1. An experiment designed to investigate the growth and yield of lucerne over a wide range of plant populations is described and the results discussed.

2. The mean yields of lucerne per plant were fitted to three different equations relating yield per plant to plant population, and the ‘goodness-of-fit’ of these equations was compared.

3. As plant population increased, the yield of lucerne per acre increased very rapidly up to a certain level, but further increases in plant population led to much smaller increments in yield. It is argued from theoretical considerations that the yield per acre would reach a maximum only when the plant population is infinite.

Efficiency of food utilization from 2 to 18 weeks of age has been examined in 12 MZ and 7 DZ pairs of twin calves fed standard rations. Mean efficiency reached a maximum at about 6 weeks of age; weaning brought about a rapid decline followed by a recovery. Animals became more alike in efficiency as their ages increased.

Those animals least efficient shortly after birth were most adversely affected by weaning, although they tended to be relatively more efficient when fully established on either milk or solid food.

Relative to the fairly closely replicated age-efficiency trends of identical twins, different pairs followed different trends. These trends, which primarily reflected the variable success with which the calves adapted to new diets, were subject to some genetic control.

The relationship of efficiency to weight and feeding rate has been studied in 38 twin calves from 2 to 18 weeks of age. Following birth or weaning heavier animals were more efficient, but tended to be slightly less efficient when fully established on a diet. On balance, they possessed an advantage.

Heavier twins and heavier pairs were also on average more efficient. The increase in mean efficiency for contemporary animals was about 1% for each 1 lb. superiority in weight over the 4-month period. These results contrast with the well-known decline in efficiency as animals increase in weight. Different pairs declined in efficiency with increasing live weight at distinctly different rates judged by the resemblance of twin and co-twin, but evidence for genetic control was slight.

More efficient animals were associated with a relatively more rapid decline in efficiency, leading to a general convergence in efficiency as animals grew heavier.

The relationship of efficiency to feeding rate was very similar to the relationship with weight.

1. The habits of five Tanganyika Shorthorn zebus and their suckling calves were studied during periods of 72 consecutive hours at monthly intervals in each of the first 6 months of the calves' lives, during the ‘dry’ season of the year.

2. Cows grazed for 7·16 hr. per day while grass was green and plentiful, but, as grazing became dry and sparse, they ate silage at night for up to 3 hr., and reduced their grazing time by about 2 hr. The ratio of rumination time to eating time tended to increase as grazing became drier and as silage eating increased. The average ratio was 1·01 to 1.

3. All calves were actively grazing for 4·0 hr. per day by the second month, and for 5·6 hr. per day by the fifth month. They ate silage diffidently in the second month, but they were eating silage for 1·7 hr. per night at 6 months. Rumination was observed in a calf at 18 days of age, but was consistently observed in the second month when calves ruminated for 6·1 hr. per day. The ratio of rumination time to grazing time for calves declined from 1·5 to 1 in the second month to 1·1 to 1 in the fifth month. Rumination time among calves was more closely related to silage eating than to grazing time.

4. The calves acted as individuals in the first month, and thereafter their eating habits were determined more by their dam than by their age. Day-time rumination pattern was a characteristic of the age of calf, but night-time rumination by calves was more closely correlated to that of their dams.

5. Calves suckled for an average period of 9·2 min. per suckle. There was very little variation with age, but frequency of suckles decreased from 9·5 times per day at 1 month to 5·6 times per day at 6 months. The fastest-growing calf suckled less frequently for shorter periods, suggesting readier availabilty of more milk.

6. Suckling intensity was evenly spread over the 24 hr. during the first 2 months, but thereafter suckling became increasingly confined to nighttime while the cattle were yarded.

7. It was concluded that artificial feeding divided into three equal feeds per day at 05.00, 13.00 and 21.00 hr. for the first 2 months, followed by two equal feeds per day at 05.00 and 18.00 hr., would be reasonably consistent with natural suckling activities if restrictive feeding has to be applied. But further work is required to determine the cost, in terms of reduced efficiency of milk utilization, incurred by concentration of intake to restricted feeding times.

