The fatty acid composition of the depot fats of lambs reared for 4–5 months under gnotobiotio conditions have been determined and an estimate made of the endogenous synthesis of stearic acid.

In an uninoculated gnotobiotic lamb no hydrogenation of dietary lipids occurred in the rumen and this was reflected in the virtual absence of trans acids in depot lipids. In this animal the stearic acid content of perirenal depot fat accounted for 16% of the total fatty acids which was similar to the value found in newborn lambs (17%). Inoculation of the rumen of two gnotobiotic lambs with seven species of bacteria resulted in the establishment of partial hydrogenation processes in the rumen. Various trans isomers of octadecenoic acids were produced in these lambs from the dietary fatty acids but no stearic acid was formed.

These findings are compared with the fatty acid composition of depot fats of other herbivorous and omnivorous animals.

Wool production from different flocks of Ossimi, Rahmani and Barki Egyptian local sheep, raised at six different locations in the country was studied. Different genetic parameters for greasy fleece weight of the three breeds were estimated.

Location was of significant effect on annual greasy fleece weight of Rahmani sheep only. With the adjustment for differences in yield percentages, differences in clean wool production from one location to another were slight for the three breeds. Age of ewe was of highly significant effect on annual greasy fleece weight.

Heritability estimates of annual greasy fleece weight of the ewes were found to be generally low in the three breeds (range 0·00–0·34). The estimates differed markedly with age; those of the yearling fleece weight of Rahmani and Barki ewes were the highest, being 0–19 and 0–34, respectively.

Repeatability estimates of annual greasy fleece weight were also low, being 0·11–0·04 and 0·29 for Ossimi, Rahmani and Barki ewes, respectively.

Estimates of genetic correlation between yearling greasy fleece weight of the Ossimi and Rahmani ewes and their weaning and yearling body weights were high and positive. Those between annual greasy fleece weight of the ewes and their reproductive performance traits differed greatly in the two breeds.

Early-weaned lambs were penned indoors for 6 weeks and individually fed to appetite on cold-stored ryegrass (Lolium perenne) or indigenous Agrostis-Festuca herbage of differing maturity. In another experiment similar lambs grazed for 12 weeks on swards of perennial ryegrass or Agrostis-Festuca. Live-weight gain (LWG), herbage organic-matter intake (OMI) and digestibility (OMD) were measured. In the indoor experiment ryegrass was 4–6 percentage units higher in OMD than was Agrostis-Festuca;first harvests were superior to later harvests by the same amount. The intake of ryegrass was 22% greater than that of Agrostis-Festuca. The correlation between OMI/W'73 and herbage cell-wall constituents was —0·80, and that between OMI/W'3 and OMD was 0·78. OMI/W0·73 increased progressively up to about 13 weeks of age.

LWG was higher on ryegrass than on Agrostis-Festuca; and LWG on the early harvests of each herbage type exceeded those on the later harvests. LWG was significantly correlated with the intake of digested organic matter (DOMI) (r = 0·85).

In the grazing experiment, OMD, OMI and LWG were all lower than in the indoor experiment. LWG on ryegrass was again superior to that on Agrostis-Festuca, and the difference was partly explained by the relationship between DOMI and LWG which had been established indoors.

These results suggest that the increase in the growth rates of hill lambs consequent on the improvement of indigenous Agrostis-Festucaswards would be less than that due to the provision of sown pastures of perennial ryegrass.

Seven non-destructive field measurements were made on 1270 pigeon-pea plants varying widely in age, size and plant type, before determining their dry weight. The non-destructive measurements were generally highly correlated with one another, and were all significantly correlated with total, total above-ground and structural dry weights. In one experiment dry weights were best predicted by a multiple regression using stem diameter, length of longest branch and number of branches as predictors. Field height and stem diameter were the best predictors in a second trial. It is suggested that dry weights can be estimated by taking certain measurements at regular intervals, simultaneously sampling a number of plants to determine the best predictive equation. Where it is unnecessary or impracticable to do this, stem diameter appears to be the best single index of dry weight.

