In the communication: ‘Studies of the skeleton of the sheep. III. The relationship between phosphorus intake and resorption and repair of the skeleton in pregnancy and lactation’, D. Benzie, A. W. Boyne, A. C. Dalgarno, J. Duckworth & R. Hill, J. Agric. Sci. (1959), 52, 1–12, Plates 3 a and 3 b have been interchanged.

1. Pure swards of S. 48 timothy and S. 215 meadow fescue were cut (a) after ear emergence, (b) before ear emergence and in the aftermath to prevent flowering, and (c) every 4 weeks. The number and weight of tillers and leaves were determined.

2. Tiller numbers declined considerably from early spring to the middle of summer. This fall was reduced by a system of frequent defoliation in the wet summer of 1956, especially in timothy.

3. Leaf weight per unit area of sward increased rapidly from early spring until about the time of ear emergence; no further significant gains were recorded after ears had appeared, when the plots were cut for hay.

4. The weight per leaf also increased in the spring and was similar in both species. In the regrowth following a cut meadow fescue produced considerably heavier leaves than timothy.

5. As both grasses approached the flowering stage, their leaf canopy was increasingly raised above ground level. Variable proportions of foliage were thus removed by cutting according to the developmental stage of the plant. Crop growth rates following a cut appeared to be related to the amount of leaf material remaining in the sward.

6. Relative growth rates during uninterrupted growth were greatest around the time of ear emergence.

During the 12 months from September 1955 to August 1956, the reproductive tracts and ovaries of 4094 adult Merino ewes, recovered from the municipal abattoir at Pietermaritzburg, were examined. The great majority of the ewes had been consigned to the abattoir from one of three regions, between which differences in the nutritional value of the natural vegetation at different times of the year are recognized. From observations of the occurrence in the ovaries of active corpora lutea, it appeared that in some areas, mating Merino ewes during autumn and early winter is likely to result in the greatest percentage of ewes conceiving and in the highest lambing percentages. There was a suggestion, however, that in the more arid karoo areas, the percentage of ewes ovulating, as well as the mean ovulation rate per ewe, may remain relatively constant throughout the year. It seems likely that the low fertility of ewes of this breed may be due partly to the practice of introducing the rams into the flock at a time of year (spring and summer) in which many of the ewes are anoestrous, a practice which is often adopted in South Africa in order to avoid the poor growth rates which are known to occur among young lambs as a result of the high temperatures and the internal parasite infestations that are comcommon in the summer months. A need, in different areas, for extensive experimental evidence of the most suitable season for mating, is indicated.

No evidence of nutritional effects on fertility, either within or between areas, was obtained, but it is suggested that a higher proportion of ewes in certain areas may be capable of lambing in autumn as a result of more effective selection for this trait in these areas. There is also evidence that lack of fertilization of ova and early embryonic death may contribute significantly to the breed's low fertility.

Corpora lutea were observed more frequently in the right ovary than in the left. In gravid uteri, a greater proportion of foetuses were found in the right horn and, in addition, significantly more ova apparently migrated from the left ovary to the right horn than from the right ovary to the left horn. The numbers are given of large (diameter > 4 mm.) and medium (diameter 2–4 mm.) follicles observed in the ovaries both of non-pregnant ewes and of ewes in different stages of pregnancy, these stages having been estimated from measurements of foetal crownrump lengths.

1. Three calves were individually exposed in a climatic room to an environment of 45° C. dry-bulb and 28° C. wet-bulb temperature for 21 successive days up to 5 hr. each day.

2. In the 21-day period, mostly during the first half of it, the following changes in the physiological reactions of the animals were observed: progressive reductions in rectal temperature, in heart rate and in respiratory rate with a change of breathing from a laboured to a less laboured type.

3. It was suggested that a decrease in metabolic heat production might play a part in the observed acclimatization.

1. Three calves were exposed in a climatic room to an environment of 40° C. dry-bulb and 38° C. wet-bulb temperature for up to 110 min. each day for 1-2 weeks.

2. These exposures produced progressive changes in the physiological reactions of the animals to heat:

(a) Rectal temperature and skin temperature (for a given time of exposure) declined. In consequence there was a marked increase in the tolerance time, i.e. in the time for which the animals could withstand the hot environment before reaching a rectal temperature of 42° C.

(b) Respiratory rate rose earlier and assumed higher levels (for given levels of body temperature).

(c) Heart rate decreased markedly.

