Part of the variation among butterfat yields in dairy cows arises from genetic differences among the animals. The proportion which this bears to the total variance is known as heritability. In the ‘narrow’ sense it is defined (Lush, 1940), as the proportion of the total variance that is due to additive gene effects; the ‘broad’ sense definition includes genetic variation arising from non-additive gene effects as well as that due to additive effects. Since related animals have a proportion of their genes in common the covariance among their production records can be used for estimating genetic variation and hence heritability. This paper discusses three groups of related animals most frequently used for this purpose, twins, daughter-dam pairs and paternal half-sibs, and presents the results of analysing production records of artificially bred heifers in New Zealand, including evidence of the magnitude of the sampling errors of the heritability estimates.

1. Continuous cropping with perennial ryegrass in the glasshouse was used to measure the release of non-exchangeable potassium from twenty soils representative of a wide variety of soil series.

2. Releases of non-exchangeable potassium ranged from almost none to > 2000 lb. K/acre.

3. The main reason for the variations in the potassium-releasing powers of the soils was traced to differences in the amount and potassium content of the finer clay fractions. Small potassiumcontents in the fine clay and small contents of fine clay were associated with small releases of nonexchangeable potassium.

4. Accumulated potash fertilizer residues or the presence of such minerals as glauconite can be responsible for the good potassium-releasing powers of some soils.

5. Some of the limitations of glasshouse work for assessing the potash status of soils are discussed.

6. Evidence was obtained for the existence in many soils of at least two categories of useful nonexchangeable potassium.

1. The potential herbage yield of Hyparrhenia veld under mowing and fertilizer managements was measured, as a part of the work to study the utilization of the natural grassland for the feeding of cattle in the dry season.

2. The uninterrupted seasonal pattern of herbage growth results in a relatively large yield of stemmy, low-quality fodder at the end of the growing season.

3. Cutting at simulated ‘silage’ and ‘hay’ stages of growth reduced herbage yields compared with one, end-of-season harvest, but because of increased leanness, the regrowth herbage had a higher crude-protein content.

4. The seasonal crude-protein yield was unaffected by mowing treatments, and a reduction in herbage yield was counterbalanced by an increase in percentage crude protein.

5. The use of nitrogenous fertilizers resulted in a large increase in both herbage yield and percentage crude protein. The calculated nitrogen recovery was approximately 40%.

6. There were no harmful effects on either veld vigour or botanical composition after 4 years of mowing and fertilizer treatments. The nitrogen fertilizer treatments alone showed a transient residual effect.

7. The practical bearing of the results is discussed briefly. Only a low-quality fodder can, in practice, be harvested from the natural grassland, unless nitrogen fertilizers are used.

Three methods of utilizing the natural Hyparrhenia grasslands for the dry-season nutrition of ranch cattle were tested in grazing trials. The feed regimes were:

(A) Late-cut veld hay plus aftermath grazing.

(B) The accumulated, seasonal growth of mature grass left as ‘standing hay’ for dry-season grazing.

(C) A combination of both practices in which half the area was cut for hay, and half left as ‘standing hay’. These treatments were compared with and without the feeding of supplementary protein.

Mature Hyparrhenia veld whether cut for hay or left as ‘standing hay’ was a stemmy, low-quality forage deficient in protein. The qualitative deficiency was such that all unsupplemented treatments were equally ineffective in preventing large cattle weight losses in the dry season.

The only significant treatment effect was that due to feeding a protein supplement. Otherwise, there were no differences between the three managements, i.e. there was no marked benefit from conserving forage as veld hay compared with in situ grazing of the standing grass.

The voluntary intake of veld hay was low; and with heifers, declined to negligible amounts. The feeding of supplementary nitrogen, either as protein or urea, increased the daily hay intake by 140%. As a result, a diet deficient in energy was altered into a productive ration, with consequent cattle weight gains.

Although the cattle preferentially sought-after, and grazed the aftermath from late-cut veld hay; its practical nutritional value was slight, and was not reflected in cattle weight gains.

A score card is suggested for the judging of lamb and mutton carcasses. To apply the score card, measurements have to be recorded on length of leg (F), circumference of buttock (D), width (A) and depth (B) of ‘eye muscle’ (m. longissimus dorsi) and depth of back fat (C) and rib fat (J). In addition, visual judgement is required of fat covering on leg (E), marbling (G) and texture and colour of eye muscle (H). Points are deducted beyond an optimum weight which differs for lamb and mutton carcasses respectively.

