Thirty-eight experiments on swedes and turnips, using factorial designs without replication, were carried out to measure the responses and two-factor interactions produced by applying nitrogen, phosphorus and potassium. The effect of F.Y.M. was measured at fourteen of the centres.

The yield of tops was substantially increased by nitrogen. Phosphorus produced a moderate response but potassium had practically no effect on top growth.

The yield of roots showed small to moderately large responses to nitrogen in most experiments. There was a considerable variation in the rate required to produce the largest response, depending on the previous cropping of the field.

Phosphorus increased the yield of roots in all but four of the experiments and this nutrient generally had a greater effect than either nitrogen or potassium.

The response to potassium was significant in only half of the experiments and its effect on yield was normally less than that of nitrogen.

The two-factor interactions were practically without exception small and far from significant, the highest values usually occurring on responsive soils. The means show no interaction between nitrogen and phosphorus, and small positive interactions between nitrogen and potassium and between phosphorus and potassium.

F.Y.M. produced higher yields at the majority of the centres but had very little effect at some. At suboptimal P2O5 levels F.Y.M. tends to increase the response to nitrogen, but with adequate phosphorus this manure reduced the most profitable nitrogen rate. The response to phosphorus was markedly reduced by placing F.Y.M. in the bottom of the ridges but the effect of ploughing-in this manure during autumn or early winter on the phosphorus response was very small. In all experiments F.Y.M. produced a substantial reduction in the response to potassium.

As a result of the inadequate phosphorus rates these experiments do not provide satisfactory estimates of the amounts of nutrients supplied by F.Y.M. but suggest that 15 tons per acre will supply at least 15 lb. N, 15 lb. P2O5 and 70 lb K2O to the first crop grown after application.

The mineral composition of the roots showed large variations between crops grown on different soils. The application of a nutrient generally produced a small increase in its percentage in the roots. The nutrient uptakes showed a much greater apparent recovery of both nitrogen and potassium than of phosphorus.

The most profitable nutrient dressings have been calculated from these experiments, and at current prices about 65 lb. N, 125 lb. P2O5 and 125 lb. K2O should be about the average optimal rates per acre in the absence of F.Y.M. In the presence of a normal dressing of the latter suitable optimal rates seem to be about 50 lb. N, 110 lb. P2O5 and 55 lb. K2O.

Data from the chemical and dissection analyses of thirty-nine New Zealand Romney Marsh ewe carcasses are presented and compared. One side of each carcass was dissected into muscle, fat, and bone and the other side was totally ground and chemically analysed for water, fat, protein, and ash. There were strong statistical relationships between the two methods of carcass analysis and accordingly the quicker and more simple chemical technique could replace dissection in many carcass studies.

1. In the seeding year the total dry-matter yield in swards sown without a cover crop was increased by infrequent defoliation, but the yield of crude protein was decreased. The highest production of starch equivalent was obtained when a cover crop was used.

2. In the absence of a cover crop, the yield of red clover was higher under infrequent defoliation, but the yield of white clover was higher under frequent grazing.

3. Frequent grazing, and the use of a cover crop, reduced the ingress of weeds more than infrequent defoliation. Nitrogen applied to the cover crop also reduced the growth of weeds.

4. Nitro-chalk increased the total yield of herbage except when under a cover crop; it reduced the growth of red and white clovers, but this was not so marked under frequent grazing.

5. Nitro-chalk increased the annual yield of crude protein under frequent grazing, but decreased it in all herbage mixtures under infrequent defoliation; nitrogen had no effect when a cover crop was used. The increase in yield of starch equivalent due to the application of nitrogen and its apparent recovery was greater under frequent grazing than under the other two managements. Under infrequent defoliation, in the absence of a cover crop, the recovery of nitrogen was particularly low.

6. The ryegrass mixture and ryegrass-dominant general-purpose mixture made more growth, and suppressed clover and weeds to a greater extent than did the timothy and cocksfoot mixtures. This was modified by management in that ryegrass was particularly aggressive under frequent grazing (management 1) but not under managements 2 and 3.

7. In the autumn of the seeding year the yield of total herbage was highest under infrequent defoliation, particularly in the cocksfoot, and general-purpose swards. All undersown mixtures gave lower yields than when no cover crop was used.

8. Nitrogen increased the yield of herbage in May and June under frequent grazing, and in the August cut under infrequent defoliation, but in the autumn particularly it was reduced where a cover crop was used.

