Growth rates of Shorthorn and Friesian heifer calves from 0 to 6 months of age were studied from live-weight data collected over a 10-year period.

Friesian calves were heavier than Shorthorn. Male calves were heavier than female. Calves born to the first pregnancy were smaller than those born to later ones. Gestation length was 5 days shorter for Friesian than for Shorthorn cows. It tended to be slightly shorter for female than for male calves. Non-foetal loss of weight at calving was greater with male than with female calves.

High-level feeding before calving was associated with heavier calves but the effect was not statistically significant.

Calf birth weight increased by 0·026 lb./lb. increase in post-calving live weight of the dam and by 0·564 lb./day extension of the gestation period.

Growth rate accelerated from birth to 3–4 months of age and then declined slightly. Autumn-born calves grew faster in the first 90 days than springborn calves. Age of dam and level of feeding before calving had no effect on rate of growth of the calf.

For both breeds there were significant negative correlations between birth weight and rate of gain in the first month after birth.

1. Two cuts, the leg and the loin, were taken from the right sides of 102 pig carcasses. Their densities were determined by weighing in air and in water and the cuts were dissected into fat, muscle, bone, skin and connective tissue. Samples of the muscular and fatty tissues were taken to obtain a measure of the analytically determined fat content. The weights of each tissue were expressed as a percentage of the weight of each cut and related to density by the methods of correlation and regression. Correlation coefficients and regression equations were calculated separately for legs, loins and the composite leg plus loin for each pig and for legs and loins rogarded as 204 separate pieces of pig carcass.

2. Correlations and regressions were used to relate the composition of the loin cut to three measurements of backfat thickness taken over the eye muscle at the level of the last rib, and to eye muscle area. These allowed a comparison of density and backfat thickness as measures of the fat and lean content of the loin cuts.

3. There was evidence of a high degree of association between the fat or muscle contents of the cuts and the density or the reciprocal of density. In no case was the simple correlation coefficient between muscle and density or fat and density less than 0·84. The greatest standard error of estimate of any of the regressions of porcentage fat or percentage muscle on density was 3·3% fat, for the regression of percentage separable fat on the reciprocal of the density of the loin cuts. Density was found to be a better measure of the muscle or fat content of the loin cuts than eye muscle area or any of 3 measurements of backfat thickness taken over the eye muscle.

4. Dissection data from 25 whole sides supported these results showing a high correlation between density and percentage fat or percentage muscle.

5. There was a low correlation, r = 0·41, between percentage bone and density of 102 leg cuts. That between density and percentage bone of 25 whole sides was r = 0·47; suggesting that bone content has but a small influence on carcass density.

6. It is suggested that carcass density is a better measure of carcass fatness or leanness than measurements of backfat thickness or eye muscle area.

An experiment is described in which four pairs of individually fed identical twin calves were used to investigate the effects of castration at 1 and 7 months, on growth, efficiency of food utilization and carcass composition and conformation.

The results indicate that up to 28 weeks of age the late-castrated animals wore superior in liveweight increase, width of head and efficiency with which they converted food to live weight. By slaughter time, at about 18 months, these differences, except width of head, had been eliminated.

The carcasses from both treatments were very similar except that a slightly greater percentage of the total muscle occurred in the thoracic and abdominal muscles of the late-castrated animals than in the early-castrated ones. A statistically significant higher percentage of the total fat occurred as subcutaneous fat in the late-castrated animals than in the early-castrated ones.

For three years the persistence of six grasses and one herb sown singly or in combination under poultry grazing was studied. Established swards were regularly mown and either not grazed (control) or grazed every other week or every other month. The results are compared with those from earlier trials and reasons for the differences are discussed. Red fescue, perennial rye-grass and smooth-stalked meadow grass increased in amount, red fescue being particularly unpopular with poultry. Meadow fescue and timothy were slightly, and cocksfoot and yarrow drastically, reduced under poultry grazing.

The preferences of poultry for certain herbage species and varieties are discussed but no reasons adduced owing to lack of data.

One week's and 4 weeks' grazing made no difference to the persistence and palatability of the grasses tested, but these were always in a short leafy condition when grazed.

Data from thirty-five digestibility trials with sheep in metabolism cages were used to investigate statistically the relationships between organic matter intake (I), faecal organic matter output (F), and the nitrogen concentration in faecal organic matter (N).