1. The average length of gestation in Friesian cattle under Egyptian conditions was found to be 282·28 ± 10·7 days.

2. Neither the sex of the newborn calf nor the season of the year affects the gestation period significantly.

3. The average interval between calving and the first post-partum heat was found to be 85·52 ± 2·15 days.

4. The sex of the newborn calf does not affect significantly the interval of heat after calving whereas the month and the season of the year of calving affect this interval significantly.

1. Fourteen experiments with winter wheat on heavy-land farms from 1958–60 compared autumn dressings of sulphate of ammonia with equivalent early (March) or late (May) spring top-dressings. Dressings applied on two or all three dates of application were also compared.

2. Consistent and significant gains in yield from low (0·5 or 0·6 cwt. N/acre) and high (1·0 or 1·2 cwt. N/acre) levels were obtained at most centres, which were on fields under arable rotation.

3. With the low level of N, gains in yield were greatest from a single May top-dressing. There was no gain from dividing the dressing.

4. With the high level of N, dressings divided between autumn-May or March-May were best. March-May was the most consistently satisfactory treatment and gave the highest mean increases in yield in 1959 and 1960, but in 1958 autumn-May was better. Single May dressings gave slightly lower yields. There was no advantage from dividing N between all three dates of application.

5. Single applications of N in autumn gave lower yields than single applications in spring; supplementing autumn N with a late spring top-dressing gave almost the same yield as giving all the N in spring. Dividing the dressing in this way may be convenient on many heavy-land farms.

6. The percentage of N in the grain was highest with a late top-dressing of fertilizer-N, lowest with autumn N and intermediate with March top-dressings.

1. A general survey of the histological changes of the fore-stomachs of the lambs from 46 days of foetal life to 77 days of post-natal life is presented.

2. In all the rumen foetal specimens the mucosal surface was smooth. At birth small, conical papillae were visible and from this age onwards these papillae increased rapidly in size and tended to be long and tongue-shaped in appearance. Little change occurred in the appearance of the rumen papillae after 56 days of age.

3. The outlines of the reticulum reticular ribs were visible in the 100-day-old foetal specimen. At birth the normal honeycomb-like structure of the reticulum was well developed, but the papillae on and between the reticular ribs were small and had rounded tips. From 20 days of age onwards the reticulum features increased in size and the papillae became pointed in shape.

4. At 46 days of foetal life the omasum wall was folded to form developing laminae and by 70 days of foetal life laminae of four orders were present. The main age changes in the appearance of the mucosal surface from this age onward was an increase in the length of the laminae, the formation of small conical papillae on the laminae, and an increase in the inter-laminae spaces.

5. All three fore-stomachs showed the same general histological changes with age. The epithelium changed from a stratified cuboidal type in the foetal specimens to a keratinized, stratified, squamous epithelium in the post-natal specimens. The basal layer of the epithelium became folded to form papillae, reticular ribs and laminae, and in the rumen and reticulum further folding of this layer took place to form papillary bodies.

1. A study on the effects of the type of diet on the histological development of the fore-stomachs of the lamb is presented.

2. The rumen papillae were well developed in a 7-week-old lamb that had been fed solely on milk from birth, but compared to a lamb of the same age that had access to lucerne chaff from birth, they were smaller in size and more conical in shape. There was no difference in the appearance of the rumen mucosal surfaces of two lambs of 13 weeks of age, one of which had access to lucerne chaff from birth and the other access to lucerne chaff for only 4 weeks prior to slaughter.

3. The type of diet appeared to have little effect on the appearance of the reticulum mucosal surface.

4. The appearance of the omasum mucosal surface was only normal when lucerne chaff was fed to lambs.

5. The histology of the rumen wall was normal in the milk-fed lamb. However, compared to the lamb of the same age that had been fed on lucerne chaff, the papillary body formation, stratum granulosum and stratum corneum were less well developed.

6. Apart from a thinner stratum granulosum and stratum corneum, the histology of the reticulum wall of the milk-fed lamb was little different from that of the lamb of the same age that had been fed on lucerne chaff.

7. The histology of the omasum wall of the 7-week-old milk-fed lamb was very similar to that found in the lamb at birth.

1. In a population of Hereford crossbred steers carcass conformation was measured by weighing wholesale joints cut in London and Home Counties fashion and dissecting a single rib sample joint. Correlations were calculated between weight of joints and certain linear carcass measurements.