9. The application of nitrogen decreased the protein content in all herbage mixtures when a cover crop was used or when defoliation was infrequent. Under frequent grazing the nitrogen increased the percentage of crude protein in the first two grazings, but decreased it in the September grazing.

10. The production from the various mixtures was modified by management: under frequent grazing in May the ryegrass-dominant mixtures were higher yielding than the others, but in July the general-purpose and cocksfoot swards were the most productive. Under infrequent defoliation in August the timothy mixture had the highest yield and cocksfoot the lowest, and under this management cocksfoot and timothy swards had the highest yield in the autumn of the seeding year.

1. The rectal temperatures of shorn and unshorn Awassi sheep were measured at various hours of the day and during various seasons of the year in two different locations in Israel.

2. An increase in body temperature accompanied an increase in environmental temperature. A steeper temperature increase was noted in shorn sheep kept in the shade. When ambient temperatures were below 30° C. the body temperature of shorn sheep was lower than that of the unshorn sheep by an average of 0·16° C.

3. When ambient temperatures were above 30° C. the body temperature of shorn sheep was equal to or higher than that of unshorn ones.

4. Upon exposure to direct sunlight, the body temperature of shorn sheep exceeded that of unshorn animals. However, when the animals were transferred to the shade, or after sunset, the shorn sheep cooled at a faster rate. Their body temperature fell below that of the unshorn sheep during the cool hours of the day.

5. Wind velocity, both in the shade and in the sun, had a greater effect on shorn than on unshorn sheep.

6. A rise in the relative humidity of ambient temperatures above 25° C. caused body temperature to rise, particularly in unshorn animals. The body temperature of shorn sheep exceeded that of unshorn ones when the animals were maintained in a hot and dry environment.

7. While the body of the shorn sheep was entirely affected by the macroclimate, the unshorn sheep were greatly influenced by the microclimate existing in the fleece. Fleece temperatures always lagged behind and were rarely equal to environmental temperatures. Since it was postulated that heat tolerance of certain animals was related to their ability to exploit cool hours of the day, it is suggested that in certain ‘tolerance tests’ records should be taken not only during exposure to heat but also during cool hours of the day.

1. The method of establishment markedly affected the yield of red clover in the first harvest year, the highest yield being obtained when a cover crop was used, in the absence of which red clover yield was reduced by frequent grazing during establishment. White clover made little growth in the first harvest year; the yield was best without a cover crop under frequent grazing during establishment.

2. Nitrogen applied in the seed bed did not affect the growth of red clover in the first harvest year, but depressed the white clover under infrequent defoliation without a cover crop. There was no significant effect under the other management.

3. The total yield of red and white clovers was lower, when sown with the rapidly establishing ryegrass or ryegrass-dominant general-purpose mixtures, than with cocksfoot or timothy mixtures. Weed growth, although not prominent, was far greater in the timothy and cocksfoot swards than in those based on ryegrass.

4. A close parallel existed between the growth of red clover and the dry matter and yield of crude protein. The highest figures were recorded when management during establishment had favoured the growth of the red clover.

5. Nitrogen applied in the seed bed reduced the percentage of crude protein in all mixtures in the spring and autumn grazings, and in the hay crop of the first harvest year. Management which encouraged the growth of red clover increased the crude protein percentage of herbage in the spring and autumn, but depressed it in the aftermath cut.

6. A number of interactions occurred when the relative yields of dry matter and crude protein of mixtures in the first harvest year were modified by treatments applied during establishment. There are significant indications that the method of establishment is a factor to be considered in evaluating various mixtures.

1. A survey of commercial crops of spring oats suggested tilth as a major factor affecting emergence.

2. In field experiments conducted on clay and sandy soils, the surface tilth was regarded as a population of aggregates characterized by size which was analysed by means of a five-point quadrat. A tilth index was calculated from the data thus obtained. Under the rough tilths on the clay soil emergence and tilth were directly related, but on the sandy soil there was an optimum degree of cultivation, the plots with the finest tilth had been over-cultivated and gave a low rate of emergence (Fig. 2).

3. A greenhouse pot experiment examined the effect of a cover above the seed of 21 tilths, of varying proportions of 0·03–0·25 in., 0·25–1·25 in., 1·25–2·25 in. diameter aggregates, the soil below the seed being uniform in all treatments. This confirmed that emergence rates were higher under fine surface tilths than under very rough tilths (Fig. 3). An increase in the proportion of 0·03–0·25 in. fraction increased emergence regularly whereas an increase in the proportion of the 1·25–2·25 in. fraction reduced emergence regularly. The presence of 0·25–1·25 in. aggregates reduced emergence compared with that where 0·03–0·25 in. only were present, but the effect of an increase in the proportion was not regular (Fig. 4).

