An experiment was designed to test the response of growing pullets to two changes in photoperiod (an increase from 8 to 14 h followed 5 weeks later by the reverse change, or a decrease from 14 to 8 h followed by an increase). The first change was made either at 35 days or at 56 days of age, to test the influence of age on the responses observed. Control groups were kept on constant 8-h and constant 14-h photoperiods and the responses to appropriate single changes were also tested. Mean age at first egg varied from 111 days for birds given a single increment at 56 days to 166 days for pullets given an increase in photoperiod at 35 days followed by a reduction at 70 days. Responses to the single changes confirmed earlier reports that sensitivity to change in photoperiod varies with age in a manner that is quantitatively predictable. Responses to the double changes could be explained by postulating that the initial change altered the ‘physiological age’ of the bird to an extent that was also quantitatively predictable. An early increase in photoperiod advances sexual development and makes the bird more sensitive to a subsequent decrease than would be expected by reference to its chronological age. An early decrease in photoperiod delays sexual development, which can have the effect of making the bird more or less sensitive to a subsequent increase since, in layer-strain pullets, sensitivity to an increment in photoperiod normally increases up to about 9 weeks of age but decreases thereafter. Mean age at first egg predicted using these concepts was very highly correlated with observed age at first egg. The results provide a rational basis for constructing a model to predict age at first egg for any combination of increases and decreases in photoperiod applied to growing pullets.

Border Leicester ewes were kept in three contrasting photoperiodic environments, the rhythm at latitude 30° 32′ S (group 1) - 12 h light: 12 h dark interrupted by 6 weeks of continuous light (group 2a) and 12 h light: 12 h dark (group 2b) - from August 1972 to September 1973. In group 1 all ewes exhibited oestrus compared with 87·5% and 57·1% in groups 2(a) and 2(b) respectively. The mean number of oestrous periods per ewe ranged from 4·4 in group 1 to 3·0 in group 2(a) and 1·0 in group 2(b). It is concluded that the non-fluctuating light rhythm had an adverse effect on the reproductive potential of the treated groups and that Border Leicester ewes are dependent on a fluctuating light rhythm for normal reproductive function.

An analysis of variance is developed for data from an incomplete mixture diallel experiment, where one subset w of the p genotypes are not grown together in mixtures. Estimation procedures and tests of hypotheses concerning relative yield totals and aggressivities are discussed, and an example is presented.

Individual variation in the triple relationship of food intake, live weight and gain was examined in 40 twin calves. Appetite largely determined food intake.

Regression analyses of fortnightly gain on protein and starch equivalent and mean weight are presented. Gain per lb. of P.E. or S.E. showed real but irregular changes from fortnight to fortnight. The food differential between heavier and lighter animals decreased during adaptation to new surroundings and diets.

The failure of a high proportion of fertile eggs to hatch still remains a major cause of financial loss to the poultry industry. Payne (1919) pointed out the consistent manner in which embryonic mortality manifested peak periods at the fourth day and the nineteenth day of incubation, and he drew attention to the fact that the latter period of susoeptibility showed an increased level of mortality with artificial incubation compared with natural methods. Romanoff (1949) summarized the explanations put forward to account for these two peaks of embryonic mortality. Riddle (1930) suggested that the first period was caused by respiratory maladjustments, and he, and others, considered that the failure of the developing embryo to make the fine adjustments at this time and to deal effectively with the excretion of various toxic substances may be a major cause of death. The second peak period of mortality occurs at the transition from allantoic to pulmonary respiration. Failure to achieve this change, with the consequent death of the chick in the last stages of development, may be greatly influenced by the cumulative effect of all the unfavourable conditions to which the hatching egg has been subjected. Not the least of these will be environmental conditions in the incubator and the incubator house adversely affecting the oxygen supply and the relative humidity.

The fate of abomasal and intravenous doses of [35S]cystine and [35S]methionine was investigated in sheep to determine their relative efficacy as supplements for wool growth.

