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. Twenty-four Merino ewes acclimatized to a hot environment were compared with twenty-four kept at normal temperatures, with respect to ovulation rate and embryonic loss by 25 days' pregnancy. Possible modifying effects of the three subsidiary factors, thyroxine level, vitamin A intake and progesterone level, were sought. The design of the experiment was a balanced factorial one.

2. While the differences between the hot-room and yard groups as a whole were not significant, in the former there were fewer ovulations, a smaller proportion of the potential embryos actually began to develop and, of these, a larger proportion had died by 25 days' pregnancy. Consequently only thirteen hot-room ewes contained live embryos compared to twenty in the yard; the total numbers of live embryos were fourteen and twenty-seven, respectively.

3. Of the subsidiary factors only thyroxine produced any marked effect. Both in the hot-room and in the yard the proportion of potential embryos developing and the proportion of actual embryos surviving at 25 days' pregnancy were greater where thyroxine injections were given. There appeared, however, to be no effect on ovulation rate. There was a significant increase in the proportion of hot-room ewes with live embryos due to thyroxine. Grouping hot-room and yard ewes together, thyroxine injections were associated with a significant increase in the proportion of potential embryos developing and in the proportion of actual embryos surviving; also, consequently, in the proportion of ewes with live embryos.

4. The results are discussed in relation to published work on the effects of high temperatures on reproduction.

1. Honey-bee colonies were fed either concentrated or dilute sugar syrup, or remained unfed, in spring, summer, and autumn of 1958 and 1959.

2. More concentrated than dilute syrup was accepted in every experiment, but the proportion of concentrated to dilute syrup accepted decreased during the course of both years.

3. The concentration of syrup fed made no apparent difference to the gain in weight relative to the sugar taken, probably because the greater efficiency in storing concentrated syrup was offset by the diminution in foraging produced.

4. Feeding dilute or concentrated syrup increased brood rearing during and after feeding in one year (bad weather) but had no effect on brood rearing in the other year (good weather).

5. While being fed colonies usually collected more pollen than they otherwise would.

6. Feeding either concentration of syrup probably decreased nectar gathering when foraging conditions were good, and concentrated syrup may have decreased it more than dilute syrup.

1. Worker bees learnt the colour of their hive in the close vicinity to their hive entrance and took little or no notice of colours above the lower brood chamber. They orientated to a colour below the entrance more than to a colour above. They did not learn combinations of colours.

2. They distinguished between certain symbols placed immediately above the hive entrance.

3. They learnt the height of their hive and the height of its entrance above ground.

4. More worker bees and drones from queenright colonies drifted to queenless than to queenright colonies. Drones expelled from queenright colonies did not drift to queenless colonies.

1. From repeated fibre samplings and several skin biopsies on six Tasmanian Fine Merinos and eight Wiltshire Horn adult ewes variations in fibre diameter, fibre growth rate, and fibre regeneration or shedding frequency were measured over a period of 15 months. Slight differences were present in the treatment of the two breeds, but from the combined evidence of the live weights and fibre diameters maintained, it was concluded that these were negligible, that both breeds were under closely comparable conditions, and that their performance was at a moderately high and typical level for each breed.

2. In the Merinos fibre diameter (ca. 20 µ) fluctuated little during the period of observation, whereas in the Wiltshires it varied over a wide range from less than 40µ in winter to more than 80µ in summer. There were negligible differences between the three body regions, back, side, and belly, in the Merinos, but in the Wiltshires the belly grew markedly coarser fibres than the other two regions.

3. The fibre growth rate in the Merinos did not vary greatly from 7 to 8 mm. per 28 days throughout the period of observation or between the body regions. In the Wiltshires, fibre growth rate showed extreme variations from a minimum of about 3 mm. during the winter to a maximum of about 12 mm. per 28 days at the end of summer, with significant differences between the three body regions. However, in spite of these differences in the mode of growth, the total length of fibre grown per annum at the midside was approximately the same (10 cm.). Thus, were it not for fibre shedding, the Wiltshire Horn breed would grow a short-wool fleece.