Digestibility trials were carried out to study the digestibility of Rhodes grass fed alone and in mixed concentrate diets. Twelve Awassi rams were used to examine the seasonal effect on the digestibility of Rhodes grass harvested at 21-day intervals.

A consistent increase in the content of crude protein up to the 6th harvest was observed, being accompanied by an increase in crude protein digestibility and voluntary feed intake.

In the second experiment Rhodes grass and concentrate mixed diets were examined. Sixteen Awassi rams were allocated to four diets which included 16, 32, 52 and 100% Rhodes grass. Dry-matter digestibility was found significantly different between the all-grass diet and the rest. The digestibility of crude fibre in the whole diet decreased significantly with the increase in concentrate content. The digestibility of crude fibre of Rhodes origin was calculated. It appears that the detrimental effect of concentrate on the digestibility of crude fibre of Rhodes grass origin is limited. This finding is supported by the high C2/C3 ratios in rumen liquor which were maintained up to 68% concentrate in the diet.

This study indicates that Rhodes grass may serve as a highly efficient roughage component in dairy rations.

The total body water (TBW), its distribution and water turnover were measured in native fat-tailed Awassi sheep, a breed well adapted to desert conditions, and in imported German Mutton Merino (GMM) sheep, a breed that evolved in a temperate climate, under semi-arid conditions.

TBW (tritiated water space;TOH space), extracellular fluid volume (SCN-space) and plasma volume (T·1824 space) were measured during the summer while these sheep grazed natural pasture that remained as dried stem-cured hay and in the winter while they grazed lush natural pasture. No differences were found between the breeds in any of the measurements in both seasons. Within both breeds, the percentage TOH and SCN-spaces were larger in the summer whereas the percentage T·1824 space remained the same.

TBW and water turnover were measured in these breeds in eight trials while the sheep grazed native pasture in the autumn, winter and spring, shrubs in the winter and legumes in the summer. Water and shade were freely and easily accessible throughout the grazing period. The TBW was found to be consistently lower in the Awassi, indicating a higher energy reserve. The water turnover in 1/24 h/kg wt.0·82 was found to be higher in the GMM in all trials; the differences ranged between 3 and 28%. However, in only two out of the eight trials were the differences significant. Thus, the water turnoverwas only slightly lower in the Awassi although this breed evolved under Middle Eastern arid and semi-arid regions.

The total body water (TBW) and water turnover of fat-tailed Awassi ewes, a dairy breed well adapted to desert conditions, and of German Mutton Merino (GMM) ewes, a mutton breed that evolved in a temperate climate, were measured during the 3rd, 4th and 5th months of pregnancy and during the 1st month of lactation. Measurements were taken under grazing conditions with unrestricted water in a semi-arid region.

Both breeds of sheep lost weight during this period. The percentage of TBW increased, especially during the 5th month of pregnancy when the GMM increased their TBW by 5·2% and the Awassi by 1·0%. It was concluded that the nutritive intake was not sufficient to supply the increased energy demands and that the ewes were mobilizing body solids, the GMM at a faster rate.

The GMM ewes turned over about 20% more water per kg wt.0·82 during pregnancy and lactation than did the Awassi ewes. There was little difference in water turnover between the control and pregnant sheep within either breed during gestation. During lactation the experimental Awassi increased their water turnover by 29% over the control Awassi and the experimental GMM increased their water turnover by 26% over the control GMM. In both breeds the increase in water turnover during lactation was smaller than that found in other lactating semi-arid ruminants and the increase in water turnover during pregnancy and lactation was smaller than that recommended by the Agricultural Research Council (1965).

Resistance in Rossol and Nematex is separately conditioned by single genes. The genes are incompletely dominant and non-allelic. It was not possible to distinguish between homozygous and heterozygous resistant plants in segregating families.