2. Weights of individual joints in a group of good cuts were studied in relation to carcass composition estimated from sample joint dissection. Carcass fatness at constant carcass weight was correlated positively with some joints and negatively with others. A thigh width measurement was related to the weight of these joints in a similar fashion. This accounted for the low value of thigh width as an index of the proportion of good cuts.

3. The weights of joints, and many of the measurements, were highly correlated with carcass weight. When carcass weight was allowed for, partial correlations were too low to support the use of linear measurements to predict weight of joints in individual carcasses.

This paper reports various investigations of the effects of meteorological factors on the yields of crops in England and Wales. The investigations were undertaken primarily with the objects of seeing (a) whether variations in temperature had any direct effect on yields, and (b) whether Penman's concept of actual transpiration gave a better measure of the overall effect of rainfall than the use of a multiple regression on variates representing total rainfall and its distribution.

The effect of temperature and its seasonal distribution on the yields of wheat on various plots of the classical wheat experiment on Broadbalk field at Rothamsted was studied in conjunction with rainfall and its seasonal distribution, using the regression method devised by Fisher. Variations in temperature were found to show no effects on the final yields.

The relationship between actual transpiration and yield was investigated for the Broadbalk field and for sugar beet and potatoes, using average yields determined by sampling methods, for various districts in England and Wales. For sugar-beet virus yellows infection, and for potatoes blight attack, were also taken into account.

No relationship between actual transpiration and wheat yields on Broadbalk field was found, but sugar beet and potatoes both showed a positive association between actual transpiration and yield except for sugar beet in the Spalding area, where there is a high-water table. Actual transpiration was in general more effective than a regression on total rainfall and its distribution accounting for variations in yield. As might be expected virus yellows and blight also account for a good deal of the variation in yield.

Over the 3 years of the experiment the salt in the top 2 ft. of the soil was reduced by almost a half of the original amount, and nearly all this was removed in the first season. The movement was downwards, and there was little evidence of any upward movement; flushing was not very effective in removing salt from the soil. The type of cultivation affected the amount of salt removed, deep subsoiling being most successful with over 50% removal, but irrigation without any cultivation removed 29%. The penetration of irrigation water was very restricted in the first waterings, but became increasingly deeper as the experiment continued.

Crop yields showed a steady improvement from season to season, the final average of about 1500 lb. per feddan being above the average for the district. The various treatments did not appear to have much effect on the yields, and the general improvement in yields is attributed to the reduction of salt content and to the deeper water penetration, chiefly the latter. The detrimental effect of the dry north winds was more apparent than the effects of the different treatments.

1. Dry-meal diets based on whitefish meal or soyabean oil meal, balanced in respect of minerals, and containing 28, 23 or 18% crude protein were given to pigs from 10 to 25 lb., and similar diets containing 18% crude protein were given from 25 to 40 lb. From 40 to 100 lb. and from 100 lb. to bacon weight all pigs were given the same diets with 16% crude protein and 14% crude protein, respectively.

2. From 10 to 25 lb. live weight the results showed that:

(a) With diets based on whitefish meal there was an improvement in growth rate of 11% (P < 0·05) and an improvement in feed conversion efficiency of 14% (P < 0·001) when the level of crude protein was increased from 18% to 23%. Growth rate and feed conversion efficiency were not improved further by increasing the level of crude protein from 23 to 28%.

(b) With diets based on soyabean oil meal, feed conversion efficiency and growth rate were not improved by increasing the protein in the diet from 18 to 23%, and performance was similar to that on the 18% protein diet based on whitefish meal. Pigs fed on the soyabean diet containing 28% protein were unthrifty and grew very slowly; some showed gastric ulceration.

(c) Consumption of the diets containing 18% crude protein was 8% higher (P < 0·05) than consumption of the other diets.

(d) Apparent digestibility of the dry matter of the diets, as measured by the chromic oxide marker method, rose as the pigs grew older, and apparent digestibility of the dry matter and crude protein of the diets based on soyabean oil meal was consistently lower than when whitefish meal was the main supplementary source of protein.

1. On cropping Agdell Experiment topsoils to exhaustion with perennial rye-grass in the glasshouse the total K uptakes were directly proportional to the initial exchangeable K contents of the soils.

2. The ability of the Agdell topsoils to release non-exchangeable K under glasshouse conditions decreased in the order: PK-rotation with fallow < NPK rotation with fallow < PK-rotation with clover < NPK-rotation with clover < no-fertilizerrotation with fallow = no-fertilizer rotation with clover.

3. Releases of non-exchangeable K were at least 2·5 times larger than the falls in the exchangeable K for all the Agdell soils.

