Field and pot experiments were carried out to determine how copper deficiency can be corrected on some soils in north-east Scotland. Spring-sown oats and barley are more susceptible to this deficiency than mixed herbage, while potatoes and swedes have not responded to Cu. The deficiency can be corrected by applying 10–20 lb CuSO4.5H2O per acre to the soil. Both field and pot experiments show that such treatments have large residual effects and under field conditions are effective for at least 8 years. A foliar spray supplying 1 lb CuSO4. 5H2O per acre is usually less effective than a soil dressing.

Using soil undiluted with sand, the increase in grain yield produced by Cu treatment in pots was appreciably greater than in the field. The Cu content of mature oats and barley was practically unaffected by soil dressings but foliar spraying produced a considerable increase.

Significant correlation coefficients have been obtained between soil Cu, extracted by 0·05 M EDTA, and the increase in grain yield produced by Cu applications in both field and pot experiments. In field experiments in north-east Scotland, cereal yields were not restricted by a deficiency if the EDTA-extractable Cu was above 1·1 ppm. With soil contents below 0–75 ppm Cu, the grain yields from spring-sown oats and barley were usually increased considerably; small responses were possible with contents between 0·75 and 1·1 ppm.

The biuretolytic activity of the ruminal flora which developed in the ingesta of Merino sheep in response to feeding biuret with practical rations was demonstrated. The activity was determined by measuring the rate of disappearance of biuret in an in vitro fermentation system. Biuret was determined by a specific, semi-micro, colorimetric method based on the formation of a yellow nickel-biuret complex and adapted for use with ruminal fluid. The activity was evoked only when biuret was included in diets of poor quality teff hay with or without maize meal. With ruminal ingesta from sheep fed teff hay and biuret the activity was low, but when maize meal was given in addition the activity was about three times as high, and sufficient to account for the disappearance of up to 16–4 g daily in Merino sheep with a volume of ruminal ingesta of 61. The course of development of biuretolytic activity is discussed in relation to retention of biuret-nitrogen.

In a randomized block experiment, seventy-two Large White type weaner pigs (thirty-six hogs and thirty-six gilts) were individually and restrictedly fed to 200 lb live weight six diets (as wet mashes). Five of these diets contained high levels (85 % in the starter diets and 90 % in the finisher diets) of either maize, flaked maize, sorghum, wheat or barley. The sixth diet, which acted as the control diet for the experiment, was similar to the barley diet except that 25 % of weatings replaced a similar percentage of barley. A further three groups of six litter-mate hog pigs per group were used to measure the digestibility of these diets.

For the starter diets the maize diet had the highest digestible energy content, for the finisher diets the highest values were for the wheat and sorghum diets which in turn were similar to each other. The digestible energy content of the flaked maize diet was higher than the contents of the barley and control diets but lower than the contents determined for the other three diets.

Three of the pigs fed the sorghum diet developed leg weaknesses and this affected growth rate and food conversion efficiency. The symptoms suggested a pantothenic acid deficiency but the results of assays carried out on all the diets indicated that the condition was not necessarily due to a deficiency of this vitamin. Growth rates in the starter period (up to 115 lb) did not differ significantly between diets but food conversion for the maize and barley diets was significantly superior to that for the wheat and sorghum diets. In the finisher period growth rate and food conversion efficiency for the maize and wheat diets was significantly superior compared with that for the other four diets. Overall, from start to slaughter, the maize diet was significantly superior to the flaked maize, sorghum and control diets in both these parameters of performance. The energetic efficiencies of growth tended to be poorer for those diets with the better food conversion ratios, the best efficiency being for the control diet.

Carcass length differences were not significant but backfat thickness and eye muscle area differences followed closely the pattern found for lean and fat content of the carcass. In this context the highest percentages of lean were found first in the control and, secondly, in the barley treatment carcasses. Some differences were found in the development of anatomical regions and tissues within these regions. In particular, and relative to the five other diets, there were in the control diet carcasses (1) higher percentages formed by the leg and shoulder and (2) a higher percentage of lean in the middle.

Nitro-chalk was applied to S.23 ryegrass swards, at approximately monthly intervals, at two contrasting levels in 1961 and three levels in 1962. Steer calves, 3–6 months old, grazed in rotation round a series of four paddocks on each treatment. Paddocks were trimmed and fertilizer applied after each grazing. The herbage intakes of the calves were determined on three occasions in 1961 and four occasions in 1962. Faecal output was estimated by chromic oxide dilution. In vitro digestibility determinations were carried out on samples of herbage clipped from the swards.

There was a close linear relationship between the digestibility of the herbage and the amount eaten, over the full range of digestibility encountered (68–82%). Regression equations calculated within seasons and fertilizer levels, and within years, did not differ significantly. The regressions of faecal output on herbage digestibility were not significantly different from zero.