1. Between 1955 and 1961 nineteen experiments were carried out on Majestic potatoes in various parts of England comparing muriate and sulphate of potash at three rates of application, in the range 75–336 lb./acre of K2O. Most of the experiments were on light soils.

2. Total yield of tubers was on average the same from both sources at all rates of application, and this similarity was not affected by environmental conditions.

3. Muriate of potash consistently gave a higher yield of large tubers than sulphate, with an average difference of 0·6 ton/acre. Conversely, muriate gave a lower yield of medium tubers than sulphate, again with a mean difference of 0·6 ton/acre.

4. Muriate of potash significantly depressed tuber dry-matter content in eleven of the experiments, particularly at the higher rates, while sulphate had this effect in three experiments. Muriate gave a small increment in two experiments, at low rates only, while sulphate had this effect in five, most markedly at low rates. Sulphate gave a higher dry-matter content than muriate in most of the experiments. The mean difference was 1·0% at 300 and 336 lb./acre of K2O and 0·4 to 0·5% at lower rates.

5. Sulphate of potash gave a more floury texture to the boiled tubers than muriate in three experiments, but otherwise no difference in texture was detected between the sources.

6. The degree of off-flavour was not appreciably affected by rate or source of applied potash.

7. After-cooking blackening was more marked at low than at high rates of applied potash in seven of the nineteen experiments. Muriate and sulphate of potash had similar effects.

8. Farmyard manure ploughed down in winter was tested in three experiments and did not influence to any important extent the relative effects of muriate and sulphate of potash on tuber yield and quality.

9. Application of the two sources on the flat before ridging and in the open drills was compared in the same three experiments, but did not alter the relative effects of the sources on yield or dry-matter content.

1. Three groups of twenty, 3½ to 4-year-old zebu steers, replicated four times in each quarter of the year, were used to examine the effects of 30 and 45 mg. hexoestrol implants on their beef production, under ranch conditions in Tanganyika.

2. Significant advantages in mean live-weight gains of 20·8–47·3 lb. for 30 mg., and 9·8–47·3 lb. for 45 mg., were obtained when treated at any time of the year; but during the dry-season implantation is contra-indicated as initial response is adverse although followed by pronounced recovery when pasture conditions improve.

3. There was no significant difference between dosage rates in growth response, but on smaller steers, and as the pasture deteriorated, 45 mg. showed signs of being excessive.

4. Duration of significant response was about 3 months during the period of adequate grazing, but was delayed to 5 months, and probably longer, during the dry season.

5. Steers were slaughtered 6–9 months after implantation and at that time showed: no significant difference in dressing percentage, shrinkage in store, proportion of bone, or carcass grade; there was significantly less fat, and more lean, but increased proportion of moisture in the muscle accounted for the extra proportion of lean in the sample joints.

Treated carcasses were significantly longer by 1·0% and highly significantly larger in circumference of hind quarter by 2·0%.

1. Regression equations for the ratio of organic matter (O.M.) feed intake to O.M. faecal output on faecal N%, and the N% in the O.M. intake on faecal N% were established over a 52-week period by feeding caged Corriedale wethers on pasture cut from a Wimmera rye-grass (Lolium rigidum Gaud.), subterranean clover (Trifolium subterraneum) sward in a Mediterranean-type environment.

2. The regression equations and their application to grazing sheep together with the relation between O.M. intake and faecal N, are discussed.

1. Recordings of faecal organic matter (O.M.), faecal N% (O.M. basis) and live weight, were made over 52 consecutive weekly periods on ten Corriedale wethers grazing a pasture consisting mainly of Wimmera rye-grass (Lolium rigidum Gaud.) with some subterranean clover (Trifolium subterraneum) in a Mediterranean-type environment. The amount of available O.M. and its N% were also recorded.

