Voluntary intake of hay by steers was measured when supplements of barley were given: (1) whole unprocessed, (2) NaOH treated, (3) torrified (infra-red heat treatment), (4) crimped, (5) rolled, (6) ground and (7) ground and pelleted. The cereal supplements were given at 50 g/kg live weight0·75/day. The voluntary intakes of hay dry matter were 42·1, 43·0, 38·1, 35·1, 34·9, 34·4 and 30·5 g/kg W0·75/day respectively.

Dry-matter digestibilities of barley given without hay were (g/kg): whole, 672; NaOH treated, 807; torrified, 813 and rolled, 834.

Incubation of feed samples in the rumen in polyester bags showed that rolled barley disappeared much more rapidly than NaOH treated and torrified barley.

It is concluded that the deleterious effect of a cereal based supplement on rate of digestion of cellulose and consequently voluntary intake can be largely overcome by use of processing methods which reduce the rate of release of starch and yet ensure complete digestion. Treatment with NaOH looks promising in this respect.

Merino sheep were given abomasal infusions of either mixtures of amino acids or protein during periods of 8 or 12 days. Effects on wool growth were measured using autoradiography and a clipping procedure which allowed time for the emergence of the wool fibres. Estimates of volume growth rate, from the autoradiographic measurements, and of mass of wool grown, from clipping, were in good agreement.

An infusion of a standard mixture of 13 amino acids, which included ten essential amino acids in approximately the proportions in casein, consistently stimulated wool growth. The mean increases in volume and mass of wool grown, during 30 infusions, were 66 and 67% respectively. A mixture of ten essential amino acids alone appeared to be as effective as the standard mixture for stimulating wool growth, and there were no significant differences between the effects on wool growth of casein and the standard mixture of amino acids.

The omission of methionine from an infusion of the standard mixture of amino acids, or from a mixture of essential amino acids only, inhibited wool growth rate; both fibre diameter and length of wool grown per day were reduced to below the control values. In addition, the strength of the fibres was considerably reduced.

Infusions of zein and of an amino acid mixture simulating the essential amino acid composition of zein both inhibited wool growth rate, due to a reduction in fibre diameter. Similar effects on wool growth were observed when any one of three essential amino acids (lysine, isoleucine or leucine) was omitted from an infusion of the standard mixture of amino acids. The omission of five other essential amino acids (arginine, histidine, phenylalanine, threonine or valine) from the infusion, or variations in the proportions of leucine, lysine or methionine, had no appreciable effects on wool growth.

Four varieties of Italian ryegrass (Lolium multiflorum), which have been found to differ in voluntary intake by livestock at the same level of digestibility, were examined in the year of sowing and in the two subsequent years in a field experiment. Eight dates of first harvest during May–June in the years after the year of sowing were compared. During May–June in these years the proportion of leaf in the crop was closely related to the stage of development of the crop relative to heading date, whereas yield and digestibility were more closely related to calendar date. As a result the later-heading varieties, S. 22 and Sabalan, had a higher proportion of leaf than the earlier-heading varieties, RvP and Tetila Tetrone, at a given yield and digestibility and this may at least partly account for higher intake in the former varieties. In addition, in Sabalan, the proportion of green leaf relative to dead was particularly high and the proportion of cell wall particularly low. The surface area per unit dry weight of leaf blade was much higher than that of ‘stem’, which may contribute to shorter retention time in the reticulo-rumen. Surface area per unit weight of both leaf blade and ‘stem’ declined with delay in date of first harvest.

The yield of RvP relative to the other varieties was modest at the first harvest in the years after the year of sowing and high at subsequent harvests, in accord with National Institute of Agricultural Botany results. The high yield of RvP relative to the other varieties after the first harvest appeared to be associated with a relatively large number of tillers with their shoot apex below cutting height at the time of first harvest. It seemed that most of these tillers had emerged during the few weeks before that harvest. The proportion of tillers with their shoot apex below rather than above cutting height at the time of first harvest was higher in all four varieties than casual observation would suggest and the proportion remained rather high throughout May and June. The rapid rate of turnover of tillers in Italian ryegrass was confirmed.

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

The amino acid, mineral and collagen composition of certain different components of the bodies of preruminant calves was determined. The amino acid composition (g/kg crude protein) of the empty bodies of preruminant calves was: hydroxyproline, 40; aspartic acid, 81; threonine, 40; serine, 44; glutamic acid, 129; proline, 81; glycine, 113; alanine, 71; cystine, 13; valine, 39; methionine, 17; isoleucine, 28; leucine, 69; tyrosine, 25; phenylalanine, 36; lysine, 64; histidine, 25; arginine, 70; tryptophan, 8. The hydroxyproline, proline and glycine contents were much higher than in bovine muscle because about one-third of the total protein of the calves was collagen, a protein particularly rich in these amino acids. The collagen content of the individual body components varied considerably as did their amino acid contents. There were also some marked differences in the contents of some of the major constituents and minerals in the individual components. In particular the internal organs and blood (component (6)) contained significantly lower concentrations of crude protein, ash, Ca, Mg and P but significantly higher concentrations of Cu and Fe.