4. A second greenhouse pot experiment compared the effect of 3 tilths above the seed and 2 irrigation treatments. The low emergence rate (58%) caused by a very rough tilth under restricted irrigation was raised to 86% by liberal irrigation.

5. From the evidence of both pot experiments it is postulated that a covering tilth above the seed of 25% or more by weight of fine soil (0·03–0·25 in.) and not more than 40% of coarse aggregates (1·25–2·25 in.) will permit a rate of emergence of at least 80%.

6. As the fine covering tilths in the pot experiment gave high rates of emergence as compared with rougher tilths, it is suggested that the low rate of emergence, on the sandy soil field experiments, was due to a lack of soil moisture induced by over-cultivation.

The following conclusions were obtained from a comparison of growth and carcass characteristics of pigs slaughtered at 150, 200 and 260 lb. liveweight.

(a) The ranking of boars at the three weights, according to the quality of their progeny at each weight, was similar for the carcass characteristics, i.e. percentage of lean meat, length, backfat and eye muscle area—but was not associated for the efficiency factors, i.e. daily gain and food conversion. Results from singly-penned progeny pigs confirm that food consumed up to 150 lb. live weight is not indicative of the food consumed between 150 and 200 lb. live weight. A similar result is true for daily gain. It thus does not appear that the results obtained at 150 lb. live weight could be used to represent results at heavier weights and this is particularly true for performance testing when only one animal is concerned. Rather it would appear that if the pigs were raised to a given weight, carcass information at an earlier weight could be obtained on the live pig by ultrasonic means and by subjective estimates, whilst food conversion and daily gain could be calculated exactly at any live weight.

(b) The weights of the different cuts as a percentage of the side weight does not appear to change much between slaughter weights. The carcass becomes less lean as the slaughter weight increases and this difference in leanness is more observable between the 200 and 260 lb. weights than between the 150 and 200 lb. weights. In these ranges at least as much lean as fat is put on in the shoulder and ham but more fat than lean is put on in the back and in the streak. For example, between 200 and 260 lb., 5 lb. of lean to 9 lb. of fat is added in the back cut.

(c) For all cuts and for both sexes, the percentage of lean meat added in the range 200–260 lb. live weight is less than that for the range 150–200 lb. live weight. This difference is more severe for hogs, especially in the back cut. The sex difference (in favour of the leaner gilt) becomes more pronounced at the heavier weight range. This is not so obvious in the ham but is marked in the shoulder and streak and particularly in the back. 3·9 lb. of food is required to put on 1 lb. of live weight between 150 and 200 lb., whilst 4·3 lb. of food is needed for each 1 lb. gain between 200 and 260 lb. live weight.

(d) Percentage of lean meat prediction equations fitted to the data at the three weights are of equal accuracy. In all cases the reduction in variance is highly significant and the percentage of lean meat of a pig can be estimated with a standard error of approximately 2% of carcass weight.

1. A comparison was made between the pulse rate of shorn and unshorn sheep maintained in the shade and direct sunlight during the various seasons of the year.

2. The variability of the pulse rate during the day generally agreed with the daily changes in body temperature and presumed level of metabolism. Fluctuations were greater in unshorn sheep.

3. Pulse rate was lower during summer (60–100 for unshorn and 63–100 for shorn sheep) than in winter (90–130 for unshorn and 90–115 for shorn sheep). It tended to increase with a rise in ambient temperature, especially during winter and spring. A lower pulse rate accompanied a rise in environmental temperature, during summer. The slowest pulse rate of 42 per minute was observed during summer in the hot dry area.

4. The pulse rate of both groups increased with a rise in rectal temperature, particularly at low ambient temperatures. At comparable rectal temperatures, a higher average pulse rate was observed in shorn sheep during winter and spring. With elevated summer temperatures, equal pulse rates were noted in both groups of equal rectal temperatures. Since the rectal temperatures of the shorn exceeded that of unshorn sheep, in high environmental temperatures, and in the sun, their pulse rate under these conditions was also higher.

5. The differences in pulse rate between the two groups appeared to reflect the combined effects of metabolic rate, body temperature and the vasomotor activity, all of which vary with season and environmental temperatures.

1. Ten experiments were carried out on grassland in various parts of England and Scotland to compare ammonium nitrate, ammonium sulphate, urea with less than 1% biuret and urea with about 4% biuret. The grass was cut a number of times during the season and each nitrogen fertilizer was applied at rates supplying 30 and 60 lb. per acre of nitrogen in spring and after each cut except the last.

