From metabolism experiments carried out on the pigs enumerated in the first paper of this series the following conclusions are drawn:

(a) The metabolism in a state of inanition appears to be more a function of a power of the weight than of the true surface area as determined by the photographic method.

(b) Hogs born in the summer and autumn of one year appear to show two maxima of metabolism; one almost immediately, as has been observed previously, and another during the following summer, provisionally ascribed to the effect of light on thyroid activity, produced by the intermediary action of the anterior pituitary.

(c) Actual, and theoretically computed average growths are shown to agree remarkably well in the case of eleven of the pigs which were treated in an exactly similar manner. Individual growth curves showed no such agreement. This is considered to strengthen the evidence for the writer's previously stated view that nett energy is a statistical rather than a physiological constant.

In a preceding paper(1) were deduced some of the consequences of assuming that water movement in a heavy clay soil is a process akin to diffusion. The only idealisation of the medium was the assumption that the ratio of k, the diffusion coefficient, to σ, the apparent specific gravity of the dry matter in the soil, is constant, independent of depth, and we shall see that this is justified by the experimental evidence. As long ago as 1907, Buckingham(2) showed that the quantity of moisture moving in a given time from a block of wet soil to a drier block in contact with it was dependent mainly on the difference between the respective water contents, and that there was no definite dependence on the actual water contents themselves. Veihmeyer(3), in 1927, placed blocks of wet soil between blocks of drier soil, arranged in a vertical column. Subsequent moisture profiles were typical of a redistribution obeying diffusion laws, and were nearly the same both for upward and downward movement. He demonstrated furthermore that the movement of the water in these conditions was extremely slow, and that the rate of movement was related to the difference in moisture content between the dry and wet soil. Unfortunately insufficient numerical data were given to apply diffusion theory to Veihmeyer's experimental results.

1. The effect of undernutrition on the levels of five enzyme activities has been observed in liver biopsy specimens taken from Suffolk-cross ewes in late pregnancy.

2. There was no significant effect on the levels of three important NADPH2-generating enzymes (i.e. glucose-6-phosphate, 6-phosphogluconate and tsocitrate dehydrogenases) when comparisons were made between groups of animals at the same stage of pregnancy. However, the proportion of very low 6-phosphogluconate dehydrogenase levels assayed in livers of the undernourished ewes was significantly increased as parturition approached.

In experimentally infected birds a clear viscid discharge from the nostril is sometimes the first symptom noticed, and may occasionally be the only one for a long time (turkey E). This is followed by a soft fluctuating swelling under one or both eyes. After the development of a well-marked swelling, the course of the disease may vary both in naturally and experimentally infected birds. In some cases the swelling gradually diminishes and finally disappears (turkeys 3, C, D, F, and G), in other cases the soft fluctuating swelling persists for considerable periods (turkeys 1, E and H), and in others the swellings become hard and the gelatinous contents are replaced by cheesy, foulsmelling material (turkeys 2, A and B). The latter condition may be due to secondary infection. Sometimes the disease only attacks one side leaving the other quite normal. Death occurred in some instances, but could not be definitely attributed to the disease.

The term “guano” is applied almost wholly to the excrement of sea-birds and, since it contains a high proportion of nitrogen and phosphorus, guano forms a very valuable fertilizing material. The Union of South Africa has a large number of small islands scattered round the coast which are used as breeding grounds by various sea-birds. The deposits of guano from different islands vary considerably and are therefore systematically mixed to obtain an approximately uniform grade of material. The average analytical results for the years 1921–8 were: 10·0 per cent nitrogen, 11·2 per cent phosphoric oxide, 2·0 per cent potash.