3. These changes are discussed in relation to heat loss and heat production and have been interpreted as reflecting chiefly a reduction in the metabolic heat production of the animals.

The evidence from these combined variety × plant density experiments, together with the additional data on varieties previously reported (Bunting & Willey, 1958), suggests that, for fodder or ensilage production in Britain, the varieties we have designated as ‘medium’ (i.e. within the range represented by the hybrids Wis. 275 and Wis. 341 A), sown to give a final density of 9–12 plants/sq.yd. would be most suitable. Higher plant populations probably give slightly higher yields, but the differences will rarely be of practical importance and are likely to be offset by the greater incidence of lodging and the consequent increase in harvesting difficulties.

1. Eight experienced judges used a 20-point scoring scale in different ways when assessing the ‘proportion of lean to fat’ from the same photographs of cut bacon sides presented in the same arrangements. The average score for the 220 judgements made during the experiment by a single judge, which represents his over-all level of scoring or ‘standard of judging’, ranged from 13·7 to 12·0. The standard deviation, a measure of the degree of discrimination attempted by the judge, ranged from 3·26 to 4·74.

2. The judges varied in their consistency of assessment or ‘repeatability’. The standard error for a single judge, measuring the extent of the variation of his scores within photographs, ranged from 0·89 to 1·99. The judges who attempted to discriminate most between photographs tended to be the least consistent in their judgements, although one judge was a notable exception to this trend.

3. The consistency of judgement tended to decrease from the good (high-scoring) rashers to the poor (low-scoring) rashers, but this effect was more marked for some judges than for others.

4. Some of the variation in the scores awarded to each photograph was due to alterations in the standard of judging from batch to batch. When this was allowed for, the standard errors were all reduced and ranged from 0·61 to 1·31. The judges tended to adjust their standards according to the average quality of the batch being assessed. This led to the variation among the average scores for the batches being less than it would have been had their standards remained constant.

5. Alterations in the standard of judging during the experiment affected the scores awarded to good (high-scoring) rashers rather less than those awarded to poor (low-scoring) ones.

6. The correlations between the individual judge's mean scores for the forty-four photographs and the over-all mean scores were very high. For seven judges, they ranged from 0·962 to 0·984, whereas for the eighth judge the correlation was 0·918. The lower correlation for this judge was due to two rashers with very thin fat being heavily marked down.

7. The correlations between the over-all mean scores and two different combinations of three objective measurements were both about 0·92; these measurements were therefore slightly less closely related to the over-all scores than were an individual judge's mean scores.

8. The possibility of making the experimental technique more realistic and of improving the precision of such visual judgements by providing photographic scales of reference are discussed.

1. Attempts to investigate the physical properties of bran, and other feedingstuffs, with regard to their ability to absorb and retain water, have been outlined.

2. Two experiments have been described in which pigs were fed bran, fibrous cellulose, or different levels of powdered cellulose, added to normal pig rations. These experiments involved 24 hr. faecal collections, and ultimate slaughter of the animals, together with analysis of faecal material and gut contents.

3. The addition of bran or fibrous cellulose to a ration causes a reduction in the average percentage of dry matter in the faeces, but tends to emphasize fluctuations in faecal dry-matter percentage, which are attributed to fluctuations in rate of passage through the large intestine.

4. The behaviour of the powdered cellulose was anomalous, giving rise to hard stools. It appeared to be almost inert in relation to water.

1. Two experiments have been described in which pigs were fed different levels of fibrous cellulose superimposed on a highly digestible purified basal ration. These experiments involved 24 hr. faecal collections and ultimate slaughter of the animals, together with analysis of faecal material and gut contents.

2. The results of these experiments, together with those from experiments described in the previous paper in this series, have provided the basis for a discussion of the effects of adding bran and cellulose to pig rations, and of the influence of the progress of the residues of feeds through the digestive tract, on the pattern of excretion and the dry matter content of the faeces.

1. An experiment has been described in which pigs were fed rations containing four different levels of cellulose, each ration being fed successively at three different levels of water intake. The cellulose levels were superimposed on a highly digestible basal ration.

2. It appears that altering the level of water intake, while keeping the ration constant, has only a very limited effect on the level of faecal dry-matter percentage, and on the pattern of variation therein.

3. Further evidence is cited in support of the theories, advanced in a previous paper, relating to the influence of fibrous cellulose on water relationships in the digesta and faeces.