2. By applying regressions of (i) the ratio of O.M. feed intake to O.M. faecal output on faecal N% and (ii) the N% in the O.M. intake on faecal N%, to the above observations it was possible to estimate the following quantities: O.M. and digestible organic matter (D.O.M.) intake, N and digestible N intake and O.M. digestibility percentage.

3. The patterns of O.M. and D.O.M. intake, and N and digestible N intake are described. Similar patterns exist for each of these quantities. Two maxima, a large one in the spring and a smaller one in the autumn, and two minima, one in the summer and one in the winter, are exhibited. The values for these various maxima and minima are presented in the text.

4. Attention is drawn to variations from the general pattern for these quantities and factors which could influence these patterns are mentioned.

A description is given of a building and equipment which have proved suitable for cows in experiments involving the separate collection of faeces and urine.

1. The effects of two heights of cutting—down to either 1 in. or 2–2½ in. from ground level—on herbage yields were studied for five seasons with a perennial rye-grass-white clover mixture and for three seasons with a timothy-white clover mixture. Superimposed on these height-of-cutting treatments were treatments simulating strip grazing with and without a back-fence, and also three fertilizer nitrogen treatments.

2. Over the 5-year period the rye-grass mixture consistently gave greater dry-matter and crude-protein yields of herbage when cut to 1 in. than it did when cut to 2–2½ in. from ground level, the mean dry-matter yield difference being 34%. The decline in the total yield per season with increasing age of the grass sward was similar under both heights of cutting.

3. The effects of the height-of-cutting treatments on the timothy mixture were similar to those noted on the rye-grass mixture in the first three seasons of the experiment, but in the third year the beneficial effects of close cutting were much reduced. It is suggested that this resulted from the rest period between cuts being insufficient for timothy to recover fully from the close defoliation.

4. The effects of the height-of-cutting treatments on the botanical composition of the sward were slight, particularly on plots of the rye-grass mixture.

5. Possible factors leading to the observed effects of the height-of-cutting treatments are discussed with reference to the results of other workers and to the results from a preliminary study of the differential effects of the treatments on stem and leaf formation in perennial rye-grass.

6. A simulation of strip grazing with and without a back-fence showed that the herbage yields from both seeds mixtures under both height-of-cutting treatments were considerably reduced by the removal of the regrowth which could take place in the absence of a back-fence.

7. The effects of delaying the first nitrogenoua fertilizer application of the season noted in an earlier experiment were fully confirmed in this experiment.

There is a strong correlation between the digestibility of the organic matter and the percentage crude fibre, percentage lignin, and percentage cellulose plus lignin in the foodstuffs examined.

There is evidence that the holocellulose and xylan in grasses are different from those in legumes in the extent to which they are digested. It is suggested that this is due mainly to the xylans or hemicellulose fraction in the forages, and may be a reflexion of a different molecular structure for the xylans in either group.

Within each group of plants both the holocellulose and xylan percentages are strongly correlated to the percentage digestible organic matter.

Excessive heating of hay led to a marked rise in the percentage lignin. This is probably due to the xylans becoming horny and insoluble, therefore being determined as lignin. This also offers an explanation for the decrease in digestibility of the organic matter.

1. Rumen and caecal wall tissues were taken at slaughter from lambs varying in age from newborn to 11 weeks. The ability of these tissues to metabolize the short-chain fatty acids, acetic, propionic and butyric acid was compared with tissues from adult sheep. Ketone body production was measured.

2. The utilization of butyrate by the rumen wall in the newborn lamb was lower than in the adult, but exceeded the adult levels at 3 weeks of age and maintained this higher utilization to 11 weeks and probably longer. Ketone body production was negligible at birth but followed butyrate utilization closely thereafter.

3. The caecal wall in the newborn lamb utilized butyrate at a much higher rate than the adult sheep tissue. Foetal lamb caecal tissue utilized butyrate to the same extent as in the newborn lamb. Levels were, however, typical of the adult within a day or two of birth and showed no subsequent effect of age. Ketone body production was negligible at all ages.

