1. The visual judgement of bacon quality called the ‘proportion of lean to fat’ has been simplified by breaking down the overall assessment of the surface seen on the cut bacon side at the last rib into four simpler scores—of the ‘eye’-muscle size and shape, the amount and distribution of fat on the back rasher, the streak thickness and the proportion of lean to fat in the streak, each judged on a 10-point scale. An experiment is described in which eight experienced judges attempted to score these new characteristics in conjunction with the overall assessment.

2. The judging standard adopted in the overall assessment of the proportion of lean to fat varied less from batch to batch in this experiment (in which the seven batches were arrayed in fixed positions and assessed in one day) than in an earlier experiment (when the examples seen in each batch could be shuffled and the eleven batches were seen several days apart). The ranking of judges according to their discrimination and repeatability for the overall assessment was also changed in the second experiment.

1. In an experiment conducted on an established perennial rye-grass/white clover sward close cutting was carried out over a 3-year period (1956–58), either with a lawn mower to simulate gang mowing or with a reciprocating-knife mower. The sward was cut either six or eight times in each season, and received 0 or 2 cwt. ‘Nitro-Chalk’/acre for each cut.

2. Swards cut with the gang mower yielded from 3·5 to 12·5% more herbage dry matter than swards cut with the reciprocating-knife mower and also gave a greater mean yield of crude protein.

3. The difference in dry-matter yield between swards cut with each of the mowers is attributed to the slightly closer cutting level of the gang mower having a greater inhibiting effect on flower development in the grasses and hence stimulating leaf production and increasing total yields.

4. In the second and third years of the experiment swards cut with the gang mower outyielded those cut with the reciprocating-knife mower by a proportionately greater amount when eight cuts rather than six cuts were taken in the season.

5. When no nitrogenous fertilizer was applied the proportion of broad-leaved weeds in the sward increased more rapidly over the 3-year period where the herbage was cut with the gang mower rather than the reciprocating-knife mower. This disadvantage of gang mowing did not apply where the fertility was maintained at a high level by applications of nitrogenous fertilizer.

6. It is concluded that the gang mower is a more suitable machine than the reciprocating-knife mower for close cutting on a field scale.

1. A study was made of the effects of a milk diluent on bull, ram and boar spermatozoa. Respiration and fructolysis of spermatozoa were used as the two main criteria of sperm activity. The milk diluent was a standardized and commercially available milk product, consisting of sterilized and homogenized milk, supplemented with milk fat.

2. The rate of oxygen uptake measured manometrically in the presence of air was increased by the addition of the milk diluent throughout the entire incubation period. Fructose utilization was assessed by the rate of lactic-acid production. The rate of the anaerobic lactic-acid formation was higher in the presence of the milk diluent during the later stages of incubation.

3. The effect of the milk diluent on sperm respiration was most striking in experiments with the sperm-rich portion of boar ejaculate obtained by fractionated collection. A somewhat less marked effect was observed with bull semen, and in ram semen the effect was comparatively weak.

Gilts of the ‘Palouse’ breed were divided into two groups; one group was full fed from weaning to 1501b. and the other group was fed 70% of full feeding. After six generations, one-half of the pigs in each group were shifted to the other plane of nutrition, thus forming four groups: high-high (HH), low-high (LH), low-low (LL) and high-low (HL). F10 gilts were slaughtered 38 or 100 days post-coitum to study reproductive and prenatal phenomena.

1. Ten successive generations of controlled feeding had no significant effect on: length of Fallopian tubes, weight of corpus luteum, percentage of implantation, number of viable foetuses, foetus weight, weight of placental membranes, volume of placental fluids or embryonic mortality.

2. There were significant differences between the high and low planes of nutrition in: weight of pituitary, thyroid and adrenals, weaning weight, puberty weight, puberty weight to birth weight, puberty weight to weaning weight and puberty age. The effect of six generations of controlled feeding was not maintained when the plane of nutrition was changed from high to low or low to high.

3. The frequency of silent heat and the number of services per conception was lower in the low planes than in the high planes.

4. Ova migration occurred in both directions in 41% of the gilts; one to four ova migrated. The foetal sex ratio ranged from 4:0 to 1:7 with an average of 1:1. The sexes were unevenly distributed in the horns.

5. Foetus weight at 38 or 100 days post-coitum was not affected by plane of nutrition or sequence in the uterine horn.

6. Within-litter variations were highest in the volume of allantoic fluid followed in order by variations in weight of placental membranes and then the amniotic fluid and foetus.

7. Foetal mortality was not related to sequence in the uterine horn or the number of implantations.

8. There seemed to be two peaks of early prenatal mortality, one at implantation and another at the onset of organo-genesis.