2. Total yield and yields at most individual cuts of both dry matter and nitrogen in the herbage were increased by each increment of applied nitrogen.

3. Ammonium nitrate and ammonium sulphate gave similar dry-matter yields at all cuts in six experiments, while in four on calcareous soils ammonium sulphate gave lower yields than ammonium nitrate at one or more cuts. Ammonium sulphate gave lower yields at the second or third cuts in more experiments than at the first cut.

4. Urea with < 1% biuret gave lower dry-matter yields than ammonium nitrate at one or more cuts in eight of the ten experiments. Urea became less efficient relative to ammonium nitrate as the season advanced.

5. The efficiency of urea with < 1% biuret relative to ammonium nitrate in each experiment was positively correlated with the ammonia absorption potential of the soil.

6. Urea with < 1% biuret and urea with about 4% biuret gave similar yields.

1. Respiration rate of shorn and unshorn sheep was compared; animals were maintained in the shade and in direct sunlight during various seasons of the year, and at different hours of the day. The average respiration rate, for all seasons when sheep were maintained in the shade, was 55 and 32 respirations per minute, for the unshorn and shorn sheep, respectively.

The diurnal trend of the respiration rate of shorn sheep resembled that of the ambient temperature. There was a delay in the lowering of respiration rate of the unshorn sheep during the evening hours.

2. The critical temperature for the increase in respiration of animals maintained in the shade was 22° C. and 26–30° C. for the unshorn and shorn sheep, respectively.

When the animals were exposed to the direct sunlight the critical ambient temperature for the increase in respiration rate was 15–18° C. and 18–22° C. for the unshorn and shorn sheep, respectively. The respiration rate of the shorn sheep exceeded that of the unshorn but decreased very steeply when the animals returned to the shade.

3. The effect of humidity was noted particularly with ambient temperatures exceeding 27° C. The respiration rate of the unshorn sheep increased and that of the shorn decreased with the rise in the relative humidity. In the sun there was a rise in the respiration rate of both groups with increase in humidity. The rise was steeper in the shorn animals.

4. The effect of the wind in reducing respiration rate was particularly noted on shorn sheep and at elevated ambient temperatures.

5. With equal rectal temperature, the respiration rate of shorn sheep was lower than that of the unshorn ones. Assumed critical rectal temperature for the rise in respiration rate was lower in the unshorn sheep.

6. The differences between the respiration responses of the unshorn and shorn sheep stemmed from the variation in their thermal balance. The latter resulted from the differences in the insulating characteristics of body surface and the differences between the macroclimate and the microclimate existing in the fleece.

Correlations between various characteristics at each weight indicate that (i) a good percentage of lean is associated with increased bone, a larger eyemuscle area and, in particular, less backfat; (ii) the carcass conformation score for 260 lb. hogs has a high negative association with average backfat and this may be because the extreme amounts of fat on some these hogs adversely affected the balance of the carcass.

Visual scores or assessments made on the shoulder, ham, streak and on the carcass conformation bear no relationship to the proportionate weights or to the leanness of the respective parts of the carcass. They reflect only the requirements of the trade which are based on shape and are not substantiated by dissection. In nearly all cases, gilts achieve better scores than hogs. The back rasher score assessed on a good fat to lean ratio and a good eye muscle is much higher for gilts than for hogs and decreases as the slaughter weight increases. There is a positive association between back rasher score and the leanness of the back.

1. 4 g. of Mg per day given as either magnesium oxide or magnesium nitrate failed to increase plasma magnesium levels of fourteen lactating ewes which had initial values of about 1·0 mg. Mg/100 ml.

2. Increases which were recorded 4 hr. after drenching were not sustained for the full 24 hr. period between drenches.

1. An experiment is described which investigated the effects of potassium fertilizer, age of ewe, and a small magnesium supplement, on the plasma magnesium and calcium levels of ewes shortly after lambing.

2. Three potassium treatments (0, 1, and 2 cwt. muriate of potash/acre) were used, each being replicated six times, which gave a total of eighteen plots. Each plot was grazed by two old and two young ewes. One ewe of each age in every plot was given supplementary magnesium in the form of two magnesium heavy pellets, which released a total of 150 mg. Mg/day.

3. 22% of the ewes had plasma magnesium values below 1·0 mg. Mg/100 ml. on at least one sampling occasion during the experimental period. There was only one clinical case of tetany.