4. Rumen development in milk-fed lambs slaughtered at 7 and 9 weeks of age was retarded anatomically and showed decreased capacity in the utilization of butyrate.

5. The utilization of acetate and propionate by rumen and caecal tissues showed no marked change due to age. Ketone body production from these acids was low.

A rapid and accurate atomic absorption method for the determination of chromium in faeces samples from pasture experiments using chromic oxide ‘markers’ is described. Of the elements present after ashing and digesting the samples in a phosphoric acid—manganese sulphate—potassium bromate solution silicate, aluminium, calcium and magnesium were found to interfere in the determination. The effects of these interferences were overcome by the addition of calcium to the test solution and by the addition of silicate to the standards, which were prepared in ‘blank’ solutions.

The sensitivities of a number of alternate chromium resonance lines relative to that of Cr 3578·7 Å. are given. These lines may be used to increase the concentration range of the analysis.

The results of a comparison of the atomic absorption method with a chemical method are given.

Italian rye-grass given ammonium sulphate or sodium nitrate at 56 or 112 lb. N/acre was analysed for total nitrogen, soluble nitrogen (non-protein-nitrogen) and soluble carbohydrates.

Ten days after applying fertilizer the differences in total-N between the grass receiving 56 and grass receiving 112 lb. N/acre were very small. Total-N in grass decreased with growth, but the effect of the rate of nitrogen on total-N increased. At first the grass given sodium nitrate contained more soluble nitrogen than grass given ammonium sulphate, the difference being greater at 56 lb. N/acre; soluble nitrogen decreased with increasing growth. Ten days after applying fertilizer, the nitrate-N content of grass was very high (ranging from 0·1 to 0·9% in the D.M.) and it gradually decreased. At both levels of nitrogen application, grass given sodium nitrate contained much more nitrate-N than grass given ammonium sulphate. Forty days after applying nitrogen the nitrate-N contents of grass which received 56 and 112 1b. N/acre as ammonium sulphate were 0·039 and 0·222% of the dry matter, respectively; the grass supplied with sodium nitrate gave values of 0·082 and 0·438%.

Total soluble carbohydrates in the grass were small early in growth and gradually increased. Nitrogen dressings had little effect on the content of soluble sugars (glucose + fructose + sucrose) but greatly decreased the fructosan. The pattern of changes in the total soluble carbohydrate content followed that in fructosan content. Early in growth, the total soluble carbohydrate/crude protein ratio was very small in grass from all treatments except the ‘control’. This ratio increased with growth and at the last sampling was 2·13 in grass receiving no nitrogen, and in grass supplied with 56 and 112 lb. N/acre as ammonium sulphate it was 1·44 and 0·72 respectively; the corresponding figures for grass receiving sodium nitrate were 1·13 and 0·66. The total soluble carbohydrate carbon/soluble nitrogen ratio in grass with no nitrogen was 18 at the first sampling and it increased gradually, reaching 70 at the last sampling. This ratio was considerably less with all nitrogen treatments than with ‘control’. The values obtained with 112 lb. N/acre were less than those obtained with 561b./acre, irrespective of the form of nitrogen used.

The relationship between the soluble carbohydrate carbon content and the soluble nitrogen in grass is illustrated graphically and discussed.

An experiment using 528 day-old chicks was conducted to determine the nutritional effects of terephthalic acid, when added at the rate of 0·4% to a ration containing 100 g. oxytetracycline per ton, in the rearing of chicks to 30 days of age in East Africa.

No significant gains were produced in the growth rates or feed-conversion rates, of male and female chicks of four cross-breeds, over the periods 0–10, 0–20 and 0–30 days of age.

A regression for feed-to-faeces ratio on faecal nitrogen percentage was formulated from trials in which perennial irrigated pasture cut to ground level was fed to cattle and sheep at various times over several years.

