The organic matter intake of two breeds of sheep grazing a dry medic pasture was estimated by five different methods. The methods used were the calibrated weight estimate for measuring available herbage before and after grazing; a total faeces collection and digestibility trial; a tritium dilution technique; an established ratio of dry-matter intake to water intake; and an estimation using established energy requirements and the estimated metabolizable energy of the pasture. All methods gave similar estimates. It was concluded that the tritium dilution technique was the most useful method and that the dry-matter intake to water intake ratio was the easiest technique to use. The relative merits of the different methods used are discussed. The maintenance requirement for grazing German Mutton Merino and Awassi sheep was found to be 0·64 MJ ME/day/kg W0·75. When both breeds were caged in an open field the maintenance was 0·37 MJ.

Sowing date directly affected the grain yield of chick peas. Optimum sowing date was found to be between the end of October and the end of November, but different soil types showed some differences within this optimum.

Grain yield was highly correlated with number of pods per plant and number of plants at harvest.

Plant loss at the seedling stage was highly correlated with daily mean maximum air temperature, and was also significantly associated with sodium accumulation in shoots.

This paper reports a continuation of previous work on the mineral constituents of ewe's milk, in particular copper, iron, manganese and zinc. Milk taken at weekly intervals from four groups of Clun Forest and Suffolk x Clun Forest ewes was studied over lactations varying from 6 to 12 weeks. The copper content showed a marked decline as the lactation advanced, while there was no consistent trend in iron content. Maximum, minimum and mean values for iron and copper are given for the sheep in each group.

Manganese was determined in the milk from two groups and zinc in. that from one group of ewes. There were significant differences in weekly manganese content in both groups, but no consistent trend as lactation advanced. Zinc content showed no significant differences from week to week, but the milk of one ewe was consistently very much lower in zinc than that of the other five sheep.

The determination of feed phosphorus content using oesophageally fistulated cattle is reported in this paper, from an experiment in which salivary phosphorus was labelled with 32P.

An intravenous infusion of Na232PO4 to cattle produced an immediate increase in the specific activity of salivary phosphorus, which then fell rapidly to an essentially linear asymptote by 3 h after the infusion. The phosphorus content of consumed feed was calculated from the degree of reduction in salivary specific activity by the feed phosphorus, expressed as the ratio of the specific activities of bolus and saliva phosphorus.

A dose of 100 /μCi 32P allowed the accurate prediction of phosphorus content ranging from 0·07 to 0·25% in various feeds, at intervals from 3 to 24 h after the infusion; the predicted and actual phosphorus concentrations were highly correlated (r = 0·95). Similar observations for feeds ranging from 0·14 to 0·25% phosphorus suggested that accurate prediction was also possible 144 h after infusion. Comparison of estimated feed phosphorus content of grazed material with that measured in hand-plucked herbage indicated that this approach is applicable to grazing studies.

Seventy-nine Finnish Landrace x Dorset Horn ewes in lamb to Suffolk rams were used in a comparative slaughter experiment to assess the effects of numbers of foetuses on the growth of the products of conception. The mean number of foetuses was 2·7, with a range from 1 to 5. The ewes were individually penned and given a standard diet with metabolizable energy concentration 7·7 MJ/kg and N concentration 21 g/kg, rationed at 2 kg/day during the first month and 1·25 kg/day during the second and third. Allowances beyond that time were on two scales and depended on the number of foetuses being carried as diagnosed by radiography. The ewes were slaughtered between 50 and 145 days of gestation. The gravid uterus was dissected into foetal, placental, foetal fluid and empty uterus components. Equations were fitted to the weights of each component to describe the effects of stage of gestation, litter size and ewe weight. For the mean weight per foetus (Y, kg) the preferred equation is

In (Y)= 2·419–17·574e-0.01976t–00079ft+0–0046w,

where tis the time in days from conception, / is the number of foetuses and wis the weight (kg) of the ewe at mating. This is a version of the Gompertz equation, with additional terms to express the effects of / and w.The weights of the placenta and of the empty uterus were similarly fitted by versions of the Gompertz equation but the mean weight of fluids per foetus (Z, kg) or, rather, its natural logarithm was best described by a third degree polynomial, which is

In(Z) = –11·518 + 0–326t;–0·00316t2+0·0000102t3.

None of the weights was significantly affected by the level of feeding in late pregnancy.

