Seven Wiltshire Horn rams were subjected to unilateral thoracic sympathectomy. Wool shedding was observed during the following 9 months. Fleece samples were collected on two occasions during winter from tattooed areas of skin on both the sympathectomized and unoperated sides. Skin samples were also taken from the sympathectomized and unoperated sides of the sheep during August and examined for catecholamine fluorescence using a fluorescence histochemical technique. While there was no difference in fleece casting between the sympathectomized and unoperated sides, there were increases in both wool growth and the number of brush end fibres on the sympathectomized side. Fluorescent histochemical evaluation of the skin samples revealed that the increases in shed fibres and wool growth were accompanied by a decrease in amine fluorescence in nonvascular tissue adjacent to the wool follicles.

By comparing growth rates of Brahman (B), Hereford × Shorthorn (HS), their reciprocal F1, hybrid (F1BX), their Fn hybrid (FnBX) and an F1 Charolais × Brahman hybrid (Fl CH x B) in environments that differed in their levels of stresses that affected growth, it was shown that heterosis for growth realized in any environment arose because of heterosis in its underlying determinants, namely growth potential and resistance to environmental stresses. Growth potential of the F1 BX was similar to that of the better parent (HS) whilst resistance to environmental stresses was similar to or approached that of the more resistant parent (B). This combination of high growth potential and high resistance to environmental stresses enabled the F1 BX to outgain both parents at all levels of environmental stress above zero. However, some or all of the heterosis in both growth potential and resistance to environmental stresses was lost in the Fn BX. Thus, although previous selection for increased live-weight gain should have favoured the Fn BX, they realized lower live-weight gains than the Fl BX in all environments and lower live-weight gains than the parental breeds in all but intermediate environments.

Because the breeds differed in both determinants of growth, the magnitude of estimates of heterosis for realized growth was dependent on the environment in which it was measured. A figure depicting this interaction was constructed.

Comparative estimates were also made of the rate of approach to sexual maturity of bulls of each breed. The F1 BX had similar values to the better parent (HS) for both scrotal circumference and plasma testosterone concentrations. However, the Fn BX had values that were intermediate to those of the parental breeds.

Generally, gains of the -F, CH × B exceeded those of all other breeds in all environments but their rate of approach to sexual maturity was slower than that of the F1 BX.

Fifteen treatments were applied in 1966 to Molinia caerulea dominant rough grazing on wet hill land at 305 m in mid-Wales. Improvement methods varied from controlled sheep grazing, application of lime, basic slag and nitrogen to the introduction of grasses and white clover with and without cultivations. Pasture productivity, feed quality and botanical composition were studied in the 4th, 9th, 14th and 18th harvest years. Controlled grazing increased D.M. production from 1·1 t/ha on the native vegetation to 3 t/ha in the 18th year. Application of lime, basic slag and 75 kg N/ha gave mean pasture production of 4·5 t D.M./ha which increased to 6·3 t D.M./ha on application of 290 kg N/ha per year. The quickest and greatest improvement was achieved by the introduction of grasses and clover following rotary cultivation or ploughing. At the lower N input these swards produced on average 6·3 t D.M./ha. Reseeds also showed the best response to 290 kg N with mean production on S. 23 perennial ryegrass (Lolium perenne L.) swards of 9·0 t D.M./ha. In vitro digestibility, crude protein and water-soluble carbohydrates were also highest on the reseeded swards.

Increased grazing eliminated Molinia before the 4th year and it was replaced by Nardus stricta and Festuca ovina. Subsequently, Agrostis tenuis replaced Nardus. On the swards given fertilizer the rate of botanical change was accelerated with the ingress of Poa spp., Holcus lanatus and Festuca rubra. The proportion of sown grass remained high on the seeded plots throughout the duration of the experiment but the white clover content was lower than expected and it virtually disappeared from most of the swards before the 18th year.

The results show the potential improvement possible on wet hill land. Given good fertilizer and grazing management, this improvement can be maintained for several years.

The effects of controlled grazing, application of N, P, K, Ca, and Mg and the introduction of grasses and white clover, with and without cultivations, on Molinia caerulea dominant rough hill grazing were studied over 19 years in mid-Wales. Nutrient concentration in, and uptake by, the herbage and changes in soil physical, chemical and biological characteristics were monitored periodically. Concentrations and uptake of N, P, K, Ca, Mg and Na were highest on the reseeded pastures. Nutrient balance sheets showed that the nutrients applied were most efficiently utilized on reseeded swards. They also highlighted the considerable losses of applied Ca and Mg that occurred.

Implications of the results are discussed in relation to both future agricultural use of such areas in the hills and the effects on the environment.

A method is described in which a liquid suspension of sheep faeces is used as an inoculum in the in vitro determination of digestibility of feedingstuffs for ruminants. The modified method was applied to 21 samples of grass, ten of lucerne, and a variety of other food materials. The results correlated closely (r = 0·98) with the in vivo digestibilities, and the relationship between in vitro and in vivo digestibilities was represented by the equation: in vivo digestibility = in vitro digestibility × 1·003.