Yields of sugar and responses to fertilizers were determined in about 400 fertilizer experiments on farms throughout the sugar-beet growing areas of Britain during 14 years from 1957 to 1970. The soil at each experimental site was described and classified and the records of the experiments have been examined to determine which properties of the soil influence sugar yield. The effect of year, rainfall, elevation, region and other factors such as sowing and harvesting date were also investigated.

Year-to-year variation accounted for 20 % of all variation in yield; increasing amounts of rainfall during the growing season appeared to decrease yield. There was a significant long-term trend of increasing sugar yield from the experiments of 0·042 t/ha/year. The experimental yields closely followed national yields each year but were always greater. Delay in sowing and early harvesting depressed yield by 0–02 and 0·01 t sugar/ ha/day respectively. Yields in Scotland (average 5·23 t/ha) were approximately 1·4 t/ha less than in England and Wales, but there were no evident regional differences within England and Wales.

Soil regarded as moderately drained yielded better than either well-drained or imperfectly drained soil, which in turn yielded better than droughty and poorly drained soil. The difference in the adjusted yield between drainage classes was 1·0 t/ha. Surprisingly, topsoil texture had no consistent effect on mean yield (as distinct from response to fertilizer). Subsoil texture, however, had an appreciable effect, the crop on sandy subsoil and chalk or limestone yielding poorly whilst that on silt or peat yielded best. The range of differences in sugar yield due to subsoil texture was almost 2 t/ha.

Yields were also examined in relation to soil profile type. Broad division into major soil groups gave meaningful differences but fine division by soil series was only useful for the 11 series on which at least ten experiments had been made. The crop yielded most sugar on gleyed calcareous soils, peats and humic gleys, and least on rendzinas and brown calcareous soils. Responses to nitrogen and potassium but not to phosphorus were affected by both topsoil and subsoil texture. Nitrogen and potassium both increased yield most on sandy soils and least on fine silts and peats.

The morphology, chemical and physical condition of soil clearly affect sugar yield greatly and further research is needed in experiments planned specifically to measure their influence and provide more precise guidance for selecting the best land for the crop.

Dissection data for 753 steer carcasses from 17 breed-type x feeding system groups were used to examine the prediction of lean content in the side (half carcass) from the lean content of standardized wholesale joints. Different prediction equations were examined and the joints compared both in terms of predictive precision and the stability of their prediction equations between groups.

The relative precision of the joints for predicting weight of lean in the side depended on whether or not the prediction equation included joint weight. With side weight and weight of lean in joint as independent variates, there was little difference between most joints in precision, and the smaller joints, shin and leg (hind shin) appeared to be best because they are convenient and easy to dissect. The addition of joint weight to the equation improved considerably the precision of all the joints except the shin and leg. The coast and top piece gave the most precise predictions with the trivariate equation (residual standard deviations about the common regression line computed ignoring groups, RSD overall, were 1·44 and 1·48 kg respectively) and the fore rib probably offered the best compromise between cost and precision (RSD overall = 1·82 kg).

The stability of prediction equations between groups was influenced in a similar way by the inclusion of joint weight as an independent variate. The joints which gave the most precise predictions tended to have the most stable equations. The average biases between the actual group means and the means predicted using the trivariate equation computed ignoring groups were ± 0·46, ± 0·49 and ± 0·76 kg for the top piece, coast and fore rib respectively.

Skin was examined from a total of 70 lambs obtained at the foetal age of 75, 90, 100, 120 and 135 days. The rate of follicle development was not greatly dissimilar from that previously described in improved breeds. The Shetland showed least difference from improved breeds, and the Mouflon x Soay was most retarded, but the pure Soay foetuses were closer to the Shetlands than to the Mouflon cross-breds.

Three herbicides, Treflan, Basagran and Avadex BW and three pesticides, Metasystox 55, Nicotine and Hostathion stimulated the growth of Fusarium solanif. sp. phaseoli in culture and increased the virulence of this pathogen on Phaseolus vulgaris. The implications of these results to the chemical treatment of this crop are discussed.