A field experiment was carried out to study the effect on spring oats of undersowing with broad red clover, Italian rye-grass and a mixture of both. Two levels of nitrogen were used, namely, no nitrogen and 3 cwt. per acre of ‘Nitro-Chalk’.

1. Oat shoot weight was reduced by undersowing, Italian rye-grass having a greater effect than red clover, particularly where nitrogen was applied.

2. In the absence of nitrogenous fertilizer undersowing did not reduce oat plant height, but where nitrogen had been given, Italian rye-grass either alone or in a mixture with the clover, reduced the height; the legume alone had no effect.

3. Undersowing generally reduced the number of oat panicles. Italian rye-grass had no effect when nitrogen was not applied, but a marked reduction was observed when nitrogen was applied. The legume had the greater influence where nitrogen was not applied.

4. Red clover increased the number of whorls, and the number of single-grained spikelets per panicle. Grass sown alone or with clover reduced the number of single-grained spikelets per head.

5. The total number of grains per panicle, 1000 grain weight, percentage husk and the percentage of saleable grain were not influenced by undersowing.

6. No lodging occurred but there was an indication that resistance to bending of the straw was affected by undersowing with Italian rye-grass.

7. Seeding herbage under the oats had a bigger influence on the yield of straw than grain. Italian rye-grass sown alone or with clover reduced the yield of straw where nitrogen had been applied. The legume alone had no effect. Grain yields showed a similar trend.

8. Yield and percentage crude protein in the straw were reduced by Italian rye-grass alone or in a mixture with clover when nitrogen was applied, but there was no effect where nitrogen was withheld. The grass had a greater effect than red clover while a mixture of both was intermediate to the legume and grass sown separately. Italian rye-grass greatly reduced the recovery of applied nitrogen by the cereal.

9. The percentage moisture in the oat sheaves was increased by undersown herbage and red clover had a bigger influence than the grass. The application of nitrogen reduced the bulk of clover under the cereal and its adverse influence on the harvesting of the oats. In the absence of undersowing, nitrogen had no effect on the percentage moisture in the sheaves.

1. The effects of annual applications of 0–12 cwt. per acre of sulphate of ammonia on the herbage levels and yields of sulphate sulphur and total sulphur were investigated in four seeds mixtures 1 year and 4 years after seeding down.

2. There were significant increases in the levels and yields of both forms of sulphur up to the 2 or 4 cwt. per acre level of application in both years. The maximum values occurred at the 6 or 8 cwt. level and the corresponding values at the 12 cwt. per acre rate of application declined in many cases.

3. The cumulative effects of the annual dressings of sulphate of ammonia resulted in substantial increases of approximately 50% in the levels of sulphate sulphur and total sulphur with much smaller increases in the levels of non-sulphate sulphur.

4. Duplicate plots which received 2, 4 and 6 cwt. per acre of sulphate of ammonia also received an additional 2 cwt. per acre immediately after the first cut each year. This splitting of the dressings had no significant effect on the accumulation of sulphur by any seeds mixture. A second cut from the cocksfoot plots in the first year showed the sulphur levels in the plots which received the additional sulphate of ammonia to have increased less than the levels in those which received only the initial dressing. This was explained in terms of the yields of the components.

5. There was a tendency for the rye-grass mixture to contain more sulphate than the other mixtures particularly in the fourth year.

6. The possible significance of the increases found in sulphate levels in the copper-molybdenum metabolism of grazing animals is discussed.

Swarm preparations are leas frequent (at least during July and August in southern England) among colonies with queens reared in the current year than among those with queens of the previous year (Simpson, 1957). Queens which had survived one and two winters are now considered; they are described as 1- and 2-year-old, respectively.

1. Statistics of several measured parameters are reported. They show that fermentation rates of rumen contents from zebu and European-type cattle in East Africa differ due to time of feeding, to individual animals, and to differences between zebu and grade.

2. The fermentation products were determined as acid, CO2 and methane. The proportion of methane showed an inverse correlation with the rate of fermentation.

3. The mean fermentation rate showed a trend in the direction expected from the weight gains of the animals.

1. A factorial experiment on wether hoggs was carried out to examine the effects on bone growth and composition and on blood composition of four dietary factors. The factors were extra calcium, phosphorus, vitamin D, and energy in the form of starch, and each was fed in all possible combinations, so that there were sixteen dietary treatment groups in all. Each group consisted of three animals.

2. Serum calcium and blood inorganic phosphorus concentrations were determined monthly, and radiographs of most parts of the skeleton were taken at the beginning and end of the experiment. After about 6 months on the experimental diets the animals were killed and the ash weights and percentage of ash of different parts of the skeleton and of the whole skeleton were determined. Live-weight changes and food intakes were also measured.