A 4 × 4 latin-square design experiment was carried out to determine the effects of increasing nitrogen (N) intake by feeding diets containing increasing amounts of fishmeal upon the digestion of organic matter (OM) and N by cattle equipped with rumen and duodenal cannulae. A basal diet (B) containing 600 g silage and 400 g ground barley/kg diet and three diets (BF1, BF2 and BF3) in which increasing amounts of the silage and barley basal diet were proportionately replaced by fishmeal were fed. The mean daily intakes of OM and N when each diet was fed were 4·29, 4·28, 4·22 and 4·20 kg OM and 90, 108, 125 and 143 g N for diets B, BF1, BF2 and BF3 respectively.

Neither the amounts of OM entering the small intestine nor those voided in the faeces were altered by the diets fed. Thus mean apparent OM digestibility for all the diets fed was 0·74 ± 0·007 and the proportion of digestible OM intake apparently digested in the rumen was 0·83±0·011.

Mean daily concentrations of ammonia N in the rumen were significantly (P <0·01) increased from 85 mg N/l (diet B) to 129 mg N/1 (diet BF3) as fishmeal intake increased.

The quantities of non-ammonia N (P <0·05) and of amino acid N (P <0·001) entering the small intestine were significantly increased as more fishmeal was added to the diets fed. As fishmeal intake increased apparent N digestibility was significantly (P <0·001) increased.

Neither the quantities of microbial N entering the small intestine daily nor the apparent efficiency of microbial N synthesis within the rumen were increased by the diets fed. The quantities of feed N entering the small intestine daily were significantly (P<0·01) increased as fishmeal intake increased; thus apparent feed N degradability in the rumen was significantly (P <0·05) decreased from 0·84 (diet B) to 0·73 (diet BF3) as fishmeal intake increased. Similarly, the rates of disappearance of N from each of the four barley or barley and fishmeal concentrates when incubated in the rumens of the cattle in porous synthetic fibre bags were decreased as the proportion of fishmeal in the concentrates increased. Thus, the rumen N degradability of the diets fed, when calculated from the rates of disappearance of N from porous synthetic fibre bags placed in the rumen, decreased as fishmeal intake increased.

As fishmeal intake increased the amino acid composition of duodenal digesta (expressed as g/kg determined amino acids) changed such that the content of arginine increased (P <0·01) and the content of isoleucine decreased (P <0·01). The concentrations of arginine (P <0·01), leucine and lysine (P <0·05) in blood plasma increased as fishmeal intake increased.

Adult Finn-cross ewes, pregnant from September matings, were kept under natural photoperiod (control, 30 animals) or with an additional exposure to a 1 h long. 300 lux light pulse, 16–17 h after an artificial dawn (light-pulse treatment, 32 ewes) for 2·5 months. After lambing, the supplementary light was discontinued and half of the ewes from each group were injected daily with 2 mg melatonin for an additional 2·5 months.

The light-pulse ewes produced heavier lambs and more milk, as can be deduced from the higher rate of growth of their lambs during the first 10 days of life, than the control animals. The light-pulse and/or melatonin treatments delayed the occurrence of the first post-partum ovulation and oestrus (which occurred in the untreated animals about 4 and 6 weeks, respectively, after lambing), by 1–3 weeks. However, more ewes exhibited oestrus and cyclic activity in the light-treated than in the other groups. The fertility in the light-treated group was, consequently, superior to that in the group kept under natural photoperiod, in spite of the similar lambing rate of the mated ewes of the different groups.

It is concluded that the light-pulse, but not the melatonin treatment, had a beneficial effect on the reproductive performance of the ewes, as measured by the weight of the newborn lambs, the milk production of the dams during the first 10 days post-partum, and the cyclic activity of the ewes after February lambing in Israel.

The results on the influence of growing various crops in five fixed annual sequences on the changes in available and total phosphorus and potassium content of a Tolewal sandy loam (Typic Ustipsamment) are reported. The available phosphorus content showed an increase in each of the five crop rotations after completion of two cycles. The maximum increase was observed in groundnut-based cropping sequences whereas the increase under the other three rotations was more or less of the same order. A slight decrease in the available P content during the 3rd year was observed after the harvest of bajra in a bajra fodder–potato–wheat sequence which was replenished after the harvest of potato and wheat. Total P content of the soil also showed an increase in all five rotations after completion of two cycles. A decrease in total P content of the soil was also observed after the bajra harvest. Balance sheet of P indicated net gain of P in all five crop rotations and the maximum gain of 62 kg P/ha was observed in the maize–wheat–moong rotation. Theavailable K status of the soil showed an increase in each of the five cropping sequences after completion of two cycles. The available K status after harvest of various crops in the rotation could not fully explain the dynamics of K availability. The total soil K content indicated a negative K balance in each of the five crop rotations after completion of three cycles and the maximum negative balance occurred in a maize–wheat–moong sequence. The negative K balance was related to the amount of fertilizer K added and that removed by the crops. The results suggested the need for modifying the existing K fertilizer recommendations to compensate gradual loss of native K soil fertility.