The observed relationship between herbage digestibility and herbage intake may reflect (a) the greater sensitivity of young ruminants than adult stock to changes in the digestibility of the diet, and (b) the reduced importance of the chemostatic control of food intake, except at very high levels of digestibility, in young rapidly growing animals.

Studies were made of the proximate and mineral compositions of modern strains of both spring· and winter-sown beans. The majority of the winter beans were of the Throws M.S. variety, of the spring beans Minors. On the dry-matter basis spring beans averaged 31·4% crude.protein, winter beans 26·5%—a highly significant difference. The true protein values showed a parallel trend. Winter beans averaged 9% crude fibre, spring beans 8%, again a highly significant difference. The strains confirmed the usually accepted levels of oil and of the principal mineral components, except that modern beans appear to be richer in phosphorus.

An experiment begun in 1956 and using a five-course rotation of barley, grass-clover ley, potatoes, wheat and kale and a block of permanent grass was continued.

N decreased yields of the rotation ley, slightly increased yields of potatoes (after the ley), but greatly increased yields of wheat, barley and kale and permanent grass. P increased the yields of all arable crops, of kale dramatically, but not of permanent grass. K greatly increased yields of wheat and the rotation ley and even more of potatoes, but it increased yields of barley, kale and permanent grass little.

F.Y.M. increased the yields of all crops; potatoes responded most. Applying fertilizers with the F.Y.M. diminished its effects, but except for wheat and barley grain a combination of the two produced the largest yields.

Mean yields from all combinations of N, P and K were a little smaller between 1961 and 1965 than between 1956 and 1960, and the yields were maintained best by applying F.Y.M. and fertilizers together. Responses to N and to K were similar in both rotations, but responses to P became larger with time.

The teat-length increases observed in wether lambs grazing pure legumes have been compared directly with the oestrogenic activity demonstrated in mice fed samples of these pastures.

In the case of red clover, the mouse assay gives a good indication of the oestrogenic effect to be expected in the wethers. There was no such correlation when samples of clover and lucerne were tested. These were much more active in the wethers than would have been anticipated from the mouse assay, where lucerne and white clover appeared almost entirely lacking in oestrogenic activity.

In an 8-year field experiment, potassium sulphate and to a lesser extent magnesium sulphate increased yields of all crops both when applied alone and together. Although K/Mg interactions did not affect yields they considerably affected the ratio of concentrations of these elements in the dry matter of the crops. Sodium chloride increased yields of kale but not of barley harvested at ear-emergence.

Percentage yield response to potasium followed the order

Potatoes (218%) < clover = barley < sugar beet < kato; < ryegress (17%).

Magnesium increased yields from 3 to 10%, most with potatoes.

Changes in exchangeable magnesium in the soil reflected differences between applied magnesium and crop uptakes. Changes in exchangeable potassium were less than expected, probably because non-exchangeable potassium was released on plots without added potassium and ‘fixed’ in non-exchangeable forms on plots where much fertilizer potassium had been given.

Increase in the incidence of magnesium deficiency symptoms reported recently in South. East England are attributed to the local liming materials containing only small amounts of magnesium and to less F.V.M being applied to crops than previously.

In an experiment on nine Kumaoni bullocks, the effect of supplementing paddy straw rations with calcium carbonate or lime was studied. The digestion coefficients of dry matter, crude protein, ether extract and total carbohydrates and balances of nitrogen and phosphorus were not significantly affected by such supplementation; the calcium balances were significantly improved. It is concluded that supplementation of paddy straw rations with calcium carbonate (which is cheap and easier to handle), or with slaked lime, can be used with advantage in combating the problem of negative calcium balances frequently encountered on paddy straw rations. Incorporation of a small quantity of wheat bran (about 4 oz) helps in meeting the phosphorus requirement of adult animals.

Yields and quality of herbage from a cocksfoot/white clover sward were compared over a 3-year period when cut repeatedly with a reeiprocating-blade mower to either 1 in or 2½ in from ground level or with a cylinder lawnmower to 1 in from ground level. The comparisons were made under two frequencies of cutting, namely five times per season at the ‘grazing’ stage, or three times at the ‘silage’ stage.

Cutting to 1 in from ground level with the reciprocating-blade mower gave a greater total yield of dry matter and crude protein than did cutting to 2½ in with the same mower in the first year, when the average dry-matter yield difference was 10·7 %, but no significant differences were recorded in subsequent years. It is suggested that the difference noted in the first year was due mainly to the harvesting at the first cut in the season of the layer of herbage between 1 and 2½ in from ground level, and not to any differential effects of the treatments on stem and leaf development of the cocksfoot.

