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.

Field experiments were made in both 1974 rainy seasons in Ibadan, Nigeria, to evaluate the effect of harvest time on seed quality and viability of soya beans (Glycine max (L.) Merr.). The first harvest was made when about 85% of the pods had ripened and subsequent harvests were made at 7-day intervals. Delaying harvest increased the percentage purple-stained, cracked and black seeds in the first season, and of cracked seed in the second season. In the second season soya-bean seeds showed neither purpling nor dark discoloration on the seed coat; the crop matured during sunny, dry weather. However, in both seasons the reduction in seed quality was accompanied by a corresponding decrease in germination percentage. Varietal differences were noted in that the small-seeded Improved Pelican was least affected, and Hardee was the most affected by field weathering in both seasons. Kent and Bossier were intermediate between the two extremes. The results point out the importance of proper timing of harvest of soya beans in rainy seasons, and the need for screening soya beans for resistance to weathering in the tropics.

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.

Measurements of 21 bone lengths and breadths were made on radiographs of 215 foetuses of known gestational ages ranging from 50 to 145 days obtained from 80 Finnish Landrace x Dorset Horn ewes. Number of foetuses per ewe varied from 1 to 5, but the main statistical analyses were based on the 22 sets of twins, 34 of triplets and 11 of quadruplets. Equations were fitted to relate each of the linear measurements to foetal weight alone, to foetal age alone, to foetal age together with number of foetuses, and to foetal age together with foetal weight. It was found that there were significant differences between the twins, triplets, and quadruplets in the lengths their bones attained at any specified weight or at any specified age but not when both weight and age were fixed. The relationships to weight and age jointly were significantly closer than to either of them alone even after allowing for number of foetuses. The mathematical model that fitted best was a modified Gompertz equation of the form

where ywas the measured length, w was the number of days prior to expected parturition, w was foetal weight, wu was an estimate of the expected foetal weight at time u, and P, Q, R and Dwere fitted constants.

A total of 886 cows of two herds belonging to the Ministry of Agriculture, Egypt, were used in this study to investigate the effects of inbreeding and cross-breeding on dairy traits. The first herd consisted of the native breed Domiatty (D), Shorthorn (S) and different grades between them while the second of Jersey (J) and its different crosses with D. There were 1027 lactations from the first herd and 460 from the second. Inbreeding coefficient (F) averaged 0·06 in the first herd and 0·08 in the second, both ranging from 0·00 to 0·30. The range was partitioned into three classes: the first with 0·0 ≤ F ≤ 0·1, the second 0·1 ≤ F ≤ 0·2 and the third F ≥ 0·2. Traits studied were first and second lactation 305-day milk yields, age at first calving, first calving interval and first dry period.

Inbreeding had no statistically significant effect on any of the traits except dry period in the first herd. Inbreeding was not associated with decrease in yield when F ≤ 0·2 in the first herd, while there was consistent decrease with inbreeding in the second herd. No clear trend could be observed on the effect of inbreeding on any of the other traits in the first herd whereas in the second the rise in inbreeding was always associated with greater age at first calving, with wider calving interval and with longer dry period.

This paper describes the effect of three different growth rates on some offal components of Angus cattle. The growth rates were: high (H, 0·8 kg/day), low (L, 0·4 kg/day) and high-maintenance (HM, 0·8 kg/day followed by a period during which body weight was held constant).

Equations are presented which enable the weights of the offal components to be calculated within the body weight range 300–440 kg.

For most tissues, weights in the H group were greater than in the L and HM groups and included: liver, rumen-reticulum, small intestine and the total alimentary tract. Weight of fat trimmed from the rumen-reticulum, omasum, large intestine and total alimentary tract was also greater in the H than in the L and HM groups. The reverse situation held for head, feet and tail and the spleen.

In spite of these differences between groups in weights and composition of offals, the carcass composition in all groups was similar (Murray, Tulloh & Winter, 1974). It appears that, at a given body weight, changes in the offals may buffer the carcass against change in composition when cattle are exposed to different growth patterns.

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 acute thermoregulatory responses of normally feathered (control) and poorly feathered laying hens were studied in the ambient temperature range from 0 to 38 °C.

Core body temperature in the poorly feathered birds began to fall at between 15 and 20 °C but this difference from the controls was significant only at 0 and 5 °C, when there was severe hypothermia. The temperature on the skin of the back was significantly lower at 20 °C and below, but the comb temperatures did not differ.

The rate of oxygen consumption in the poorly feathered hens was significantly higher than that of the controls at 30 CC and below; at the acclimation temperature (20–25 °C) the difference was about 62%. The rate of increase of heat production with falling ambient temperature was 2–6 W/ma/°C in the poorly feathered group and 1–0 W/ma/°C in the controls.

Absolute rates of evaporative heat loss did not differ between the two groups.

