Teff (Eragrostis tef) was cut at various stages of growth and divided into leaf, stem (including leaf sheath) and inflorescence. Cell walls were isolated from the leaf and stem fractions and their composition determined. Acetyl groups and individual sugars were determined by gas-liquid chromatography.

Recoveries of cell walls from the same fresh weight of leaves or stems were similar at each stage of growth, but increased with maturity.

Throughout the growing season the leaf cell walls differed in composition from those of the stem. At the start of growth the leaves had a lower content of xylose and acetyl groups but were otherwise similar to the stems. However, with increasing maturity and the production of a flowering stem the stem cell wall composition changed much more than that of the leaf cell walls, with a marked decrease in the content of arabinose and an increase in the content of lignin and acetyl. Over the same period the leaf cell walls showed a smaller increase in acetyl content and decrease in arabinose and uronic acid, but were otherwise unchanged.

Digestion of the cell walls with a fungal cellulase preparation showed that although the two cell wall types were equally degradable while the grass was in the vegetative state, the digestibility of the stem cell walls decreased well below that of the leaves with the onset of maturity and the production of a flowering stem. This was confirmed by in vivo incubations of the cell walls in nylon bags.

A survey of sheep production was undertaken in rangeland areas of western Afghanistan to provide basic information of ewe body-weight changes throughout the year and on production variables, including mortality and lambing performance. Ewes lost up to 31% of body weight between December and March and mortality over the same period was 7%. On the basis of the results of this survey, an experiment was made to test the effect on lambing performance of pre-lambing supplementation of range-based ewes.

Supplementation reduced weight losses in ewes, but the feeding treatments did not produce significant results in terms of lamb birth weights or survival to 10 days. However, there were indications that selective feeding of weak ewes can produce economic benefits, given that the costs of supervising such animals are minimal and the price of grain supplements is low relative to the price of meat.

A selection of the hemicellulose-utilizing rumen bacteria isolated by Henning (1979) were partially characterized. These and a number of other cellulolytic organisms were incubated in vitro with teff (Eragrostis tef) cell walls, and the extent of solubilization and utilization by the bacteria of individual cell wall sugars was determined. Results were compared with the action of the bacteria on isolated xylan and cellulose.

The cellulolytic rumen bacteria solubilized more of both cellulosic and hemicellulosic sugars in the cell wall than the non-cellulolytic organisms. Bacteria which were unable to solubilize isolated cellulose could also degrade very little of the cell wall cellulose, and this appeared to limit the amount of cell wall hemicellulose which could be attacked.

There was no direct relationship between the extent of degradation of isolated xylan and solubilization of cell wall hemicellulose, but those xylanolytic organisms which produced freely diffusible enzymes (as evidenced by production of clearings in 3 % xylan-agar) were more effective in attacking the cell wall than those which did not.

Examination of thin sections in the electron microscope showed no relationship between attachment of bacteria to the cell walls and ability to degrade them.

In Expt 1, lactating dairy cows grazing kikuyu grass (Pennisetum clandestinum) were given no supplement (C), supplements of rolled barley grain at 4 (4R) and 6 (6R) kg/day and supplements of NaOH-treated whole barley grain at 4 (4A) and 6 (6A) kg/day. Daily production of milk (kg/day), fat and protein (g/day) and live-weight changes (g/day) respectively were C 7·82, 303, 276, 450; 4R 9·26, 338, 315, 865; 4A 10·23, 366, 349, 529; 6R 10·09, 352, 343, 672; 6A 10·61, 363, 348, 361.

Milk production was significantly higher (P < 0·05) and live-weight gain significantly lower (P < 0·05) on NaOH-treated grain than on rolled grain.

In Expt 2, yearling steers in pens were fed pasture hay ad libitum with no supplement (C) and 3 kg/day of barley grain which was either rolled (3R) or NaOH-treated whole grain (3A). Mean intakes of hay (g/day) and DOMD in vivo (%) respectively were C 7684, 60; 3R 5224, 65; 3A 6209, 60.

Hay intake was significantly higher (P < 0·05) on NaOH-treated grain than on rolled grain.

Fractional disappearance rates of rolled and NaOH-treated grain from nylon bags suspended in the rumen were, respectively, 0·15 and 0–07/h for the period 0–4 h, and 0·07 and 0·02/h for the period 4–12 h incubation. In Expt 2, rumen pH was higher and the digestion rate of hay in nylon bags in vivo was higher on C than on 3R and 3A. Volatile fatty acid (VFA) concentrations in the rumen did not differ significantly between diets.