4. In a ‘take-down’ experiment in the glasshouse on a soil receiving K fertilizer each year in the Saxmundham Rotation I Experiment, loosely held non-exchangeable K was released at a near-linear rate. At least a part of the loosely held non-exchangeable K in the Agdell soils was also released at a near-linear rate.

The exhausting effect of dura for a single year in a rotation was shown. Rotations including dura consistently yielded less than those including lubia or fallow. With 2 successive years of dura the reduction in yields of cotton was extremely large.

Substantial increases in yields of cotton were obtained when the first fallow of the CFF rotation was replaced by lubia. The superiority of the rotation CLF appeared to be firmly established in the Gezira, where the soil was known to be deficient in nitrogen. By growing lubia, instead of leaving a fallow 2 years preceding cotton, an average annual increase of 0·65 k.p.f. of cotton was obtained. Itwas interesting to note that fertility of rotation CLF over CFF was still increasing.

The use of a bone biopsy technique for skeletal studies with sheep is described. Histological examination of samples of pelvic bone removed at about mid-lactation from Scottish Blackface ewes grazing on two hill farms revealed little or no evidence of skeletal resorption. This was in agreement with the results of in vivo radiography carried out in this and another field experiment reported as part V of this series (Benzie, Cresswell, Duckworth, Hill and Boyne, 1961).

1. Studies on the mineralization of the skeletons Scottish Blackface wethers and breeding ewes have been carried out on three widely scattered and differing Scottish hill farms using field radiography and bone-ash analysis.

2. Regular small autumnal improvements in the density of the ewes' skeletons were detected by in vivo radiography using the right radii although, in general, the radii of the ewes were at all times considered to be in good condition (for Scottish Blackface sheep on the hill) and underwent no marked resorption (as judged from in vivo radiographs) during pregnancy and lactation. This was contrary to what was expected in view of the results of previously reported laboratory experiments (Benzie et al. 1955, 1956, 1959) and also in view of commonly held beliefs that hill pastures are, in general, deficient in calcium or phosphorus, or both of these dietary factors.

3. There were few significant flock differences (both ewes and wethers) for the values assigned to the radiographs or for the results of skeletal ash determinations even though the flocks were maintained in widely separated and differing locations and husbandry systems.

4. It is suggested that further field work along these lines may be of great value to the obtaining of a clearer understanding of the ewe: hill pasture relationship.

1. Two panels of eight students, with no previous experience in scoring bacon sides for eye-muscle qualities or for fatness, co-operated in an experiment involving thirty-five photographs of back rashers of bacon presented to them in batches of twenty at a time. The members of the first panel made their assessments without any guide, whereas those of the second were provided with sets of photographic reference standards showing a graded sequence of rashers scoring from 0 to 10 for each of the two characteristics involved.

2. Those provided with the reference standards spread out their scores over the available range more than those who judged without them.

3. Judging discrimination between markedly different groups of rashers was improved when the reference standards were available. This was not true of discrimination between similar rashers since repeatability of scoring was to some extent decreased when the standards were used.

4. When the reference standards were not available, these inexperienced judges tended to adjust their level of scoring according to the quality of the batch of rashers being assessed. This adaptive effect was eliminated when reference standards were available although apparently random fluctuations of level of scoring from batch to batch still occurred.

5. Differences between judges due to their different uses of the available range of scores were less marked, although not entirely eliminated, when reference standards were used by the naive judges. Systematic differences between the scores awarded by various judges remained, as did a few differences of opinion on the relative quality of certain examples.

1. The utilization of the energy of the same ration by sheep and by cattle was measured using three steers and three sheep in twenty-one and twentyfour experiments, respectively. Five different amounts of the ration were given to each steer and six different amounts to each sheep.

2. No differences of any magnitude were found in the percentage losses of dietary energy in faeces, in urine or as methane if comparisons were made at comparable nutritional levels. Faecal energy losses increased and urine energy losses and methane production fell with increase in feeding level, the feeding level being defined as the ratio of food intake to that required to attain an energy retention of zero.

3. The net availability of metabolizable energy for maintenance was the same in both species at 80·4%. The net availability of energy for the production of fat was 53·5 ± 1·4 in sheep and 51·4 ± 2·6 in cattle.

4. The results are discussed in relation to the effect of the amount of food given on the utilization of its energy. It is pointed out that net energy per unit of food declines with increasing intake, due firstly to a decline in digestibility and secondly to the fact that oxidative processes operative at and below maintenance are more efficient processes than is the synthesis of fat.