The reproductive development and seed production characters of a Lolium multiflorum × Festuca pratensis tetraploid hybrid and a Lolium perenne × Festuca pratensis tetraploid hybrid were compared with those of their tetraploid parental cultivars. Experiments were carried out under glasshouse and natural conditions; single plants were studied as only small quantities of seed were available from the breeder. The lowtemperature/short-day requirements for inflorescence induction of the two hybrids were in between those of the corresponding parental species. The variance of the date at which vegetative primordia changed to the reproductive condition was greater in the hybrids than in the parental cultivars, but the variance of the dates of inflorescence emergence were similar for the hybrids and parental cultivars. Inflorescences ranged from the Lolium type with only sessile spikelets to the Festuca type with primary branches. Inner glumes, which are absent in the Lolium parents but present in Festuca pratensis, were found in the hybrids, though not in all spikelets. In the Lolium perenne × Festuca pratensis hybrid pollen release, potential pollen viability and floret fertility were low, but the Lolium multiflorum × Festuca pratensis hybrid produced large amounts of pollen with a higher potential viability and had floret fertilities similar to those of its two parental cultivars. There was sufficient variation in reproductive characters for further selection, particularly in the Lolium perenne × Festuca pratensis hybrid.

Jones & Sandland (1974) examined the validity of the linear model for gain per animal on stocking rate. This paper examines the alternative models of Conniffe, Browne & Walsh (1970, 1972) and a proposed extension of the model of Owen & Ridgman (1968). Discrepancies between these models and the linear model are studied in detail.

Under specified conditions these models are shown to be very close to the linear model. It is concluded, from the earlier work of Jones & Sandland (1974) and these results, that the empirically justified simple linear model has the advantage of being much easier to fit as well as embodying (approximately) the theoretical advantages of these conceptually superior models under a range of assumptions.

This paper describes the chemical composition of dressed carcasses of Angus steers and relationships between chemical and dissected components of these carcasses. These cattle were grown from 300 to 440 kg at three different rates. The rates were: High (H, 0·8 kg/day), Low (L, 0·4 kg/day) and High-Maintenance (HM, 0·8 kg/day followed by a period during which body weight was maintained constant).

There were no significant differences between treatments in the regression equations for weight of water, protein or chemical fat against left side weight (half carcass). However, weight of ash was significantly greater in the HM group than in the H group. These results are similar to those obtained with dissection data on the right side of the same carcasses.

There were no significant differences between treatments for regression equations predicting dissected composition from chemical composition. The common regressions for each component are as follows:

log y (total side muscle) = 0·282 + 1·061 log × (protein) (Sν,× 3%), (i)

log y (total side bone) = 1·055 + 0·836 log × (ash) (Sν×) (ii)

log y (total side fat) = – 0·380 + 1·076 log × (chemical fat) (Sν,× 4%), (iii)

where all values of × and y are in grams.

Equations (i) and (ii) were used to predict the dissected composition of Angus steers from another experiment in which one group of cattle lost weight. Equation (i) gave useful predictions but equation (ii) did not.

Eight laboratory and three field experiments were made on seed of Rottboellia exaltata, a grass weed of maize.

Seed stored dry, indoors or outside, either on the soil surface or buried, was unable to germinate for 5–6 months after being shed. Its ability to germinate then increased rapidly, reaching 50–70% by 8–9 months, and, indoors, continued to increase slowly to reach 80% by about ayear after being shed. Periodic wetting hastened the increase in ability to germinate of seed kept indoors or on the soil surface, but slowed down that of buried seed. When germination was tested with husks removed the ability of the caryopses to germinate began increasing soon after seed was shed, reaching 60% after 3 months and, later, up to 85–95% in different experiments. Dehusking was only effective if the inner bracts as well as the outer husks were removed, but pricking a hole through the husk and inner bracts had an effect similar to removing them. Germination decreased when in-husk seed was immersed in water before being incubated, whether this was done in air or oxygen, or in light or light/darkness, and increased again when seed was dried or its husks pierced before incubation. Wetting and drying in light, but not in darkness, increased germination of in-husk seed, and constant high temperature enhanced the increase.

