro digestibility of the dry matter, on average 4·7% higher, than coloured-flowered varieties of similar seed size. In subsequent trials where the testa and cotyledon were examined separately, this difference was shown to be largely due to a mean D value (digestibility of the organic matter) of the testa in tannin-free varieties of 56·4% compared with 17·2% in tannin-containing varieties. Seed size was positively correlated with D value but not because of differing proportions of testa.

Differences between varieties in acid-pepsin solubility and protein content of the testa were much smaller and not associated with presence of tannin. The testa colour of some tannin-free F2 plants was a darker shade of grey than either parental population. An inbred line completely lacking in anthocyanin in flowers and stem but with the normal black wing spot had tannin in its testa.

Grains of peas from the coloured-flowered variety, Minerva, reacted to a tannin test wheieas those from white-flowered varieties, Greenshaft and Flavanda, did not.

The case for breeding further tannin-free varieties of Vicia faba is discussed.

Calves from three breeds, Brahman, Hereford × Shorthorn (HS) and Brahman × HS (BX), were divided equally into two groups, one of which was treated every 3 weeks from birth onwards to control ticks and gastrointestinal helminths, and one of which was untreated. Mortalities, growth rates and levels of resistance to environmental stresses that affected both mortality and growth under grazing conditions were recorded for all animals up to weaning (6 months) and for all males up to 15 months of age. The Brahmans were the most and the HS were the least resistant to environmental stresses, each of which was shown to depress growth in proportion to its magnitude and to contribute to the high mortalities of the HS. All breeds responded positively to parasite control with the greatest response in both survival and growth in the HS breed and the least response in the Brahman breed.

Samples of males from the various breed-treatment groups were taken into pens where they were protected from environmental stresses and fed both low-quality pasture hay and high-quality lucerne hay ad libitum. Measurements were made of fasting metabolism, maintenance requirement, voluntary food intake and gain, variables related to the growth potential of each animal. The HS animals had the highest whilst the Brahmans had the lowest values for each variable.

However, despite their low growth potential, the Brahmans had the highest growtli rate, and the HS, despite their high growth potential, had the lowest growth rate, when growth was measured in the presence of all environmental stresses. When parasites were controlled, growth rates were highest for the BX, the breed with intermediate growtli potential, and did not differ between the HS and Brahmans. These interactions arose because of the different contributions of resistance to environmental stresses and growth potential to growth rate measured at the different levels of environmental stresses. The relevance of these interactions to breed evaluation and cross-breeding is considered.

Growth potential and resistance to environmental stresses were negatively correlated both between and within breeds, though the latter was biased by the effects of compensation. The influence of these relationships on the likely outcome of selection for increased growth rate, both between and within breeds, is discussed.

The effects of water deficit on growth of spring barley were analysed under five irrigation treatments. One crop was irrigated at weekly intervals from emergence throughout the growing season, and one was not irrigated at all after emergence. Soil water deficits in the other treatments were allowed to develop early, intermediate or late in the crop's development.

Weekly irrigation produced a crop with a large leaf area index (maximum value 4) and maintained green leaf and awns throughout the grain-filling period. Early drought decreased leaf area index (maximum value 2) by slowing expansion of main-stem leaves and decreasing the number and growth of tiller leaves. Leaf senescence was also increased with drought. Drought late in the development of ears and leaves and during the grain-filling period caused leaves and awns to senesce so that the total photosynthetic areas decreased faster than with irrigation. Photosynthetic rate per unit leaf area was little affected by drought so total dry-matter production was most affected by differences in leaf area.

Early drought gave fewer tillers (550/m2) and fewer grains per ear (18) than did irrigation (760 tillers/m2 and 21 grains per ear). Late irrigation after drought increased the number of grains per ear slightly but not the number of ears/m2. Thus at the start of the grain-filling period crops which had suffered drought early had fewer grains than irrigated (9·5 and 18·8 × 103/m2 respectively) or crops which suffered drought later in development (14 × 103/m2).

During the first 2 weeks of filling, grains grew at almost the same rate in all treatments. Current assimilate supply was probably insufficient to provide this growth in crops which had suffered drought, and stem reserves were mobilized, as shown by the decrease in stem mass during the period. Grains filled for 8 days longer with irrigation and were heavier (36–38 mg) than without irrigation (29–30 mg). Drought throughout the grainfilling period after irrigation earlier in the season resulted in the smallest grains (29 mg).

Grain yield depended on the number of ears, the number of grains per ear and mass per grain. Early drought decreased tillering and tiller ear production and the number of grains that filled in each ear. Late drought affected grain size via the effects on photosynthetic surface area.

