Growth and nutrient uptake by an upland rice variety, Agbede and a swamp rice variety, BG 79, were studied under four different soil moisture regimes (60, 80, 100% soil moisture saturation and flooding).

BG 79 (Swamp rice) ultimately attained greater mean total dry weight than Agbede (Upland rice), except in the flooding treatment, where the reverse applied. For both, 100% soil moisture saturation gave the greatest total dry weight increase, whereas the driest soil depressed dry-matter production: plants grown on soil maintained at 80% moisture saturation ultimately attained greater mean total dry weight than those grown on flooded soil. Flooded plants of the swamp rice outyielded plants grown on soil maintained at 80% moisture saturation, but the reverse applied to the upland rice.

Total leaf numbers were usually greater in BG 79 than in Agbede during the tillering and mid-vegetative stages. Increase in the soil moisture up to complete saturation increased the total leaf number in both varieties.

Mean leaf area was greater in Agbede than in BG 79 during the tillering and midvegetative stages. During these two periods of growth the 100% saturation treatment produced plants with the greatest leaf area, whereas 60% soil moisture saturation produced plants with the smallest leaf area in both varieties.

BG 79 had more shoots than Agbede. During tillering saturated and flooded soil encouraged the production of shoots in both varieties, but the driest soil prolonged the tillering period, especially in BG 79. Final shoot number tended to decrease with decreasing soil moisture. The percentage shoot mortality in Agbede was not significantly affected by soil moisture regimes, but BG 79 plants grown on the driest and saturated soil had significantly greater percentages of shoot mortality than flooded plants. In both varieties, plants grown on the driest soil had significantly greater percentage shoot mortality than those grown on soil maintained at 80% moisture saturation.

Mean Relative Leaf Growth Rate and Net Assimilation Rate were significantly faster in BG 79 than in Agbede variety, but the reverse applied with regard to Leaf Weight Ratio.

In both varieties flooded plants had the lowest concentration of manganese, especially during tillering. The small adsorption of Mn with flooding is attributed to a probable antagonism between iron and manganese.

The effect of time of application of nitrogen and potassium on the growth, development and yield of the second early variety Craig's Royal was studied by the technique of growth analysis. There was an indication that witholding nutrients led to the earlier initiation of tubers, but this was of no practical consequence and all treatments affected tuber bulking rate rather than the duration of bulking. Compared with early application, late application of nitrogen depressed tuber yield, although total drymatter yield was not affected. Late application of potassium, however, increased tuber yield; this was associated with an improvement in the recovery of applied potassium. Delaying the application of nitrogen also resulted in its more efficient recovery in the crop. Late application of potassium improved the recovery of early applied nitrogen and vice versa. Reasons are put forward to account for these effects.

Thirty-two growing bullocks were fed long barley straw ad libitum in each of three experiments; urea was added to the latter or to a diet of straw supplemented with either 1·36 or 2·72 kg meal. The amount of urea fed was 75 g per animal daily. In a fourth experiment, a basal allowance of 3·64 kg chopped hay was fed to thirty-two bullocks weighing 287 kg; in addition 4·55 kg of meal was fed in which none, one-half or all the supplemental nitrogen was supplied as urea. Rate of gain and straw intake of animals given straw only was similar to that of animals given straw and urea. Feeding 1·36 kg of either rolled barley or rolled barley supplemented with 10% soyabean meal, in addition to straw, did not elicit a response from urea. A response was obtained from urea when 2·72 kg of a barley–soyabean meal mixture was fed with straw. Blood urea concentrations generally reached a maximum at the third week of urea feeding and declined thereafter. Addition of urea to straw raised blood urea to about the same extent as incorporating urea with 1·36 kg of rolled barley. Blood concentrations were higher when the urea was fed with meal than when mixed with molasses. Nitrogen retention from urea was not significantly increased by feeding 1·36 kg of barley with straw ad libitum as compared to the retention on an all-straw ration. Slightly more nitrogen was retained when urea was added to rolled barley instead of a rolled barley–soyabean meal (10%) mixture. A ration of hay (3·64 kg) and 4·55 kg of barley promoted gains which were not significantly different from those of animals fed additional nitrogen as soyabean meal or urea. This indicates that the foregoing ration supplied enough nitrogen to meet the animals' requirement.