When seed was buried in soil at a range of depths between 2·5 and 30 cm, the more deeply situated seed remained viable for longer than that near the surface, but there was little viable seed at any depth after 4 years. Many seedlings emerged in the first two rainy seasons after shedding of seed was prevented in an infested field which was ploughed each dry season, but by the third season the number of seedlings had greatly decreased and in the fifth season no seedlings emerged. Most of the seedlings emerging in maize fields came from seeds situated near the surface of the soil.

Experiments with main-crop potatoes were made at Rothamsted and Woburn in 1971 and 1972 to measure the effects of applying four amounts (1260, 1880, 2510 or 3140 kg/ha) of granular NPK fertilizer (containing 13% N, 13% P2O5 and 20% K2O)for two pairs of varieties (Pentland Crown and King Edward at Rothamsted; Pentland Crown and Record at Woburn) planted either 30 or 45 cm apart in the row.

Yields of each variety were greatly increased by the first and second increments of fertilizer at each farm each year (mean increases of 5·5 and 5·2 t/ha respectively), but less by the third (2·1 t/ha); total yields were increased from 35·7 t/ha with 1260 kg/ha of fertilizer to 48·5 t/ha with 3140 kg/ha. As yields increased the proportion of small tubers (< 44 mm) decreased, whilst that of medium (44–70 mm) and large (> 70 mm) tubers increased.

The removals of N, P and K by each variety of potato were calculated; for those given 2510 kg/ha of 13·13–20 fertilizer, the mean amounts (kg/ha) removed were 154, 20·6 and 242 of N, P and K respectively, or 47, 14 and 58% of the amounts given. A balance sheet showed the amounts remaining in the soil after potato harvest.

Winter wheat was grown after the potatoes to value residual N. In 1972, when average amounts of winter rain fell, grain yields were increased by these residues on the heavy Rothamsted soil, but not on the sandy Woburn soil. In 1973, after an unusually dry winter, the residues consistently decreased yields because of lodging, showing that little N had leached during the winter. % N in the grain was increased by the fertilizer residues each year.

Washed suspensions of mixed rumen protozoa readily hydrogenated fatty acids in cottonseed, soya bean and corn oils in addition to free oleic and linoleic acids. Protozoa belonging to the family Ophryoscolecidae appeared to account for almost all the activity of mixed protozoa, protozoa of the family Isotrichidae possessing little or no ability to hydrogenate the added substrates. The hydrogenation of oleic acid was markedly increased by Fe and Mn. The addition of starch cellulose, urea and sodium formate greatly stimulated hydrogenation of oleic acid by rumen protozoa. Glucose, casein, ammonium sulphate, L-cysteine and n-valeric acid had no or little effect on extent of hydrogenation.

When suspensions of mixed protozoa were incubated in a buffer solution, an increase in iodine value was observed. The desaturation in the protozoal cells was appreciably increased by DL-methionine and was not influenced by L-cysteine. No desaturation activity by the pure suspensions of Ophryoscolecidae or Isotrichidae was observed.

The presence of protozoa in the rumen of sheep greatly increased the levels of saturated fatty acids over those in the ciliate-free animals. The concentrations of saturated fatty acids in the plasma of faunated sheep were significantly higher than those in the same animals after the removal of rumen ciliate protozoa.

The milk production of 14 Finnish Landrace × Blackface ewes suckling either single, twin or triplet lambs was recorded while they were wholly maintained on a high-quality grazed pasture. Intravenous administration of oxytocin followed by hand milking was used to estimate milk production within 4 days of parturition and then at weekly intervals during a 12-week lactation period. At each milking the milk from each ewe was retained for analysis. Herbage samples for analysis were cut by hand shears at weekly intervals at a height simulating the harvesting by the sheep. In vitro analysis showed a decline in the digestible organic matter in the herbage from approximately 75% in the early stages, to around 67% at the end of lactation. The percentage crude protein in the dry matter of the herbage was variable but tended to increase towards the end of the lactation period. The estimated mean total milk production values were 125, 176 and 193 kg for single-, twin- and triplet-suckled groups of ewes, respectively. Almost all of the difference in total yield between the groups of multiplesuckled ewes occurred in the first 4 weeks of lactation. Analysis of variance showed no significant differences between suckling groups in the concentration of any of the milk constituents. Regression analysis showed significant evidence for differences between the linear and quadratic components of the regressions on stage of lactation for the suckling groups only in respect of daily milk yield, energy and protein production. The concentration of constituents other than lactose was higher in colostral milk but the differences were statistically significant only in respect of energy, total solids and fat. The lactose content of ordinary milk was significantly higher than that of colostral milk. The mean daily live-weight gains of the single- and twin-suckled lambs were significantly greater than that of the triplet-suckled group.

