Forty-four turkeys including both sexes of two genetic strains were drawn at mean weight-for-age at 2 week intervals from a flock of 380 birds from hatching to 20 weeks post-hatching. Birds were dissected and linear measurements of skeletal units and breast dimensions were compared with keel length using the logarithmic form of Huxley's allometric growth equation. Live weights and weights of selected muscles were similarly compared with breast muscle weight. Wing bones and the biceps brachii muscle grew at approximately the same rate as keel length and breast muscle, respectively. However, leg bones and semitendinosus and gastrocnemius muscles exhibited slower growth than the breast region. Growth of maximum breast length and width was closely matched to keel length but growth in keel depth was much slower. The desirable convexity in breast shape lateral to the keel was considered to be directly proportional to maximum meat depth over the sternum and inversely proportional to keel depth. Maximum meat depth increased at a faster rate than either keel length or depth.

Photosynthetic rates, chlorophyll content and activity of ribulose 1,5-diphosphate carboxylase (RuDPC) were determined for 18 genotypes of wheat (Triticum aestivum L.) in pot culture. Measurements were made at various growth stages. Correlation studies between physiological characteristics and seed yield were made at each stage separately.

Genotypic variations were observed at different growth and developmental stages in photosynthetic rates (1·8–2·7-fold), chlorophyll contents (1·2-fold) and enzyme activities (2-fold). Chlorophyll content and enzymic activity increased in plant leaves with advancing age while apparent rates of photosynthesis decreased.

RuDPC activity in flag leaf at anthesis showed significant positive correlation with grain yield (r = 0·55). Other attributes did not show significant association with grain yield.

The yield and quality of herbage produced by six grasses (perennial ryegrass, cocksfoot, timothy, rough-stalked meadow grass, tall fescue and Italian ryegrass) were examined both without irrigation and under two irrigation regimes. Water was applied according to the potential soil water deficit (potential SWD): the soil was either partially returned to field capacity (FC) after each cut or fully returned to FC whenever the potential SWD reached 25 mm. The swards were cut either at 3 (C3) or 6 (C6) week intervals over a 2 year period.

Partial irrigation increased yields by 12–14% in the first year and by 36–58% in the second. Full irrigation produced little more growth than partial irrigation in the first year (maximum SWD, 188 mm) but increased yield by 78–93% in the second, very dry, year (maximum SWD, 311 mm). Under treatment C3 response per unit of water applied was similar with both partial and full irrigation, but under C6 the response was greater with partial (2·86 kg D.M./m3) than with full irrigation (1·79 kg D.M./m3).

There were marked differences between the species in their ability to grow under drought conditions in the second year of the experiment. Without irrigation, roughstalked meadow grass and Italian ryegrass did not survive the drought. The performance of tall fescue was markedly superior to both perennial ryegrass and cocksfoot in these conditions. Of the surviving grasses timothy made least growth.

The use of soil water by six grasses (perennial ryegrass, cocksfoot, timothy, rough stalked meadow grass (RSMG), tall fescue and Italian ryegrass) was measured over 2 years. The swards were cut either at 3-week (C3) or 6-week (C6) intervals. In both years the maximum soil water deficit attained under C6 was greater than under C3. Following several of the cuts from C6 there was a marked, although temporary, reduction in the rate of water uptake.

An extended dry period in the second harvest year revealed substantial differences in the total water used and in the patterns of uptake from the soil profile by the grasses. Effective depths of utilization of water under treatment C6 were: RSMG, 40 cm; timothy, 70 cm; cocksfoot, 70 cm; perennial ryegrass, 80 cm; tall fescue > 100 cm. This order of depth of utilization corresponded with the order of yields obtained during drought conditions. An examination of the root systems of four grasses also showed that, particularly under treatment C6, roots of tall fescue were more numerous at depth than those of timothy, cocksfoot or perennial ryegrass, and under this treatment it showed its greatest tolerance to dry conditions. Drought tolerance in these grasses appears largely determined by the volume of soil exploited by the roots for water.

Male and female (Suffolk × (Finnish Landraee × Dorset Horn)) lambs were used in three experiments to examine the replacement of milk by undried and dried fish protein hydrolysates (FPH), a mixture of lard and coconut fat, and partially hydrolysed starch (Protamyl 110). The animals received the experimental diets from 1 week of age in Expts 1 and 2, and from 4 weeks of age in Expt 3. They were given the diets in eight equal feeds (i.e. every 3 h) from an automated teat bar system. The level of feeding was 1·046 MJ/kg0−76/day. Experiments 1 and 2 lasted for 35 days, during which live-weight gain and food conversion ratios were recorded and at the end the digestibility of N, dry matter and starch was determined. Experiment 3 consisted of three small digestibility trials.