The diversity of methods for jointing meat animal carcasses is indicated and the need for a standardized method with good repeatability is considered. A standardized butcher-type method of jointing, in which anatomical reference points were used to determine cutting lines, is described briefly. A semi-anatomical method in which the jointing was based still more closely upon the anatomy of meat animals is described in full. Three modifications to the semi-anatomical method are suggested to improve the consistency of jointing.

Experiments wore carried out to compare wet and dry feeding for bacon pigs and to study the effect of temperature of feed on the utilization of wet feed. There was no significant difference in growth rate between wet and dry feeding; food conversion ratios tended to be lower on wet feeding and were significantly lower in one experiment. There were no significant differences in growth rate or food conversion between wet feed given at 5 °C, 13 °C or 35 °C. None of the treatments had any significant effect on carcass characteristics. Nitrogen balance and digestibility studies confirmed the results of the production trials. There were no significant differences in the digestibility of dry matter or nitrogen between wet and dry feeding or between extreme temperatures of the feed.

Upland rice (Agbede) and swamp rice (BG 79) varieties grown on flooded soil, and on soil maintained at 80 and 100% moisture saturation were sprayed with solutions containing 0 ppm (MO), 10 ppm (Ml), and 20 ppm (M2) of manganese.

The M 2 treatment depressed total dry weight and dry weights of leaf laminae, stems, leaf sheaths and root of both varieties grown on soil maintained at either 80 or 100% moisture saturation. The M 1 treatment increased the ear weight of Agbede grown on soil maintained at either 80 or 100% moisture saturation, while the M 2 treatment increased the ear weight of plant grown on saturated soil. In flooded soil both the M 1 and M 2 treatments significantly increased dry weight of Agbede plants, but only the M 2 treatment increased ear dry weight of BG 79. The ear weight of Agbede plants receiving M 0 and M 1 treatment decreased with increasing soil moisture while that of BG 79 increased.

It is considered that manganese supply limits yield of Agbede grain grown on flooded soil.

Variations in the host–parasite relationship of bacterial blight of cotton, caused by Xanthomonas malvacearum, E. F. Smith (Dowson), axe elucidated in terms of the three main components of variation, namely, genetic variation in the host, genetic variation in the parasite and variations in environment.

Although the relative resistance shown by host varieties differed both with the culture of the pathogen used for inoculation and with the environmental conditions, over-riding patterns of host resistance could be detected, showing that certain varieties maintained their resistance over a wide range of conditions.

It was found that phage type in X. malvacearum was not related to virulence. Moreover, none of the cultures of the pathogen which had been isolated from different sources, could be shown to be identical when inoculated into a range of host varieties under a range of environmental conditions. It was concluded that the pathogen showed continuous variation in virulence and that it would be difficult and of little value to attempt to define races.

Some success was achieved in relating observed variations in the host–parasite relationship to easily measured components of the environment, by using multiple regression analyses. It is suggested that this might provide a means of characterizing the complex variations observed and that the host–parasite relationship could be regarded as a dynamic system, in which disease expression is a function of the interactions of environmental factors and two polygenic systems, that of the host and that of the parasite.

Intrapopulation variances were also studied in the host varieties. A population which showed little variation for resistance under one set of conditions might show considerable variation in a different environment or when inoculated with a different culture. It is suggested that selection for resistance under conditions which favour the expression of variation can lead, by repeated selection and inbreeding, to the production of resistant populations which retain their resistance under conditions in which the parental stocks showed no worthwhile resistance. These conclusions are discussed in relation to problems in resistance breeding and genetics.

Three experiments were performed in which variation in metabolizable energy (M.E.) determinations was studied using a total of 137 laying hens. Consistent breed differences in classical M.E. estimates were found, and there were statistically significant differences between pullets within strains. Estimates were obtained of the within-bird variation in classical M.E. determinations and, from the estimated variance components, standard errors of the mean classical M.E. value were predicted for determinations using various numbers of pullets of one breed and various numbers of measurements per pullet.