Milk production (305 day lactations, 3·5% fat-corrected milk), and lengths of time between calving and conception for 541 heifers and 1127 older cows were examined. These data were collected from 11 herds in collective farms in Israel during two successive years. Herd lactation means ranged from 5046 to 8570 kg for cows and from 5021 to 7250 for heifers; the ranges of time between calving and conception were 89–123 days and 99–141 days, respectively.

A significant correlation was found between the weight of milk given per lactation and the length of the interval between calving and the next conception, with coefficients of 0·298 (cows) and 0·333 (heifers). There was a positive non-linear regression of length of calving to conception interval on production of milk, the regression line becoming steeper, both for cows and heifers, as yield rose.

All herds practised first insemination at the first heat exhibited after 60 days from calving. The results indicate that, when this is done, cows yielding 8000 kg or over per lactation, and heifers yielding 6750 kg or over, will show calving to conception intervals exceeding a mean length of 110 days.

The drying rate of leaves and stem internodes from flowering culms of two varieties of Italian ryegrass (Lolium multiflorum) were measured in the laboratory in controlled conditions of temperature (28 °C), relative humidity (22%) and air speed (40 cm/sec), without treatment, or after being subjected to thermal treatment or to mechanical damage followed by thermal treatment. The two treatments increased the drying rate of leaves and, to a greater extent, stem internodes.

While it cannot be concluded that all treatments that increase crop drying rate will increase the rate for stems more than for leaves, these results are considered to indicate the possibility of devising practical treatments which will. Such treatments could reduce leaf shatter and consequent serious loss of dry matter during the field drying of grass crops.

Experiments with winter wheat in 1972 and 1973 tested all combinations of ‘Nitro-Chalk’ ν. liquid N-fertilizer, 56 ν. 112 kg N/ha, 0 ν 5·6 1/ha of herbicide (2·8 kg acid equivalent/ha) and 0 ν 0·7 1/ha of mildew fungicide, all applied at growth stage 4–5 of the Feekes scale. The liquid fertilizer (26 % N) was a solution of ammonium nitrate and urea, the herbicide was a mixture of dichlorprop and MCPA and the mildew fungicide contained 75 % (w/v) of the active ingredient tridemorph.

The herbicide and mildew fungicide were sprayed either alone or together and neither scorched the wheat leaves. Liquid N-fertilizer by itself slightly scorched the wheat leaves and scorch was increased by adding herbicide to it, but more by adding the fungicide and most by adding both; it was then severe, especially with 112 kg N/ha.

Weed control after adding herbicide to the liquid fertilizer was at least as good as from herbicide sprayed alone.

In July, foliar diseases were much more severe with 112 than with 56 kg N/ha, but effects of the other treatments, including fungicide, on foliar diseases, were then very small.

With 56 kg N/ha, yields were slightly larger with ‘Nitro-Chalk’ alone than with the liquid N-fertilizer alone, but with 112 kg N/ha they were slightly larger with the liquid fertilizer; adding herbicide to the liquid fertilizer did not change these results. With either amount of N, adding mildew fungicide to the liquid fertilizer made it less good than ‘Nitro-Chalk’, presumably because of the damage from leaf scorch; adding both herbicide and fungicide to the liquid fertilizer increased the damage.

The relation between composition of food and numbers of rumen ciliates was examined in three buffaloes fed once a day. Depending on the diet and time after feeding, the total protozoa varied from 0·97 x 105 to 9·11 x 105/ml rumen fluid. Entodinia formed from 87·0 to 97·1%, Diplodinia from 1·9 to 11·4%, and Holotricha from 1·0 to 1·7%. The numbers of Entodinium, Polyplastron multivesiculatum and Holotricha were least in animals fed on hay only, while the smallest number of Anoplodinium denticulatum and Eudiplodinium maggii was found in buffaloes given a mixed diet containing 13·3% of concentrates. The highest number of protozoa was found in animals fed a mixed diet containing 26·9% of concentrates. No correlation was found between level of protein, crude fibre or nitrogen extracts in food and numbers of Entodinium, Polyplasstron and Holotricha in the rumen, but numbers of Anoplodinium denticulatum and Eudiplodinium maggii increased as protein content increased.