An experiment on the use of wheat straw (ploughed in or composted at the rate of 53⅓ cwt./acre every second year) and NPK fertilizers in the maintenance of fertility was carried out at Rothamsted between 1933 and 1958. The effects of these treatments on the yields of the crops of the rotation used in the experiment—barley, sugar beet, potatoes—are discussed in the present paper.

The treatments appear to have had no effect on crop yields through improvements to the soil caused by better structure or increased organic matter content. All the effects obtained can be attributed to changes in the supplies of available nutrients. The most important of these changes appear to have been: (1) nitrogen deficiencies due to the immobilization of soil nitrogen or nitrogen fertilizer by the straw: there is some evidence that this added to the store of slowly available nitrogen; (2) additions to potassium supplies from potassium in the straw. Factor (1) affected all three crops. Factor (2) affected potatoes, the only crop of the three to give good responses to potassium.

It was found that when the straw was ploughed in directly about 0·08 ewt. N fertilizer applied to the crops for each ton of straw was sufficient to overcome losses in yield due to nitrogen deficiencies. The straw improved the yields of potatoes in the first and second years after application. Provided that allowance was made for losses of available nitrogen the yields of potatoes from ploughed-in straw were about the same as the yields obtained by adding K fertilizer to the crop, equal in amount to the potassium in the straw. When part of the fertilizers was ploughed in with the straw instead of being given directly to the crop the yields of potatoes were reduced.

Compost made with NT fertilizers and straw and ploughed in with K fertilizer gave much poorer yields than were obtained by ploughing the straw in directly and applying the fertilizers to the crops. Losses of available nitrogen were severe, all the N fertilizer used in making the compost (0·15 cwt. N for each ton of straw) being either lost through drainage or immobilized by the straw. In addition, more than one half of the potassium in the straw was lost in composting.

There was no evidence that any of the nitrogen immobilized in the decomposition of the straw became available in the first or second years after application. Residues from repeated applications of straw every second year over 18 years increased the yields of potatoes and sugar beet in the last 6 years of the experiment. The increases may have been due to the release of previously immobilized nitrogen.

1. The ratios of water drunk:hay eaten were studied for groups of Zebu and grade Hereford steers.

2. In all comparable conditions the ratio was significantly smaller for the Zebus.

3. Restricting water availability to about half significantly reduced the ratios for both types of steers.

4. The decrease in hay eaten resulting from restriction of water was less for the Zebus.

5. Restricting the hay intake to approximately half significantly increased the ratios for both groups.

6. The Zebus drank significantly less water than did the grades in relation to body weight.

7. It is concluded that the results of water restriction may not be as disastrous as would have appeared likely from the constant ratio relationship of water and food intakes previously suggested, particularly in the case of the Zebu steers who have been shown to be better adapted to dry conditions.

Studies have been made on calcium and inorganic phosphorus in pasture grass and their relationship to blood levels in Zebu cattle.

Excitement, adrenaline injections and fatigue were investigated as possible causes of variations in the inorganic-phosphorus levels of the blood of Zebu cattle.

Sudden rainfall appeared to cause alterations in the inorganic phosphorus levels of blood. This hypothesis, when tested on two separate batches of cattle on two occasions, showed that there was a highly significant relationship between water intake and the level of inorganic phosphorus of Zebu cattle blood.

Water starvation caused a steady increase in the level of inorganic phosphorus and when water was available for the cattle to drink the inorganic phosphorus level fell rapidly to a subnormal level before returning to normal. These results are discussed in the light of the available literature.

1. An experiment was carried out over 2 years to study the effect of stocking rate on the efficiency of pasture utilization by dairy cows on irrigated perennial pasture.

2. Two matched groups of milking cows grazed throughout the experiment on two unequal areas of pasture at stocking rates of 1·0 and 1·7 cows/acre during the first season and 1·2 and 2·0 cows/acre during the second season (L and H groups, respectively). The same rotational grazing technique was used on both areas.

3. In each season the experimental period lasted 249 days. During the first 200 days and 215 days of this period in the first and second seasons, respectively, pasture, grazed or conserved (from the same proportion of both areas), comprised the entire ration.

4. The H group produced 57 and 59% more milk per acre than the L group during the first and second seasons, respectively. Milk production per cow in the H group was not significantly depressed. The solids-not-fat content of the milk in both seasons, and the butterfat content in the first season, were significantly depressed at the higher stocking rate.

5. The body-weight gain of the cowa in the H group, relative to those in the L group, was depressed by 68% (from 170 to 55 lb./cow) and 88% (from 172 to 20 lb./cow) in the first and second seasons, respectively.