Groups of ewes kept under hill conditions were killed at intervals during October to July 1965–66. Supplementary feed was given between February and May. The carcasses were divided into soft tissue, uterus and its contents and skeletal fractions. Each fraction was dissolved in HNO3 and its fat and mineral content measured. The sheep were heavier in November and lighter in May during lactation than at other times. The content of fat in the body fell progressively from October to May and then increased; initially fat was withdrawn only from the soft tissues but by April and May the fat contents of both skeleton and soft tissues were exceedingly low. The weight of fatfree soft tissue remained relatively constant but was heaviest in July. Fat-free skeleton fraction was lighter in January than in April.

The contents of the predominantly intracellular ions, P, Mg and K in the soft tissue fell between November and January, remained constant between January and May and then increased. There was an increase in Na towards the end of pregnancy followed by a marked fall after parturition. The contents of Ca and P in the skeleton fell between November and January and during lactation between April and July. There was a marked increase between February and April when supplementary feeding was given. Evidence that Mg was selectively removed from the skeleton was obtained in November and January, two sheep having Ca:Mg ratios in skeleton greater than 100. Na and K contents of the skeleton were greatest at the end of pregnancy in April. For the lambs between 6 and 23 kg live weight, each kg of live-weight gain contained 8·8 g Ca, 5·0 g P, 0·27 g Mg, 0·83 g Na and 1·85 g K.

Two experiments were carried out in which pigs were grown at controlled high, moderate or low growth rates from 18 kg to slaughter at 57 kg live weight. Linear measurements and density determinations were carried out on the carcasses. In the second experiment the right-hand side of each carcass was divided into four joints and each joint was physically dissected into three components, bone, subcutaneous fat plus skin and ‘lean’ meat. The boneless tissue of each joint was analysed for moisture, ether extractable fat and nitrogen.

It was found that an increase in the rate of live-weight gain tended to improve the efficiency with which feed was converted into live weight.

The percentage of fat in the side was significantly increased by more rapid growth rates.

The conformation of the side was altered by treatment, the proportion by weight of the middle region increased with increasing rate of live-weight gain and was accompanied by corresponding reductions in the proportions of the gammon and shoulder regions. These changes were largely due to an effect on the distribution of fat throughout the side, but there were also minor changes in the distributions of bone and fat-free lean.

The high rate of gain was associated with a greater proportion of belly in the side. This was due to an increase in the proportion of lean meat in this region, presumably a functional effect caused by an increased intestinal volume.

There was no treatment effect on the chemical composition of the fat-free boneless meat which was found to differ significantly between joints.

The effects of different levels of first-winter nutrition over 3 years were studied on the subsequent life-time production from the hill of groups of North and South Country Cheviot ewe hoggs (sheep between 6 months and 1½12 years).

Lamb production was examined in terms of the percentage of lambs born and reared per ewe alive at each lambing and was expressed as a mean of five lamb crops. An overall measure of flock life-time production was calculated from the data on lamb production. This was the total number of lambs weaned at a mean 15 weeks in each treatment group over five lamb crops expressed as the mean per experimental animal alive at 6 months.

All productive components were analysed for differences between breeds, treatments, and weight-classes, i.e. those animals above or below average weight at 6 months.

There were no significant treatment differences in life-time production, although the treatment groups showed different trends with increasing age. Higher production in early life following higher levels of first-winter nutrition was associated with less efficient later production and poorer ewe survival in a hard hill environment.

It is concluded that improvement in first-winter nutrition above that available on the hill is undesirable and uneconomic without equal improvement in adult nutrition.

A total of 1659 ejaculates was collected from four Friesian bulls imported from Europe and ten of their offspring born in Iraq while in regular artificial service at the Abu-Ghraib Experiment Station. The work covered a period from 1 January 1965 to 30 June 1967.

The five semen characteristics, volume, density, mass activity, individual motility and pH were studied and the influence of age of bull and season on these characters was investigated. The relationships between the characters were also investigated.

Deterioration was observed in volume of ejaculate, density, mass activity and individual motility in the Iraqi Friesians. Influence of season on all semen characters lacked significance with the exception of mass motility in the European Friesian bulls (P < 0·05). Highly significant positive correlations were found between most of the characters studied.