The data fell easily into groups due to botanical or seasonal differences in the feed. These groups of data were homogeneous and provided highly significant linear equations of the forms I = bF + cFN and I = a + cFN. When compared these groups of data sometimes showed differences in slope, position or both. A quadratic expression

I = bF + cFN + dFN2

was found to accommodate a majority of the data but to be less precise than I = a + cFN.

A further expression incorporating N as an independent variable was also examined,

I = a + cFN2 + eN.

This expression, although far from being universally adequate, proved to be generally better than existing formulae. When applied to the data of Greenhalgh et. al. (1960), it substantially reduced heterogeneity between data for spring and data for summer pastures.

Causes of variation in the relationship between organic-matter intake and nitrogen in faeces, and some of the hazards of extrapolation from empirical regression relations, are discussed.

The relative importance of variation in the components of wool production to variation in wool production itself was estimated by two methods of analysis. About 30% of the attributable variation in total fleece weight was found to be due to variation in surface area and 70% was due to wool production per unit skin area. Between 50 and 60% of the variation amongst sheep in the latter character was found to be due to variation in fibre weight, the rest being attributed to variation in number of fibres per unit area (fibre density). The variation in mean fibre weight was further partitioned into 50 to 70% due to variation in mean cross-sectional area and the remainder to variation in mean fibre length.

Variation in wool production per unit skin area was also analysed according to growth period and position on the body. The results are discussed in relation to the partition of variance in wool production of other breeds.

For highest revival rates in experiments on the deep-freezing of bull spermatozoa to – 79° C., a period of incubation of the undiluted semen at 30° C. did not eliminate the need for overnight equilibration at 5° C. The addition of 1·25% fructose or arabinose to the diluent improved revival rates of non-equilibrated spermatozoa but these rates still did not equal those of equilibrated spermatozoa.

Glycerol apparently penetrated spermatozoa rapidly and spermatozoa survived in glycerol solutions as high as 2·0m if 0·1m buffered citrate was also present. Omission of the citrate solutions caused immediate death of the spermatozoa.

A one-ninth replication of a 37 factorial experiment showed that, by all scoring criteria, 40° C. was superior to 0° C. as a thawing bath temperature. A diluent containing 8% (v/v) glycerol was superior to either 4% or 6% if activity of spermatozoa after thawing was the scoring criterion, but there was no difference in the percentage of spermatozoa stained by congo-red-nigrosin when frozen in diluents containing these levels of glycerol.

In the range of tonicity 80, 100 and 120% (0·9% NaCl = 100% tonicity), using the diluent composed of a mixture of fructose and citrate, there were more motile spermatozoa than in buffered citrate or fructose alone. Increasing tonicity had an adverse effect on revival rates of spermatozoa in the buffered citrate diluent. Spermatozoa stored chilled at 5· C. for periods up to 36 hr. prior to freezing survived best in the mixture of fructose and citrate.

The investigation of the equilibration phenomenon showed that an improvement in survival after deep-freezing occurred if diluted semen was stored for up to 12 hr. after dilution, but this was not dependent on the presence of glycerol in the diluent during this ageing process.

The very fast development of maize plants at Ibadan, Nigeria, has been described and an attempt has been made to obtain a better understanding of their development with the aid of a growth analysis. Two varieties of maize have been studied, which, again during this experiment, proved to have a very different yielding performance, in spite of a rather similar vegetative development. It was shown that Lagos White, the local variety, produced approximately 2000 lb./acre and ES 2 3000 lb./acre.

From approximately the ninth week onwards the ear starts rapid development, and the retention of a larger functional photosynthetic area by the introduced variety ES 2, from the eighth week onwards, seems to be the major factor controlling its higher production of dry matter in the latter part of development, when compared with Lagos White.

On the average, n.a.r. had similar values in both varieties and had similar deviations at various stages of development; external or internal factors could not be separated. The l.a.r. indicated that, certainly in the latter part of development, ES 2 plants and Lagos White plants had a similar leaf area per gramme of dry matter; but ES 2 had more of both. This factor stresses the similarity of efficiency in both photosynthetic mechanisms.

The l.a.r shows in clear terms the difference between the two varieties grown at equal spacing. The variety ES 2 still increased its leaf area with its additional laminae, when Lagos White, which had a more rapid loss of leaf by senescence, had come to a standstill. The more pronounced longevity of the photosynthetic area in ES 2 appears therefore the major determinant of the higher production of dry matter by this variety. The possible significance of variation in longevity of leaves had been pointed out already in 1929 by Boonstra, who found some evidence of an association of longevity of leaves and high yields in four varieties of oats.