No correlation was found between the seed yield per plant of oil-seed rape, the percentage of podless stalks and the percentage of pods infested with seed weevil larvae. The weight per seed and the percentage of podless stalks of winter and spring rape plants were similar.

In winter crops the mean number of seeds per plant, weight of seeds per plant, and number of pods per plant were greater near the crop centre than near the crop edge. Plants with relatively few seeds tend to compensate by having heavier ones.

Pods infested with seed weevil had fewer and lighter seeds than pods not infested, but the overall decrease in weight of seed per pod was small. The proportion of pods infested with seed weevil in winter rape was twice that in spring rape plants, but was not great. In lightly infested fields the weevils were concentrated at the edges, but the opposite occurred as infestation increased.

Infestation of pods of winter rape by seed weevil increased with the number of years rape had been grown on the farm. There was no correlation between insecticide application and yield, but the number of insecticide applications to spring rape crops was positively correlated with the number of years for which the farmer had grown rape.

Two group-feeding and one individual-feeding experiments were made for 112 and 182 days, respectively, with 76 cross-bred and eight Zebu bulls. Simmental, Friesian and Jersey sire breeds were mated to three Ethiopian Zebu breeds, namely Boran, Horro and Barca, while Zebu bulls were included for comparison purposes in Expt 3. The trials were conducted in confinement at Holetta Research Station, located at 2400 m elevation and having a mean maximum temperature range of 18·7–24 °C. In the group-feeding trials (Expts 1 and 2) a common diet was fed, consisting of native hay (30%) molasses (20%) and a concentrate supplement. In the third experiment, two diets containing 30 and 50% native hay were supplemented by concentrate and fed individually to eight Simmental and eight Friesian cross bulls, while eight Zebus served as a control.

The average daily gains, feed intake and conversion did not differ markedly between Simmental and Friesian crosses, but lower values were generally found for Jersey crosses. Cross-breds outgained Zebus, consumed more feed and converted it more efficiently to live-weight gain. Performance differences were noted between the Zebu breeds as well as some evidence of sire × dam breed interactions. Significantly higher gains were achieved with the low than with the high roughage diet.

Factors affecting the nylon-bag technique, for examination of digestion in the rumen of extrusa and hay samples of low nutritional value, were studied. Effects of: the method of placement of bags in the rumen; saliva in extrusa; drying and milling techniques; a second-stage digestion with acid-pepsin solution; sample size; and losses of particulate matter through bag cloth were studied. Digestion of dry matter (d.m.) and cell walls after 12, 24, 48, 72 and 168 h in the rumen were used to indicate treatment effects.

Attaching bags with nylon cord to a weight was a better method than enclosing them in perforated jars in the rumen which restricted digestion. Drying technique had little effect on digestion, although frozen extrusa was digested more than oven-dried feed, especially in samples of Heteropogon contortus. Chewing of forage was sufficient to obtain maximum rates of digestion. Milling extrusa through 1 or 2 mm screens did not increase digestion. An extra period of digestion in acid-pepsin solution increased digestion of feed samples more than that of extrusa, but the effects were small. It reduced between-bag variation slightly, but did not alter the significance of differences between treatments. The effect of sample size on digestion was small. Sample weight (3, 6 and 9 g) was kept proportional (42 mg/cm2) to bag cloth area.

Digestion of d.m. after 24 h reflected digestion of cell walls. Digestion of cell walls was faster in grasses than in legumes. The higher digestibility of legumes was due to solubilization within 24 h of the greater amounts of cell contents found in legumes. Cell contents were only partially solubilized, and up to 10 g per 100 g original d.m. were not removed. Losses of particulate matter averaged 4·6% (range 0·5–10·6%). Losses were high when samples were finely milled (1 mm screen) but varied between species. Pore aperture of cloth was 25 μm. Methods for determining loss and correction of digestion data for such losses are given.

When coffee trees have a good supply of nitrogen they are less affected by drought. Explanation and evidence are presented. Trees treated with extra nitrogen contained more adenosine triphosphate, aqueous protein and ‘bound water’.

Such N-rich trees exhibited lower transpiration rates than trees relatively poor in N when water supply was limiting. They had lower stomatal density and water saturation deficit values. Leaves maintained higher chlorophyll and turgidity. The conclusion is that nitrogen increases the drought-resisting capacity of coffee trees. This aspect was clearly reflected in yield, as nitrogen-rich trees produced more coffee beans.