Two trials were conducted to study the seasonal variation in oestrous activity over the year in Suffolk (S) or mutton Merino (M) temperate breeds, and their crosses with the local Ossimi (O) sheep under the prevailing subtropical conditions. In the first trial, groups of S, 75% S, 50% S, and O were used and the second trial involved groups of M, ¾M, ½M, ½M and O. The incidence of oestrus was measured by teasing with vasectomized rams. Suffolk ewes had a restricted period of oestrous activity (August–January) whereas M had a longer breeding season (August–March) with high incidence of long and double cycles. Local O showed irregular oestrous activity almost around the year, with particular decline in April. In both trials, all crosses had better oestrous activity than the pure parents, with the 50% S and the ½M having the best performance in the two trials, respectively. The period from September to February seemed to be the period of normal cycling activity in all breed groups, whereas the period from March to May was associated with marked breed-group variation in oestrous activity. Normal cycle length of the S was significantly (P < 0·01) shorter than the local O (16·0 v.17·7 days) and was more consistent than other breed groups. In the two trials, normal cycle length of the cross-breds was ranked between the two purebred parents.

1. Moderate percentages of urea are widely and successfully used in compound fertilizers but the use of large proportions may be accompanied by two disadvantages:

(a) the loss of nitrogen as ammonia from surface applications,

(b) the occurrence of toxic effects when urea and seeds are drilled together in soil. This paper shows that both these effects are consequences of the rapid hydrolysis of urea to ammonia and carbon dioxide.

2. The effect on brairding of the presence of urea and of ammonium sulphate drilled with wheat seeds, and the loss of ammonia from top-dressings of the compounds on bare soils have been studied on a range of soils. Phytotoxicity was most pronounced in those conditions in which ammonia evolution was greatest. Thus, in a sandy soil, from which about 75% of the nitrogen of a top-dressing of urea was evolved as ammonia in our conditions, more than 15 lb. nitrogen as urea per acre reduced the braird of wheat seeds; while in a clay soil, from which only 10% of a top-dressing was lost as ammonia, up to 60 lb. nitrogen as urea per acre could be added before braird was reduced. Intermediate results were obtained with three more soils and ammonia evolution and brairding were always closely parallel.

Lactation in ewes is associated with hypertrophy of the liver, due to cell proliferation and enlargement. The mean diameter of hepatic parenchymal cell nuclei increased after parturition to reach a maximum at 6 weeks, after which there was a decline.

The liver regressed in weight after weaning but total DNA declined less than liver weight and remained elevated in comparison with livers of unmated ewes, while DNA concentration increased. Total liver DNA remained relatively high for approximately 6 months. It is suggested that the final fall to control values was associated with cell death and disorganization of the hepatic parenchyma.

These results imply that the life span of one type of liver parenchymal cell may be at least 6 months.

It has been shown that lucerne/grass mixtures, especially those containing a high proportion of cocksfoot, can make a valuable contribution to the winter feeding of livestock when the autumn growth is allowed to stand in the field until the winter. For instance, Hughes (1954) showed that it was possible to carry store cattle right through the winter on such herbage with little supplementary feeding. Other experimental work (Barker, Hanley & Ridgman, 1955) has shown that mowing or grazing this autumn growth in September may lead to poorer production in subsequent years than October defoliation. It therefore seemed desirable to determine the effect of date of grazing in the winter on the subsequent yield of a lucerne/grass ley and two experiments for this purpose were carried out at Cambridge from 1953 to 1957.

The current study was carried out to examine the effect of cottonseed processing and chitosan supplementation on lamb performance, digestibility and nitrogen digestion. Eighty uncastrated Santa Inês lambs (23 ± 2.2 kg average weight, 4 months old) were distributed in a completely randomized design in a 2 × 2 factorial arrangement that consisted of two cottonseed processing forms (whole or ground) and two chitosan levels (0 or 136 mg/kg live weight). Higher dry matter and organic matter apparent digestibility coefficient (ADC) was achieved with the diets containing the whole cottonseed. Ether extract ADC was higher in the animals fed the chitosan-containing diet. There was an interaction effect on the ADC of neutral detergent fibre corrected for ash and protein, which increased with chitosan inclusion associated with the whole cottonseed. The lambs that received the treatment containing the whole cottonseed showed higher microbial protein synthesis. Chitosan addition increased nitrogen retention. The animals fed chitosan-containing diets showed higher microbial protein synthesis. There was an interaction effect on microbial protein synthesis. Whole cottonseed associated with chitosan in lamb diets increases ether extract ADC and microbial protein synthesis.