1. A total of forty pigs (four litters) were slaughtered at weekly intervals from birth to 5 weeks of age.

2. Results are given for the changes in weight of different parts of the digestive organs and their contents with increasing age, and for the content of NaCl and of total acidity in the stomach contents.

3. Stomach pH was on average more alkaline than pH 3.4 at all ages up to 5 weeks; the average pH of the duodenum was 6.5 and of the small intestine 6.4.

4. Total NaCl and total acidity in stomach contents remained roughly constant from birth up to 5 weeks of age. No free HCl was detected in any of the stomach contents of the pigs.

5. The consistency of the stomach contents varied with the age of the pig; the hard milk clot which was characteristic of the contents at 2–3 weeks of age appeared softer and more broken in older pigs.

1. Forty Large White pigs varying in age from birth to 5 weeks were slaughtered and their carbohydrate digesting enzymes studied for any change in activity with increase in age.

2. Pancreatic amylase, sucrase and maltase increased from low levels at birth to high levels at 5 weeks of age.

3. The total amount of lactase present at birth and of small intestine amylase at 1-week-old was maintained at a constant level up to 5 weeks of age. The increased weight of the intestine with the growth of the pig made the quantity of these enzymes appear to decrease with age when the values were expressed per kg. body weight or per g. dry tissue.

4. Anaemia had no marked effect on the activity of the enzymes though the rate of enzyme development appeared to be retarded in the case of maltase.

5. The quantity of pancreatic amylase present in the pancreas was sufficient at all ages to digest the amounts of starch likely to be included in a synthetic diet. Maltase, on the other hand, appeared to be limiting in early life.

1. The efficiency of food conversion by pullets and yearlings fed on high- and low-energy diets has been determined.

2. Egg production was slightly higher by birds fed the low-energy diet for both pullets and yearling hens; pullets laid more eggs than yearling hens.

3. For each age, the gross food intake was greater for birds fed the low-energy diet; the consumptions of digestible protein, non-protein digestible energy and metabolizable energy were the same for both diets and both ages of bird.

4. The food cost per dozen eggs was slightly greater in the yearling year when the cost of rearing the pullets was ignored, and about the same when it was included.

5. The efficiency of utilization of digestible energy and protein showed only a slight decrease from the pullet to the yearling year.

6. The variation in the composition and digestibility of eighteen consecutive mixes of the highenergy diet and twenty-five of the low-energy diet was: crude protein 2%, non-protein digestible energy 5% and metabolizable energy 0·4 kg. cal./g. The digestibility of the crude protein and oil was 87%, for both diets; carbohydrates were 81% digestible in the high-energy diet and 59% in the low-energy diet.

1. The normal pattern of grazing behaviour of free-range indigenous cattle under conditions of lenient stocking and overstocking has been studied throughout the year.

2. There was a fairly fixed daily pattern of herd behaviour. The cattle usually started day grazing round sunrise and ceased approximately 1 hr. after sunset. There was a morning and afternoon peak of intense grazing activity separated by a rest period and watering about midday. There was usually one peak of night grazing.

3. The average daily grazing times varied from 8 hr. during the rains period of relative feed abundance, to about 13 hr. during the dry season period of malnutrition.

4. During the dry season there were no major differences in grazing times between the leniently stooked and overstocked groups. Both herds were losing weight.

5. The relatively greater weight gains of the overstocked herd compared with the leniently stooked group during the rains resulted from the increased grazing times of the overstocked herd.

6. The night grazing remained fairly constant at approximately 20% of the total daily grazing time.

7. There were no seasonal effects on the pattern of grazing behaviour. High daytime temperatures did not cause an increase in the proportion of night grazing of indigenous cattle.

1. The structure of the muzzle of the cow, its blood supply and the histochemistry of its glands have been studied.

2. The nasolabial glands are multilobular compound tubulo-acinar glands similar in structure to salivary glands. They secrete a watery mucincontaining fluid. It is suggested that they may be sweat gland homologues.

3. Arterio-venous anastomoses are present in the muzzle. Their possible function is discussed.

4. Although this investigation has shown how much the muzzle differs from the rest of the integument no particular function can be ascribed to it on the basis of the findings described.

Ten calves were exposed for 3 hr. to an atmosphere in which the dry-bulb temperature was 40° C. and the wet-bulb temperature 33° C, (a) with their normal coats, and (b) after their coats had been clipped.

When clipped the calves tolerated the same hot environment better than they did before they were clipped, as evidenced by significant reductions in skin temperature, rectal temperature, respiratory rate and heart rate, as well as by a lessening of various manifestations of distress.