It was concluded that greater milk production and hay intakes when cattle were fed NaOH-treated whole barley than when they were fed rolled barley were attributable to the slower rate of digestion of the former. The NaOH treatment (30 g NaOH/kg grain) was probably too low and further study is necessary to determine optimum levels of treatment, which are likely to vary with the ratio of grain: forage in the diet.

DNA and protein concentrations were measured in selected muscles from foetal and neonatal pigs; the protein: DNA ratios of hind-limb muscles were similar to those of the forelimb from 83 days gestation to 27 days after birth. The ratios increased during the perinatal period, providing evidence that maturation of muscle began in the last few days of pregnancy. RNA concentration, cathepsin D activity and tritiated thymidine incorporation were measured in muscles from the neonatal animals and the results indicated a surge of biosynthetic activity in the first days of life. Values obtained from the hind- and forelimb muscles were similar throughout the period of study with RNA: DNA ratio, cathepsin D activity and thymidine incorporation reaching maximum values at 4 days of age. A considerable proportion of thymidine incorporation was attributed to the mitotic activity of satellite cells.

The aims of this work were to determine the feasibility of using the incorporation of radio-labelled thymidine into fat cell DNA in vivo as an index of cell division in the adipose tissue of young pigs, and to distinguish between the processes of new cell synthesis and the ‘filling’ of existing ‘empty’ cells.

Five Large White pigs were given tritiated thymidine as follows: two animals were injected at 2 days of age, two at 9 days of age and one at 40 days of age. The animals were killed at different times after the injection and adipose tissue was removed from various sites. The tissue was separated, using collagenase, into ‘fat cell’ and ‘stromal cell’ fractions. The specific (radio)activity of DNA isolated from each fraction was measured.

Fat cell synthesis occurred rapidly in pigs aged between 2 and 40 days of age. It appeared that by 40 days of age the rate of synthesis declined in backfat such that the filling of pre-existing empty fat cells became a more important contributor to the increased mass of adipose tissue than the filling of newly synthesized cells.

Data from 266 pregnancies of 144 Finn x German Mutton Merino and Finn x Awassi ewes were used to determine the effects of season of mating, dam and sire breeds, litter size and sex of the offspring, and age of the ewe on the duration of gestation.

June, September–October and January matings resulted in significantly different durations of gestation of 143·3, 145·3 and 146·1 days, respectively.

Suffolk rams’ matings resulted in a significantly shorter gestation than matings with German Mutton Merino, Schwarzkopf or cross-bred rams.

A highly significant linear regression (b = –0·80) of the duration of gestation on the number of lambs was found.

Male lambs were carried longer than female lambs.

The intraclass correlation between the gestation periods for lambs which were maternal half-sibs was highly significant.

The effects of N, P and K fertilizers on the yield and N, P and K contents of grass cut for conservation, measured during 1958–63, were again measured during 1964–7. Grass given 38 kg N/ha per cut needed 31 kg K/ha per cut for full yield, grass given 75 or 113 kg N/ha per cut needed twice as much K. With sufficient K, at least 75 kg N/ha per cut was justified. The grass responded little to P.

Percentage N in the grass, though greatly increased by N fertilizer, was little altered by K fertilizer. Percentage K, whilst greatly increased by K fertilizer, was decreased by N unless 62 kg K/ha per cut also was given. Percentage P in the grass was little increased by P fertilizer.

Exchangeable K in the surface soil (0–20 cm) was maintained with time where the grass was given either 38 kg N plus 31 kg K or 75 kg N plus 62 kg K/ha per cut, corresponding to an N:K ratio of 1:0·82. Percentage K in the grass decreased with time throughout. Whereas a N:K ratio of 1:1·66 best maintained % K in grass during 1958–63 it was no better than an N:K ratio of 1:0·82 during 1964–7.

Although exchangeable Mg in the surface soil decreased markedly between 1958 and 1967 (Mg fertilizer was not applied), % Mg in the grass did not. Mg in the grass was increased by N, but decreased by K fertilizer, and exceeded 0·2% (in dry matter) only in 1967 and then only where 75 or 113 kg N/ha per cut was applied.

The performance of Suffolk cross-bred ewe lambs produced either by Suffolk crossbred ewes, 70–90% Suffolk (HS), or by Ossimi ewes, 35–45% Suffolk (LS), was investigated. Forty-three ewe lambs from both groups were available, and were given two different levels of feeding.

The LS ewe lambs showed, insignificantly, better growth performance than the HS group, and breed group differences increased with age. They also reached puberty earlier (305·4 v. 334·6 days for the HS ewe lambs). Using the HS breeding rams rather than the imported Suffolk ones, for improving lamb production from the local sheep flocks, is recommended.