Estimates of mean weights from the equations and of daily rates of gain in weight from the first differentials of the equations are tabulated against stage of gestation and litter size, and the forms of the weight, growth rate and specific growth-rate curves are illustrated graphically.

The equation for foetal weight estimates that at the end of pregnancy the mean weight per foetus is reduced by a factor of 0–89 for each additional foetus being carried. The mathematical model implies that the differences originate in early pregnancy, when the factor is very close to unity, and that the mean weights gradually diverge. In the absence of direct evidence this would appear to be the simplest hypothesis, rather than the assumption in most of the earlier literature that the effect is entirely confined to the last 4 or 5 weeks of gestation.

Just before parturition the total daily weight gain of quadruplet foetuses was about 250 g and was associated with a similar gain in weight of foetal fluids, the ratio of fluid weight to foetal weight appearing to increase with litter size. The ewes were clearly under considerable physical stress. It is suggested that this aspect must be closely considered when greater prolificacy is sought.

A radiographic study was made of the skeletons of 216 Suffolk x (Finnish Landrace x Polled Dorset Horn) sheep foetuses of known gestational age within the range 50–145 days. They comprised 10 singles, 42 twins, 105 triplets, 44 quadruplets and 15 quintuplets.

The ages at which the primary and secondary centres of ossification first appeared are presented together with a description of the normal pattern of skeletal development. Attention is drawn to the variations which are found from one foetus to another. The main anatomical features of ovine foetal bone development are illustrated by line drawings and charts.

By anatomical grouping the number of ossification centres was reduced to 80, including 40 primary and 40 secondary centres. Scores were obtained for each foetus by taking the numbers of primary and secondary centres that were present as percentages of the possible totals. The primary score was linearly related to foetal age up to about 100 days, and the secondary score was linearly related to foetal age beyond about 100 days. The relationships to foetal weight were similar but less close.

Navy beans were precision drilled in 1973–5 at a range of plant population densities. Within each growing season the density treatments did not influence seed yield, but mean yields differed significantly between years. The results suggest that cultivars similar to Purley King can only be regarded as a reliable break crop in a season such as 1973 which was slightly warmer and drier in mid-summer than average. Although the rate of drying increased with increasing plant density in two of the growing seasons, no practical advantages are proposed.

The effects of temperature and method of feeding on the intake characteristics and digestibilities of two milk substitutes were examined.

Forty Finnish Landrace x Dorset Horn lambs (20 males and 20 females) were fed one of two milk substitutes from 3 to 25 days of age when they were slaughtered and chemical composition of the empty body was measured.

The two milk substitutes contained 30% fat in the dry matter as butter fat (diet B), or tallow and coconut oil (diet TC).

The diets were offered at either 34°C (W) or 5 °C (C) and three methods of feeding were used. The diets were given: ad libitumcold (AL1), four feeds to appetite per day either warm or cold (AL2W and AL2C) and four feeds restricted to an intake of 62 g D.M./kg live weight0·5 either warm or cold (RW or RC).

Digestibilities of the milk substitutes were not affected by the temperature at which they were offered or the feeding regime used. Diet B had an apparent dry-matter digestibility of 97·6% and diet TC 92·5%. The fat digestibility of diet TC was 13·6 units lower than diet B and this affected the digestibility of all the other dietary components.

Lambs tended to consume more of diet B and grow faster.

Lambs on treatment AL1 consumed 21% more milk substitute than those on treatment AL2.

The composition of the body-weight gain was found to alter with rate of gain.

The temperature at which the milk substitutes were offered had only a minor effect on the performance of the lambs. The type of milk substitute and feeding regime used had a greater influence on both lamb intake and growth.

Effects of phosphorus fertilizer, initial profile water storage and seasonal rainfall on yield and water use by dryland wheat on loamy-sand and sandy-loam soils were studied for a 2-year period (1973–5). Plant available water at seeding varied from 62 to 205 mm, seasonal rainfall varied from 62 to 154 mm and available P status ranged from 9·5 to 18·5 kg P/ha. Four rates of phosphorus 0, 15, 30 and 45 kg P2O5/ha were tested. Available water at seeding, seasonal precipitation and the available P status of soil determined the yield response to phosphorus fertilizer. Response to P application was observed up to 15 kg and 30 kg P2O5/ha in loamy-sand and sandy-loam soils respectively. Growth and yield of wheat were highly correlated with the available water at planting plus seasonal rainfall. Total water use did not change in loamy-sand soil, but it increased by 16 mm in sandy-loam soil with the application of phosphorus. The profile water depletion pattern, further, indicates that the fertilized crop used more water from layers below 135 cm in loamy-sand and 22·5 cm in sandy-loam soil.