Cutting to 1 in from ground level with the lawnmower gave smaller dry-matter yields than did cutting to 1 in with the reciprocating-blade mower at both stages of growth in the first year, but a slightly greater yield at the ‘grazing’ stage in the third year. The type of mower used affected the botanical composition of the sward.

Five non-pregnant ewes and seventeen ewes at various stages of pregnancy were fed on a medium quality hay for several weeks before being slaughtered and frozen. Each ewe was sawn into 5 cm cross-sections.

The sections were photographed. The uterus was extracted from the sections and its volume measured. Volumes of reticulo-rumen contents, intestinal contents and abdominal fat were estimated from the photographs.

Models of the uterus and rumen were constructed and examples of these and of the photographs are shown.

The volume of the uterus increased steadily as pregnancy progressed, but rumen volume was not reciprocally depressed until the last 5 weeks of pregnancy. Volume of digesta was inversely related to volume of incompressible abdominal content (uterus and fat). Abdominal fat was a particularly important factor in the depression of rumen capacity in pregnancy when there was great competition for space in the abdomen.

Samples of a Colombian criollo breed of cattle, the Blanco Orejinegro, and contemporary onequarter Jersey crossbreds were kept on a farm in the Andes. Records were included of all calvings which occurred over an 8-year period, giving totals of 1357 lactations from 514 purebreds and 424 lactations from 137 crossbreds.

Age at first calving was about 41 months for both breed groups. Cattle were milked twice daily by hand without calf at foot. Mean lactation yields were 220 kg (purebreds) and 612 kg (crossbreds). The repeatability and heritability of milk yield are estimated. Statistics are also given for lactation length, daily yield, calving interval and butterfat percentage. The effects on yield of age at first calving and calving year were negligible, but month of calving was important.

It is concluded that the low level of performance was partly due to failure to eject milk without calf at foot, at least in the case of the purebreds, and that this was itself mainly due to genetic causes. The improvement in yield due to crossbreeding was not accompanied by a loss of other desirable traits. The development of the local cattle industry is discussed in the light of these results and the general characteristics of the region.

Between 1964 and 1966 thirty-one field trials were completed in twelve factory areas of the British Sugar Corporation to examine the feasibility of using mechanical thinning in conjvinction with low seed rates (3–6 in spacing) and chemical weed control to minimize the demand for labour in the spring. The results showed that where chemical weed control was effective in machine-thinned crops no hand labour was required for establishment, but there were mean losses in yield of 1·3 tons per acre (7%) compared with similar crops that were hand singled. These losses in yield were unaffected by variations in seed rates. Mechanical harvesters worked more efficiently in low seed rates, especially where monogerm seed was used.

Differences in fatty acid composition and other body components were studied in two inbred lines of mice and crosses between them (reciprocals). The two inbred lines differed significantly (P < 0·05) in percentage moisture and percentage fat in the carcass, but there was no difference between the two kinds of crossbreds. Percentage protein of the carcass did not differ among the lines. Seven fatty acids were identified and considerable variation in the amount of each was found in the mice. About 65 % of the fatty acids identified was composed of palmitic and oleic. The two inbred lines differed significantly (P < 0·05) from each other for four of the seven fatty acids. The crossbred mice also differed for four of the seven fatty acids, but not necessarily the same acids as for the parental lines. Heterosis (crossbreds exceeding the mean of the parents) was observed for several traits. Crossbreds had a larger percentage protein and less fat in their carcasses than the inbreds. Crossbreds exceeded the inbreds for percentage lauric and percentage myristic acids, but had less palmitoleic acid than the inbreds. In general crossbreds had a higher percentage of saturated fatty acids than the inbreds.

Soil samples taken in the autumn after ploughing ryegrass, clover, and ryegrass/clover leys were used to measure the mineral-N (ammonium-N + nitrate-N) in the fresh soil (mineral-Nfresh), the increase in mineral-N on incubating the fresh soils (Δmineral-Nfresh), and the increase in mineral-N on incubating the re-wetted air-dry soils (Δmineral -Nair-dry). Mineral-Nfresh and Δ mineral-Nair-dry were measured on further soil samples taken the following spring. Values of Δmineral-Nair-dry, not only correlated best with grain yields and N uptakes by wheat without fertilizer-N, but also with yield responses and fertilizer-N recovered from fertilizer-N applied to the winter wheat.

Treatment of the ley altered measurements on samples taken in the autumn but not those taken the following spring.

Soil samples taken in the autumn 1960 from under three-year grass leys were used to measure mineral-Nfresh, Δ mineral-Nfresh and Δ mineral-Nair-dry Spring wheat was grown in 1961 followed by spring barley in 1962. Further soil samples were taken in spring 1962 after cultivations were complete and before the barley was sown or fertilizers applied.