The ratio of the coefficients of dry heat transfer in the poorly feathered and control birds at 0–30 °C was 2–1:1.

Rectal, external auditory meatus and skin temperatures and panting rates were measured in native fat-tailed Awassi and imported German Mutton Merino (GMM) sheep. The Awassi evolved under desert conditions, have a localized fat deposit, coarse carpet wool, long pendulous ears and long, spiral horns (males). In contrast, the GMM evolved under temperate conditions, have well-distributed fat, medium fine wool, short, straight ears and are polled. The study was carried out during the summer in the northern part of the Negev desert.

The mean daily rectal temperature fluctuation was higher (P < 0·01) in the GMM than in the Awassi (1·78 °C v. 1·08 °C). The external auditory meatus temperature was lower than the rectal temperature by 1·5 °C in the GMM and by 1·7 °C in the Awassi, indicating a cooler brain temperature. The maximum skin temperature was similar to the maximum rectal temperature in both breeds, thus sweating was of little importance. The panting rate of the GMM increased fivefold (40·6–199·4 pants/min) whilst the rate of the Awassi increased fourfold (35·3–135·0 pants/min). There was no between-breed difference in either the rectal temperature or panting rate until 25–30 °C ambient temperature and it is thought that the higher rectal temperature of the GMM at this ambient temperature might have triggered off the higher panting rate. It seems that the GMM use panting to a greater extent than the Awassi whereas the Awassi dissipate heat through the skin more efficiently than the GMM. It is concluded that both breeds are thermostable, much of the between-breed difference in rectal temperature can be attributed to their anatomical differences.

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.

The relationship between the selected food and rumen fermentation was investigated in Thomson's gazelle, Grant's gazelle, impala and Maasai haired sheep and goats. All animals were shot in the same grass-bushland area within 1 week during the dry season.

According to rumen contents, sheep were almost exclusively grazers. In goats, Thomson's gazelle and impala, grass accounted for about 70% of all plant parts identified. In Grant's gazelle, browse including Acacia seed constituted 68% of rumen ingesta. The two gazelle species showed a very marked preference for green grass leaves.

In sheep and goat rumens, concentrations of NH3-N and volatile fatty acids, and in vitro fermentation rates (262 and 272 μmoles gasNTPD/g D.M./h, respectively) were lowest. In the wild ruminants, concentrations of fermentation end-products were higher and the rate of fermentation significantly (P < 0·05) faster, namely 420 in Thomson's gazelle, 356 in Grant's gazelle and 376 in impala. Rumen pH was not significantly different between species, with mean values ranging between 6·3 and 6·0. Total VFA concentrations ranged between 124 and 178 m-equiv/1 in the rumen and around 25 m-equiv/1 in the abomasum. Acetic acid accounted for about 75% of the total VFAs.

It is concluded that there are large differences in the pattern of rumen fermentation between wild and domestic mixed-feeding ruminants which reflect their respective food preferences.

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.

Twenty-one Jersey cows in their 6th–8th week of lactation grazed Chloris gayana pastures fertilized with nitrogen and were treated in three ways, no casein (control), casein (1 kg/cow/day) or formal-casein (1 kg/cow/day) in seven 3 x 3 Latin squares to measure the effect of protein protection on milk yield and milk composition. Additional animals fitted with oesophageal and rumen fistulae were used to determine composition of the diet selected and rumen characteristics on three treatments.

Cows ingested herbage containing 20% crude protein with a protein solubility of 40%. The untreated casein supplement increased milk yield by 3%, fat 5% and protein 2·4%. Formal-casein produced 20% (3·3 kg/day) more milk than the control, a 13% higher yield of butterfat and 27% more protein. Rumen ammonia concentrations in the afternoon were similar for the control and formal-casein supplemented cows (21 and 23mg/100ml) but significantly higher when casein was fed (74 mg/100 ml) indicating extensive deamination of the untreated protein.

Yields of C4–C16 fatty acids in milk fat were 8 and 21% higher for the casein and formal-casein treatments than for the controls, which together with the higher live weight of formal-casein supplemented cows indicated that the milk yield response to the protein supplements was mainly due to a higher daily intake of herbage.

Mesomorphic, stress-sensitive Pietrain pigs were found to have a lower insulin secretory response to intravenous tolbutamide, glucose and arginine, when compared with ectomorphic, stress-resistant Large White pigs. Pietrain pigs have also been observed to be insulin-insensitive in comparison with Large White pigs. The combination of a low production of and low sensitivity to insulin in the Pietrain breed could account for their enhanced sensitivity to lipolytic agents and for their reduced ability to deposit body fat.