Twelve digestibility trials were carried out using three adult rams on seven legumes and five nonlegume roughages.

In vitro fermentations were carried out over 24 hr. and the percentage cellulose digestion was determined. The whole rumen juice used to inoculate the fermentation tubes was obtained from a sheep with a permanent rumen fistula. Carbon dioxide was bubbled through during the fermentation run, unless otherwise indicated, to ensure anaerobic conditions.

The following significant correlations were calculated from the results:

In vivo and in vitro cellulose digestion for non-legumes: r = 0·93.

In vivo cellulose digestion and D.E./kg. D.M. for non-legumes: r = 0·90.

In vitro cellulose digestion and D.E./kg. D.M. for non-legumes: r = 0·90.

In vitro cellulose digestion and D.E./kg. D.M. for non-legumes + alfalfa and cashrangeeg: r = 0·91.

In vitro cellulose digestion and D.E./kg. D.M. for all forages tested gave a highly significant correlation: r = 0·73.

In vitro cellulose digestion and D.E./kg. D.M. for legumes: r = −0·77.

Regression equations calculated for non-legumes and for all tested forages, when used for predicting D.E./kg. D.M. gave values which differed from the determined digestible energy by ± 8·70and ± 9·90% respectively. Applying Hershberger's regression equation to the present data, the D.E./kg. D.M. values differed by ± 8·69%.

It seems safe to say that all official performance testing and progeny testing schemes for bacon pigs, up to the present, have been based on an implicit assumption that the pigs found to be superior under the management methods at the testing station would also be superior under other systems of management on commercial farms. If consideration is limited to reasonably good standards of management there is probably little danger in this assumption, though there is little direct evidence as yet to support it. The danger of mistakes in the selection of superior genotypes would be more likely to arise if there were systematic differences between the methods of management at the testing stations and on commercial farms. Actually such a difference does occur as regards methods of feeding. At testing stations, the pigs are generally fed more or less to appetite, being given as much as they will readily clear up in two feeds per day in England (N.P.B.A., 1957) and Northern Ireland (Heaney, 1962) and in three feeds per day in Denmark (Clausen & Thomsen, 1957). In the Republic of Ireland (Department of Agriculture, 1960) three feeds per day are given on a scale which must involve little, if any, restriction in the later stages of fattening. Such practices have the object of discovering the strains which become too fat before they reach bacon weights. Many farmers, on the other hand, adopt some form of restriction during the later stages of fattening, with the object of finishing the pigs at the right stage of fatness, and thus of improving the grading of the carcases at the factory.

1. The results of a trial designed to investigate the effects of sheep excreta on sward growth and yield are described.

2. The quantities of plant nutrients excreted, and their distribution, by the grazing animal are discussed. An assessment is made of the value of excreta to pasture growth in the light of the results gained.

3. Under Boghall conditions, the return of excreta had little affect on sward output, the main effect was for the pasture to become progressively more grass dominant. In general, weather and soil nutrient limitation had a greater effect on nitrogen yields from the swards than did excreta. Recovery of excreta nitrogen would appear to be influenced by rainfall and the age of the sward.

4. On a soil inherently low in available potassium, it was found that this element and nitrogen both affected the pattern of herbage growth and composition when returned in excreta. Phosphorus return by the sheep was, however, of no observable value in either the levels of the element in the soil or in the herbage. It was found that rainfall and the botanical composition influenced the contents of mineral elements in the herbages.

5. Balance studies suggest that sheep grazed in small paddocks need adequate pre-conditioning before being moved into a trial. Only by this means can return of excreta reflect consumption of herbage. The limitations of small-scale animal grazing experiments are discussed.

The use of the percentage of crude protein in grass consumed by cattle as a means of estimating the nutritive value of grass was investigated. Regression equations expressing the correlation between crude protein and the digestibility coefficients of crude protein, organic and dry matter were calculated.

A close correlation between the percentage of crude protein in faeces and in consumed grass was found, and a regression equation was calculated.

The correlation between chemical composition and nutritive value of grass fed to short-horn zebu steers in Uganda was investigated. The following regression equations were calculated from the experimental results and discussed in part I of this paper.

Dig. coef. of C.P. = 100·89 log c.p. – 44·45;

r = 0·9738, P < 0·001.