A mineral-Nair-dry was the best measurement to use on soils from under grass leys. Values depended on grass species, and were increased by N applied to the ley. Differences had largely disappeared 18 months later. A mineral-Nalr.dry was positively correlated with grain yields of spring wheat grown both with and without fertilizer-N, and with the yield response or the nitrogen recovered from, a dressing of 56 lb N/acre.

With fertilizer-N yields of winter wheat after the mixed leys tended to the same maximum value independently ofmineralizable-N in the soil. After grass leys maximum yields of spring wheat given fertilizer-N increased with increasing mineralizable-N in the soil.

Eighty-nine cattle were treated to induce high superovulation with 3000 i.u. PMSG on day 16 of the cycle and slaughtered shortly after breeding and injection of 2000 i.u. HCG. In the 79 cattle that came in oestrus, the mean number of ovulations was 9.0. The percentage of follicles ovulating and the mean ovulation rate increased markedly as the interval between PMSG and oestrus increased from 2 to 5 days. Seventy-one percent of eggs shed were recovered; 68% of eggs recovered were cleaved. Evidence on cleavage stages attained, and on the location of eggs in the Fallopian tubes and uterus, suggests that a majority of eggs were capable of normal development.

Culture studies were conducted with eggs recovered from cattle following super-ovulation treatment. Transfer of eggs to pseudo-pregnant rabbits led to continued cleavage in 71 of 138 attempts. Culture of eggs in vitro met with limited success in 58 of 189 attempts. The maximum cleavage stage reached in the in vivo studies was 64 cells; in the in vitro work it was 24 cells.

Oestrogenic activity was recorded by teat length extension in wether lambs grazing red clover S. 123 in September and October 1965 and between 21 April and the end of October 1966. The number of lambs born alive to ewes grazing red clover (S. 123) for the 2 weeks prior to mating and for 4 weeks after mating was reduced. Oestrogenic activity was also recorded in wether lambs on lucerne var. Eynsford and on white clover S. 100 from mid-June to mid-October 1966.

Oestrogenic activity was confirmed in red clover, but not in lucerne, by mouse bioassay. Slight oestrogenic activity was shown in one white clover sample only.

Approximately 15 weeks before parturition, forty-eight pregnant Blackface ewes were divided into three similar groups. During the 15–6 weeks prepartum period the ewes were fed to increase the live weights and body condition scores of ewes in each of groups A and B and to decrease those of ewes in group C. At 6 weeks prepartum mean differences of approximately 11 kg live weight and two grades of body condition had been created. Food was rationed to the ewes in all groups per kg live weight based on their weights 6 weeks prepartum, to provide the theoretical requirements of Blackface ewes bearing twin lambs. All groups of ewes made similar live-weight gains in late pregnancy and the mean birth weights of the lambs were also similar. Blood plasma F.F.A. values confirmed that the ewes were similarly nourished in late pregnancy regardless of live weight or body condition. During lactation the ewes were fed 9·2 g D.O.M./kg based on their immediate post-partum live weights, plus an allowance for a predicted level of milk production. Ewes in groups A and C were fed 0·5 and ewes in group B, 0·25 g D.O.M. per g of predicted milk production. The ration was increased after the 1st and 2nd weeks of lactation, then maintained at a constant level for the remainder of lactation. Milk production of the ewes was measured using a lamb suckling technique during a 10-week lactation. The mean daily milk production of ewes in groups A and C were similar and the yield of each of these groups was substantially greater than that of group B ewes. The mean total milk production of ewes suckling twin lambs in groups A, B and C was 127, 108 and 142 kg respectively, and of ewes suckling single lambs 104, 81 and 91 kg respectively. The mean live-weight changes of ewes in groups A and C were similar during lactation. Except for group A ewes suckling single lambs, which maintained their mean live weight, all ewes lost weight in early lactation and consistent gains were not made until late lactation. Greatest live-weight loss occurred in group B ewes and extended further into lactation. Changes in body condition followed a similar course to live weight changes. The mean daily live-weight gain of twin lambs in groups A, B and C was 279, 275 and 284 g respectively, and of single lambs, 318, 300 and 319 g respectively. The evidence indicates that ewes in lean body condition have a higher efficiency of food conversion to milk and that in situations of continuous undernourishment a high state of body condition is undesirable during lactation.

Soil aggregates of different sizes, separated by sieving, and artificial aggregates stabilized by a chemical conditioner were used to study the effect of particle size on the uptake of nitrogen and phosphorus by plants growing in pots. Phosphate uptake was consistently less from the coarser than from the finer fractions of soil. The uptake of nitrate was also greater from smaller than from larger aggregates, despite its mobility in soil moisture.