Six pairs of gilts were taken at first mating. One of each pair was given about half the A.R.C. recommended amounts of protein and energy during pregnancy and lactation until she became anoestrus (thin group). The other gilt of each pair was given the same amount of protein, but double the amount of energy (standard group).

All the thin sows lost condition and became infertile. Their appearance conformed to that of sows with the ‘thin sow syndrome’. This took up to three reproductive cycles. There was no clear effect on the number of piglets born, but the litters of the thin sows contained an increasing proportion of small piglets. One of the thin sows died in her second pregnancy. The standard sows performed well producing an average of 10·3 piglets weighing 1·4 kg over three parities.

There were no differences between the two groups in their digestive efficiency. The thin sows retained less nitrogen in the later stages (days 80–100) of their first pregnancy than did the standard sows.

There were no differences between the groups in milk production during the first lactation when litters were standardized at eight piglets. There was some evidence that in the second lactation the thin sows secreted less fat and lactose.

The five remaining thin sows were repleted at the end of the experiment when their average weight was 96 kg. They were mated as quickly, produced litters which were as large, and piglets which were as heavy as those produced by the standard sows whose mating weight was 182 kg.

The experimental animals were sows which had been made thin by underfeeding for several parities (thin sows), and siblings which had received adequate energy (standard sows).

The energy metabolism of three thin anoestrous and three non-pregnant standard sows were measured at 20 and 5 °C. There were no differences between the two groups of sows. The fall in temperature increased the average maintenance requirement by 60% from 476 to 753 kJ/kg0·75/day (1192–1922 kJ/kg0·56/day).

The tissue insulation of the thin sows was 28% lower than that of the standard sows, although this difference was not statistically significant. The thin sows compensated by having a better external insulation. The average total body conductance was 306 kJ/m2/°C/day.

The standard sows were in positive nitrogen balance (+ 4·2 g/day, 95% confidence limits 1·5 to 7·0 gN) and the thin sows in negative nitrogen balance (– 4·4 g/day, 95% confidence limits – 2·1 to – 6·8 g N) at energy equilibrium. It is suggested that this difference might be explained if the total nitrogen requirement of the two groups of sows was similar, but that their requirement for energy was related to their body surface area.

There were no differences between the two groups of sows in their digestive efficiency, but the digestibilities of both energy and nitrogen were reduced at 5 °C.

It is concluded that the primary cause of the ‘thin sow syndrome’ is underfeeding, particularly in cold environments. Other features of the syndrome are probably a consequence of undernutrition and depletion of the body energy reserves.

A study was made of the birthcoat and the birth weight of Merino lambs, coarsewoolled Ossimi and the reciprocal crosses. The pre-natal maternal environment had a clear effect on the fineness of the birthcoat of cross-bred lambs born to Merino ewes (Ossimi × Merino) where 22·6% had fine arrays, whereas those out of coarse wool Ossimi dams (Merino × Ossimi) were all coarse like pure Ossimi lambs.

Merino birthcoats were the most highly evolved, having the highest curly tip/precurly tip ratio, whereas the Ossimi were the least evolved. Ossimi × Merino lambs had more evolved birthcoats than Merino × Ossimi. CT/Pre-CT ratios were 1·00, 2·35, 4·41 and 8·06 in Ossimi, Merino × Ossimi, Ossimi × Merino and Merino lambs, respectively.

Ossimi birthcoats had almost straight fibres. Merino × Ossimi showed a low incidence of crimp post natally, Ossimi × Merino exhibited more post-natal crimp and that in Merino predominant crimp occurred throughout.

Strong (coarse) fibres were more frequent in Merino × Ossimi whereas Ossimi × Merino possessed higher frequencies of the less strong fibres and CT/Pre-CT ratio than the other cross. The difference between the two means of the crosses was highly significant in all fibre types.

Lambs with strong fibre type arrays were heavier at birth than those with finer ones.

Free amino -N estimations were used to monitor the movement of amino acids in the vascular system of sheep. The net uptake of free amino-N by portal drained viscera was measured in whole blood and compared with the net gain in the plasma flow.

