Applying large dressings of fertilizer nitrogen to the seed bed lessened nodulation of spring field beans by as much as 50%.

The largest mean responses to broadcast nitrogen ranged from 1·9 cwt grain/acre in 1967 (3 cwt N/acre) to 3·1 cwt grain in 1966 (3 cwt N/acre).

About one-sixth of the nitrogen applied to beans was used by a following winter wheat at Rothamsted, one-twelfth at Woburn.

The results suggest that there is no prospect for the economic use of fertilizer nitrogen in the seed bed for spring beans.

Iodine values, melting (slip) points and fatty acid analyses for back (‘bung’) and perinephric (kidney) fats from 114 pure and cross-bred pigs are reported.

In most cases the effects of breed were small, but half-Hampshire crosses showed a high proportion of pigs producing abnormally soft and highly unsaturated fats, though others were normal.

Although a general correlation existed between iodine value and melting-point the relationship broke down in some cases, and the ratio of monoene to saturated fatty acids of carbon chain length 16 and 18 is suggested as a better chemical index of softness due to causes other than dietary lipid.

This study is the first comprehensive estimation of breed parameters for the Jamaica Hope breed of dairy cattle. It has shown that the breed has considerable potential for milk production undser good husbendry in a tropical environment. Improvements in reproductive performance may be achieved, without prejudice to production performance, by using milk yield per day of calving interval (which has a moderatoly high repestability) as a criterion for selection.

The largest mean responses to nitrogen ranged from 2·1 cwt grain/acre in 1966 (2 cwt N/acre) to 3·6 cwt grain in 1968 (1–5 cwt N/acre). Responses to the largest dressings were increased by dividing them, the increases ranged from 0·2 cwt grain in 1968 to 4·0 cwt grain in 1966.

In 1968 1·5 cwt N applied in late May increased grain yield by 5·5 cwt, more than the response to any other amount applied either to the seed bed or as a divided dressing. Removing the growing point of the plant at the 4-leaf stage promoted tillering but lessened yield by 5·4 cwt grain. Removing the growing point of the plant after flowering increased yield by 2·1 cwt grain in 1966 and lessened it by 1·7 cwt grain in 1967.

CCC (2-chloroethyltrimethylammonium chloride) had no visible effect on growth and lessened yield by 1·9 cwt.

B9 (N-dimethylaminosuccinamic acid) greatly affected growth and shortened stems by as much as 30%, depending on how much and when it was applied.

B9 had inconsistent effects on yield. Without fertilizer nitrogen, it increased yield by 2·5 and 2·6 cwt grain in 1966 and 1968 but decreased it by 2·1 cwt in 1967.

The main effects of B9 on the components of yield were to increase the number of stems and pods/acre and lessen 1000 grain weight. Plants given B9 in 1968 produced half a million more grains/acre than untreated plants. 1·5 cwt N had similar effects to B9 on the components of yield in 1968. Stems and pods/acre were increased, but there was also a small increase in 1000 grain weight. Plants given 1·5 cwt N produced half a million more grains/acre than plants not given N. A further1·5 cwt N lessened number of stems/acre but this was more than compensated for by an increased number of pods/stem, leading to a further increase of 160000 grains/acre. The effects of season were large and exceeded the effects of any of the treatments.

Using data (1950–64) from the government-owned herd of Jamaica Hope cattle at Bodles, Jamaica, it was estimated that the fraction of cows called on the basis of their milk production in any given lactation was of the order 0·00 to 0·05. Using data (1967–68) from ten high–and ten low-producing farmer herds of the same breed, it was found that the level of calling was low and that cows proceeding from one lactation to the next had a yield superiority over the total population of only + 4 gallons. It is suggested that one of the principal reasons for the apparent lack of response to selection in dairy herds in the tropics may be that little or no selection for production is in fact practised.

Eighteen trials were carried out to test factorial combinations of N, P, K and Na fertilizers on sugar beet over 3 years on deep light peat soils in the area surrounding the Wash. The average yield responses to all fertilizers were very small, and only rarely profitable, except to sodium. Nitrogen increased yield on a few sites, but there was no obvious way of distinguishing these, and on average there was no justification for using this fertilizer, which depressed sugar percentage. The difference from earlier work, which showed good responses to P and K, is ascribed to repeated heavy dressing of fertilizer given to these soils during the last two decades.