4. Neither potassium fertilizer use, nor magnesium supplementation influenced plasma magnesium and calcium levels of the ewes. Old ewes had greater temporary falls in plasma magnesium values and had consistently lower plasma calcium values.

5. Attention is drawn to the large individual variation between animals and the consequent need for providing adequate statistical analysis of experiments of this type.

Four hundred and twenty-two ewes, of a number of different breeds and ages (flocks 1–9) were used in experiments with hormones in the normal breeding season. Two main trials were conducted, the first making use of 377 animals, the second involving 45.

Trial 1

Three hundred and seventy-seven ewes were observed, in eight farm flocks, in a study of response to different treatments involving the administration of progesterone (in oil solution) and p.m.s. The trial sought to determine the effect of various dosage levels of progesterone and intervals of injection on the normal breeding performance of the ewe. Hormone treatment was applied at such time in the breeding season as to make it most improbable that conception would be limited by adverse animal or environmental factors. The aim was to determine the effect of the hormone technique per se on both immediate and long-term reproductive performance. Injection procedures and methods of flock management were arranged so that they might later be repeated in applications during the period of anoestrus.

Two hundred and thirty-three ewes were injected intramuscularly with doses of progesterone in oil solution over a 7-day period. For eighty-nine ewes, four doses of 40 mg. were administered at 2-day intervals; for 144, 3 doses of 50 mg. were given at 3-day intervals. A single injection of 750 i.u. of p.m.s. was given subcutaneously to each ewe 2 days after the final dose of progesterone. One hundred and forty-four ewes remained untreated and served as a control.

Progesterone therapy was effective in inhibiting oestrus and ovulation in the majority of ewes. Most injected animals came in oestrus 1–5 days following the injection of p.m.s.; 10% showed evidence of ‘silent heat’. 70% of ewes receiving progesterone at 2-day intervals and 68·2% of those receiving it at 3-day intervals conceived at the ‘controlled’ oestrus. 75% of the controls conceived at first mating. Treatment did not adversely affect the conception percentage to any appreciable extent.

In animals conceiving at first oestrus, the average number of lambs born per ewe was 1·78 for injected and 1·44 for controls. In each flock there was an increase in lamb-crop, which would seem to be the result of the p.m.s. injection. Information on the effect of therapy on subsequent ewe fertility shows that 6·4% of ewes failed to conceive; this figure was the same for both treated and control animals. An attempt to use A.I. in conjunction with progesterone- p.m.s. therapy gave a conception percentage of 24, as compared with 68 in normally bred sheep.

The results are discussed in relation to factors such as breed and age of ewe, and according to the particular mating procedure employed. There is no evidence that the forms of progesterone-p.m.s. therapy employed in this work would constitute a limiting factor to conception in out-of-season breeding.

Trial 2

The forty-five mature Welsh Mountain ewes used were in one flock. Each animal was injected on the 13th day of the oestrous cycle with a single dose of either 50 or 100 mg. of a micro-crystal suspension of progesterone. Two forms of suspension were used, the difference between the two being in the size of the individual crystals. Ewes came in oestrus 7–13 days following injection, the range for 50 mg. dosage being 7–13, and for 100 mg. 10–13 days. 25% of animals showed ‘silent heat’. Results suggest that injection of suspension adversely affects the normal expression of oestrus.

1. A comparison was made between the skin temperature, humidity and temperature within and on the surface of the fleece of unshorn and shorn sheep. This study was conducted during various seasons of the year, at different environmental temperatures, while sheep were maintained in the shade or subjected to direct sunlight.

2. Accompanying the rise of ambient temperature (in the shade) from 10 to 43° C. there was an increase in skin temperature from 34 to 40° C. and from 28 to 40° C. of the unshorn and shorn sheep, respectively.

3. The relationship between the rise in skin temperature and that of ambient temperature was not linear, but showed a stepwise pattern in which the ‘breaks’ occurred at similar environmental temperatures for both groups, although skin temperatures of shorn sheep were lower than the unshorn.

4. The diurnal change in skin temperature of the shorn sheep was similar to that of the ambient temperature. The decrease in skin temperature of unshorn sheep sometimes lagged behind the fall in environmental temperature. The seasonal variations between summer and winter were more significant in shorn than in unshorn sheep.

5. Fleece surface temperatures measured at the same ambient temperatures ranged between 13 and

42° C. and 16·5–39·5° C. in the unshorn and shorn sheep, respectively. In the break points of the rise in skin temperature, there occurred a drop in temperature gradients between the skin and fleece surface. This probably indicates a rise in thermal conductivity of the fleece at these points.