Similar data derived from ‘top’ (mainly leaf) and ‘bottom’ (mainly stem) cuts of a spring and of an autumn stand of pasture from the same vicinity did not conform with the ‘whole’ cut relationship and the three regressions which were established were heterogeneous.

It is suggested that due to selectivity, the application to grazing animals of a regression derived from pasture cut to ground level may result in considerable error.

The skeletons of most of a group of lame buffalo from an area around Pasir Puteh and of some of a group of similarly lame animals from an area S.W. of Pasir Mas were poorer than those of a control group from around Kota Bharu. Analyses of blood and liver indicated that the defective mineralization of the skeleton was caused by a shortage of phosphorus rather than of calcium or copper.

Evidence for a relationship between lameness and the quality of the skeleton was not strong and further study including a feeding experiment is needed to establish the validity of this.

1. Liver samples were taken from 95 mature zebu cattle and buffalo in Malaya for determinations of copper. A larger proportion were from Perak than from other States but whether the Perak samples were considered alone or with the remainder about 80% had liver copper values below 20 p.p.m.

2. Among Perak animals (all cattle) almost all those with low copper values were in moderate to poor condition but among the remainder about 50% of these with low copper values were in good condition.

3. In 12 Perak animals the numbers of parasites of the gastro-intestinal tract and of pancreatic and liver flukes were determined as well as the concentrations of liver copper. There were very few parasites other than pancreatic and liver flukes. Liver flukes may have caused low copper values in some animals but in general there was little evidence for a relationship between parasites and a low copper status. Anaemia did not accompany low liver copper values in these animals.

1. Two experiments are described in which the effects of grazing a lucerne/cocksfoot ley at various intervals throughout the season were examined, together with the effects of a June hay cut and an autumn rest period. The results are discussed.

2. In the year of treatment: (a) The wet year 1954 favoured the grass fraction and the dry year 1955 favoured the lucerne fraction but, in general, the proportion of lucerne in the sward decreased as frequency of defoliation increased. (b) The largest yields of lucerne dry matter were obtained from treatments that included a June hay cut and the largest yields of grass dry matter came from those treatments that included an autumn rest period, (c) Within the chosen programmes of defoliation, there was a tendency for greater yield of dry matter from those treatments defoliated four times when compared with one cut three times, but yields from treatments defoliated more frequently tended to be smaller, with a marked reduction from seven grazings.

3. In subsequent years: (a) Treatments in the wet year had a greater effect on subsequent lucerne vigour than treatments in the dry year, (b) Yields of lucerne dry matter from three hay cuts in the first residual year were reduced by all the grazing treatments, the greatest difference occurring at the first cut. Lucerne yield decreased with increasing frequency of treatment defoliation. There was a tendency for the autumn rest period to increase lucerne yield and for the June hay cut to reduce it. (c) Total grass dry matter yield was greatly increased by grazing treatments, the majority of this difference occurring at the first cut, and it also increased with increasing frequency of treatment defoliation. (d) The proportion of cocksfoot in the grass fraction of the sward was reduced by treatments that included defoliation during the period September–October, and it was further reduced by treatments that included a June hay cut. (e) In the second year following treatment the effect of grazing on the grass fraction had disappeared but reductions in lucerne vigour from too frequent defoliation were still evident, though reduced.

4. Grazing a lucerne/cocksfoot ley reduced the subsequent vigour of the lucerne more than would have been expected from cutting it a similar number of times. This reduction is attributed to increased competition from the grass arising from its response to nutrients in the excreta of the grazing animals. In a wet year four grazings caused a permanent reduction in lucerne vigour and more frequent grazing almost eliminated the lucerne, but in a dry year four grazings caused only a temporary reduction in lucerne vigour and had no lasting effect.

5. The interval between defoliation and the subsequent onset of flowering in the lucerne was very much less in the hot dry year than in the cooler wet year. There appeared to be a relationship between the onset of flowering and the ability of the lucerne to recover from defoliation.