Seventeen gnotobiotic lambs were reared up to 21 weeks of age on cows’ milk followed by sterile solid diets similar to diets fed to conventional lambs. Seven were given limited defined populations of rumen bacteria, seven were left uninoculated and three were dosed with rumen contents from conventional sheep (‘conventionalized’). The lambs were reared in four groups corresponding to four lambing seasons.

Gnotobiotic lambs fed cows’ milk ad libitumgrew at similar rates and converted feed into live-weight gain with similar efficiency to conventional lambs. The gnotobiotic lambs irrespective of inoculation and the two conventionalized lambs in the first three groups failed to maintain growth on solid diets when milk feeding had been stopped. However, three gnotobiotic lambs in the fourth group, two of which were inoculated, continued to grow satisfactorily for at least 6 weeks on a solid diet alone, and the inoculation of defined populations of bacteria appeared to confer an advantage. The conventionalized lamb in the fourth group suffered a severe temporary setback, following which it grew well.

The effects of irrigation and nitrogen on S. 23 perennial ryegrass grown for seed were investigated in a series of field experiments from 1972 to 1974. Irrigation significantly increased seed yield by 16% in 1972 and 52% in 1974 but had no effect in the wet year of 1973. In 1972 maximum deficit reached 110 mm at the end of July and coincided with anthesis. Consequently the yield response was due to an increase in number of seeds per unit area and no other seed yield component was affected. In 1974 peak deficit also reached about 100 mm but started to build up rapidly very early in the season and had reached 80 mm by the time that the first ears emerged. Consequently the yield response was due to increases in number of fertile tillers, number of seeds per unit area and 1000-seed weight.

Irrigation had no significant effect on number of florets or seeds, except in 1974 when percentage of florets which produced seed was increased by 2%.

Irrigation had some effect on threshed straw yields, total dry matter, harvest index and total number of tillers but where this occurred the response was much smaller than that of seed yield which indicates that irrigation had greater effects on the reproductive development of the crop than on yield of dry matter and tillering patterns. Increasing the quantity of nitrogen from 0 to 80 kg/ha increased seed yields, all seed yield components except 1000-seed weight, threshed straw yields and total dry matter and number of tillers at most sampling dates. Increasing the quantity of nitrogen from 80 to 160 kg/ha had little further effect on the above components except in 1972 where seed yields were significantly decreased.

In 1972 number of florets was increased and percentage of florets which produced seed decreased with increasing quantities of nitrogen.

The effects of irrigation and nitrogen on the soil-water regimes developed by S. 23 perennial ryegrass grown for seed were investigated in 1972 and 1974 by neutron scattering. Boots extracted water from a depth of about 105 cm by early May in 1972 and by early April in 1974. Extraction from greater depths was insignificant in both years. Without irrigation the maximum deficit was about 110 mm in both years. Deficits built up rapidly in 1974 but in 1972 were delayed to the end of the growing season. Irrigation limited maximum deficits in the top 35 cm of soil to less than 25 mm whereas without irrigation deficits reached as high as 40 mm in both years.

Transpiration from unirrigated grass was close to that calculated from meteorological data in 1972, but in 1974 measured crop transpiration was only about 60 %of the potential throughout the growing season. Roots of grass, whilst undergoing inflorescence initiation, apparently may be impaired in their efficiency of water uptake by deficits as little as 30 mm. For irrigated grass agreement between measured and calculated crop transpiration was poor, principally because of surface run-off. Nitrogen in the absence of irrigation appeared to enhance the rate of crop transpiration in 1972 but comparison with 1974 suggested that this effect was not real. Because of surface run-off resulting in uneven distribution of water, and the restrictions to crop transpiration imposed by limited soil water reserves, actual deficits should be monitored in irrigation experiments rather than relying on estimated values.

A field experiment was made on Gurdaspur clay loam to assess the relative efficiency of various sources of fertilizer phosphorus for a paddy-wheat cropping sequence. Urea ammonium phosphate, superphosphate, a nitrophosphate fertilizer containing 30% water-soluble P and fertilizers containing 50 and 70% water-soluble P prepared from the nitrophosphate and superphosphate, dicalcium phosphate and rock phosphate were applied to the paddy crop at the rate of 0, 15, 30, 45 and 60 kg p2O6/ha and to wheat at double these rates.