In normally fed sheep eating dried grass, lucerne or silage the net gain of free amino -N in the plasma of portal blood contributed less than 80% to the total uptake in whole blood. When the protein component of the diet was added into the abomasum (casein supplement to a low nitrogen basal ration) the plasma contribution to the net gain in portal blood averaged 95%.

The results suggest that the cells as well as the plasma are involved in the transport of amino acids in blood and that in ruminants all amino acids have to be measured in blood for a quantitative calculation of the absorption from portal drained viscera.

Studies of the day-time activity of night-enclosed eland, oryx, buffalo and cattle in a hot, semi-arid area in Kenya showed that, on average, eland spent 70% of the day feeding, oryx 60% and buffalo and cattle 52%.

The distribution of activity throughout the day of all species was similar and the mobile activities of feeding and walking tended to be concentrated in the early morning and late evening.

Correlation and multiple regression analyses were used to investigate changes in the activity of the animals in relation to changes in meterological and vegetative factors. The activity of both eland and buffalo was found to be particularly sensitive to the meterological factors.

The duration of feeding for cattle and buffalo was related to the state of the vegetation, but that of the oryx was not. Similar analyses were not possible for eland.

The activity of each species could be related to mouth size, feeding habits and the effectiveness of the animals' coat in dealing with conditions of high heat load.

It is concluded that a naturally short daily feeding time and an independence of activity from the environmental heat load on the animals are advantageous characteristics for a species under domestication in a hot semi-arid environment.

Forty-two Awassi lambs, 21 males and 21 females, were used to investigate the effect of early shearing, before the hottest months, on their performance and heat tolerance as indicated by rectal temperature and respiration rate.

Within each sex, half the number of lambs were sheared and the rest were left unshorn. All lambs were fed for 132 days, covering the hottest period of the year, on a concentrate mixture at the daily rate of 2% of their average live weight plus green roughage offered ad libitum. Rectal temperatures and respiration rates were recorded 1 day of each week on three occasions each day.

Shorn lambs of both sexes had significantly (P < 0·01) higher values for body gain and final body weight than the unshorn ones. Average total digestible nutrients intake was slightly higher for shorn lambs. However, average dry-matter intake as a percentage of body weight was almost the same for shorn and unshorn lambs. Shorn lambs of both sexes were more efficient than the unshorn ones in converting food to body gain.

Shorn lambs were more heat-tolerant than the unshorn ones as indicated by their significantly (P < 0·01) lower rectal temperature and respiration rate.

Marked significant differences were found between the crossbreed means in the percentages of palmitoleic, stearic, octadecenoic and the ratio of palmitoleic to stearic acids and in the percentages of subcutaneous, intramuscular and internal fats.

The percentage of carcass fats and age were strongly correlated with the acids palmitoleic, stearic (negative), octadecenoic and the ratio of palmitoleic to stearic. Covariance adjustment for percentage carcass fat and age made little difference to the significant differences of the variates which indicates that significant breed differences exist between these variates.

Aberdeen Angus and Friesian cattle were reared from 4 months of age to slaughter weight at 18–24 months on either high-barley or high-hay diets. Samples of subcutaneous fat were taken by biopsy at 3 monthly intervals, and the degree of fatness of each animal was estimated ultrasonically prior to slaughter, and by visual inspection of the carcasses.

The barley-fed animals gained weight more rapidly, and fattened more quickly than the hay-fed animals with the Angus being fatter than the Friesian at the same age. The percentage stearic acid (C18:0) in subcutaneous fat decreased with age and was replaced by octadecenoic acid (C18:l) and hexadecenoic acid (C16:l), these changes being more rapid in barley-fed than in hay-fed animals. At the same degree of fatness the depot fats of the Friesians were more unsaturated than those of the Angus, and in both breeds the fatter the animal the more unsaturated was its depot fat.

In the hay-fed cattle the percentage C16:0 in subcutaneous fat increased during the last half of the experiment and at slaughter the percentage C16:0 was significantly higher, and C18:l significantly lower, in all depot fats compared with those of the barley-fed animals.