This effect of clipping was thought to be due mainly to an improvement in skin, evaporative cooling.

Farmyard manure affected the response of the potato crop to fertilizers similarly in seven series of experiments (sixty-two in all) at Rothamsted, and in the West Midlands and north of England.

In the absence of f.y.m. there were large interactions between each of the fertilizer nutrients, but with f.y.m. the interactions were small. These interactions appear to have been ignored by previous workers, who claimed that N responses ar unaffected by dressings of f.y.m. In fact, f.y.m. increased the response to N applied alone, but decreased the N response where basal P and K fertilizers were also applied. For P the results were similar to those for N.

Most of the experimental sites were low in K, and K responses were very large, especially in the presence of basal NP fertilizer. Farmyard manure greatly reduced the response to K, particularly in presence of basal NP fertilizer.

A few Rothamsted experiments with f.y.m. and fertilizers and several times of planting showed that the large responses to f.y.m. alone and to fertilizers used in combination (but without f.y.m.) were not reduced by late planting. The result conflicts with previous reports of these data, in which interactions between nutrients were ignored. The combined effect of f.y.m. and fertilizers at late planting was little more than their separate effects, presumably due to delayed maturity, the influence of which would be exaggerated by the early burning-off of haulm in this series of experiments.

Most of the experiments were limited to testing fertilizers at two levels (presence and absence), so the effective quantities of nutrients provided by f.y.m. for the crop to which it was applied could only be estimated approximately; the average amounts suggested for normal f.y.m. are 0·3 cwt. N, 0·4 cwt. P2O5 and 0·75 cwt. K2O in 10 tons f.y.m.

These results lead to the practical conclusion that, in manuring potato crops on average land, much the same plant food ratios will be appropriate whether or not F.Y.M. is given, and the amount of fertilizer applied can be decreased to allow for the nutrients contained in the f.y.m.

Since this paper was completed, Reith & Inkson (1958) have presented results for a further series of factorial experiments with f.y.m. and fertilizers in north-east Scotland, 1947–54. The authors claimed that for N their results confirmed those of Crowther & Yates; however, their Table 3 gives results very similar to those presented here: i.e. in the absence of f.y.m., PK basal greatly increased the response to N, but was ineffective where f.y.m. was also applied. The authors appear to have appreciated that these results, based on individual plot yields, were inconsistent with their main conclusions drawn from main effects and first-order interactions only, but do not seem to have realized their significance.

Eighty-three fertilized sheep ova were stored at 0–8° C. for 6–72 hr. in sterile sheep serum or Ringer's solution and subsequently transferred to suitable recipient ewes in order to determine their viability following storage.

In Exp. 1, nine out of twelve ova stored in sheep serum, but none out of five ova stored in Ringer's solution, continued development after subjection to storage at 5–8° C. for 6–9 hr. Seven out of fifteen, none of nineteen, and none of nine ova were found developing in recipients after subjection to 5–8° C. in serum for 24, 48 and 72 hr., respectively.

In Exp. 2, lambs were born to recipients of four out of six ova stored for 24 hr. at 4·5–7° C, and of two out of five ova stored for 72 hr. at these temperatures. None of the recipients of twelve ova stored for 24, 48 and 72 hr. (four ova of each duration) at 0·4° C. produced live lambs.

In Exp. 3, none of thirty-four ova developed after subjection to freezing to −79° C. in 12·5% glycerol in serum.

1. Symptoms of zinc deficiency and toxicity have been studied in guar, brinjal, maize, tobacco and Mosambi (Mozambique) using a sand-culture technique.

2. In zinc-deficient guar plants, depressed vegetative growth and smaller leaves than normal ones were found. Only few flower buds were seen, and there was abscission of leaves at the time of flowering.

3. Chlorosis followed by necrosis and finally the drying up of leaves was the most characteristic deficiency symptom in the case of brinjal; growth was stunted and flowers failed to set fruits.

4. In the newer leaves of maize, intermittent light yellow bands were formed just parallel to the midrib.

5. In the lower leaves of tobacco, chlorosis followed by necrosis was observed; growth was stunted and leaves were small in size.

6. In Mosambi (Mozambique), whitish yellow patches in between the veins were observed; leaves were small, pointed and quite unhealthy.

7. There was an increase in zinc uptake with increased rates of application of zinc.

8. Crude protein increased with increasing zinc supply up to levels beyond the optimum for growth.