Pigs were grown at controlled rates of live-weight gain from 20 to 55 kg and from 55 to 87 kg live weight, at which weight they were slaughtered. Six growth-rate treatments were compared and were referred to as High-High (HH), High-Moderate (HM), High-Low (HL), Moderate-High (MH), Moderate-Moderate (MM) and Low-High (LH). The right-hand side of each carcass was divided into the four primary jointsand each joint was physically dissected into bone, skin, subcutaneous fat and lean meat. The boneless tissue of each joint was analyzed for moisture, ether extractable fat and nitrogen.

It was found that an increase in the rate of live-weight gain in the first growth period, tended toimprove the efficiency with which feed was converted into live weight. In the second growth period the efficiency of feed conversion was dependent on the rate of gain both in that period and in the preceding period. Restricted growth in the first period improved the efficiency of feed conversion both in the second period and over the entire experimental period compared with rapid early growth. The implications of compensatory growth are discussed.

There was no treatment effect on carcass length, but hindleg length and ham circumference measurements showed that the proportion of gammon in the side was lower in the HH pigs compared with the other five treatments. This was confirmed by the weight of the gammon joint expressed as a percentage of the trimmed side. There was also a decrease in the proportion of shoulder and an increase in the proportion of middle in the HH pigs. Differences between the other five treatments were small. The changes in conformation were due largely to the effect on fat distribution throughout the side particularly in the gammon and back regions.

The HH treatment resulted in a significant increase in the percentage fat in the side compared witheach of the other five treatments. Within these five treatments there was no significant difference in the percentage fat in the side. This suggests that equal importance may be attached to the rate of live-weight gain in both the growing (20–55 kg) and finishing (55–87 kg) periods in determining the fatnessof the bacon weight carcass.

The treatments had little effect on the chemical composition of the fat-free boneless meat.

The results are discussed in relation to current growth theory.

The micro-Kjeldahl technique and paper electrophoresis were used to measure the total protein and γ-globulin concentrations in the sera of 423 2-day-old Finnish Landrace, Scottish Blackface, Merino and Merino × Cheviot lambs, and the total protein concentrations in the sera and colostra of their mothers. The concentrations were higher in Finnish lambs than in lambs of other breeds. The interbreed variations between single lambs were not significant, but the variations between lambs from larger litters were highly significant, because the concentrations in Finnish twins and triplets were as high as in single lambs, whereas the concentrations in Blackface and Merino × Cheviot lambs were negatively correlated with litter size. The differences between the breeds were attributable to the particularly high protein concentrations in the colostra from the Finnish ewes, to the small size of their lambs, and, probably, to a higher rate of production of colostrum by Finnish than by other ewes. There was some evidence of a positive correlation between the lengths of the gestation periods and the γ-globulin concentrations of the lambs.

Two flocks of Merino wethers ranging in age from 3 to 87 months grazed a poor (L) or high (H) quality pasture for 3 months. The flocks were then combined, and intake was estimated while the sheep grazed four different pastures in succession. In a second experiment, flocks of Merino, Border Leicester, Southdown and Dorset Horn ewes of varying ages grazed in succession six pastures on which intakes were estimated and live weights recorded. The digestibility of the diet selected, as estimated from the faecal nitrogen concentration, declined with age by 0·053 units per month in Exp. (2) and curvilinearly in Exp. (1). In both experiments faecal output of sheep of similar breed receiving similar treatments increased with age to approximately 3 years and declined thereafter. In neither experiment was there a significant allometric relationship between intake and live weight.

The intake of the L group was consistently greater than that of the H group when both groups grazed together. The differences were correlated with the quantity of green feed available. The faecal output of Dorset Horns, Merinos, Southdowns and Border Leicesters at 28·7 months of age was calculated to be 451, 402, 346 and 588 g per day respectively in Exp. (2). Mean digestibility of the diet selected estimated by the faecal nitrogen procedure was 65·1, 63·0, 64·7 and 64·5 units at 28·7 months for the Dorset Horns, Merinos, Southdowns and Border Leicesters respectively. Differences between breeds in faecal output and in the digestibility of the diet were significant.