It is concluded that the fatty acid composition of bovine depot fats is modulated by the degree of fattening, and can be affected by diet.

Over 14 h of daylight and high day temperature singly or in combination delayed flowering of the upland cotton J 34, whereas the photosensitive variety MCU 5 did not flower under long days alone or long days plus high temperature. These treatments promoted vegetative growth and made the plants tall and bushy. Though the treatments were discontinued 75 days after germination the subsequent reproductive growth was adversely affected with significant reduction in boll weight.

The upland genotypes when grown at latitudes 29° N, 21° N and 11° N flowered progressively earlier and at lower nodes at more southerly latitudes because of reduction in daylength and temperatures. It is concluded that the upland cottons of northern India differ from classical types because daylength together with temperature appeared to determine flowering.

The (early maturing) maize hybrid, Anjou 210, was sown on 1 May (1975) and 50000 (LD) and 150000 (HD) plants/ha established. Leaf, stem, ear and husk components of the shoots, and whole shoots were separately examined for changes in dry weight, soluble sugars, starch, hemicellulose and cellulose at regular intervals from 104 to 154 days after planting together with whole shoots after ensiling.

Throughout the sampling period whole shoot and ear dry weights increased steadily whereas those of leaf and stem decreased in plants from both treatments.

Total soluble sugar contents for plants grown at LD were at a maximum 104 days after planting compared with 125 days after planting for the HD crop. Immediately prior to ensiling whole shoot soluble sugar content was 74 and 93 g/kg D.M. for LD and HD treatments respectively.

Small amounts of starch (g/kg D.M.) were found in stems (10–25), husks (40–80) and leaves (17–35) of plants grown at both densities. The starch content of the ear increased from 57 to 390 g/kg D.M. and 168 to 376 g/kg D.M. in plants grown at LD and HD respectively.

For plants from both treatments hemicellulose contents of husks, leaves and whole shoots increased with age whereas those of stems decreased. Cellulose contents did not vary greatly over the growing season.

On ensiling plants from both densities, total soluble sugars had virtually disappeared after only 3 days. Apparent losses (approximately 0·3 g/g), over a longer period of time, were observed in hemicellulose sugars and starch. Apparent increases were observed in cellulose contents of approximately 0·15 g/g.

Feeding and balance trials with 32P were carried out to measure the true absorption of P in battery and broiler waste and to assess the risk of urolithiasis in sheep.

Groups of six, 8-week-old Scottish Blackface lambs were given one of eight experimental diets containing barley and either 15, 30, 45 or 60% of dried broiler or battery waste. After about 12 weeks on the diet, balance trials with 32P were conducted on a sample of the female lambs from each dietary group. The phosphorus intakes ranged from 4·6 to 15·9g/day.

Poultry waste was a good source of P. The proportion of dietary P absorbed by the lambs (A) ranged from 0·49 to 0·90 and was inversely related to the dietary intake of P (I). The relationship was A = 0·893 – 0·0219I. All lambs were in positive P balance (0·24–2·81 g/day), but only the bones from the lambs consuming the diets containing 45 and 60% broiler waste were not osteoporotic.

All lambs absorbed more P than they retained and the partition of the excess between urine and faeces were very variable.

No clinical cases of urolithiasis were seen, but uroliths were found at post-mortem. The incidence was highest in lambs consuming broiler waste and in lambs consuming the diets containing 15% poultry waste.

Studies were made on the effect of 50% reduction in daily water intake during summer on food intake, digestibility coefficients of the cell-wall constituents (CWC), nitrogen retention and water excretion in urine and faeces in the Marwari breed of sheep of the Rajasthan desert, India. The water-restricted animals consumed 54 and 42% less dry matter and digestible energy respectively than normally-watered animals. The digestibility coefficients of different CWC were apparently, though not significantly, higher in water-restricted animals. Throughout the study period, animals of both the groups, particularly the water-restricted group, remained in negative nitrogen balance. Moisture loss through the faeces was about 22% less in the water-restricted group than in the control animals. The water-restricted animals lost 21·1% of body weight in 23 days and these animals, when allowed water ad libitum, were able to recover 71·5 % of the lost body weight within 3 days.