(For use when fodders of wide range of proteins are compared.)

Dig. coef. of c.p.= 5·14 c.p.;

r – 0·9339, P < 0·001.

(For quick calculation when only approximate figures are required.)

Dig. coef. of c.p. = 9·588 + 4·284 c.p.;

r = 0·9521, P < 0·001.

To be used between 4·5 and 17% of crude protein.)

% c.p. in grass eaten = 1·677 c.p.in

faeces – 6·93; r = 0·958, P < 0·001.

Dig. coef. of d.m. = 41·81 + 1·63 c.p.;

r = 0·9362, P < 0·001.

Dig. coef. of o.m.= 46·05 + 1·4152 c.p.;

r = 0·8851, P < 0·001.

The regression equations calculated from the experimental results in the present paper (part II) are as follows:

Dig. coef. of d.m. = 150·88 – 1·179 (c.f. + n.f.e.);

r = 0·9634, P < 0·001.

Dig. coef. of d.m. = 120·03 – 1·778 c.f.;

r = 0·721, P < 0·01.

Dig. coef. of o.m. = 142·50 – 1·045 (c.f. + n.f.e.);

r = 0·9320, P < 0·001.

t.d.n.= 129·39 – 0·9419 (c.f. + n.f.e.);

r = 0·9288, P < 0·001.

t.d.n. = 7·76 + 0·8192 dig. coef. of d.m.;

r = 0·9886, P < 0·001.

s.e. = 0·9367 dig. coef. of d.m. – 20·15;

r = 0·9832, P < 0·001.

s.e. = 120·80 – 1·104 (c.f. + n.f.e.);

r = 0·9468, P < 0·001.

s.e. = 99·44 – 1·868 c.f.

r = 0·7948, P < 0·01.

1. Four in vitro fermentation experiments, in duplicate, were carried out over 24 hr. periods, to estimate the production of v.f.a. and o.a from forages.

2. A new technique for determining the total organic acids produced in the rumen is described.

3. The o.a. produced in the earlier part of the fermentation are considerably higher than the v.f.a. but the difference then diminishes. There is practically no difference in the amounts produced after 24 hr.

4. Highly significant correlations were found between the in vitro production of v.f.a. or o.a. and d.e./kg. d.m., for all the roughages tested. Nonlegumes gave a more highly significant correlation than legumes.

5. Regression equations show that o.a. or v.f.a. were more accurate than in vitro cellulose digestion for predicting the d.e./kg. d.m. of non-legume forages. It is concluded that V.F.A. production in vitro is the best criterion in this respect.

1. Continuous waterlogging and 4 weeks' waterlogging immediately after transplanting produced plants with higher leaf and shoot numbers.

2. There was no difference in the final shoot number between plants continuously waterlogged and those waterlogged for 4 weeks, immediately and 4 weeks after transplanting. The shoot mortality was higher in the continuously waterlogged plants and those waterlogged for 4 weeks immediately, 8 weeks and 12 weeks after transplanting than in those waterlogged for 4 weeks, 4 weeks after transplanting.

3. Continuously waterlogged plants and those waterlogged for 4 weeks, 4 weeks after transplanting, were taller than those waterlogged for 4 weeks, immediately, 8 weeks and 12 weeks after transplanting.

4. Leaf area per bucket, leaf area per shoot and per leaf lamina were higher in continuously waterlogged plants and those waterlogged for 4 weeks, 4 weeks after transplanting, than in those waterlogged for 4 weeks immediately, 8 weeks, and 12 weeks after transplanting.

5. Continuous waterlogging and waterlogging for 4 weeks, 4 weeks after transplanting, increased the physiological age of the plants as evidenced by earlier ear emergence and grain ripeness.

6. Fresh-weight yield, yield of grain and panicle were greater in continuously waterlogged plants and those waterlogged for 4 weeks, 4 weeks after transplanting, than in those waterlogged for 4 weeks immediately, 8 weeks and 12 weeks after transplanting.

7. The critical period for waterlogging in the cultivation of the rice variety studied is 4 weeks after transplanting and waterlogging applied during this critical period for 4 weeks favours higher yield of grain than when applied for the same period earlier or later than this period. Where water supply is limited the plants should only be waterlogged at this period and the soil kept moist throughout the remaining growing period. However, where there is enough water to waterlog the plants for 8 weeks this should be started immediately after transplanting.