The cumulative yield data for paddy and wheat show a slight reduction in efficiency of phosphatio fertilizers, with the exception of dicalcium phosphate, as their watersoluble content decreased below 70%. In general, the relative efficiency of the less water-soluble sources and of rock phosphate was considerably higher for paddy than for wheat.

The results show that the relative efficiency of low water-soluble phosphate fertilizers increased with time. The efficiency of phosphorus fertilizers declined with the rate of their application, more so in the case of higher water-soluble materials.

Five cultivation systems for spring-sown barley were tested on a clay to sandy-clay loam for 4 years and their cumulative effects on soil and crop measured. Four primary cultivations in the autumn, shallow (7·5 cm), medium (15 cm) and deep (23 cm) tine cultivation and mouldboard ploughing (23 cm deep) followed in spring by secondary cultivations and sowing, were compared with direct drilling seed into uncultivated soil after controlling weeds with herbicides. At the same rates of seed and fertilizer for all systems, direct drilling and shallow cultivation yielded significantly less grain than deeper tillage in the second year only; over 4 years the differences in mean yield were small and non-significant. In terms of crop output per unit of implement net energy (estimated) direct drilling was eight times more efficient than ploughing.

Direct drilling and shallow cultivation caused concentration gradients of ‘available’ phosphorus and potassium to form in the top soil. Soil strength and to a lesser extent bulk density were greater without than with cultivation but these changes had only a relatively small effect on root distribution in the profile. In untilled soil the proportion of the root system was less in the surface 2·5–12·5 cm and greater in the 12·5–32·5 cm horizon than in shallow or deep tilled soil.

Mean nitrogen uptake by the crop in the third and fourth seasons was least in direct - drilled barley probably due to lower rates of mineralization of soil nitrogen in compacted than tilled soil. It was deduced that for spring barley the ‘yield plateau’ was the same for each system but that optimal rates of nitrogen would be higher for crops in untilled than tilled soils.

The artificial fibre bag technique was evaluated for assessing the proportions of dietary D. M. and N which disappear in the rumen. The most important factor determining the variability in disappearance from bags incubated together was the sample size in relation to bag size. For incubation of 5 g air dry feed, a bag size of 17 ✗ 9 cm was found to be adequate. There were also variations in substrate disappearance between animals and between days of incubation. It was estimated that three sheep and the measurement of substrate disappearance twice were necessary in order to obtain acceptable repeatability.

The technique was found to be satisfactory as a simple and rapid guide for measuring nutrients disappearance in the rumen such as protein degradation and carbohydrate fermentation. It has been used in subsequent work to measure the effect of features of the rumen environment, such as pH and NH3 concentration, on rate of fermentation.

Greasy fleece weight (12 months growth) and wool samples from hip and shoulder regions were taken on 15 Dorset, 20 Leicester, 20 Suffolk and 17 DLS ewes (a cross of ½ Dorset, ¼ Leicester, ¼ Suffolk obtained by mating DL rams to DS ewes and DS rams to DL ewes). The purpose of the study was to compare wool production and characteristics of the first generation of DLS with that of the three breeds of origin. Wool production of DLS was 3·58 kg, 8·8 and 14% higher than that of Suffolk and Dorset, but 11% lower than that of Leicester (P< 0·01). The percentage of clean wool was highest in Leicester (78·3%), followed by DLS, Dorset and Suffolk (76·1, 74·3 and 70·5%, respectively). The average fibre diameter of the DLS and Leicester was 38 /m, 4 /m thicker than that for Suffolk and Dorset (P < 0·01). Average fibre length was 15 cm in DLS and Dorset, 6 cm shorter than in Leicester, and 3 cm longer than in Suffolk (P < 0·01). The variability in fibre diameter and length was highest in Leicester, followed closely by DLS.

Forty (20 barrows and 20 gilts) Large White and Landrace pigs allocated on the basis of litter origin, sex and initial weight to four treatment groups with mean initial weights of 50 kg were individually and semi-restrictedly fed to about 93 kg one of four diets containing 18·8, 28·5, 38·2 and 46·5% palm kernel meal (PKM) and 11·3, 8·4, 5·5 and 4·6% blood meal respectively such that the ratio of protein contribution to the diet from blood and palm kernel meals were 2·7:1, 1: 1·3, 1: 1·6 and 1: 2·30 for diets 1, 2, 3 and 4 respectively. Growth performance was measured over the liveweight range of 50·93 kg at which latter weight the pigs were slaughtered for carcass evaluation. Live-weight gain and feed efficiency were highly significantly influenced by varying the levels of palm kernel meal and blood meal, the lowest level of palm kernel giving significantly the best rate and efficiency of gain. There was a tendency for carcass leanness to improve as the proportion of dietary protein supplied by palm kernel meal was increased, only the differences for lean meat percentage were however significant. Carcass cuts as percentage of total carcass did not appear to be influenced by the level of palm kernel meal in diets except for percentage fat cuts which decreased significantly (P < 0·05) as the dietary levels of palm kernel meal were increased.