Three experiments were carried out with adult sheep in order to estimate the effect of light and darkness in determining the incidence pattern of rumination.

In the first experiment the jaw movements of four sheep were recorded when they were housed in cages in a single room. Continuous records were made before and after black-out was applied to the room in order to investigate the effects of times of lighting and of feeding. The results showed that under these conditions the pattern of ruminating behaviour changed with the lighting system used and that the different feeding times had no effect upon rumination.

The first experiment was repeated with four sheep. Equal 12 h light or dark periods running from 10.00 and 22.00 h were applied and also days of continuous light or darkness. Food was given as equal meals at the beginning of each 12 h period. The results confirmed those of the first experiment and showed that rumination was greatest during the second half of each 12 h period of darkness. With permanent light or darkness rumination was least in the period from 10.00 to 16.00 h.

An attempt was made in the third experiment to impose a 16 h cycle on four sheep. The results showed no adaptation to a 16 h ‘day’. Instead, behaviour was circadian and probably based on cues external to the experimental room.

The total P contents of soils, analysed after fusion with sodium carbonate, were consistently larger than after digestion with boiling perchloric acid. For 37 soils from southern England, values by fusion analysis (Pf) were related to values after digestion with perchloric acid (Pp) by the following equation:

The recovery of P, applied to six soils as superphosphate, was the same by both methods of analysis.

Thirty-six Hereford cross Friesian calves weighing on average 82.4 kg at an average age of 90 days were allotted in randomized blocks to a 2 x 3 factorial design. Castration by the open method was performed on half the number of calves and three dietary crude protein levels, 20, 14 and 11 % in dry matter were used in a mainly cereal concentrate diet fed ad libitum individually to the animals in stalls. Slaughter was at a fixed weight of approximately 420 kg.

Steers compared with bulls gained weight at a significantly slower rate and with less efficiency. Castration's greatest effect in reducing rate of gain occurred during the later stages of rearing when puberty in the bulls, as measured by a steep rise in seminal fructose, was associated with their relatively well maintained live-weight gain. The influence of testicular hormones was also apparent in the bull's carcass with its heavier head, horn and hide and significantly higher proportion of lean and lower proportion of fat in the side.

Dietary protein level affected rate of gain in both bulls and steers but at each level bulls performed better than steers. With circumstances similar to those in this experiment, a 14 % crude protein level in concentrate dry matter appears adequate for both categories up to a live weight of circa 270 kg and a reduction to 11 % thereafter. The effect of protein level on tissue proportions of the side and carcass composition generally was minimal.

The contemporary comparison method of evaluating the progeny test of sires has been employed in estimating the breeding values of bulls used in the development of the Jamaica Hope breed. The need to test a larger number of bulls by combining the programme at the national level is stressed.

Calorimetric experiments were made with a complete extruded diet for ruminants, ‘Ruminant Diet A’ prepared by Messrs U.K. Compound Feeds Ltd. Twelve determinations of energy and nitrogen retention were made using sheep and it was found that the diet had a metabolizable energy value of 2–32 kcal/g organic matter, and the net availabilities of its metabolizable energy were 42–7 % for fattening and 68–0 % for maintenance. These values agreed well with those predicted from equations published by the Agricultural Research Council. On a dry basis the starch equivalent was 38–3 %.

Nine Merino wethers were used in a cross-over experiment to compare the voluntary intake of three diets after a 4-week period in which the intake of the same diets was restricted, either to a level which maintained the live weight and energy status of the sheep, or to one which resulted in losses of 18% and 26% in their live weight and total energy content respectively. The diets were prepared from lucerne hay; chaffed (L), ground and pelleted (P) and pelleted after mixing with ground wheat (W).