Administration of L-[35S]cystine and L-, DL- and D-[35S]methionine via the abomasum produced similar patterns of 35S labelling in blood plasma. Only 10–16% of the administered 35S was excreted in urine over 7 days and 22–32% of the dose was incorporated into wool over 21 days. All isomers were utilized by the sheep with similar efficiency and it was concluded that D- and L-methionine and L-cystine are equally effective as supplements for wool growth at optimal dose rates. Abomasal supplementation with a large amount of methionine (10 g/day) resulted in the excretion of a high proportion of the 35S in urine (55% of the dose over 7 days) and low incorporation into wool.

A comparison of the extent of incorporation of 35S into wool from intravenous doses of L-[35S]cystine and L-[35S]methionine in the same sheep, and in sheep from flocks selected for high and low wool production, showed that incorporation from methionine averaged 80% of that from cystine. It was concluded that, at moderate (2–3 g/day) methionine availability, methionine is utilized for synthesis of wool with about 80% of the efficiency of cystine, conversion of methionine to cysteine occurring via the transulphuration pathway.

The largest yields of potatoes in the Woburn Reference Experiment were obtained by giving both farmyard manure (FYM) and fertilizers, rather than fertilizers alone; an explanation was sought in experiments made on the coarse sandy loam there from 1968–71. Each year, single and double amounts of NPK fertilizer (supplying 250 or 500 kg N/ha plus P and K) were incorporated, either deeply or shallowly, into the seed bed. From 1969, FYM also was tested at rates giving the same amounts of N, similar amounts of K, but more P than the fertilizers; it was tested both alone and with fertilizers.

FYM was less effective than fertilizer when given alone. The combination of FYM and fertilizer gave a larger yield than the single amount of fertilizer and a larger yield than the double amount of fertilizer incorporated shallowly, but a smaller yield than the double amount of fertilizer incorporated deeply, which gave the largest yield each year.

The NPK contents of the potato tubers were used to construct nutrient balance sheets; large residues of N, P and K remained in the soil after harvest. Winter wheat was grown to value these in 1971 and 1972. Fertilizer residues increased only straw yields, but FYM residues increased yields of both grain and straw. Both kinds of residues were less effective than freshly applied N, so most of the N leached during winter.

The yield of saleable tubers was increased, not decreased, by the double amount of fertilizer.

Soils from 55 maize fields in southern and eastern England were tested for available zinc, copper, magnesium and potassium by routine extraction procedures. A high proportion (64%) of the samples contained less than the recommended 50 mg/kg available magnesium, and 24% were within the deficiency range (< 25 mg/kg) for this element. Fewer sites were deficient in copper (7%) and zinc (5%) and these were mainly sandy soils or loams developed on Clay-with-Flints over Chalk. Zinc deficiency in maize does not appear to be a serious potential problem in Britain even though it occurs frequently in other countries, including parts of France.

A field of maize with growth problems of varying severity was studied in detail and the available magnesium concentrations found to correlate most closely with the degree of stunting. Soils with healthy plants differed from those in stunted patches of the crop by having higher extractable magnesium, copper and potassium contents. In general the composition of the maize leaves tended to reflect the supply status of the soil, except in the case of chlorotic plants.

The influence of factors affecting the availability of the elements investigated and the significance of marginal deficiencies of magnesium and micronutrients in maize are discussed.

1. The necessity for further information on the digestibility of heather, with particular reference to the effect of age, has been discussed.

2. The digestibility of well-defined samples of heather of 4 and 10 years of age has been determined.

3. Four-year-old Blackface wethers in crates were fed diets containing 50% of heather and 50% of medium-quality meadow hay.

4. The younger sample of heather was found to have appreciably higher digestibility coefficients for all nutritive constituents other than crude fibre.

5. Agreement between duplicate sheep in respect of their capacity to digest crude protein was found to be good, and faecal metabolic nitrogen outputs were similar.

6. Faecal metabolic nitrogen output was inversely related to the percentage of heather contained in the diet. No relationship between faecal metabolic nitrogen and bulk, as measured on a basis of volume per unit weight, could be established.

7. It has been concluded that heather, though inferior as a source of protein, provides rather more energy than a poor-quality meadow hay, and is thus of value as a winter feed.