Nine field experiments (1970–5) investigated the effects of single or split applications of nitrogen fertilizer in February, March, April and May to in situ sugar-beet seed plants in their second year's growth. All experiments were within commercial crops of existing multigerm and monogerm varieties grown on fertile, deep soils in south Lincolnshire, north Cambridgeshire and Northamptonshire and on shallow limestone soils in the Cotswolds.

Yield of seed averaged over years and sites ranged from 4·3 to 4·6 t/ha and so was not affected by nitrogen treatments, which also did not noticeably delay harvest. The usable proportion of seed from multigerm crops was 350–650 g/kg, and from monogerm ones 90–200 g/kg but neither was affected by nitrogen treatment. Application of nitrogen in May reduced laboratory germination by about 3% and seedling emergence in the field by about 5 seedlings per 100 fruits sown. The proportion of single seedlings fmonogermity') was not affected by nitrogen treatments, although it was affected by the monogerm or multigerm nature of the crop. An attempt to assess seed vigour was made by determining average seedling weight when grown in the field in the year following harvest, but results were inconsistent. Leaf petiole nitrate concentrations declined progressively throughout the season, but were increased by about a quarterin the month following nitrogen application. At all times they were large and probably not limiting growth. The test had no value for predicting nitrogen application rates or times.

In practice it appears that the spring top dressing of nitrogen fertilizer should be made as a single application at the end of February or as soon as possible thereafter.

An experiment on spring barley (cvs Impala and Julia) on sandy loam soil near Oxford was made from 1969 to 1973 to compare mouldboard ploughing, deep and shallow tined cultivation followed by conventional seed-bed preparation, and direct-drilling.

In 1969 fewer barley plants on the direct-drilled plots than on cultivated plots gave fewer fertile ears/m2 and significantly less grain. In 1970, 1972 and 1973 yields did not differ between treatments. In 1971 there were more ears/m2 and more grain was obtained from direct-drilled than from ploughed plots. Mean grain yields over 5 years did not differ significantly between cultivation treatments. Ploughing and deep tine cultivation resulted in better shoot growth early in the season, more straw and more dicotyledonous weeds than direct-drilling. In comparable tillage operations on the same farm considerably less energy was needed for direct-drilling than for mouldboard ploughing and conventional seed-bed preparation.

This paper gives measurements of soil physical conditions and root growth made in the experiment described in the previous paper. The effect of methods of tillage on soil properties (strength, bulk density, nutrient distribution and fauna) and the effects on root development and the absorption of nutrients from different depths in the soil were investigated. The procedures used for these measurements are described.

Greater soil compaction occurred in all years after direct drilling. The growth of seminal roots of young plants was reduced by direct drilling in each year but only in the first year were there significant differences in root development between treatments at later stages of growth. Similarly, in each year early shoot growth was reduced by direct drilling but, with the exception of the first year, the plants were subsequently able to compensate adequately. Direct drilling resulted in more earthworms being present in the soil, and caused the surface soil to be more friable and contain a higher concentration of available phosphorus and potassium.

Data are presented on the relationship between seed yield, its distribution and the duration of growth. A plant model is proposed to achieve earlier ripening as well as high yield. The possibility of achieving this model is evaluated.

The F1 and F2 progenies of a complete diallel cross between seven inbred lines of field beans (Vicia faba spp. minor) were studied in order to elucidate the possibilities for breeding for earlier ripening without sacrificing seed yield. In a space-planted field trial the inheritance of and relationship among yield and earliness characters were examined.

On average the F1 generation was superior to F2 in seed yield as well as earliness of flowering and ripening. General combining ability (g.c.a.) effects were highly significant for all the characters studied and very high narrow-sense heritabilities were found for most characters. Specific combining ability (s.c.a.) effects were significant for all characters except for number of inflorescences, and significant reciprocal effects were found for seed yield and date of anthesis.