The voluntary intake of food increased only slowly during the 4 weeks after restrictions were removed; the total intake of digestible organic matter from diets W, L and P was in the ratio 100:122:146. Differences between diets L and P, but not W, were associated with their rates of disappearance from the rumen. Sheep which had been severely restricted ate less food during the first fortnight and no more during the second fortnight than those which had previously maintained their energy status. The difference in the first fortnight was less for diet P than for diet L. The process of adaptation by the sheep to unrestricted feeding was associated with an increase in the net rate of disappearance of volatile fatty acids from the rumen.

Sheep offered food ad lib. after a period of submaintenance feeding gained more weight than sheep which had previously been fed to maintain weight and this increase was greater with diet P than with diet L. However, the differences in live-weight change consisted largely of water in the gut and did not result from a relative increase in the voluntary intake of food or in the efficiency of energy utilization.

A heat-exchange chamber made of perspex was inserted beneath the skin of a Merino sheep. By passing water at predetermined temperatures through the chamber, the normal subdermal temperature of 37°C was raised approximately 4°C for 4 days, then lowered approximately 5°C for 4 days.

In response to heating, the animal's temperature regulating mechanism was able to maintain a fairly constant subdermal temperature. However, it was unable to maintain as constant a subdermal temperature in response to cooling. There was, during the cooling period, an obvious nervous response to environmental disturbances manifested by sudden transient decreases in subdermal temperature over the chamber.

During the cooling period there was a decrease of 12% in mean length growth rate of wool over the chamber but mean fibre diameter was unchanged. Heating produced a small decrease in mean fibre diameter, but no change in mean length growth rate. Heating appeared to produce a slight reduction in pigmentation of some fibres but neither heating nor cooling produced demonstrable changes in crimping.

The fibre length and diameter distributions of the wool of two Merino flocks were evaluated at the neck, mid-side and breech positions, to determine the incidence of fibres which were off-type by reason of excessive length, diameter or possession of a medulla.

The ranges of fibre lengths for 10·5–11·0 months' growth were 1·0–17·5 cm. in flock 1 and 1·0–16·5 cm in flock 2. There was no evidence of a bi-modal length distribution in either flock.

Fibre diameters at 15–16 months were observed in the range 6–69 μ in flock 1 and 5–52 μ in flock 2. Medullated fibres ranged from 7 to 50 μ in flock 1 and 5–64 μt in flock 2. The incidence of medullation increased in an antero-posterior direction from 0·17 to 0·28% in flock 1 and 0·11 to 0·28% in flock 2.

Tests for homogeneity of variance were applied to the estimates of fleece characters in this study as well as estimates of other workers. From these comparisons it is suggested that sheep in the present study are representative of the Merino breed in staple length, fibre diameter and to a lesser extent crimp frequency. The considerable between-animal variation in the observed incidence of medullation should aid in selection against that character with a consequent improvement in wool quality.

A study was made of the live-weight gains of four ¾-bred Brahman and four purebred Hereford steers over a 12-month period. At 950 lb live weight each animal was slaughtered, after which the carcass characteristics of the two breed types were compared.

The Herefords showed the highest live-weight gains over the whole year but during autumn, when nutritional levels were poor, the Brahmans had an advantage in average daily gain.

Although both breed types varied greatly in body conformation, there was little appreciable difference in weight distribution of joints on the carcass. A higher dressing percentage was observed in the Brahmans, this being attributed to their smaller alimentary tracts. The Brahmans had a greater carcass muscle and smaller carcass fat content than the Herefords. The necessity for fat trimming of the Hereford carcasses reduced their calculated retail value index to a level below that of the Brahmans in a market which discriminated against excess fat.

Thus it was concluded that even in a temperate climate, Brahman cattle can have a place in improving productive efficiency. Apart from the heterosis developed in crossbreeding, benefits should flow from the Brahmans superiority on poor pastures and the improved production of lean meat on their carcasses.

Changes in yield and quality of an Andropogon gayanus sward were traced throughout the 1964 wet season and part of the following dry season.