The potential digestibility of leaf and stem fractions of Rhodes grass (Chloris gayana) and Pangola grass (Digitaria decumbens) were determined by incubating in vitro with rumen fluid for 4, 7, 11 and 14 days with reinoculation after 7 days. The mean drymatter solubility (DMS) of four leaf and four stem samples from the two species, increased from 53·6% after 4 days to 63·8% after 14 days with increases of 14·9 and 5·7% for leaf and stem respectively. Prolonged incubation of sheep faeces from these feeds gave similar patterns of DMS as those for the original feed.

To determine the cause of the observed rise in DMS, leaf and stem of Rhodes grass was incubated for 21 days with rumen fluid and Onozuka cellulase. When using cellulose, DMS increased by 7·7% compared with 14·6% when using rumen fluid. The higher DMS with rumen fluid was associated with an increase in the mean disappearance of lignin from 33·6% at 4 days to 52·6% after 21 days. After 14 days there was no further loss of lignin from most samples indicating the existence of a hard resistant lignin core.

It was concluded that when determining potential digestibility forages must be incubated with rumen inoculum for at least 21 days and that shorter incubation times may lead to biased conclusions.

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.

Six experiments on winter wheat, three in 1974 and three in 1975, evaluated aqueous ammonia, aqueous urea and a solution of ammonium nitrate and urea, using ammonium nitrate granules as the standard. Aqueous ammonia and aqueous urea were injected 8–10 cm deep in bands either 25 or 50 cm apart during April. The ammonium nitrate/urea solution was sprayed and the ammonium nitrate granules were broadcast (a) partly in April and partly in May or (6) wholly in May. All were applied at 50, 75, 100 or 125 kg N/ha. Yields and % N in grain were measured and N removed by grain calculated. In two experiments lodging diminished yield and complicated the comparisons.

Elsewhere, aqueous urea and aqueous ammonia were of similar value, and each gave a larger yield when injected in bands 25 rather than 50 cm apart. Both fertilizers gave yields similar to those from broadcasting the ammonium nitrate granules, but larger yields than from spraying the ammonium nitrate/urea solution. Yields were slightly larger when divided rather than single topdressings were given, but % N in grain and the amounts of N removed were smaller. Yields and % N in the grain were smallest when the ammonium nitrate/urea solution was sprayed. The other three fertilizers were each of greater value judged by N uptake, the ammonium nitrate granules having a slight advantage.

Three constant and four variable heights of cutting were applied to swards of Italian ryegrass (Lolium multiflorum Lam.) cv. Aberystwyth S. 22 and perennial ryegrass (Lolium perenne L.) cv. Aberystwyth S. 23 for a period of 2 years. The treatments were initially given in the seeding year of the Italian ryegrass swards and first harvest year of the perennial ryegrass. The same swards were used throughout the duration of the two experiments. The three heights of cutting 3, 6 and 9 cm were defined by the mean lengths of tiller remaining after defoliation with a flail harvester.

The yield of dry matter (D.M.) was relatively low from Italian ryegrass cut repeatedly to 3 cm because many plants died. Higher yields were obtained by cutting repeatedly to 6 or 9 cm but only when the grass at the end of the season was cut to 3 cm. Italian ryegrass produced more herbage by variable than constant heights of cutting, especially when a lax cut occurred in mid-summer.

Perennial ryegrass gave higher yields of D.M. by constant low than high cutting, but there were no differences in yield when the constant high cut swards were closely defoliated at the end of each season. More herbage was produced by variable than constant heights of cutting in the second year, especially when several lax cuts occurred in the variable height of cut treatments.

As perennial ryegrass had a very prostrate growth habit in swards which received several close cuts tillers were not defoliated too severely. In contrast, Italian ryegrass remained erect in growth habit even in swards which were closely defoliated and thus tillers were cut more severely than those of perennial ryegrass. The need to measure accurately the actual lengths of tillers after defoliation is emphasized in height of cutting treatments.

The results obtained showed that there was a clear relationship between the ability of larvae to assimilate mulberry leaves and the resulting cocoons. The mulberry varieties, Morus alba var. rosa, M. rubra and M. alba var. Ihu, had a conspicuous effect on weights of the resulting cocoons in the three races of silkworm (Novi, Belgharia 4 and S.A. 105) studied.

Results obtained also indicated that the length of the silk fibre and the weight of silk cocoons that yielded 1 kg of silk were largest when the larval diet was M. alba var. rosa or M. rubra, and were smallest when the larval diet was M. alba var. Ihu.

Results also showed that the protein content determined in the resulting silk was proportional to the protein percentage in the different mulberry leaves.

Feeding of larvae of the races Novi, Belgharia 4 and S.A. 105 on M. alba var. rosa and M. rubra leaves caused approximately one- to twofold increase in the fresh weights of larvae or pupae. Weights of fresh cocoons and cocoon cortex constructed by pupating larvae were largest when larval diet was M. alba var. rosa or M. rubra and were smallest when the larval diet was M. alba var. Ihu.

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.