Drought decreased the concentrations of phosphorus, potassium and magnesium in the dry matter of crops, and irrigation after drought increased them. Concentration of nitrogen was little affected by treatment. Possible mechanisms by which water deficits and nutrient supply affect crop growth and yield are discussed.

The Woburn Market-Garden experiment was started in 1942 to investigate the development of a market-garden type soil from an ordinary agricultural soil on light land by applying organic manures regularly. The ‘organics’ used were farmyard manure, sewage sludge, and composts of these with straw and farm waste. The use of sewage sludge was discontinued in 1961 and the yields of the crops up till then were published by Mann & Patterson (1963).

The Japanese rice cultivar, Akenohoshi, has numerous spikelets in a panicle (extra-heavy panicle type) and achieves a large yield sink capacity. However, this cultivar, as well as other extra-heavy panicle types, does not always produce higher yields because of poor grain filling of the spikelets on the secondary branches in a panicle. To determine whether the poor grain filling found in Akenohoshi was due to source-limited or sink-limited conditions, the present study examined the responses of grain-filling characteristics to several spikelet-removal treatments immediately after heading. Only when the spikelets on secondary branches remained was a significant increase in filled grain percentage in this spikelet position observed. This increase seemed to be associated with the increases in rate and duration of the grain-filling process and in single grain weight in this spikelet position. These results clearly indicate that the poor grain filling in the spikelet on secondary branches of Akenohoshi could mainly be attributed not to sink-limited conditions, but to source-limited conditions probably at specific stages of grain filling.

Information on the total dry-matter intake (TDMI), concentrates supplied (C), live weight (LW), week of lactation (WL), milk yield (MY) and composition, quality of forage fed to, and parities of, 385 cows from five different sources were assembled to develop appetite prediction equations. The equations were based on multiple regression and least squares constants and were calculated using the data from each source and the data pooled from all sources. The major factors affecting total dry-matter intake (TDMI) were C, LW, WL and MY and for the pooled data these factors explained 73–76% (R2) of the total variation in TDMI. The predictive values of some of the equations were tested against independent sets of data and for groups of cows and individual cows, the equations predicted TDMI within ±1·1 and 1·6 kg, respectively. The application of the equations in the field is discussed and some suggestions made for increasing the R2 of future appetite equations.

A dynamic model of rumen processes is constructed. The nine state variables considered are: rumen metabolic volume, non-rumen-degradable β-hexose, rumen-degradable β-hexose, α-hexose, water-soluble carbohydrates, non-protein nitrogen, rumendegradable protein and non-rumen-degradable protein. The dietary and salivary inputs to the rumen may be continuous, or pulsed. Rumen outflow given by the model is compared with data on sheep fed with different diets. Reasonable agreement is obtained when the model is run in the continuous mode, but there are considerable discrepancies between the experimental data and the pulsed model.

The Green Revolution era focused on enhancing the production and productivity of rice and wheat. New challenges demand that the issues of efficient resource use and resource conservation receive high priority to ensure that past gains can be sustained and further enhanced to meet the emerging needs. Extending some of the resource-conserving interventions developed for wheat to rice culture is a major challenge for researchers and farmers alike. The present paper shares recent research experiences on resource conservation technologies involving tillage and crop establishment options and associated agronomic practices which enable farmers in reducing production costs, increase profitability and help them move forward in the direction of adopting conservation agriculture.

The influence of the maternal environment on the size of lambs from birth to 8 months has been studied by reciprocally crossing the large Border Leicester and the small Welsh Mountain breeds of sheep and by transferring fertilized eggs between ewes of these breeds.

Ewes which lambed later in the spring gained more weight during the last 6 weeks of pregnancy than did the earlier-lambing ewes. The birth weight of the lambs was not, however, affected by either the date of lambing or the ewes' gain in weight during the last six weeks of pregnancy.

Significant breed differences in gestation length were recorded; these were 144·7 days for the Border Leicester and 147·1 days for the Welsh Mountain. Border Leicester ewes carrying pure-bred Welsh lambs had an average gestation of 149·6 days, while Welsh Mountain ewes carrying pure-bred Border Leicester lambs had an average gestation of 146·0 days. From the births of ‘transferred’ lambs, it appeared that the genetically smaller lamb was a cause of a longer gestation period. On the other hand, within groups, both live weight and length of ‘cannon bone’ of the lambs at birth increased when the gestation period was longer.