One hundred Large White x Landrace barrows and gilts were used in two experiments involving 50 pigs (25 barrows and 25 gilts) allocated on t h e basis of sex, litter origin and initial weight to five treatment groups of t en pigs each and individually and semi-restrictedly fed one of five diets. Diet one, t h e control, was a conventionally used fattener's diet based on groundnut, blood meal and maize mixtures, and containing 16 to 17% crude protein on dry-matter basis. The remaining four diets were approximately 17% crude protein diets based on palm kernel, blood meal and maize mixtures. The maize fraction was however replaced by 0, 10, 20 and 30% cane molasses in diets 2, 3, 4 and 5 respectively. Growth performance, feed efficiency, nutrient utilization and carcass quality were studied.

I n both trials, the groundnut meal (GNM) based diet (treatment 1) supported significantly faster rates of gain t h a n all other diets except 3. I t also tended to produce fatter pigs than those on t h e palm kernel meal (PKM) based diets. Addition of 10% cane molasses (CM) to t h e basal PKM diet (treatment 3) significantly improved feed and dry-matter intake, r a t e and efficiency of gain, crude fibre digestibility and nitrogen retention. Higher levels depressed performance as well as d ry matter, protein and ether extract digestibility. Addition of cane molasses did not significantly influence carcass characteristics.

Four groups of eight sheep, 4 months of age and reared parasite-free from birth, were used to investigate the effect of the abomasal parasite Ostertagia circumcincta on the intake and efficiency of utilization of food. One group (CI) was killed initially as control. Two further groups (ALC and ALI) were offered ad libitum a complete ruminant diet. The ALI group was dosed daily for 14 weeks with 4000 infective larvae. Sheep in a further group (PF) were individually paired to members of the ALI group and offered the same amount of food as was consumed by their pair. Balances of N, Ca and P, and the digestibility of energy and N were determined for the ALI and PF groups during weeks 2–3, 7–8 and 12–13. After 14 weeks of dosing the sheep were killed and the bodies of these and the CI sheep analysed for water, fat, N, Ca and P contents.

Parasitism caused a 20% reduction of food intake by week 2 which was maintained throughout the experiment. Apparent digestibility of nitrogen was reduced from 60 to 44% at weeks 2—3 but subsequently showed a gradual recovery. Nitrogen balances of infected sheep were inferior to those of controls which, with the exception of the first trial during which urinary N excretion of infected sheep was increased, was entirely related to the reduced digestibility. Energy digestibility was reduced by 2 percentage units during all trials.

Weight gain of ALI sheep was only 80% of that of PF sheep. Nitrogen anabolism was reduced by parasitism, but pair-feeding showed that reduced food intake rather than a specific effect on protein metabolism was responsible. Fat deposition was markedly reduced. It was calculated that the gross efficiency of utilization of metabolizable energy for growth was reduced by 30% compared with either ALC or PF controls.

Mineral deposition (Ca or P) in the skeleton of the ALI sheep was reduced to about 35 and 50% of that in ALC and PF groups, respectively.

Experiments were carried out over two growing seasons to find out the effects of fertilizer application and age at harvest on the yield, available carbohydrates and hydrocyanic acid content of Manihot palmata.Fertilizers were applied at the following rates: 0–0–0; 45–45–0; 45–45–45; 45–45–67, and 45–45–90 kg/ha of nitrogen, phosphorus and potassium respectively. Harvests were at 9 and 15 months after planting. Application of nitrogen and phosphorus resulted in significant yield increases. Fertilizer application had no significant effect on the hydrocyanic acid content of the tubers. Harvesting at 15 months gave more than double the tuber yields and a higher percentage of hydrocyanic acid than harvesting at 9 months. It is, therefore, desirable to use efficient methods of processing the tubers harvested at 15 months to obtain safe products for industrial and nutritional uses.