In a glasshouse experiment, sulphur was applied to 22 soils as 35S-labelled gypsum. Estimates of available sulphur using different extractants were correlated with yield responses and sulphur uptakes by oats. The largest correlation coefficients were obtained with ‘A’ values and sulphur soluble in 0·5 M-NaHC03, 1% NaCl after heating and ammonium acetate–acetic acid. Critical levels of available sulphur obtained by relating these four methods to yield responses were 24·0, 22·0, 11·0 and 10·5 mgS/kg soil respectively.

Metabolism trials were conducted with sheep to study the effects of conservation of herbage as silage, frozen or artificially dried grass upon the magnesium and calcium availabilities in the conserved products.

When the diet was changed, approximately isomagnesaemically, from hay and barley to each of the conserved products, there was a highly significant (P < 0·001) decrease in the plasma magnesium concentration. However, the plasma magnesium concentrations of the ewes eating the artificially dried grass were significantly lower (P < 0·05) than the corresponding values when they ate the frozen grass or silage. No changes were seen in the plasma calcium concentrations.

The apparent availability of magnesium in the silage was significantly higher (P < 0·05) than that in the frozen and artificially dried grasses. Also, the apparent availability of magnesium and calcium was lower in the dried grass than in the other two products, whilst the retention of both magnesium and calcium was significantly lower (P < 0–05) when the dried grass was eaten as compared with the frozen grass and silage. The percentage urinary loss of magnesium was greatest on the silage and least on the dried-grass diet.

It was concluded that artificially drying grass caused a reduction in magnesium availability.

A small-plot experiment was made to assess the influence on dry-matter output from grass of a wide range of fertilizer nitrogen and defoliation interval treatments. There were five defoliation treatments, 22, 28, 45, 75 and 112-day regrowth intervalsroughout the growing season each at six levels of nitrogen application, ranging by 300 kg increments from 0 to 1500 kg/ha/year.

There was a marked interaction effect between treatments; a positive dry-matter response was maintained to a higher level of applied nitrogen with more frequent defoliation. In 2 years out of 3 maximum dry-matter yield was produced under a 75·day defoliation interval although the mean yield advantage over a 45-day defoliation system was only 11%. Mean yield of digestible dry matter appeared to reach a maximum under a 45·day defoliation interval at 600 kg N/ha but at the lower levels of N the maximum yield was reached at the longest growth interval.

Seasonal response to nitrogen under the 22–day and 28–day defoliation systems measured as the increase in yield resulting from increased N at each cutting date reached its peak in July–August. Application for these short growth periods early and late in the growing season appeared to be a relatively inefficient use of nitrogen.

The less frequently the sward was harvested and the higher the nitrogen application the greater was the reduction in ground cover as estimated by eye at the end of the growing season, this reached an estimated 25% reduction under 112·day defoliation at 300 kg N/ha/year.

In relation to published figures nitrate content of herbage did not reach dangerous levels until nitrogen application reached levels beyond those at which maximum dry·matter yield was achieved.

One hundred and fifty-nine Corriedale x Dorset Horn lambs were slaughtered at 32 kg live weight at ages varying from 98 to 303 days. The youngest lambs were from ewes on a pasture with high herbage availability and had not been weaned; the next youngest were from the same group of ewes but had been weaned at 6 or 12 weeks of age. Older lambs had been weaned at 6, 12 or 29 weeks from ewes on a pasture with low herbage availability. The weaned lambs grazed either a phalaris or a lucerne pasture.

Lambs that grazed lucerne had a greater dressing percentage and a heavier carcass. Over all lambs, ultimate pH of the m. semimenxbranosus ranged from 5·4 to 6·0 and Warner-Bratzler shear values increased twofold from lowest to highest pH. Minimum ambient temperatures during the nights before the slaughter days ranged from 13 to – 1°C; ultimate pH increased by 0·25 units with decreasing temperature over the range, equivalent to an increase in shear value of 26%. Shear values adjusted for pH differences increased from about 3·4 kg/cm2 at 130 days of age to about 7·5 kg/cm2 at 300 days.