The effects of growing pinto peanut mixed with elephant grass-based pastures are still little known. The aim of the current research was to evaluate the performance of herbage yield, nutritive value of forage and animal responses to levels of pinto peanut forage mass mixed with elephant grass in low-input systems. Three grazing systems were evaluated: (i) elephant grass-based (control); (ii) pinto peanut, low-density forage yield (63 g/kg of dry matter – DM) + elephant grass; and (iii) pinto peanut, high-density dry matter forage yield (206 g/kg DM) + elephant grass. The experimental design was completely randomized with the three treatments (grazing systems) and three replicates (paddocks) in split-plot grazing cycles. Forage samples were collected to evaluate the pasture and animal responses. Leaf blades of elephant grass and the other companion grasses of pinto peanut were collected to analyse the crude protein, in vitro digestible organic matter and total digestible nutrients. The pinto peanut, high-density dry matter forage yield + elephant grass treatment was found to give the best results in terms of herbage yield, forage intake and stocking rate, as well as having higher crude protein contents for both elephant grass and the other grasses, followed by pinto peanut with low-density forage yield + elephant grass and finally elephant grass alone. Better results were found with the grass–legume system for pasture and animal responses.

Experiments were carried out in 1985 and 1986 on a sandy clay–loam to investigate the effects of above average rainfall in May and early June on the growth of the spring barley cv. Klaxon in three systems of cultivation. The cultivation treatments, ploughing (P), shallow-tine cultivation (S) and direct drilling (D), had been repeated on the same plots and cropped with spring barley each year since 1971.

A total of 112 mm water was applied to the waterlogged subplots in 1985 and 168 mm in 1986.

Compared with plots receiving the normal seasonal rainfall, extra water had no effect on shoot or grain yield in 1985 (mean grain yield 6·38 t/ha) and there were no significant differences between cultivation systems. In 1986, in contrast, water, in excess of normal rainfall, depressed both shoot growth and grain yield (mean grain yields 4·49 and 4·07 t/ha for the normal rainfall and the additional water treatments, respectively), the effect being greater on P than on either S or D.

In both years, saturation was achieved in the topsoil for a prolonged period during May and early June in the waterlogged subplots. In 1985 this was associated with a period of low oxygen flux and low redox potential, but this did nothave a significant effect on root or shoot growth. In 1986 there was no comparable period of reduced aeration, nor any significant differences in oxygen flux or redox potentials between water and cultivation treatments. In 1986, reduced growth and yield were directly associated with a mean reduction in N recovery by shoots of 36 kg N/ha, the effect being greatest on the ploughed plots where water was added. The results do not support the hypothesis that waterlogging per seaffects the growth of barley more on ploughed than on direct-drilled land.

Methane (CH4) consumption in agricultural soil is imperative for the mitigation of climate change. However, the effect of tillage and cropping systems on CH4 consumption is less studied. Experiments were carried out in Madhya Pradesh, India with soybean-wheat (SW), maize-wheat (MW) and maize-gram (MG) cropping systems under conventional tillage (CT) and no-tillage (NT). Soybean/maize was cultivated during the kharif season (July–October) and wheat/chickpea in the rabi season (October–March) for 9 years consecutively. Soil samples were collected during vegetative growth stages of soybean and maize from different cropping systems. Methane consumption, the abundance of methanotrophs as particulate methane monooxygenase (pmoA) gene copies, soil and crop parameters were estimated. Methane consumption rate was higher in NT and upper soil layer (0–5 cm) than CT and 5–15 cm depth. Methane consumption rate k ranged from 0.35 to 0.56 μg CH4 consumed/g soil/d in the order of MW>SW>MG in 0–5 cm. The abundance of pmoA gene copies ranged from 43 × 104/g soil to 13 × 104/g soil and was highest in MW-NT and lowest in MG-CT. Available nitrogen, phosphorus and potassium were higher in 0–5 cm than in 5–15 cm depth. Soil and plant parameters and abundance of pmoA genes correlated significantly and positively with CH4 consumption rate. No-tillage stimulated CH4 consumption compared to CT irrespective of cropping system and CH4 consumption potential was highest in MW and lowest in MG. However, the magnitude of the positive effect of NT towards CH4 consumption was higher in SW and MG than MW.