Meadow hay and mixed food containing 13·3 or 26·9% of concentrates were used for culturing ciliates taken from the rumen of water buffalo. The culture medium was the sterilized rumen fluid or a solution of mineral salts. The cultures were mixed every 24h and one-half of the contents of each culture flask was transferred to an equal volume of fresh medium containing the appropriate food.

Anoplodinium denticulatum and seven species of Entodinium were the only protozoa which survived until the end of the experiment, but to maintain them on food containing 26·9% of concentrates an alkaline or neutral medium was required. Using rumen fluid and mineral medium the total number of protozoa was on average, respectively: 2·7 x 103 and 2·2 x 103/ml in cultures on hay only; 9·4 x 103 and 17·5 x 103/ml in cultures on food containing 26·9% of concentrates; and 14·0 x 103 and 17·;8 x 103/ml in cultures on food containing 13·3% of concentrates. Entodinium formed 66·6 and 72·5%; 95·5 and 91·8%; and 96·1 and 97·7% of the total counts. In cultures on hay alone there were 33·4 and 27·5% of Anoplodinium denticulatum, while they formed only 4·5 and 8·2% and 3·9 and 2·3% in cultures on food containing 26·9 and 13·3% of concentrates respectively.

The relation between number of ciliates and composition of food only partly agreed with the relation found previously under natural conditions. Changes in pH of the medium would appear to be the chief cause.

The mechanical and eleetromyographic activity of the pyloric antrum and duodenum of sheep has been studied both under resting conditions and while infusing various solutions to alter the chemical composition of the chyme.

Bursts of spike-type electrical activity, synchronized with the depolarization phase of slower potential variations, accompanied duodenal contractions. Both mechanical distension and chemical stimulation of the proximal duodenum influenced the electrical activity and led to changes in the frequency, duration and amplitude of contractions.

Grass plots, designed to provide 4 days grazing for three heifers, were divided into four equal sub-plots which were dressed with cow slurry in March at rates between 0 and 100 t/ha. The heifers were put into the plots 7 and 13 weeks after slurry application and were able to choose in which of the sub-plots they spent their time and grazed.

The main effect of slurry on the pasture at 7 weeks was to increase the height of the sward but to decrease herbage dry-matter production. Herbage dry-matter utilization over the 4 days ranged from 94% on the no-slurry sub-plot to only 41% when slurry had been applied at 100 t/ha. The heifers spent most time in and grazed more often in sub-plots with little or no slurry for the first 2 days, but as the grass was eaten down the frequency of grazing on areas with more slurry increased. This was reflected in the amount of grass removed by the heifers from each treatment on each day.

At the beginning of the second grazing, grass height and herbage dry-matter production were both directly related to level of slurry application. The heifers did not distinguish between treatments up to 50 t/ha, but herbage utilization on the 100 t/ha sub-plot was reduced.

A field experiment to compare the growth, development and yields of four varieties of oilseed rape, Cresus, Guile, Rigo and Nilla, is described and the results discussed. Cressus was the highest-yielding variety largely because it produced more pods and more seeds per pod. The numbers of pods and seeds per pod were positively correlated with the leaf area index at the onset of flowering. This suggests that the rate of supply of carbon assimilates to the inflorescences around the time of anthesis is an important yield-determining character. The mean weight of the individual seeds was greater in Cresus than Guile and this difference, which developed late on in pod growth, also contributed to the higher yields in Cresus.

The effect of age on the fatty acid composition of depot fat of Jersey cattle has been investigated. Serial samples of subcutaneous fat were obtained by biopsy of the same animals from 3 months to 2 years of age. Samples of depot fat were also obtained from various anatomical locations of animals slaughtered between birth and 11 years of age.

In subcutaneous fat at biopsy the percentage stearic acid remained constant to 1 year of age and then declined from 20% to 5% during the period 1–2 years post partum.

In perinephric fat the stearic acid content increased from 10–15% at birth to 40% at 1 year of age, and then declined during the period 1–2 years post partum.

Changes in the percentage stearic acid above the 10% level were accompanied by inverse change in octadecenoic (C18:1) acid, and below 10% mainly by change in hexadecenoic (C16:l) acid.

There was a gradient of unsaturation between subcutaneous and internal body fats, and also within the subcutaneous fat itself.