In Expt 1, the replacement of milk protein with undried FPH and of milk fat with lard plus coconut fat had no significant effects on live-weight gain, food conversion ratio or nutrient digestibility. Somewhat lower gains for the lambs given the FPH than those given milk protein were observed during the first 15 days of the experiment. Apparent digestibility of milk protein and milk fat was 95 and 99% while that of PFH and lard plus coconut fat was 94 and 96% respectively. The replacement of milk fat with lard and coconut fat caused some reduction in live-weight gains and nutrient digestibility. Lactose was completely replaced by protamyl both in diets based on milk protein or FPH with no effect on live-weight gains or food conversion ratio.

Apparent digestibility of fish protein was not affected by the drying process. Fat digestibility of diets containing undried or dried FPH ranged from 46 to 98% according to the type of emulsifier used. The results are discussed in relation to published data concerning the problems associated with the use of fish protein in milk replacers.

Nine strains of Rhizobium sp. were studied in vivo for their nodulation capacity, leghaemoglobin content, grain yield, crude protein and 16 amino acids content, in the chick pea variety C 235 grown on a calcareous saline alkali soil. There was no significant correlation between grain yield and number of nodules (r = 0·37) or dry weight of nodules (r = 0·29), but grain yield was significantly correlated with leghaemoglobin content of nodules (r = 0·95). Of the 16 amino acids analysed in seed samples, aspartic, glutamic, proline and histidine were greatest with strain H 45; glycine, leucine and arginine with strain F 6; norleucine, tyrosine and phenylalanine with strain KG 38; and alanine and valine were greatest with strain KG 41. Strain KG 38 led to significantly higher grain yield than the other strains.

When experiments are conducted on two crops in association significance tests are available for judging whether treatments are having different effects or not. If, however, differences are established, it becomes necessary to assess the various treatments in agronomic, dietetic or economic terms. Graphical methods are here advanced to aid such assessment, special attention being given to (a) the stability of recommendations when the monetary or other values of the two crops change from season to season, (b) the measurement of yield advantage of mixtures over pure stands, and (c) the maximization of yield when it is desired to produce the two crops in specified proportions. The relationship to competition experiments is discussed.

Three methods of controlling swede mildew were compared. Mildew infection was reduced by delayed sowing but yields from later sown plots were seriously reduced. Infection was reduced but not eliminated on resistant varieties. Highly effective chemical control was achieved with the fungicide Persulon, which showed both eradicant and protective properties. The yield differences between a genetically resistant and a susceptible variety were eliminated when Persulon was used.

Diurnal variations in microbial protein nitrogen, total volatile fatty acids and ammonia were examined in two wethers fed once and twice daily with 0·4 kg of concentrateand 0·4 kg hay/day. The total protein nitrogen varied during the day from 76·9 to 130·2 mg/100 ml of rumen fluid. The greatest amount of protein nitrogen was noted immediately before feeding and the smallest 4 h after feeding. The protein nitrogen of rumen protozoa formed about 39·8–53·4% of total protein nitrogen in rumen fluid. Volatile fatty acids varied from 74·0 to 130·5 m-mol/1 of rumen fluid and ammonia from 187·0 to 305·6 mg/1. The higher concentration of total and protozoal protein nitrogen and of VFA was observed when animals were fed twice daily. The changing of feeding frequency from once to twice daily caused an increase of ammonia concentration in the rumen of only one wether. The results obtained are discussed.

Field studies were made of tritiated water turnover, drinking water and dietary water intake throughout the year, in 212 animals of the following species: African buffalo, dromedary camel, zebu cow, eland, small East African goat, fringe-eared oryx, and Dorper sheep.

There were significant differences (P< 0·005) in the water drunk and water turnover between species and between seasons. Furthermore the species (or season) differences were also significantly different (P< 0·005) for each season (or species). The lowest turnover rates were found in oryx, then camel, sheep, goat, eland, cow and buffalo, when expressed in ml/l0·82/day, which was the appropriate metabolic unit for these species.

The restraints imposed by traditional African animal husbandry have drastically reduced the natural ability of eland to conserve body water but had much less effect on buffalo and oryx. The reason appears to be that eland is behaviourally adapted to a semi-arid environment, whereas a species like oryx is more physiologically adapted.

This paper presents an iterative analysis of incomplete variety × environment tables. The analysis estimates potential differences in the sensitivity of varieties to environment effect. It is noted that the technique allows unequal weighting of data, and the special case of a complete table is discussed.

Because of environmental and economic constraints, we need to determine the effects of nitrogen fertilizer application on nutrient availability and fertilizer recovery, especially in regions of limited rainfall. This study was conducted to provide information on effects of N rate on yields and N recovery by standard and semi-dwarf spring wheats (Triticum aestivum L.) sown at two dates.