6. The yield per acre of utilized pasture, based on the nutrient requirements of the cows, was 39 and 38% higher at the higher stocking rate in the first and second seasons, respectively. The estimated individual intake of these cows in the two seasons was depressed by 14 and 20%, respectively. The estimated yield per acre of utilized pasture ranged from 4092 lb. s.e. at 1·0 cows/acre to 6519 lb. s.e. at 2·0 cows/acre.

7. The mean daily herbage intake during the second season, estimated by a herbage clipping technique, was 29·5 and 22·9 lb. dry matter per cow for the L and H treatments, respectively. The cows in the H group ate, at each grazing, all the herbage that had grown since the previous grazing, whereas the estimated intake of the L group was equivalent to only 80% of this regrowth. However, the estimated rate of regrowth of the swards on the two treatments was the same.

8. Herbage intake estimates derived from a faecal-indicator technique, and observations of the grazing behaviour of the cows provided more detailed information on the pattern of herbage availability on successive days during the grazing of paddocks at each stocking rate.

9. The results of this experiment are discussed in relation to the design of grazing experiments and to farming practice.

Factors affecting the grazing habits of ruminants are discussed in relation to the attractiveness and nutritive value of herbages and the observed preferences of cattle and sheep at different times.

Methods of measuring stock preferences are considered and it is concluded that, while frequent eye estimates of the quantity of each species appear to provide an adequate method, continuous observations and herbage sampling are useful adjuncts to it.

The results of five experiments are given. Four were carried out in 3 years' winter grazing and one on spring, summer and autumn grazing over 2 years. In the latter experiment herbage samples were chemically analysed and a relationship with the observed preferences was calculated.

In the winter grazing trials the greener grasses tended to be selected first, i.e. timothy, white clover, rough-stalked meadow grass, perennial and Italian rye-grass. Cocksfoot, Phalaris, red fescue and meadow fescue were not generally relished. Meadow foxtail, smooth-stalked meadow grass, tall fescue and sometimes the different varieties of rye-grass and timothy varied in rank from year to year as a result of differential frost damage and fungal attacks.

In the summer grazing trials lucerne and white clover were found palatable in all the 1956 trials; in 1957 lucerne remained so, but white clover was less well liked, especially in June and July. The amount of grass growing with the clover seemed to affect attractiveness, mixtures being preferred to either species by itself. Meadow fescue and timothy were always ranked high, perennial rye-grass and cocksfoot usually next. Agrostis and red fescue were lowest. For the grasses, preference rank was positively correlated in 1957 with water-soluble dry matter, water-soluble ash, water-soluble carbohydrate and negatively correlated with lignin content.

Results are compared with those of other investigators and they show a marked degree of similarity. Variability in the data for sheep is possibly due to limitations in technique. The results for sheep and for cattle are compared; and it was generally found that cattle were fonder of meadow fescue than sheep, and less fond of cocksfoot.

Stock appear to graze those plants which will most readily supply their requirements for salts and energy (carbohydrates). Factors like dung, fungal attack, accessibility, density and toughness may interfere with this relationship.

The beneficial effect on the nutritive value of bread and similar cereals of adding small amounts of lysine and other essential amino acids has recently aroused considerable interest both in Great Britain and in America. Tests carried out with rats have shown considerably improved growth rates accompanied by increased efficiency of food conversion.

Three creep rations were fed in the form of meal, pellets and ground pellets. The compositions of the first two rations were similar to those of the rations used in general farming practice; the compositions of the pellets and ground pellets were identical. The experiment was carried out for 8 weeks from birth at thirteen centres and involved a total of 152 litters. No difference between meal and ground pellets was found in either food consumption or weight gain. Pigs on pellets consumed 18% more than pigs on meal, but this did not result in a significant improvement in weight gain. Treatment × centre interactions were not significant.

1. The live-weight gains and food consumption of groups of chickens subjected to two different patterns, (A) and (B), of allocation of a restricted quantity of food, were compared with the live-weight gains and food consumption of a control group (C), fed ad lib. throughout the experiment.

2. Group B (compensatory growth regime), showed a greater relative growth rate after re-alimentation than group A (mild restriction followed by ad lib. feeding). The growth rate of group B was shown to be significantly greater than that of the control group at equivalent live weights. In addition, it was shown that the increased growth rate, induced by periods of restriction of similar severity and duration, was very similar for birds within the ranges of 200–300 g. live weight and 750–1100 g. live weight.

3. The differences, due to treatment, in the growth rate after re-alimentation were in part caused by a concurrent increase in appetite. The severity and duration of the undernutrition immediately prior to re-alimentation would appear to affect appetite during re-alimentation more than the total restriction imposed. Measured in terms of food consumed, the restriction imposed upon groups A and B was the same, but in terms of live weight gain group B was very slightly more retarded than group A.