A field experiment was made to determine water uptake patterns of soya beans and water use and to compare relative effectiveness of roots at various depths in the profile.

Depth of water extraction by the root systems increased with rooting depth. Water uptake rates decreased with soil water content at all soil depths and the soil water content at which roots extracted almost no water increased with depth. The maximum rate of uptake of the deep roots was greater, per unit of length, than shallow roots.

Two fattening experiments are reported with 60 cross-bred bulls. In the first experiment three pen groups (9–16 months old) of eight Simmental, eight Friesian and eight Jersey crosses, from Boran and Barca dams, were fed for 98 days on a common diet consisting of maize cobs, molasses and concentrate. There were no significant differences among sire or dam breeds, with the Barca cross bulls performing non-significantly better than the Boran crosses. Simmentals and Friesians consumed about the same amount of feed and the latter were the most efficient feed converters. In the second experiment, 36 bulls ranging from 11 to 18 months of age were fed for 51 days diets consisting of either 30 or 50% maize stalks and concentrate; maize stalks were replaced by maize/sorghum silage for the next 61 days. There were no significant differences in rate of gain between sire breeds. Bulls from Boran dams gained faster (P < 0·01) than those from Horro dams while a higher (P < 0·05) daily gain was recorded for the diet with the lower than with the higher percentage of maize stalks.

In a previous experiment we investigated the effects of a restricted intake of dietary energy, protein or both on carcass anatomy in pigs (Carden & Goenaga, 1977). Contrary to results of Elsley, McDonald & Fowler (1964) and of Richmond & Berg (1971) we found several changes in muscle distribution, which gave rise to differences in the proportion of the commercially valuable muscles in the carcasses. The treatments had no effect on an important trait, the muscle: bone ratio.

Thirty-nine adult ewes of identical body size and age were randomly taken from the Chokla breed. They were divided into four groups which were allowed water once in 24, 48, 72 and 96 h. Seven ewes from each of the first, third and fourth groups were mated for the first time in the spring and for a second time in winter, so that they lambed in the monsoon and summer season respectively. All the ewes were maintained on uncultivated pasture. Watering once in 72 and 96 h caused body weight loss up to 26%, compared with those watered daily. The ewes which failed to maintain pregnancy lost more than 30% of their body weights due to watering only once in 96 h and there were about 43 and 100% lambing in the first and second breeding cycle of the same ewes. The remaining groups displayed 100% lambing. The water-intake increased significantly in the third month of pregnancy in the group allowed water daily and water consumption was found to be about 13% of body weight, whereas the values for those watered once in 72 and 96 h were 9 and 8% respectively. The water-deprived animals were able to drink up to 32 % of their body weights within 2–3 min. It is concluded that breeding ewes could be watered once in 72 h without any loss of lambing during summer.

The phenotypic, genotypic and environmental correlation coefficients were calculated for 13 morphological and tuber quality characters, 17 of 78 possible combinations were found to be significant. Tuber yield was positively associated with average tuber weight and with total tuber dry matter per plant. Average tuber weight was negatively associated with number of tubers per plant and with most of the quality characters. The indices for selection for tuber yield were computed using the yield components and yield only. It was observed that the selections based on tuber yield itself are likely to be superior to those based on yield components. However, an index involving the yield components and the yield was found to be most efficient.

Among the tuber quality characters, percentage tuber dry matter showed significant positive association with the percentage alcohol-insoluble solids (AIS) and with the percentage of starch in fresh tubers, and a negative association with the percentage of protein in tuber dry matter. The associations between percentage of starch in fresh tubers and the percentage of starch in tuber dry matter, between percentage of starch in AIS and the percentage of starch in tuber dry matter and between percentage of protein in fresh tubers and the percentage of protein in tuber dry matter were also found to be significant and positive.

To increase tuber yield it is necessary to break the negative linkage between its two components. High total tuber dry matter per plant can be brought about by selecting for high tuber yield. For the improvement of tuber quality together with tuber yield, the selection for yield based on a large number of tubers is likely to be useful.

The cattle of the Sudan are broadly classified into two main types, i.e. North Sudan Zebu cattle and Nilotic cattle. Of the former typo Western Sudan Baggara cattle are numerically important amounting in number to about six million head (Food and Agriculture Organization, 1972). Western Sudan Baggara cattle provide the bulk of beef consumed in northern Sudan and contribute considerably to the country's export trade in live cattle. The study herein reported was undertaken as a continuing research project directed at ascertaining carcass composition of the indigenous cattle in support of improved feeding and marketing procedures necessary as a base for developing the meat animal industry.