Ammonium nitrate was applied to spring wheat at rates up to 272 kg N/ha each year for 4 consecutive years. Only grain was removed from the plot at harvest. Wheat types did not differ in grain yields, but these yields were significantly reduced in 2 of 4 years by late sowing. Average grain yields for late sowing were greatest at 34 kg N/ha, but yields for early sowing approached maximum at the 68 kg N for semi-dwarf wheat and 136 kg N/ha for the standard wheat.

Semi-dwarf wheat was lower than standard wheat in grain and flour protein concentration and baking absorption. Late sowing (May 30) reduced test weights, flour yield and baking absorption, but increased wheat protein concentration as compared with early sowing (April 30). Leaching of fertilizer N below the 90 cm depth ranged from 152 to 378 kg/ha at the 272 kg N/ha/year rate, and was greater for the late than for the early sowing. Fertilizer N that could be accounted for averaged 87 and 82% for early and late seeding respectively. Water-use efficiency was reduced by late sowing.Soil-water extraction by wheat to the 120 cm depth was greater for high N rates.

These 4-year results showed that semi-dwarf and standard wheats had only slight differences in total grain production. Also, for efficient use of applied fertilizer and available soil water, wheat should be sown in the spring as soon as soil and weather conditions permit.

The effect of a gradual increase in dry-matter concentration from 140 g/kg (LD diets) to a maximum of 215 g/kg (HD diets), and the effect of an increase in fat concentration from 225 g/kg D.M. and reduction in protein concentration from 298 g/kg D.M. (LF diets) to 254g fat and 211g protein/kg D.M. respectively (HF diets) was examined with 32 Friesian bull calves in a 2 × 2 factorial experiment. Milk substitutes were offered ad libitum in two feeds daily from 2 days of age. The dietary changes were first introduced at 7 weeks of age and differences became progressively greater as further changes were made at 9, 11 and 13 weeks. The calves were slaughtered at 16 weeks of age.

Dry-matter intake for calves given the HD diets increased faster with age after 7 weeks than that for calves given the LD diets. For the period 7–16 weeks, calves given the HD diets consumed 17% more D.M. than those given the LD diets and had a 13% greater rate of live-weight gain (1·57 v. 1·39 kg/day), although most of the increase in weight gain occurred between 9 and 13 weeks of age.

There was no significant effect on D.M. intake or on live-weight gain of altering the fat and protein concentrations in the milk substitute, although feed conversion ratio (kg D.M. intake/kg weight gain) was higher for the HF than for the LF diets. Apparent digestibility of D.M., crude protein and fat were reduced with the HF diets, but the efficiency of retention of the digested nitrogen was improved. During the second and third weeks of life, D.M. intake reached a peak at approximately 67 g/kg0·75 and subsequently declined to stabilize at about 56 g/kg0·75. However, a gradual increase in concentration of the milk substitute from 140 to 215 g D.M./kg increased intake to about 62 g D.M./kg0·75. The results clearly indicate that, at a dietary concentration of 140 g D.M./kg, maximum D.M. intake cannot be achieved because the volume of fluid that needs to be ingested exceeds the capacity of the digestive system. In contrast, at reconstitution rates increasing from 140 to 215 g D.M./kg, distension of the stomach becomes less important and physiological and metabolic factors seem to assume a greater role in the control of feed intake.

Crosses and reciprocal crosses were made between English material of Vicia faba major × Vicia faba equina and minor.

Half the major type plants had the stem apex removed before pollinations commenced. Apical dominance affected the success of crosses between major × equina, minor. On higher nodes and, on lower nodes when the apex was removed, there was no evidence of unilateral incompatibility. All crosses produced seed.

In a preliminary laboratory experiment in Iran, not reported here, 5 out of 30 plant materials incorporated into a highly calcareous soil had a positive effect on increasing the DTPA- (diethylenetriaminepentaacetic acid)-extractable Fe and all except one significantly increased the vegetative growth of sorghum. The plant materials included Lawsonia inermis L., Malva silvestris L., Zyzyphus nummularia Wak. and Lavandula carnopifolia L. A glasshouse study was repeated with two California soils pretreated with 0·5% Fe2O3 to determine if these organic materials have practical value in making Fe available to plants. A calcareous, Fe-deficient Hacienda (fine-loamy, mixed, thermic aquic natrargid) and a non-calcareous Yolo (fine-silty, mixed, non-acid, thermic typic xerothents). The previously mentioned organic materials and Laminaria saccharina L. (Lamour) were incorporated into the soils at two rates, 15000 and 20000μg/g, as air dry and in ash form. An adequate supply of major and micronutrients other than Fe was ensured. Other treatments included 5 μg Fe/g as FeSO4, Fe-138 chelate and control. All of the plant materials with the exception of L. carnopifolia significantly increased dry-matter yield and Fe, Zn, Cu and Mn uptake by sorghum in the Hacienda soil. In the Yolo soil the above were not significant. Thin-layer chromatography of the extracts of the plant materials revealed the presence of significant quantities of phenolic substances.