Quality, in terms of crude-protein content, was highest at the beginning of the wet season, but yield increased to a maximum at the beginning of the dry season. Once flowering was completed in October, herbage quality fell to a very low level. It was concluded that the best time to cut for hay was in early October, at which time the crude-protein content showed a small but significant increase. Regrowth measurements taken in mid-November indicated the benefit of taking an early hay cut in July as a means of producing better quality hay at the end of the rains.

During the early vegetative phase of growth leaf production was greater than stem production. Quality was high because the leaves contained a higher content of crudeprotein, calcium, phosphorus and carotene than the stems. During the reproductive stage of growth, comprising stem elongation in September culminating in anthesis in early October, quality was lower due to the high fibre content of the stems. The increase in crude-protein in early October, coincided with the expansion of new leaves on the flowering stems.

It was concluded that throughout most of the latter part of the growing season A. gayanus did not provide adequate supplies of crude-protein, calcium and particularly phosphorus for normal cattle growth, especially after flowering was completed in late October.

Estimates of the incidence of coarse fibres and medullation were made from 1014 bales of Merino greasy wool, from the five major wool-selling centres in Australia. A full range of wool types was represented from the fault-free spinners types to the burry, dusty, inferior topmakers' types. The wool consisted of 36 processors' lots ranging from 1 to 120 bales.

The mean diameter of the 36 lots was 20·7 ± 5·3 μ 2·4% of the fibre population exceeded 30 μ the incidence of medullation was 1·1%.

Mean diameters of the individual lots ranged from 14·7 to 25·3 μ Twenty-one of the 36 lots had coefficients of variation of mean fibre diameter which exceeded 23%. The range of clean, oven-dried yield was 49·4–69·1%. The between-lot variation in fibre medullation was 0–3·1%.

It is concluded that fibre coarseness as measured by diameter was not a problem in the wide range of wool sampled. However, the incidence of medullation is an increase on previous estimates and should be a cause of concern to breeders.

Potatoes (var. Pentland Dell) were grown in pots containing soils from the Bothamsted ley–arable experiments. When about half the initially available K was used, the tops were harvested and the potential limiting K uptake, inferred from K uptakes, was – 4150 cals/equiv. The plants grew on until they exhausted the available K and died, having set tubers. The potential then limiting K uptake, inferred from total K uptakes, was – 4900 cals/equiv., similar to the mean potential in the exhausted soils, – 4710 ± 61 cals/equiv. The significance of these measurements is discussed.

Total K uptake was closely related to the amount of K that had to be removed from each soil to lower the potential to – 4900 cals/equiv. and the relationship suggested that the potatoes did not use any K from initially non-available reserves.

Dry-matter yields of tubers and of tops + roots, and the ratio of the two, were well related to quantity and potential of K in the soil; tuber yield was also well related to K in tops. The K potential needed for maximum yield of tubers exceeded – 2430 cals/equiv.

On seven separate occasions during a year, 24-h studies were made on the grazing behaviour of four ¾-bred Brahman and four purebred Hereford steers in the cool temperate New England region of northern N.S.W.

Although both breeds spent approximately the same time grazing, the Brahmans ruminated for shorter periods and thus had a lower ruminating time to grazing time ratio than the Herefords. No signs of cold stress were observed in either breed even though the dry bulb temperature frequently fell below freezing point. However, the Herefords sought shade more than the Brahmans when the black body temperature exceeded 32°C.

It is concluded that a climate such as that of New England, where winters are cold, should in no way adversely affect the performance of Brahman-type cattle, as judged by their behaviour.

The growth characteristics of root systems were studied in the wheat varieties Chinese Spring' Hope and the chromosome substitution lines of Hope into Chinese Spring. The growth patterns varied considerably between the lines and this was due to the fact that the plants formed different numbers of tillers and grew for different periods of time. A correlation existed between the development of the shoot and root systems although some lines differed widely in their shoot root ratios. Differences between the lines in the early stages of growth were small and they reacted uniformly to different levels of phosphorus supply. The relation between shoot and root growth was also shown by the fact that the conclusions from genetical analyses were very similar. These showed that the method of control was largely additive in nature. It was concluded that variations in shoot and root characteristics were markedly influenced by single genes affecting the duration of the vegetative growth period as well as by polygenic systems.