1. Humic acids and ammonium humates prepared by a patented process of gentle oxidation of coal were examined as fertilisers by laboratory nitrification experiments and pot-culture tests on four soils and by a number of field experiments on a range of soils and crops during a single season.

2. In all tests the effects of ammonium humate could not be distinguished from those of ammonium sulphate of equal ammonium content. The nitrification tests and the pot cultures afforded some evidence of a slow production of nitrate or available nitrogen from the humic acid.

3. In the field experiments as in the pots there was no clear evidence of any fertiliser value apart from that due to the ammonium present.

Many trials have been carried out in Australia to assess comparative values of breeds of rams and owes for fat lamb production in various environments and for different markets. Although general trends have appeared, there is much conflicting evidence in the reports of these trials as to the order of superiority of breed for a particular environmentmarket situation, especially for that of the rams. Much of this conflicting evidence arises because no completely satisfactory method of assessment of superiority has been used. Many of the studies undertaken to compare different breeds of ram have used as their basic criterion the returns per ewe (for example, McConnell, 1910; Elliot, 1926; Colebatch & Scott, 1927; Coleman, 1927; Cook, 1934; Thompson, 1951; Coleman & McDonald, 1952). In this situation random fluctuations in lambing percentages and in percentages of lambs surviving to slaughter can affect the order of superiority of the breeds. In view of the comparatively small numbers of sheep often used in the breed comparison groups (and this is, of course, particularly true in the case of rams), these deviations can bo sorious. For example, McConnell (1910) found that Border Leicester x lambs had a higher return per ewe than Southdown x lambs, but in 1911, the same author found the reverse situation which appears to have been due to a reversal in order of lambing percentages.

Changes in the amounts of nitrogen, phosphorus, magnesium, calcium and sodium present in intact grain, endosperm, testa pericarp and embryo throughout the developmental period were recorded. While the overall pattern in intact grain was one of steady accumulation, considerable variation from this pattern was found within the different parts. The results are discussed in relation to the biochemical events accompanying maturation.

Chopped barley straw was fed ad libitum to penned Romney wether sheep. Supplements of urea, ground wheat grain + urea, lucerne hay and autumn saved pasture (ASP) were given for five periods each of 3 weeks using a 5 × 5 Latin square design. The latter three supplements supplied similar amounts of nitrogen and approximately 20% of the energy required for maintenance.

The concentration of ammonia in the rumen fluid of sheep fed the basal straw diet was low and was increased by all the supplements. The concentration of total volatile fatty acids (VFA) in rumen fluid was unaffected by supplementation with urea, but was increased by the three supplements of nitrogen and energy. Differences in VFA molar proportions between treatments were small.

Sheep offered straw alone had a digestible energy (DE) intake of 69% of maintenance and showed a weight loss of 121 g/day. Supplementation with urea had no effect upon apparent energy digestibility (42%) or voluntary intake, but significantly reduced the rate of live-weight loss. The lucerne hay and ASP supplements also had no effect upon straw consumption, but increased total DE intake to 87% of maintenance due to the additional energy provided by the supplements, and reduced live-weight loss. Supplementation with wheat + urea increased the estimated amount of digestible organic matter derived from straw by 8·5%, increasing DE intake to 94% of maintenance and reducing live-weight loss to 18 g/day.

Averaged over all five groups of animals, straw intake increased by 9% in the second period of feeding and then gradually decreased with time, reaching a value in period 5 which was similar to period 1.

Gibberellic acid (GA3); monophenols, salicylic acid (SA) and β-naphthol (β-N); diphenols, catechol (CT) and resorcinol (Res); and polyphenols, chlorogenic acid (CA) and tannic acid (TA) hastened the emergence of ears and increased the numbers of branches and ears, number of seeds, seed weight and the 1000-seed weight in cheena millet (Panicum miliaceum L.). The results show that the action of phenolic compounds is not related to their structural configuration as is considered by some workers.