Experiments designed to assess differences between treatments in pasture productivity as measured by the production of animals are complicated by the stocking rates chosen. The paper attempts toderive a simple model relating production per animal and production per unit area to stocking rate for meat animals, based on biological considerations.

A method is proposed which would allow meaningful grazing experiments to be carried out employing only one stocking rate, thus considerably reducing the expense of this type of experimentation.

The model is applied to some recent data obtained by Hodgson (1966) and Appleton (1967, personal communication).

Four varieties of barley, selected for characteristics which could have value in a barley variety intended primarily for animal food, were compared with the variety Proctor under two levels of irrigation and two levels of nitrogen fertilizer. The exotic varieties yielded less grain and total dry matter than the adapted varieties, but differed in their response to irrigation. This difference was due chiefly to the ability to form extra ears when irrigated and the other yield components were less affected. Nitrogen fertilizer did not affect yield, although more ears were formed in the highlevel than the low-level treatment. The yield of nitrogen in the whole plant and in the yield of grain nitrogen were increased by high-nitrogen fertilizer and one of the exotic varieties was found to be capable of high yields of both grain nitrogen and total nitrogen, but there were no varietal differences in the response to nitrogen fertilizer.

The varietal differences in response to irrigation are briefly discussed and related to development and possible drought resistance. The nitrogen yield of the grain is analysed in terms of total nitrogen uptake and distribution within the plant and the possibility of using the variation in these characteristics in a breeding programme is raised.

Statistical analyses were carried out on the data obtained under strictly controlled conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg. The authors have calculated and studied the correlations between faecal and urinary calcium losses, calcium excretion in the milk, digestible calcium, and calcium balance, and the 75 other nutritive factors which were analysed for each of the 55 above-mentioned experimental diets. The results showed that calcium metabolism is regulated in the digestive tract, and the fact that the lactation calcium requirements increase at the same time as the amounts of digestible calcium and the calcium balance corroborates this statement. But except for this endogenous factor of resorption, the fate of the dietary calcium does not depend on the ingested amounts but on the nature itself of the components of the diets and their proportions in the diets. Cereals, and especially barley, have from this point of view a particular beneficial effect. These factors act on the absorption of calcium and thus directly on the balance, since the daily urinary excretion of calcium is generally small and independent. It has also been demonstrated that the balance is not inevitably negative in cows with a daily milk production of 11–20kg, and that a careful composition of the rations should enable one to equilibrate it.

The other nutritive factors do not work on calcium utilization, but a close parallel exists between digestibility, urinary excretion and balance of both calcium and magnesium.

Statistical analyses were carried out on the data obtained under very strict conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2 to 6 months earlier and whose daily milk production ranged from 11 to 20 kg.

The correlation between faecal and urinary losses of magnesium, magnesium in milk, digestible magnesium, and magnesium balance and the other nutritive factors of the 55 above-mentioned experimental diets have been calculated.

The magnesium absorption is enhanced by increasing magnesium and calcium intake, while nitrogen and, to a lesser extent, fat, giving higher faecal losses, have an opposite effect. There is no influence at this level of lactating requirements.

The urinary losses of magnesium are not related to the magnesium intake and digestibility, and the balance is thus directly proportional to the digestible amounts. But this balance is decreased when the diet contains more dry matter or energy, to the benefit of urine in dry cows. We were not able to determine whether this balance reduction also benefits the milk production in the lactating cows.

Our results demonstrate that the faecal endogenous losses of magnesium can be highly variable.

The balance of magnesium is frequently but not inevitably negative in cows with a daily milk production of 11–20 kg.

The pattern of dry matter (D.M.) yield, digestibility and nitrogen (N) content of two contrasted grain:straw (G/S) ratio varieties each of barley, oats and wheat grown at three levels of nitrogen was measured over the 30 days after ear emergence, D.M. yield rose with time, while digestibilityand N content declined. Although the D.M. yield was highest in the oat variety, Maelor, one barley variety, Deba Abed, had the highest digestibility and a similar yield of digestible dry matter. Wheat was lowest yielding. The low G/S varieties of wheat and oats had higher yields of digestible D.M., but the high G/S variety, Deba Abed, was the higher yielding barley. Yield of digestible D.M. increased with increasing N fertilizer, due to the increased D.M. yield.