Evidence is presented to suggest that the decrease in the unsaturation of depot fat during the period 1–2 years post partum is associated with the deposition of more unsaturated fatty acids during the fattening phase of development.

The organic-matter intake and the digestibility of grazed tropical pasture mixtures were assessed by the chromic oxide-faecal organic matter-nitrogen technique in five digestion trials. The pasture treatments were designated as: H, Cynodon nlemfuensis var. robustus in a mixture with the legumes Centrosema pubescens and Stylosanthes gracilis; J, Pennisetum purpureum in a mixture with the two legumes in H; K, treatment J plus Panicum maximum; L, a mixture of all the grass and legume species in treatments H, J and K.

The mean organic-matter digestibility of the herbages was determined in indoor digestion trials during the experimental period and varied from approximately 60·0 ± 1·73% to 62·7 ± 4·18% in treatments K and H respectively, with treatments J and L falling between these two values. The mean digestibility of the herbage as grazed, however, was approximately 66·8 ± 1·72, 69·7 ±7·68, 67·1 ± 4·40 and 67·4 ± 4·15 % for treatments, H, J, K and L respectively.

The estimated mean intake of organic matter was somewhat lower, while that of the digestible organic matter was appreciably lower than those reported for animals of corresponding live weights in temperate countries. Grazed pastures were better digested by 4·1 digestibility units in treatment H, by 7·1 in both J and K, and by 5·3 units in L, compared with the indoor digestion trials.

More intensive studies are still needed to warrant any justifiable conclusion as to whether the low intake of herbage by tropical cattle is due primarily to the high crude fibre and the low nutritional values of the pastures, or to the inherent capacity of the animals conditioned to grazing poor·quality pastures.

From 62 days of gestation to parturition, 20 Finnish Landrace x Dorset Horn ewes were each offered one of four diets with roughage to concentrate ratios of 20:80; 40:60; 60:40 and 80:20, at daily metabolizable energy and digestible crude protein intakes of 490 kJ and 3·55 g/kg W0·75 respectively. Plasma concentration of free fatty acids, glucose and urea were determined weekly, and nitrogen balance and digestibility trials were carried out at 70–80 and 130–140 days of gestation.

On all treatments the concentration of plasma free fatty acids increased during pregnancy from approximately 200–600 μ-equiv./l and the concentration of glucose and urea decreased by approximately 25%.

Digestibility coefficients for dry matter and organic matter increased from 58 to 68% and from 60 to 70% respectively as the proportion of concentrates in the diet increased and were not affected by stage of gestation. The apparent digestibility of nitrogen was not affected by the energy concentration of the diet.

Between mid and late gestation there was a mean increase in daily nitrogen retention of 2·5 g and an improvement in the efficiency of nitrogen utilization of 19 percentage units.

Nitrogen retention and the efficiency with which the apparently digested nitrogen intake was retained increased as the dietary energy concentration was increased. The mean daily increases in nitrogen retention were 0·0135 and 0·0039 g for each percentage unit increase in the concentrate portion of the diet at mid and late gestation respectively. The corresponding values for the improvement in the efficiency of nitrogen utilization were 0·13 and 0·10%.

Varietal and environmental factors which influence test weight were investigated in a field trial with ten varieties of winter wheat and two rates of nitrogen fertilizer. Varietal differences in test weight were correlated positively with the protein content of the grain and inversely with grain yield but they were not related to 1000-grain weight or to flour yield. Variation in test weight associated with varietal and environmental effects in protein content was due to differences in the density of the grain, as measured by displacement of xylene. Separation into density grades within a sample by a flotation method showed a similar relationship with protein content. There were also varietal differences in packing efficiency of the grain. In the case of Maris Huntsman a poor packing efficiency was considered to stem from morphological features of the floret and developing grain which lead to characteristic transverse folds in the ventral surface of the mature grain. For wheat grown in the United Kingdom, test weight may provide a useful guide to flour yield for samples of one variety but it is likely to be misleading for comparisons between varieties.

A method is described of determining the fertilizer P and K requirements of livestock farms from a knowledge of the stock carried and the crops grown on the farm as a whole. Recycling of P and K through organic manures is put on a rational basis and the fertilizer P and K needed to keep soil P and K at an adequate and constant level is easily measured.

A pilot scheme on 100 Northern Ireland farms is testing the method's value for giving advice. It is readily acceptable to advisers and farmers and is enabling substantial savings of fertilizers to be made.