Although the administration of pregnant mares' serum gonadotrophin (PMSG) to induce superovulation is a well established procedure (see Anderson, Schultz & Melampny, 1963), the unpredictability of the response to this treatment continues to impose a constraint on the commercial application of egg transfer techniques in the large domestic animals. In sheep, the additional use of human chorionic gonadotrophin (HCG) has been mainly centred on attempts to control the time of ovulation (Ortavant, Thibault & Wintenberger, 1949; Braden, Lamond & Radford, 1960; Dziuk et al. 1964; McGovern, Williams & Hancock, 1969). However, Killeen & Moore (1970) found that the proportion of follicles which rupture was increased in PMSG-treated ewes which had been given HCG at the beginning of oestrus. The purpose of the observations recorded here was to examine the possibility that a further gain in ovulation rate in PMSG-treated sheep might be obtained with the use of luteinizing hormone releasing factor (LHRF). No attempt was made to reproduce physiological levels of the releasing factor and dosage was aimed at achieving a superovulatory effect.

With the development of irrigation projects in intermountain areas of the Rocky Mountain States has come an enormous increase in the amount of wheat produced annually with irrigation. The crop commands the attention and consideration of millers and grain men generally in intermountain sections and will continue to do so because there is in cultivation at present a small fraction only of the acreage that can be successfully farmed with irrigation. The general run of irrigated wheat regardless of the class to which the varieties may belong is plump and relatively heavy. It is unfortunately at the same time soft and starchy and because of its relatively low protein content is almost invariably sold on markets that do not stress strength in wheat flour.

Distribution of red cell potassium in buffaloes and its possible genetic control was investigated. The mean values of red cell K+ varied between 37 and 41 m-equiv/l in LK type animals and between 87 and 91 m-equiv/l in the HK type. Red cell K+ concentration within individual animals of either LK or HK type was fairly stable over successive samplings, whereas the same values among animals within a type varied rather widely. The inheritance of red cell K+ type in buffaloes appeared to be controlled by a single pair of genes. HK animals were homozygous for the recessive allele while LK animals represented the heterozygotes and also the homozygotes for the other allele. In addition, there was indication that the gene responsible for LK phenotypes might not be completely dominant over the recessive allele. The three populations of buffaloes examined were found to be in genetic equilibrium in respect of red cell K+ polymorphism. HK animals predominated in both the breeds, the frequency of the recessive gene (h) being 0·78 and 0·74 for the Murrah and Bhadawari breeds respectively.

1. Analyses and a greenhouse experiment on soils taken from a field experiment to estimate residual values of phosphates were used to show changes in the amount and distribution of residual phosphate in the soil.

2. Total and NaHCO2-soluble P were large in the top 0–3 in. of soil after applying superphosphate. Total P was large, but NaHCO3-soluble P much less, where rock phosphate had been applied in the field. Ploughing distributed total and NaHCO3-soluble P more uniformly through the 0–6 in. layer of soil.

3. Soil analysis and crop yields in the greenhouse showed that the residual value of equal amounts of P2O5 as rock phosphate and superphosphate, three years after application, were very similar.

4. At the end of the field experiment the sand fraction of the soil (2000–75 μ) contained about 80% of the phosphate that was applied as rock phosphate in this particle-size range.

Conniffe, Browne & Walshe (1970) proposed a form of experimental design and statistical analysis for grazing experiments. The original paper did not include any example of the analysis on real data. This note presents such an example and makes some comments on the statistical validity of the method of analysis.

Results of experiments made on cultivators' fields under rainfed conditions show that response to P application decreased as available P status of soil increased. The response to N application was higher in low organic carbon soils than in medium organic carbon soils with all levels of application and the difference in response widened with increase in N level.

The number of generations and the durations of the developmental stages of the codling moth (Cydia pomonella L.) that fed on fresh pear fruits were studied during a whole year, 1973, under laboratory conditions. In the next year, diapause of larvae was investigated in relation to the larval food.

Results showed that this insect reproduced four generations on pear fruits under laboratory conditions and diapaused during the whole period of the autumn. Broods of these generations occurred during April, June, July and September, respectively.