The maternal environment affected foetal growth when the genotype for size of the foetus was different from that of the mother. The mean live weight and ‘cannon-bone’ length of cross-bred lambs born to Border Leicester ewes were 1·08 lb. and 0·37 cm. greater at birth than those of cross-bred lambs born to Welsh ewes. Comparable figures for the maternal influence from the results of transferring eggs from one breed to the other were 1·96 lb. and 0·33 cm. On the other hand, within breeds, there was no effect on the size of the lambs at birth of variations in the size of the ewes. The length of the ‘cannon bone’, which grows relatively rapidly during the early stages of growth (an early-maturing part of the body), was less influenced by the maternal environment than the late-maturing live weight.

Mature ewes produced larger lambs at birth than young ewes. The mean differences at birth in weights and in lengths of ‘cannon bone’ of the lambs born to young and mature ewes were 1·38 lb. and 0·31 cm. respectively.

From these and other experiments, the conclusions were drawn that: (i) the maternal influence on the size of young at birth is greater, in the larger species which have longer gestation periods, than the effect of the genotype of the young; (ii) the maternal organism competes with the foetus for nutrients, thus limiting the size of the young at birth; and (iii) the maternal organism may also influence pre-natal foetal growth by means of some internal secretion or metabolic substance.

The amount of milk consumed by the lambs had a marked effect on their live weight gains during the first half but not during the second half of lactation. Variations in milk consumption by the lambs did not affect the growth in length of their ‘cannon bones’. The influence of the post-natal maternal environment is largely exerted through the milk yield of the ewe and causes of variation in this milk yield were reflected in the post-natal maternal influence estimated in these experiments.

The total milk yield of ewes was affected by their date of lambing, that of late-lambing ewes being less than the yields of ewes which lambed earlier in the season.

The growth and water use of sugar beet affected by early (ED) and late (LD) drought was compared with that of irrigated (I) and unirrigated (NI) controls. Mobile shelters were used to exclude rain from ED plots during June and July, and LD plots during August and September, respectively, whereas outside these periods the ED and LD plots were irrigated as necessary.

The ED treatment affected the fibrous roots severely. Many of the roots in the top 60 cm of soil died and development of the root system below this depth was slow. Expansion of the leaf canopy slowed, radiation interception was reduced and the rate of water use fell from about 1·2 times to 0·6 times Penman potential transpiration rate. The LD treatment, which was imposed when the fibrous root system was already extensive, had little effect on the fibrous roots except in the top soil. The accessible soil water was quickly depleted and the resulting stress was accompanied by earlier senescence of leaves. The rate of converting intercepted light to crop dry matter was reduced in both treatments. However, the ED treatment was the most detrimental because the amount of light intercepted in the months of highest radiation was greatly reduced owing to the restricted leaf cover. The relative effects on growth are reflected in the final sugar yields which were 8·7, 10·5, 9·9 and 12·0 (±0·30) t/ha in the ED, LD, NI and I treatments respectively.

More of the deep soil water was used in the drought-affected plots (particularly LD) than in the irrigated controls. Maximum depths of water extraction were 140–150 cm in ED and I plots and > 170 cm in LD plots. The highest uptake rates per unit length of root (20–40 μl/cm per day) were measured in the deepest part of the root system. At all depths, uptake rates declined as the soil dried. After correcting for overestimated water use where necessary, the ratios of final dry matter and sugar yields respectively to season-long water use (June–October) were close to 1·4 and 0·8 t/ha per 25 mm for all four treatments.

Soil erosion in a field in north Norfolk is described. Gullies formed, one up to 2 m deep, 5 m wide and 214 m long, and from this gully about 450 t of soil was eroded. Other gullies and rills deposited about 275 t of soil. In the large (61 ha) field the area subject to erosion was small, about 2·5%. The soil, slope, cultural and rainfall factors which caused erosion are discussed. Erosion in this field is not a rare phenomenon and crop yields will be affected if erosion continues. A solution to the problem is suggested.

The development of stable suckling order, the incidence of fighting when suckling, weight gain during the suckling period, and the severity of facial wounding were studied with litters of piglets in which the canine and lateral incisor teeth were either clipped at birth or left intact. Facial wounding was largely confined to litters with unclipped teeth. Severity of wounding correlated with the observed incidence of fighting on the udder (P<0·01); and both wounding and fighting were more common among litters comprising a large number of piglets (P<0·05). When the effect of litter size was taken into account, there were no substantial differences in weight gain to 3 weeks between piglets with high and low scores for facial wounding, nor between clipped and unclipped litters. Piglets which habitually occupied the most anterior or most posterior teats had less facial wounding than middle-suckling piglets, and showed greater consistency in teat choice. No gross differences between clipped and unclipped litters were observed in the development of stable suckling order during the first week of life. It is concluded that the ‘eye’ teeth, although used in disputes over teat choice, have little influence on the frequency of such disputes or on the original development of stable suckling order.