Because of the importance of g.c.a. effects, the phenotypic correlations were mainly determined by, and therefore similar to, the additive genetic correlations in showing a positive relationship between yield and the duration of pre- as well as postanthesis growth. However, a relatively strong negative non-additive genetic correlation was found between yield and duration of post-anthesis growth.

Path analysis showed that 70–82% of the variation in post-anthesis growth was accounted for by the distribution of seed yield described by four yield components, thus supporting the hypothesis that the duration of post-anthesis growth is highly dependent on the distribution and size of the seeds.

Two possibilities for breeding earlier-ripening, high-yielding cultivars are suggested: (1) exploiting hybrid vigour in terms of earlier ripening and (2) reducing the duration of post-anthesis growth byselecting for more seeds per pod and more pods per inflorescence.

The codling moth, Cydia pomonella L., achieved four successive generations in Egyptian pear orchards in 1974. Indices of infested fruits showed four peaks of infestation; the first at the end of April, the second during the first week of June, the third during the first week of July and the last at the end of July.

A study of the solitary parasitoid Microplitis rufiventris on larvae of Spodoptera littoralis showed that the age of the host at parasitization influenced the rate of development of the parasite, the percentage of parasitized hosts giving rise to mature parasite larvae, the number of moults subsequent to stinging, duration of larval instars, and the fecundity and longevity of the resulting adult parasites.

The effects on seed yield of two levels of water stress at four stages of development were investigated in two varieties of sunflower, Krasnodarets and Record. The plants were grown from seed in large pots in an air-conditioned glasshouse at 26/20 °C and 70% relative humidity, with natural summer illumination. They were subjected to water stress before head formation, during head formation, during flowering, and during seed development.

The leaf water potential of plants subjected to a water stress of – 16 bars returned to normal after rewatering, but plants subjected to – 23 bars did not return to their prestress level and some leaves died. A water stress of – 16 bars caused no significant reduction in dry weight of the vegetative structures, but stress at all stages of growth reduced seed yield. A water stress of – 23 bars reduced both total dry weight and seed yield at all stages of growth, seed yield being reduced more by a stress of – 23 bars than of – 16 bars. Oil content was slightly reduced by water stress.

Water stress during anthesis reduced sunflower seed yield more than during later stages of development.

Individual feed intakes of housed mature Greyface (Border Leicester × Scottish Blackface) ewes were adjusted weekly to maintain plasma 3-hydroxybutyrate concentrations during the final 6 weeks of pregnancy at the following values: treatment 1 (adequately nourished; 17 ewes) less than 0·7 mmol/1; treatment 2 (moderately undernourished; 15 ewes) at about 1·1 mmol/1; treatment 3 (severely undernourished; 15 ewes) at about 1·6 mmol/1.

The mean energy intakes (MJ metabolizable energy (ME)/day) required to maintain the prescribed nutritional states in single- and twin-bearing ewes were: treatment 1, 14·3 and 16·3; treatment 2, 10·6 and 11·6; treatment 3, 8·1 and 10·0 respectively.

The moderate degree of undernourishment had no significant effect on the birth weight of single lambs, but reduced the birth weight of twins by 8·2%, while the more severe undernourishment reduced the birth weights of singles and twins by 21·5 and 25·8% respectively.

Foetal energy requirements, estimated by regression analysis, appeared to decrease from more than 2 MJ ME/kg/24 h at 35 days prepartum to 1·54 MJ ME/kg/24 h in the week before parturition.

The amounts of energy required to sustain the nutritional states of treatments 1–3 in non-pregnant ewes were calculated to be 348, 271 and 231 kJ ME/kg0.75/24 h, compared with a maintenance requirement, determined in this experiment, of 344 kJ ME/kg0.75/24h.

It is concluded that in individually fed ewes a nutritional state characterized by plasma 3-hydroxybutyrate concentrations of 1·1 mmol/1 would constitute an acceptable compromise between an uneconomically high energy input and an excessive reduction in lamb birth weight.