There was a suggestion that the larval food affected the induction of diapause in this insect. About 83% of larvae which fed on ‘ripe native Volos apples’ diapaused as early as the second half of June although the majority of larvae (93%) which fed on ‘immature pears’ continued development to adults and only 7% began to diapause under the same conditions. Up to 98% of larvae which fed on ‘fully mature ripe pears’ did not develop beyond the cocooning stage until the following spring, but 88% of larvae fed on immature pears stored at 4 °C for about 3 months reproduced a new generation about the end of October. These variable results should be attributed to the nourishment on different host-fruits in different maturity stages.

To assess the impact of farm management on herd fertility, a survey of 105 beef farms in Northern Ireland was conducted to establish the relationship between management variables and fertility. Each herd's average calving interval (CI) and the proportion of cows with a CI > 450 days (extended calving interval, ECI) was calculated to establish herd fertility. The relationship between each response variable (CI and proportion ECI) and each explanatory variable (respondents’ answers to questionnaire) was examined using univariate linear regression analyses. All response variables found to be associated with the explanatory variables were modelled against each group in turn using a fully automated multivariate stepwise regression algorithm employing the method of forward selection with backward elimination. The optimum 365-day CI and a proportion of 0 cows per hundred calved ECI targets were not widely attained in the current study. The distribution of CI and proportion ECI in the current study suggests more realistic targets would be a 379-day CI and 5 cows per hundred calved with ECI in commercial beef breeding herds. Six management factors were found to be associated with herd fertility: herd vaccination, bull selection, fertility management, breeding female management, perception of extension service (rural education provided by the government) and record keeping. It was found that respondents who vaccinated cows had a reduction of 5 cows per hundred calved in the proportion of cows with ECI, and as the number of vaccines administered to a cow increased, the CI decreased. Regular vaccination of breeding bulls was associated with a 9-day reduction in CI. Bull selection strategy had several associations with herd fertility; most notable was that respondents who used visual selection rather than estimated breeding values (EBVs) to select bulls were found to have a 15-day longer CI and 7 cows per hundred calved higher proportion of cows with ECI. For each 0·01 increase in the proportion of cows served by artificial insemination, CI increased by 0·16 days. Respondents who rated their beef breeding herd fertility as ‘very good’ had lower ECI and CI than those who rated beef breeding herd fertility as poor or satisfactory. Condition scoring of cows at weaning lowered ECI by 5 cows per hundred calved. Those who perceived the extension service to be very useful had the lowest CI and lowest ECI. Respondents who did not keep a record of CI to assess herd fertility had an 11-day longer CI and 6 cows per hundred calved higher proportion ECI than those who did not. In conclusion, the survey found a number of important variables linked to improved fertility including selecting sires based on EBVs and using a robust vaccination programme.

This study quantifies the effect of fertilizer and irrigation management on water use efficiency (WUE), crop growth and crop yield in sub-humid to semi-arid conditions of Limpopo Province, South Africa. An approach of coupling a cropping system model (DSSAT) with an agro-hydrological model (SWAT) was developed and applied to simulate crop yield at the field and catchment scale. Simulation results indicated that the application of fertilizer has a greater positive effect on maize yield than irrigation. WUE ranged from 0.10–0.57 kg/m3 (rainfed) to 0.84–1.39 kg/m3 (irrigated) and was positively correlated with fertilizer application rate. The combined application of the variants with deficit irrigation and fertilizer rate (120:60 kg N:P/ha) for maize turned out to be the best option, giving the highest WUE and increasing average yield by up to 5.7 t/ha compared to no fertilization and rainfed cultivation (1.3 t/ha). The simulated results at the catchment scale showed the considerable spatial variability of maize yield across agricultural fields with different soils, slopes and climate conditions. The average annual simulated maize yield across the catchment corresponding to the highest WUE ranged from 4.0 to 7.0 t/ha. The yield gaps ranged from 3.0 to 6.0 t/ha under deficit irrigation combined with 120N:60P kg/ha and ranged from 0.2 to 1.5 t/ha when only applying deficit irrigation but no fertilizer. This information can support regional decision makers to find appropriate interventions that aim at improving crop yield and WUE for catchments/regions.