6. The temperature gradient per unit of fleece thickness is inversely related to the depth of fleece and is greater the nearer to the skin.

7. With exposure to the sun, skin temperatures of both groups greatly increased and occasionally reached 47° C. Under these conditions the differences between shorn and unshorn groups were not consistent.

8. Fleece temperatures of unshorn sheep increased greatly upon exposure to the sun. The maximal temperatures were recorded midway between the fleece surface and skin. These temperatures generally reached 55° C. and sometimes even exceeded 60° C.

9. At ambient temperatures of 30–35° C. the vapour pressure close to the skin of unshorn sheep ranged between 35–40 mm. Hg. With shorn sheep, however, the vapour pressure close to the skin was similar to that of the environment. In Yotvata there was a rise in vapour pressure close to the skin when the ambient temperature increased to 40–43° C. This rise in humidity was paralleled by a rise of vapour pressure throughout the wool. It was not linear but rather showed a ‘step-wise’ pattern.

10. The vapour pressure in fleece and near the skin of sheep subjected to direct sunlight increased considerably (up to 80 mm. Hg). This rise showed a wave-like curve with various degrees of persistency. Appearance of fluid on the skin of Awassi sheep was observed on several occasions.

1. An experiment, lasting 3 years, was carried out to investigate the control of hypomagnesaemia on a medium-heavy loam soil in Northern Ireland, using as criteria herbage analysis and analysis of blood sera of grazing dairy cows.

2. Applications of calcined magnesite and magnesian limestone as soil treatments raised the magnesium contents of herbage slightly but not to levels judged to be safe. Low blood sorum magnesium levels were recorded for cows grazing this herbage although no cases of tetany occurred.

3. Magnesium sulphate, appliedas a spray, temporarily raised the ‘apparent’ magnesium content of the herbage but was easily washed off by rain.

4. Finely powdered calcined magnesite applied as a dust to the herbage immediately before grazing appeared to be a promising method of control under Northern Ireland conditions.

1. The contents of moisture, total nitrogen and intramuscular fat (and its iodine number), and the ultimate pH, were determined on longissimus dorsi (lumbar and thoracic regions), psoas major, rectus femoris, triceps (lat. head), superficial and deep digital flexor, sartorius and extensor carpi radialis muscles from ten pigs, of accurately known history, in each of three weight groups—pork, bacon and manufacturing (150, 200 and 250 lb. live weight, respectively).

2. In addition, the myoglobin content of longissimus dorsi (lumbar), psoas major, rectus femoris, triceps (lat. head) and extensor carpi radialis was also determined. In all five muscles there was an increase in pigment content with increase of body weight, but there was some suggestion that the myoglobin content of psoas major and triceps showed a proportionally greater increment between pork and bacon weights and rectus femoris and extensor carpi radialis between bacon and manufacturing weights.

3. In pigs of all three weight groups there were highly significant differences in fat-free moisture content between muscles and between animals. The mean, fat-free moisture content of longissimus dorsi (lumbar) (76·33%) is significantly less than that of longissimus dorsi (thoracic) (76·94%) and the mean value in the latter is significantly less than that in all the muscles except psoas major (77·28%). The mean fat-free moisture content of deep digital flexor (80·00%) is significantly higher than that in all the other muscles studied. There is evidence for a direct, but not linear, relationship between the contents of fat-free moisture and connective tissue (as calculated from hydroxyproline concentration).

4. Differences in ultimate pH between animals and between muscles were highly significant; but not those between the three weight groups, although there was a tendency for higher values in the muscles from bacon and manufacturing groups.

5. Both for the data overall, and within a given muscle, there was a direct proportionality between ultimate pH and fat-free moisture content. Except in the case of deep digital flexor correlation coefficients between these two parameters were significant. These correlations varied in significance for different muscles between the three weight groups.

6. Overall, the mean total nitrogen content (fat-free) of longissimus dorsi (lumbar) (3·77%) was significantly greater than that of longissimus dorsi (thoracic) (3·69%) and the latter greater than that of psoas major (3·58%). Such differences were also apparent within each weight group. The values were significantly greater than those for the six other muscles studied. The overall mean fat-free nitrogen content of deep digital flexor (3·17%) was very significantly less than that for all the other muscles. For the muscles of pork, bacon and manufacturing weights, overall nitrogen contents (fat-free) were 3·38, 3·44 and 3·55%, respectively. There was a significant inverse correlation between nitrogen (fat-free) and moisture (fat-free) (r = –0·88).