In experiments comparing the effects of different crop rotations it sometimes happens that blocks of reasonably small size can only be achieved by not letting all sequences of each rotation occur in each block. If one of the rotations carries the test crop more than once such a restriction usually leads to the confounding of some phase contrasts. Stevens (1956) and Patterson (1964) provided two classes of phase-confounded designs. The two designs, however, lack the desirable property that if, in a particular block, some of the rotations carry the test crop in a given year, other rotations also do. Furthermore, the designs do not involve equal block sizes in the sense that, in any year, in any block, the number of plots carrying the test crop is the same.

The effects of heat treatment, as measured by undenatured non-casein nitrogen (NCN gN/100 g total N), and of protein: energy ratio on the digestibility coefficients and utilization of milk substitutes by lambs were investigated.

Twenty-four Finnish Landrace × Dorset Horn lambs (12 males and 12 females) were given milk substitute diets in which approximately 20 or 30% of the gross energy was supplied by protein (PE20 and PE30). NCN levels were approximately 7, 12, 18 and 5, 11, 16 for diets PE20 and PE30 respectively.

All lambs were offered a daily allowance of milk substitutes containing 7·95 MJ of gross energy from 3 to 25 days of age, when they were slaughtered and the chemical composition of the empty body was measured. Gains in the chemical components were measured using the comparative slaughter technique.

For each unit increase in NCN value there was an increase in the apparent digestibility coefficients of dry matter (D.M.), crude protein (CP) and ash of 0·13, 0·13 and 0·93 percentage units, respectively. The apparent digestibility coefficients of all the dietary components, except lactose increased by 0·24 (d.m.), 0·24 (CP), 0·63 (fat), 0·75 (ash) and 0·32 (energy) percentage units and the metabolizability by 0·24 units for each 1% increase in PE.

Live-weight and empty body-weight gains increased with increasing PE and NCN. Lambs receiving diets PE20 had a daily live-weight gain 42 g less than those on diets PE30; increasing NCN from 5 to 18 gN/100 g total nitrogen, increased live-weight gain by 33 g/day.

Increasing PE and NCN increased water gain and nitrogen retention; increasing PE also increased ash retention and decreased fat gain.

Lambs on diets PE20 contained more fat and less protein, at the same empty body weight, than those receiving diets PE30.

Efficiencies of conversion of dry matter and energy to live-weight gain, and energy and N utilization all increased with increasing NCN, but increasing PE did not affect energy utilization and decreased N utilization.

Female lambs had lower growth rates than males (—14·5 g/day) and had a higher total fat gain (128 g).

A field experiment was made in the wheat growing season (November–April) of 1973–4 at the Indian Agricultural Research Institute, New Delhi, to compare pure and systematic mixed stands of three wheat genotypes differing in plant height. The systematic mixed stands were made to give prismatic and columnar canopy patterns. Grain yield of wheat was significantly greater in the mixed stands than the mean yield in the pure stands; the two mixed stands did not differ significantly. The grain yield in the mixed stands was almost the same or slightly more than that of the largest yielding genotype in its pure stand. When grown in the mixed stand the tall genotype yielded more than in a pure stand but the dwarf genotype yielded less.

It is generally assumed that poorly filled, or shrivelled wheat grain gives poor flour yields on milling, due to low endosperm content. Quality standards therefore often impose minimum limits of specific weight and grain size with the intention of excluding shrivelled samples. Although milling and baking quality are partly genetically determined, certain of their components are strongly influenced by environment. Flour protein, loaf score and alpha-amylase activity may be improved by nitrogen fertilizer (Pushman & Bingham, 1976), although the reaction of other characters is sometimes less favourable. Reduced flour yields and deterioration of flour colour have been reported at high rates of nitrogen fertilizer (Fuller & Stewart, 1968), and grains frequently become smaller and more shrivelled as application rate is increased (Bayles, 1977 c).

Yellowing of wool as a function of physiological stress caused by nutritional deficiency in the feed of sheep (Das, 1965) though not confirmed by subsequent studies (Singh et al. 1977) evoked interest in the role of physiological stress in causing canary staining of wool. Restricted water intake as is generally the case with sheep in arid or even semiarid regions during summer, imposes considerable physiological stress. Furthermore, canary coloration is thought to be a sequel to an adaptive mechanism to hot and humid conditions in Indian sheep which have a greater reliance on cutaneous evaporation for dissipating body heat (Acharaya & Singh, 1976). It was, therefore, decided to study the influence, if any, of restricting access to water on the canary coloration of wool (non-scourable yellow coloration of the autumn clip) in the stain-susceptible Chokla sheep