Visual attractiveness of 13th rib chops increased with increasing area of the m. longissimus dorsi. Attractiveness was least at intermediate dominant wavelength (redness) of this muscle, but was not related to its reflectance. Optimum fat depth was about 2·4 mm. In general, chops from younger lambs were more attractive than those from older lambs.

Grazing with sheep was compared with cutting, in each case at three frequencies, four, five and six defoliations per year, on a lucerne—cocksfoot ley. The treatments were applied in one year and their effects measured during that year and at cuts in June and August of the following year. One experiment began in 1963 in the second harvest year of a ley and a second began in 1964, on an adjacent site, in the third harvest year of the ley. Cutting four times in the year allowed lucerne to persist satisfactorily in both experiments. In the 1964 experiment cutting five or six times and grazing rather than cutting had no apparent, serious, adverse effect on the lucerne compared with cutting four times. In the 1963 experiment, however, increasing the number of cuts and grazing rather than cutting had a large adverse effect on the lucerne, and in the most extreme treatment, grazing six times, the proportion of lucerne was reduced to 2 % of total herbage yield the following June compared with 66% on the four-cut treatment. The contrasting results in the two experiments seem associated with weather differences, 1964 being a much drier, more sunny growing season than 1963, and perhaps with the differences in age of sward, individual lucerne plants perhaps having bigger roots with more reserves in 1964 than in 1963. During the treatment year increasing frequency of defoliation tended to increase the N content of both species and grazing compared with cutting generally increased the N content of cocksfoot. During the year following the treatment year the N content of the two species was little affected by the experimental treatments. The implications for farm practice are considered.

A simple device for recording seedling emergence force was developed. In this device, the relationship between the bending moment and displacement of the free end of a cantilever beam is used to compute seedling emergence force. The growing seedling is forced to push the free end of the beam upwards and the displacement of the free end is recorded with a pointer on smoked paper tightly wrapped on a revolving clock drum.

Total cell wall, in vitro digested cell wall and fermentation-gas production were determined in the separated tops and stubble of five tropical and two temperate grass species grown under controlled temperatures and humidities. As the day/night temperatures increased from 18/10 to 25/17 °C the total cell wall and in vitro digested cell wall increased. With a further increase to 32/24 °C the total cell wall increased, but not the in vitro digested cell wall. In vitro digested cell-wall values were also calculated from a previously derived relationship between in vitro digested cell wall and total cell wall. The differences between observed and calculated values increased (negatively) with increasing growth temperature suggesting that the in vitro digested cell wall was depressed with increasing growth temperatures, but the extent of this depression was small.

In vitro gas production from the fermentation of plant tops or stubble in buffered rumen fluid for 24 h was significantly affected by growth temperature and humidity, apparently because of changes in chemical composition induced by the treatments. The volume of gas produced between 24 and 48 h fermentation times was appreciably lower from stubble than from plant tops and this was thought to be due to a higher resistance of part of the cell wall of stubble to digestion by rumen bacteria. Gas production in this period was slightly lower in the tops of grasses grown at the lower temperatures, but this could have been an indirect effect from an associated decrease in the total cell wall.

The production of toxic levels of ethanol in the stomachs of neonatal ruminants resulting from fermentation of glucose by resident yeasts occurs only in the absence of fat from the diet. Daily levels of ethanol and numbers of viable yeast were measured on samples of stomach contents for 21-day periods. Milk fat was shown to control the ethanol production in lambs and calves (but not in vitro in culture), the quantitative nature of this control was demonstrated by experiments with cream using lambs. Nine dietary fats in commercial use homogenized in fat-free milk, a commercial catering ‘milk’, and an intravenous lipid feed were all tested in lamb-feeding experiments, compared with whole and separated milk, and an inert oily hydrocarbon, liquid paraffin.