1. An experiment has been carried out using 64 pigs individually fed. They received a common ‘grower’ ration to 120 lb. live weight and were then divided into four groups. The ‘finisher’ rations contained 0, 2·5, 5 or 10% fat.

2. The rations containing more fat also had a higher protein content and the scales of feeding were so arranged that the pigs received the same daily intake of protein and ‘energy’.

3. The growth rate was slightly more rapid with the fat-supplemented diets and the carcass characteristics were not in any way impaired.

4. The efficiency of feed utilization (f.c.r.) improved considerably when fat was included in the ration: the f.c.r. was 3·93 in the absence of fat and 3·30 when the ration contained 10% added fat.

The carcass-weight increase of beef steers of various ages receiving fattening rations of different roughage: concentrate ratios was calculated by making use of the average dressing percentage of a control group slaughtered at the beginning of the experiment.

It is shown that, in terms of t.d.n./100 lb. carcass-weight increase, which is probably the more accurate measure of efficiency, the 2-year-olds were better feed converters than the calves. When the criterion was t.d.n./100 lb. live-weight increase the calves were superior. Ration B (1 concentrates: 1 roughage) was utilized most efficiently in terms of calculated carcass-weight increase, followed in a descending order by the high-concentrate ration C and the high-roughage ration (ration A).

The relationship of live-weight increase to carcass- weight increase as calculated is discussed. The proportion of live-weight gain laid down as carcass varied with age, growth rate and type of ration. This percentage variation ranged from 57% in slow-growing calves to 81% in fast-growing 3-year-olds. On the average, calves converted 61% of their live-weight gain into saleable carcass, the 2-year-olds 70·8% and the 3-year-olds 75·9%. The steers on the A (high roughage) ration converted 65·7% of live-weight gain into carcass, those on the C (high concentrate) ration 71·5% and those on the B (1 concentrate: 1 roughage) 69·2%. Reasons for these differences are discussed in terms of so-called differential growth.

The live weights and carcass weights of steers were plotted and the regression equation

where Yis carcass weight and X is live weight, was derived. The correlation coefficient r = 0·98 and the slope of the curve indicated that for an increase of 1% in the live weight of the steers, the carcass weight increased by 1·13%.

Several methods of expressing ‘efficiency of the fattening’ were applied to the data and the results are discussed. The methods were unanimous in selecting the steers on the B ration as the most efficient followed by those on ration C and the poorest were those on the A ration. Methods based on live-weight increase showed the calves, but those based on carcass-weight increase the 2-yearolds, as the most efficient. Results obtained by applying the Efficiency Quotient and Efficiency Index suggested that the older animals wero the more efficient. They differed from all other methods since these indicated that efficiency declined with age.

Efficiency values calculated by different formulae vary and no efficiency index has yet been evolved that will embrace all the variable factors which may have an influence on the efficiency of growth and fattening.

1. The decline of a pea root eelworm (Heterodera göttingiana Liebscher) population, of which most eggs were formed in 1955, was measured annually from 1955 to 1958 in twenty-two microplots containing loamy sand, and measurements were continued in one of these microplots from 1960 to 1962.

2. Sampling errors increased when egg populations were more than 4 years old.

3. Two crop rotations (fallow, and maize, fallow, carrots) had no effect on decline rate from 1955 to 1958, nor did initial eelworm density.

4. After 3 years the egg population was still 48% of that in 1955. Subsequently the population declined on average by more than 50% per annum. It is suggested that host crops should not be grown more than once every five years.

5. Cysts declined more slowly, with a mean annual rate of 26%.

6. A sharp decline in eggs during the first year followed by at least one year's relative quiescence may be general in Heterodera species; with H. göttingiana unexpected crop failures may be associated in part with the prolongation of this relative quiescence for more than 1 year.

1. The growth of wheat plants at two depths of planting, from seed in which embryo size and endosperm size were varied independently was studied.

2. Embryo size was shown to have a negligible effect on growth, whilst endosperm size had a considerable effect; the influence of neither embryosize nor endosperm size appeared to be in any way modified by depth of planting. It is suggested that the relationship between seed size and plant size is governed by the amount of reserve material present in the seed.

3. During the first 6 days of growth small embryos had a higher relative growth rate than large ones, apparently regardless, within wide limits, of the amount of reserve material in the seed. Thereafter until the exhaustion of reserves growth appeared to be related to the amount of reserve material present.