The LS ewe lambs started their first breeding season 18 days earlier, and ended 34 days later, than the HS ewe lambs. Both cross-bred groups showed clear anoestrous periods of 225·4 and 202·2 days, respectively. The onset of their second breeding season was similar, on average 29 August. These figures are close to those of the purebred Suffolk ewes, and far away from the nonseasonal local parents.

An intercropping experiment is described in which three plant population densities of an early sorghum (82 days) were factorially combined with three plant population densities of a later-maturing pigeonpea (173 days) in a standard 2 sorghum:1 pigeonpea row arrangement. Sorghum growth was not affected by the presence of pigeonpea, and the farmers' primary objective of maintaining a ‘full’ sorghum yield was achieved if the density of the intercropped sorghum was equivalent to the sole crop optimum.

The spatial distribution of roots after 30 and 60 days of growth did not appear to be altered by intercropping, and roots of the two crops were found to intermingle freely.

The use of growth resources is examined in an intercropping combination of early sorghum (82 days) and later-maturing pigeonpea (173 days) in a row arrangement of 2 sorghum: 1 pigeonpea.

Prior to sorghum harvest, light interception by the intercrop combination was almost as high as sole sorghum. After sorghum harvest, light interception by the remaining pigeonpea was very poor and it is suggested that pigeonpea yield could be increased with higher plant population density and better plant distribution. Soil water measurements indicated that this would increase the amount of water being transpired through the crop but would not increase the total evapotranspiration demand. Higher nutrient concentrations in the intercrop pigeonpea compared with sole pigeonpea during this post-sorghum period suggested that yield of intercrop pigeonpea was not limited by nutrient stress, though the total uptake of nutrients by both crops was much greater from intercropping than sole cropping.

An experiment at Rothamsted during 1958–67 measured effects on yield, on K uptake and on soil K of applying all combinations of 38, 75 and 113 kg N and 0, 31 and 62 kg K/ha per cut to grass leys, which were cut and removed. Soil K was depleted most where most N and least K were given. Annual applications of 0, 33 and 66 kg P/ha were also tested; soil P was not depleted. The grass was then ploughed.

In 1968, residual effects were measured by spring wheat. In 1969 and in 1970 104 kg/ha of fresh K was applied on half of each plot; potatoes (1969) and spring wheat (1970) valued residual and fresh effects of K.

In 1971 potatoes tested 0, 104 and 208 kg/ha of fresh K, cumulatively with the three amounts given to the grass and also extra K (104 kg/ha) on half-plots, cumulatively with that given in 1969 and 1970. In 1972 winter wheat, and in 1974 and 1975 spring barley, measured residues of all treatments previously applied (the site was fallowed in 1973).

Finally, in 1976, potatoes tested 0, 156 and 312 kg/ha of fresh K on whole plots, cumulatively with the previous dressings of K, and also 156 kg/ha of extra K on half-plots, again cumulatively. All these test crops were given basal N.

Yields and K contents of wheat at ear emergence and yields of wheat grain were largest after grass given 38 kg N and 62 kg K/ha per cut, because here soil K depletion was least. Wheat grain yields benefited consistently from fresh K. K content of the wheat at ear emergence was a good indicator of the need for K, but K content of grain was not, because it was unaltered by K fertilizer. Barley was a poor test crop for K, because yields of grain were little affected by previous treatments.

Percentage K in potato leaves (in July in 1969 and 1971, in August in 1976) and yield of tubers were well correlated. Largest yields in 1969, 1971 and 1976 came where the leaves contained 3·43, 3·76 and 2·82% K, respectively, i.e. from soil containing most exchangeable K, plus most fresh K. There was no indication that maximum yields had been obtained, so the largest amounts (kg/ha) of fresh K tested (104 in 1969, 312 in 1971 and 468 in 1976) were insufficient to counteract depletion of soil K by the grass. Because the grass did not deplete soil P, the test crops benefited only little from either residual or fresh P.

A study was carried out during three successive years from 1970 to 1972 on different wool types. Breed groups involved were Merino (M), coarse-wool Barki sheep and five of their crosses. Traits studied were greasy-fleece weight, clean-fleece weight, kemp score and means of staple length and fibre diameter in the whole fleece.

The heaviest greasy fleeces were produced by ¾ followed by ⅝ M. Total average greasy fleece weight of the crosses was 3·43 kg. There was a general trend of increase in greasy fleece weight with increasing Merino proportion.