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.

The flock books of fourteen Lowland breeds of sheep were examined to study flock size, flock age, the number and source of rams used, the extent to which flocks differ in genetic importance within their breeds, the effect of geographical location on flock attributes, and changes in breed organization over a period of time.

All breeds taken together showed that 46% of the 2649 flocks involved had less than fifty breeding ewes and 15% had more than 200. 43% of flocks were less than 5 years old and 18% were over twenty. A third of all flocks used only one ram and 9% used five or more. All breeds were found to be arranged in a hierarchy such that only a small number of flocks in each breed supplied the majority of the rams and in particular the rams used by rambreeding flocks. The ‘top’ flocks were among the largest and oldest in each breed. Flocks in the ‘native’ region of each breed we e generally larger and older than those elsewhere, but for other flock attributes the differences between regions were more peculiar to breeds. The general pattern of breed organization appeared to apply at widely differing periods of time.

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.

The influence of undersowing on the establishment of broad red clover and Italian rye-grass was investigated under three managements and two levels of nitrogen applied in spring. The following conclusions are drawn:

1. The cereal cover crop reduced the aggressiveness of Italian rye-grass towards red clover.

2. The cereal cover crop produced a high initial yield of dry matter and crude protein. In midseason, when keep from maiden seeds is important, the highest yield was obtained in the absence of the cereal cover crop.

3. The danger of failure in the take of undersown herbage seeds is increased when soil moisture is very low.

4. Total dry-matter yield in the seeding year was increased by using a cover crop, but starch-equivalent yield was not greatly affected. Crude-protein production was increased when the cover crop was cut for silage or frequently grazed, but not when a grain crop was harvested.

5. Undersowing Italian rye-grass and clover gave a higher yield of dry matter, starch equivalent and crude protein than sowing the herbage after the cereal was harvested.

6. The cover crop depressed weed growth, and ‘Nitro-Chalk’ increased it, except where Italian rye-grass was undersown.

7. The application of ‘Nitro-Chalk’ increased the yield of dry matter, particularly early in the seeding year. ‘Nitro-Chalk’ encouraged the growth of Italian rye-grass and oats but depressed the clover. This reduction in legume yield was least when defoliation was frequent. The influence of nitrogen on plant growth was especially noticeable when soil moisture was low and a cover crop used.

1. Fifty-four dairy type calves were grazed together on a perennial-type pasture. At regular intervals from birth to 17 weeks individuals were slaughtered and the weights of their reticulorumens, omasums and abomasums were immediately recorded.

2. The recitulo-rumen had the fastest growth rate of the organs of the stomach and the abomasum had the slowest.

3. During the first few weeks after birth, the four stomachs altered rapidly in proportion to the live weight of the calf. By 17 weeks of age, the reticulo-rumen apparently had not reached a constant weight relative to live weight.

4. As a percentage of the total weight of the three organs, the reticulo-rumen reached a relatively constant proportion by about 8 weeks of age.

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.

1. Four experiments in 1958 and five in 1959 compared responses to potassium (as combinedrilled muriate of potash) in the absence of nitrogen and in the presence of single and double doses of nitrogen (as broadcast sulphate of ammonia) on soils selected because they contained very little acid-soluble potassium.

2. Responses to 0·5 cwt. K2O/acre were obtained at six centres (two significant), but the effects of a further 0·5 cwt. K2O/acre were more variable and gains and losses (each at four centres) were almost equally balanced.

3. Gains from nitrogen were associated with previous cropping. N1 raised yields at seven centres (six significantly), but N2 raised yields further at only five centres (three significantly) and depressed yields significantly at three centres where barley followed a root crop or ley.

4. Potash did little to improve the strength of straw and therefore standing capacity in a wet season (1958) and had little effect upon the size of the grain, whereas nitrogen increased lodging and reduced the average size of the grain.