The success of GM herbicide tolerant canola is demonstrated by its acceptance by the farm community in Canada. There have been continuing comments, however, including some from major customers, suggesting that GM canola has lower quality than conventional canola. Data drawn from both the Western Canada Canola/Rapeseed Co-operative Test data from 1998–2001 and from the Canadian Grain Commission's harvest surveys of canola from 1996–2001 were used to compare the quality of GM and conventional canola registered and grown. Weed seed contamination of harvest survey samples decreased significantly as the herbicide tolerant lines increased in production. While variety registration data suggested GM and conventional lines had no differences in oil content, data from harvest surveys suggested that GM lines tended to have slightly higher oil contents. Protein and oil contents remain inversely related with no differences in the inverse relationship due to GM. While registration requires that all lines have less than 12 micromoles per gram of glucosinolates, data from harvest surveys show GM lines to have significantly less glucosinolates than conventional lines, possibly due to decreased contamination with cruciferous weeds. A comparison of glucosinolate contents between non-GM herbicide tolerant canola and conventional non-herbicide tolerant canola showed similar differences. There were no significant differences in chlorophyll content, erucic acid levels or saturated fatty acids but harvest survey data showed GM lines were slightly more unsaturated than conventional lines. It would seem safe to conclude that differences in quality between GM and conventional canola are due to the functioning of the GM trait – herbicide tolerance – that allows the GM canola to perform to its potential in the field.

A multivariate linear model was developed to evaluate dairy cow body weight (BW) during lactation on a commercial dairy farm. The model was calibrated separately for first, second and greater than second parities, and also for winter and summer calvers, fed a total mixed ration of 65% concentrates. Average weekly BW was predicted using the following variables on a weekly basis: 4% fat-corrected milk (FCM) yield, time of conception (PREG), time from calving (w), initial body weight (1BW) measured within 2 days after calving, and weeks remaining until the end of the calving season (SWR). The ability of the model to predict mean BW along lactations was tested in the same herd following calibration and during the same period. The prediction capacity of the model for average BW of groups of cows was examined on two timescales: (i) time from calving (physiological timescale) and (ii) any time during the year (calendar timescale). Results indicated that predicted mean BW deviated from measured values either by 1–2% with a maximal deviation of c. 5% on the physiological timescale or by up to 2% on the calendar timescale.

Currently, the diversity of sow herd management strategies has been described but there are no tools that explore how it promotes sow herd performance nor how it or performance are linked to work organization problems. The goal of the current study was to build a herd dynamic, stochastic object-oriented model capable of representing the herd dynamics and performance, and to predict the number of events workers will have to deal with. Each sow is individually represented in the model and the model works as a discrete event simulator with a predefined time step of 1 h. At each time step of simulation, the model searches for an event to be processed. An event may imply change of sow physiological state (e.g. oestrus, farrowing and insemination) and/or request an action from a worker (e.g. oestrous detection and farrowing supervision). This action may result in the planning of a new event (e.g. farrowing after mating) and/or modification of sow state (e.g. from oestrus to pregnant). The occurrences of some technical activities such as weaning are defined in time and frequency according to the management strategy of the farmer. The model is stochastic as sow biology is represented by several normal univariate distributions according to parity or by a threshold (fertility, abortion and mortality rates). When sows return into oestrus after mating they can be moved to another batch or culled depending on batch management strategy and culling policy. Outputs of this model focus on productivity of sows and distribution of tasks over the week. Definitions of the duration of simulation and number of replications to obtain the steady state and the variability of results are presented. The model is able to simulate several batch farrowing systems (BFS) and results of 1-, 3- and 4-week BFS are presented. Several simulations with modified management (no oestrous detection during the weekend and change of the weaning day) or with modified sow biology (increased variability of the weaning-to-oestrus interval and lower fertility rate) are performed. Results indicate that these modifications have specific consequences on performance and task distribution according to the BFS. The model provides useful information concerning the effects of herd management strategies on productivity and distribution of events over time and their sensitivity to biological criteria.