The total average percentage clean yield of the crosses was 42·2, and ½ M and ¾ M produced the heaviest clean fleeces. The total average clean fleece weight of the crosses was 1·44 kg. Skirting the fleeces caused a reduction in the within-fleece variability of staple length and diameter. Percentages reduction for staple length were 10·3, 9·6 and 14·6 and those for fibre diameter were 2·4, 5·0 and 9·5 in Barki, crosses and Merino respectively.

Barki had the coarsest diameter and the whole fleece of ¾ M showed the finest mean diameter of the crosses. The within-staple variability in distribution of fibre diameter was high in Barki and throughout the crosses. The average percentage medullated fibres was highest in Barki and decreased throughout the series of crosses. The ¼ M had the highest frequency medullated fibres of the crosses.

The longest mean staple in the crosses was produced by ¼ M. The within-fleece variability in staple length was generally low. In the crosses, the variability assumed slightly higher values than those of the parental breeds.

Kemp production was mainly contributed from the dorsal line, particularly from the back and hip.

As regards some wool and mutton characteristics, ⅝ M might be considered the most suitable cross-bred type.

With increasing Merino contribution in the crosses, the mean fibre diameter showed a decreasing trend, but a high within-staple variability was maintained throughout the crosses. Inter se mating, in most of the crosses, produced animals that showed relatively more uniformity between fleeces than either both or one of the crosses. Inter se mating of the different cross-bred types with selection of the desired uniformity in length and diameter would be recommended.

Ninety triple test cross (TTC) families and 32 varieties of spring wheat (used as parents in TTC programme) were raised in three randomized blocks in 1977–8 and 1978–9 to detect additive, dominance and epistatic components of genetic variation and genotype x environment interaction at both micro- and macro-environmental levels for five quantitative traits: final plant height, spike length, number of spikelets per spike, 100-kernel weight and grain yield per plant. Epistasis was an important element for yield per plant in both years. But, absence of significant epistasis was observed for two component traits of yield, namely, spike length and number of spikelets per spike, in these 2 years. Dominance was directional in all cases. Additive gene effects were most sensitive to micro- as well as to macro-environmental differences.

The effect of three different growth patterns from 15 to 40 kg live weight on the feed utilization of lambs was studied. The treatments were: high (H) ad-libitum feed intake, low (L) restricted feed intake and high-maintenance-high (HMH) ad-libitum feed intake from 15 to 25 kg followed by a 50-day period during which live weight was maintained constant, which in turn was followed by ad-libitum feeding. Animals were individually penned and fed a pelleted lucerne chaff-cereal grain mixture. Intakes of pellets were converted to digestible organic matter (DOM) using the results of in-vitro digestion studies. Two animals were killed at the start of the experiment (15 kg) and the remaining 27 animals (nine in each treatment) were killed at common live weights of 25, 30, 35 and 40 kg.

A marked reduction was observed during weight stasis at 25 kg in the amount of DOM required daily by the HMH animals to maintain live weight. Despite marked compensatory growth by the HMH animals which were rehabilitated after the period of weight stasis, DOM intakes were similar in both these HMH animals and a corresponding number of H animals over identical live-weight ranges.

Differences between treatments were found in DOM intake per unit live-weight gain (H < HMH < L), empty body-weight gain (H = HMH < L) and carcass weight gain (H < HMH = L) from 15 kg until slaughter. DOM intake was utilized more efficiently for gains of all these components by HMH animals during compensatory growth compared with H animals over the same live-weight ranges.

DOM intakes were related to energy gains in the carcass both for all animals in each treatment from 15 kg until slaughter, and for the H and HMH animals which were killed at 30, 35 and 40 kg from 25 kg. Comparisons of these data showed treatment differences in the efficiency of DOM conversion to carcass energy (H > HMH > L) and that DOM was utilized no more efficiently by HMH animals during compensatory growth than by H animals over identical live-weight ranges.

It is concluded that the increased efficiency of utilization of DOM for carcass gain during compensatory growth was due to changes in carcass composition during the period of weight stasis.

The effects of temperature, light intensity and nitrogen supply on the amount and fatty acid composition of the seed oil in Lupinus albus has been investigated. The percentage seed oil was reduced and its degree of saturation increased at higher temperatures. High temperatures during the dark period caused a reduction in percentage oil only when combined with day temperature of 20 °C, indicating a highly specific interaction between day and night temperatures. Shading reduced oil content, an effect which may determine response to population density and the optimal phenotype for high-oil cultivars.