5. Increases in potassium uptake were associated with yield increases, whereas increases in nitrogen uptake were associated with both higher nitrogen percentage in grain and higher yields.

1. A procedure for fractionating the magnesium in fresh herbage into acetone-soluble, watersoluble and insoluble magnesium fractions is described.

2. Magnesium soluble in Analar acetone is shown to be virtually identical to chlorophyll magnesium, and generally represents less than 10% of the total magnesium.

3. Water-soluble material represents about 25% of the total dry matter, but contains more than 50% of the total magnesium when the herbage contains 0·2% or more Mg in the dry matter.

4. The fibrous material, which is soluble neither in acetone nor water, constitutes about two-thirds of the total dry matter, but has only about onethird of the total magnesium associated with it.

5. Highly significant correlations were found between total magnesium content and each of the three fractions, but regression coefficients showed that variations in total magnesium were largely reflected in the water-soluble fraction, the chlorophyll and fibre magnesium being affected to a much smaller degree.

6. Attention is drawn to the fact that at levels of pasture magnesium at which hypomagnesaemic tetany occurs in ruminants, water-soluble magnesium ceases to be the largest fraction and may be only about one-third of the total.

1. Two experiments were conducted to study the development of rumen function in young dairy calves under different feeding regimes.

2. The volume of the rumen contents increased with age whereas the volume of the abomasum contents tended to remain constant.

3. The concentration of total volatile fatty acids in the rumen liquor of milk-fed calves with free access to pasture reached constant levels at 5 weeks of age. Restricting calves to an all milk diet delayed the development of adult levels of volatile fatty acids until such time as roughage became available.

4. Levels of rumen ammonia were high soon after birth but showed a decline with age. An absence of roughage in the diet tended to maintain higher levels of rumen ammonia.

5. The pH of rumen liquor showed a steady increase from birth to 17 weeks of age.

6. Both volatile fatty acid and ammonia levels in the rumen showed a characteristic diurnal pattern of variation.

7. High figures for the digestibility of pasture by young calves were obtained. When calves which had been restricted to an all milk diet were offered roughage they quickly attained a digestive efficiency comparable with calves which had access to pasture from birth.

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. Three experiments are described in which dicalcium phosphate was fed as a phosphatic supplement to beef-type zebu cows and weaner calves grazing at Muguga in the Kenya Highlands.

2. The treatment caused an increase in the level of inorganic phosphate in the bloods only during times of drought, when it also caused an improvement in the condition of the cows. A slight beneficial effect on fertility was noted throughout the experiment.

3. Evidence was found that other nutritional factors were causing considerable variation and it is suggested that more attention should be given to improving the general level of nutrition of cattle during dry seasons.

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.

An attempt to find the effect of humidity on hatchability and at the same time indicate the optimum humidity for incubation was carried out by subjecting eggs in one incubator to various levels of humidity and comparing the results with eggs hatched as a Control in a second incubator of identical design.

Hatchability was depressed by excessively high levels of humidity but in general satisfactory hatches can be obtained between 40 and 70% R.H.

The pattern of mortality, the incidence of Malposition I but not Malpositions II, III and VI were affected by humidity level.

The optimum level found, c. 50% R.H., was lower than the previously accepted optimum and may be accounted for by a number of factors including egg size.

Eggs were incubated at various frequencies of turning (tilting through 90°) and their hatchability compared with eggs incubated as controls at 24 turns per day evenly distributed throughout the 24 hr. The turning treatments were: 0, once in 2 days, 2, 6, 12, 48, 96, 144, 192 and 480 turns per day.

Differences in hatch of fertile eggs between the treated and control eggs at each level of turning were obtained and used to indicate the trend of hatchability in response to varying turning frequency and also the optimum rate of turning. This was observed to be 96 turns per day. Nil or few turns per day gave very poor results and at very high frequencies (up to 480x) hatchability decreased only slightly relative to the turning frequency.

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.