Six experiments are reported which examined the effects of various seed cutting treatments on numbers of tubers and tuber yields of several maincrop potato varieties. Using conventional potato ridges, the cutting of seed tubers into 12 mm cubes or the use of potato peel reduced early growth and yields compared with whole tubers in some experiments but in two others had little effect on tuber yields. In Majestic, seed cutting produced large increases in number of stems and tubers and increases in yields of small sized tubers. In Pentland Crown and King Edward, the effects of seed cutting were small. In King Edward no differences in growth and yield were found between individual eyes and in this variety and Pentland Crown, 56g whole tubers produced similar yields to halves of 112 g seed tubers planted at the same seed rate. The implications of cutting for use in commercial production are discussed.

Resistance to bean common mosaic virus in the cultivars Seafarer and Aurora from the U.S.A. is controlled by the dominant gene I originally found in the cv. Corbett Refugee.

Two experiments with growing pigs grouped in pens and three with growing pigs kept in metabolism crates were undertaken in order to determine young growing pigs'dietary requirement for phosphorus of vegetable origin, the relative potency and true digestibility of that source and the effect of dietary Ca concentration on its utilization. Much of the P was contained in wheat offal, and of this 900 g/kg total P was phytin-P.

In the first two experiments the responses to vegetable P were measured by pig live-weight gain, gain: feed ratio, several conventional carcass measurements and the weight, length and density, and the ash, Ca and P contents of the fourth left metacarpal, and also by the alkaline phosphatase activity of blood serum. No significant differences were found between treatments in terms of body-weight gain, gain: feed ratio, or the commercially important carcass characteristics. The requirement of pork pigs for P was measured by bone and serum enzyme characteristics when all the dietary P was of plant origin, apart from 0·3 g P/kg from casein. Under the conditions of this experiment this P requirement appeared to be met when the diet contained 5–6 g P/kg. The potency of vegetable P in Expts 1 and 2 and of wheat offal P in Expt 3 relative to feed grade dicalcium phosphate was 0·77, equivalent to a net retention of 0·4–0·5 as a proportion of that consumed estimated from growth and digestibility measurements. A true digestibility coefficient of 0·53±0·01 for wheat offal P was obtained in Expts 4 and 5. The effect of variation in dietary N and energy, associated with variation in dietary offal concentration, on the reliability of the potency estimates is discussed.

Increasing dietary Ca concentration caused a slight decrease in the digestion of wheat offal-P. The soaking of wheat offal in water for an average of 11 h before feeding increased P digestion in one of two experiments. In vitro evidence indicated that soaking initiated the hydrolysis of insoluble P compounds.

Dilute formalin was used to sample earthworm populations after the second (1969) and sixth (1973) harvests from a continuous barley experiment in which the cultivation treatments include deep (30 cm), normal ploughing (20 cm) and tined (three passes to 20 cm) cultivations and no tillage (direct drilling), at four nitrogen rates: 0, 50, 100 and 150 kgN/ha. Eight species of Lumbricidae were found, with Allolobophora chlorotica and A. longa co-dominant in both years, joined by A. caliginosa in 1973.

In 1969, Lumbricus spp., particularly large Lumbricus terreslris, tended to be more numerous in the untilled plots.

In 1973, the total populations had increased by 170%, with 50–100% more earthworms in untilled than ploughed plots, one third more with 50 and 100 kg N/ha fertilizer than with no nitrogen, and one-third more in the slightly heavier sandy clay loam soil than the lighter loam.

Most earthworm species reacted in the same way, and the reasons for any unusual reactions are discussed.

In northern areas of maize production in Europe and America, increasing use is being made of the association between accumulated temperature and stage of crop development. Temperature is accumulated either in terms of day-degrees above a given base temperature, taken to be 10 °CC in the U.K., or in terms of developmental units (‘Ontario Units’). Formulae for obtaining the daily contribution from recorded maximum and minimum air temperatures are available for compiling accumulated temperature totals for each of these methods, but the processing of long series of data is tedious, even with the assistance of computer programs. Results are presented from several locations in the central lowlands of England to suggest that very close approximations to the true monthly or seasonal totals can be obtained from the regression relations with corresponding mean monthly or seasonal temperatures.

For the sites considered the regression equations were sufficiently close to make joint, ‘regional’, regression equations appropriate. It is believed that the results will be applicable to other areas of England, and that the methods suggested might provide a suitable basis for supplementing the information available on accumulated temperatures elsewhere in northern Europe.