Aqueous glutaraldehyde, in the presence of wetting agents Tween-20 or Haemosol, reacted with fresh cut lucerne (Medicago sativa L.), complete reaction being obtained with about 7·2 g (72 mmol)/kg herbage, or 18g/100g crude protein. Reaction with 25% w/v aqueous glutaraldehyde sprayed on to fresh lucerne was rapid, and at the rate of 66 mmol/kg lucerne, all aldehyde had reacted in 3 h and about 60% of the soluble leaf protein became insoluble. Formaldehyde at twice the molar concentration of glutaraldehyde was absorbed rapidly, but a longer time, up to 24 h, was required for the protein to become insoluble. Treatments with 22, 44 and 66 mmol glutaraldehyde/kg lucerne, and 44, 88 and 132 mmol formaldehyde/kg showed that reaction with leaf protein was approximately proportional to the amount of aldehyde. A major effect on the leaf cells was the fixation of chloroplasts, and intact fixed chloroplasts were isolated from treated lucerne with high protein: chlorophyll ratios of 5·8:1 to 9·5:1.

Two varieties of lucerne, Kabul and Europe, pot-grown in a controlled environment cabinet, reacted rapidly when sprayed with glutaraldehyde and in 3 h soluble leaf protein was reduced from 30 to 16–17% of the total N. The plants rapidly lost water and the dry matter of the leaves rose to 42% for Kabul and 45% for Europe in 24 h. Stems showed little effect. Field spraying of lucerne with glutaraldehyde similarly fixed soluble leaf protein and caused desiccation of the leaves, rising to 47–50% D. M. in 3 days. The stems were little affected and subsequent regrowth of the plants was not inhibited.

Feeding glutaraldehyde- and formaldehyde-sprayed lucerne to rumen-fistulated cattle showed that release of soluble leaf protein into the rumen fluid was greatly reduced, mean values being 40 and 43% respectively of the values obtained when control lucerne was fed. Mean ammonia concentrations were similarly reduced to 49 and 33% of the control values. Formaldehyde-treated lucerne, even after reaction for several days, frequently showed toxic effects on rumen micro-organisms, particularly protozoa. Glutaraldehyde reacted more rapidly with herbage and no toxic effects were observed. Both glutaraldehyde- and formaldehyde-treated lucerne were highly palatable to cattle.

Two breed comparisons were made: (a) between Galway and Galway x Finnish Landrace (Fingalway) lambs, and (6) between Galway x Fingalway and Galway x (Finn x Texel) lambs, for the melting point and fatty acid composition of subcutaneous tail, subcutaneous 13th rib and perinephric fat. The lambs were slaughtered at market weight from September to January, being finished off on grass except for a small number finished indoors on concentrates and hay.

Slaughter age and carcass weight, both of which had significant effects on some of the measurements, were included as covariates in the breed comparisons. Overall breed effects were small. The melting point of the fat from Fingalway lambs was lower than that of the Galway breed in each location, the difference being significant for subcutaneous rib fat. This was associated with a lower concentration of stearic acid and a higher concentration of oleic acid in each fat depot of the Fingalway breed, the difference being significant for oleic in subcutaneous tail and for stearic in subcutaneous rib fat. No significant breed differences or trends were observed for the other fatty acids measured. Results for a small number of pure Finn lambs supported the Finn ancestry influence indicated by comparison (a). In the second breed comparison, no significant breed differences were observed, the values being close to those obtained for the pure Galway lambs.

Three husbandry systems were used to promote differential live-weight gains in 603 Cyprus Fat-tailed, Chios and Awassi ewes. Ewes on the high level of feeding had heavier litters than those on the medium and low levels. Litter size was not affected by level of feeding during pregnancy. Milk production was highest (P < 0·01) for ewes on the high level. The milk production of Chios and Awassi ewes was similar on the high and low feeding levels, but Awassi ewes outyielded both other breeds on the medium level. Chios ewes had larger and heavier litters (P < 0·01) than both other breeds. The correlations between live weights during lactation and milk yield were low and negative indicating a tendency for body loss at high yields.

The variation in hardening responses under different temperature regimes for three cultivars of Lolium perenne L. is described. The relative cold hardiness of the cultivars was modified by different temperatures during hardening. A threshold temperature existed above which hardening did not occur, but this temperature varied between cultivars.

Although continuous low temperatures (2 °C) favoured hardening, hardening also occurred under warm day and cool night conditions (15:2 °C) where cultivars showed contrasting hardiness responses in daylengths of 16, 12 and 8 h. Under some of these conditions both leaf growth and hardiness were possible.

The significance of these results is discussed in terms of the development of screening techniques and breeding objectives.