7. The ranking of muscles with respect to their contents of intramuscular fat was significantly different between weight groups. In contrast to the bovine, there was no significant difference overall between the intramuscular fat contents of longissimus dorsi in lumbar and thoracic regions; and these were both significantly higher than levels in psoas major, although the converse is true in the bovine.

8. Variation in the intramuscular fat content of the lumbar region of longissimus dorsi was strongly reflected by those in longissimus dorsi (thoracic), psoas major, rectus femoris, triceps and superficial digital flexor; but little with those in extensor carpi radialis and deep digital flexor; and not at all with that in sartorius.

9. There was no significant difference overall in the iodine number of intramuscular fat between weight groups. Iodine numbers in both thoracic and lumbar regions of longissimus dorsi were significantly lower than those in all the other muscles studied. The overall correlations between intramuscular fat and its iodine numbers were r = –0·70, – 0·71 and – 0·66 in pigs of pork, bacon and manufacturing weights: each of these was significant.

10. In discussing the results, it is suggested that those circumstances causing a high ultimate pH in muscle (e.g. fatigue) may concomitantly effect redistribution of body water and hence explain the observed proportionality between water content and ultimate pH. Significant differences in moisture content between muscles may be related to their relative proportion of connective tissue or to its nature. On the basis of much of the chemical data obtained, the muscles studied appear to fall into three groups—longissimus dorsi (lumbar and thoracic), deep digital flexor, and the rest, although such a conclusion does not accord with that suggested by anatomical dissection. Aspects of the relative maturity of the muscles are considered.

This paper deals with the application of various forms of progesterone-p.m.s. therapy to lactating and non-lactating ewes in the anoestrus of 1957. Twenty-one farm flocks, and a total of 753 sheep were used in three trials (3–5). In trials 3 and 4, the treatment employed techniques similar or identical to those employed in the previous breeding season (Part I of this series). Trial 5 was concerned with the use of micro-crystal suspensions of progesterone as a possible means of simplifying hormone administration procedure; again this was a follow-on to work in the 1956 breeding season. Applications of progesterone-p.m.s. therapy were made at two periods in anoestrus, April to May (deep anoestrus) and June to early August (late anoestrus). Observations on the occurrence of spontaneous breeding were made following hormone applications at these two periods, and studies on ram libido and fertility attempted. The main objective of the work was to determine whether low conception percentage is due to defective ram performance or to a failure in the supply of hormones essential for the maintenance of pregnancy. A preliminary attempt was made to induce previously injected ewes (lactating and non-lactating) to show a ‘repeat’ oestrus by extended treatments with progesterone and p.m.s.

Trial 3

Three hundred and twenty-one ewes, predominantly Chin Forests, were treated in April/May in twelve flocks. In five of these some proportion or all animals were lactating at time of injection. Six different combinations of progesterone and p.m.s. were employed. The majority allowed for pretreatment with progesterone over a 7-day period; doses of progesterone varied from 25 mg. (at daily intervals) to 50 mg. (at 3-day intervals). In each ewe, a dose of 750 i.u. freeze-dried p.m.s. was given 2 days after the final progesterone dose. One hundred and eighty-eight ewes mated (58·6%) 1–5 days after the end of treatment. The oestrous response was affected by various factors of treatment and animal. Progesterone treatment over 7 days gave rise to a higher response than did treatment applied over 5 days. Evidence of low libido in some rams was obtained, and possible methods for overcoming this problem are described.

Sixty-six of the ewes conceived and produced lambs, this being 20·6% of all animals injected and 34·4% of ewes which mated. An average of 1·39 lambs born per ewe conceiving was recorded. Nonlactating ewes conceived more readily (41·5%) than lactating (17·4%). Where ewes were subjected to extended hormonal treatment, to induce a ‘repeat’ oestrus, 26·9% conceived at first induced oestrus and 54·1% at the ‘repeat’ oestrus, a difference which was statistically significant (P < 0·05).

Trial 4

Three hundred and thirty-two non-lactating ewes, differing in age and breed, were used in studies conducted mainly in June/July. Eight different combinations of progesterone and P.M.S. were employed. For the majority, progesterone was administered over a 7-day period at 2-day (40 mg.) or 3-day (50 mg.) intervals. A single dose of 750 i.u. freeze-dried p.m.s. was given 1–4 days after final progesterone injection. Two hundred and eightyfive animals (85%) were served 1–5 days after the end of treatment. Ninety-two ewes conceived at the induced oestrus and produced lambs; as a percentage of those injected this is 27·7, and as a percentage of those that mated, 32·6. Average number of lambs born per ewe was 1·72. In the ewes which ‘repeated’ spontaneously after hormone treatment, 58·9% conceived. This was a significant increase over conception percentage at induced oestrus, but the average number of lambs born per ewe was lower (1·25).

Results on oestrus, conception and lambing in trials 3 and 4 are discussed in relation to treatment, ram fertility, breed and age of ewe, and several environmental factors. They indicate strongly that conception failure lies at time of implantation of the egg, possibly due to some inadequacy in the uterine environment. Conception may be facilitated where animals are either hormonally induced to show a ‘repeat’ oestrus or show it spontaneously. Factors of fundamental and practical interest in out-ofseason breeding are described, including length of gestation, incidence of lamb mortality and pregnancy toxaemia.

Trial 5

A total of 100 ewes, of several breeds and ages, and including sixty that were lactating received treatment with a micro-crystal suspension of progesterone, either in conjunction with p.m.s. or with doses of progesterone in oil and p.m.s. Treatments were applied in five individual groups during the period of deep anoestrus (April/May). The majority of ewes were given an initial injection of 50–200 mg. suspension, followed 7–8 days later by a single dose of 25 mg. progesterone in oil solutions; 750 i.u. of p.m.s. was administered 2 days after the final progesterone dose. 13% of animals mated after treatment and 2% conceived and produced lambs. The results for oestrus and conception were considerably poorer than those following the normal progesterone-p.m.s. technique.

1. A survey was carried out on dairy farms in the south of Scotland during the period 1958–59 to obtain information on: (a) the mineral element composition of spring pastures associated with grass tetany or staggers and hypomagnesaemia, and (b) the influence of magnesium supplements on the incidence of these conditions and on serum magnesium levels.

2. Pastures associated with grass tetany had a significantly lower average magnesium and sodium content and a higher potassium content than those which were classed as normal. These differences were magnified in the values of the ratios K/(Ca + Mg) and (K + Ca + P)/(Mg + Na) which were considerably higher in tetany pastures. The incidence of tetany was positively correlated with the value of the former ratio. These results are similar to those obtained in Holland.

3. The analytical results for pastures associated with hypomagnesaemia in clinically normal cows were not significantly different from those for normal pastures and there was no evidence of any association between the composition of the pasture and the incidence or severity of the hypomagnesaemia or the serum magnesium levels.

4. The magnesium and sodium contents of the majority of the pastures examined would be judged as inadequate in the light of available information on the requirement of these elements.

5. There was no evidence of any correlation between the magnesium content of the pasture and that of any of the other elements studied.

6. Cases of grass tetany occurred in 25% of the 108 herds studied, the mean incidence in affected herds being 4·5 ± 0·65%. The overall incidence was 1·1 ± 0·25% and was significantly lower when a magnesium supplement was given as a prophylactic measure.

7. Hypomagnesaemia was detected in clinically normal cows after turning out in 41·2% of the herds, the overall incidence being 8·7 ± 1·0%. On tetany free farms the feeding of calcined magnesite or magnesium-rich mineral mixtures did not appear to reduce the incidence of hypomagnesaemia or the fall in serum magnesium levels which occurred after turning out.

8. These results emphasize the wide individual variation in the susceptibility of different cows to the factors causing hypomagnesaemia and grass tetany and also the differences between the two conditions in their dietary relationships. It is suggested that dietary factors may be responsible for producing the clinical signs of grass tetany in hypo-magnesaemic cows.

1200 chicks comprising 300 each of Light Sussex × indigenous, Rhode Island Red × indigenous, White Leghorn × indigenous and Black Australorp × indigenous cross-breeds were reared from day old to 24 weeks under good conditions of feeding and management and growth rates, food consumption and feed conversion measured weekly to assess any improvements brought about by cross-breeding the indigenous poultry of Uganda and compare the value of the four imported breeds for this purpose.

Growth rates of the indigenous birds were greatly improved by crossing with Light Sussex, Rhode Island Red and Black Australorp cockerels, the Light Sussex cross giving the best results, but the White Leghorn cross not greatly improving the growth rates of the indigenous birds.

Crossing with Light Sussex and Rhode Island Red cockerels gave birds with greatly improved feed conversion figures over the indigenous poultry, with the Light Sussex cross again being superior, and nearly as good as the imported breeds. Crossing with Black Australorp and White Leghorn cockerels did not produce birds with improved feed conversion rates over the indigenous poultry.