Screen house and field experiments at the Sugar Research Institute, University of Ilorin, Nigeria were carried out to evaluate the effects of various amounts of nitrogen and potassium fertilizers singly and in combinations on growth, yield and crop quality of sugarcane cultivar Co 957. Growth rate, number of green leaves per mother shoot, leaf area, plant height, stalk length and tiller density were significantly affected by nitrogen application but were not significantly affected by potassium. Similarly, cane tonnage was significantly affected by nitrogen but not by potassium. In the screen house trial, responses to N were linear from 0 to 160 kg N/ha. However, in the field, while the measured variables also increased linearly with N application from 0 to 160 kg N/ha, they decreased at 200 kg N/ha.

Cane quality decreased with increased nitrogen and potassium. However, these reductions were significant only at the highest level of nitrogen and potassium. There were no significant nitrogen and potassium interactions on any of the variables studied.

The effects of pasture height and of a cereal-based concentrate or a sugar-beet pulp supplement were studied with 30 spring-calving cows on continuously stocked, perennial ryegrass dominant pasture in a 3 × 3 latin-square design with periods of 4 weeks. Pastures were maintained at heights of about 5·0 cm (short) or 6·5 cm (control). On the short pasture, the two supplements had similar effects and were additive but on the control pasture, compared with sugar-beet pulp, the cereal concentrate depressed herbage intake. Average fat-corrected milk yields were 26·3 and 28·1 kg/day on short and control areas respectively. Both supplements increased milk yields by about 0·7 kg per kg OM supplied. Cows on the short pasture tended to lose weight. Supplements slightly increased live weight and sugar-beet pulp tended to increase body condition score. In observations continued after the conclusion of the main experiment the short pasture was more productive and of slightly higher nutritive value. Cows receiving the concentrate supplements increased total intake but this was reflected only in live weight. The total utilized metabolizable energy for the whole season was about 130 GJ/ha.

In a 2-year field study, all the maize cultivars tried (Partap-1 Ageti-76, Ganga-5 and DHM-103) produced similar length of ears and equivalent grain yields. However, Partap-1 and Ganga-5 produced greater 100-kernel weight and greater grain yield per ear but fewer ears per hectare than Ageti-76 and DHM-103. The yield attributes and grain yields of maize sown on 19 December, 29 December and 8 January were identical and were superior to those of the 19 January sowing. Maize sown on 19 December, 29 December and 8 January exhibited longer ears, more ears and fully developed kernels and thereby produced greater grain yields than the 18 January sowing.

During 1983–4, in the 19 December and 29 December sowings all the cultivars gave identical grain yields. In the 8 January sowing Partap-1 and Ageti-76 produced similar yields and proved better than Ganga-5 and DHM-103. In the 18 January sowing Ageti-76, Ganga-5 and DHM-103 yielded more than Partap-1.

The phenology of the emergence of brassica pod midge from overwintering sites previously sown with spring oil-seed rape and its subsequent infestation of spring rape crops was studied over 3 years. Adults emerged from the overwintering sites from mid-May until early July, but infestation of spring rape did not begin until late June. Two generations occurred on spring rape. Mature larvae dropped from the pods almost daily from early to mid-July until mid-August to early September to form cocoons in the soil. A small proportion of these larvae developed into pupae and emerged as a second generation of adults to lay further eggs in the crops. Larvae from these eggs dropped to the soil to diapause within cocoons.

The effects of supplementation of a barley-barley straw diet containing 4 mg copper (Cu)/kg dry matter (D.M.) either with 5 mg molybdenum (Mo)/kg D.M. or with 500 mg iron (Fe)/kg D.M. on the Cu status, growth and clinical condition of calves are described. Liver and plasma Cu concentrations declined rapidly within 12–16 weeks to levels indicating severe Cu deficiency in both the Mo- and Fe-supplemented groups. The changes in Cu status were similar for both supplements and did not differ significantly from each other. Clinical signs of Cu deficiency, as indicated by reduced growth rate and changes in hair texture and colour, were evident after 16–20 weeks only in animals on the Mosupplemented diet. The reduced growth rate was accompanied by a decreased food intake and reduced efficiency of food utilization. The Mo-supplemented animals also exhibited an altered Fe metabolism, particularly when the growth rate was affected. The results confirm earlier reports that the effects of Mo on growth and clinical condition are independent of its effect on Cu status and suggest that the altered production might be due to effects on the control of food intake, food utilization, or Fe metabolism.

Two experiments were conducted to examine the effects of supplementation of a control diet of barley grain and barley straw containing 4 mg copper (Cu)/kg dry matter (D.M.) either with 5 mg molybdenum (Mo)/kg D.M. or with 500 or 800 mg iron (Fe)/kg D.M. on puberty, fertility and oestrous cycles of cattle. Puberty occurred normally in control, Fesupplemented and control animals on a restricted intake whereas it was delayed by 12 and 8 weeks respectively by Mo supplementation. This effect of Mo was not due to the low Cu status since this was equally low in the Fe-supplemented animals, nor was it due to the reduced growth rate since puberty occurred normally in control animals that had a similar live-weight gain. A significant reduction in the pulsatile release of luteinizing hormone was observed within 11 weeks of the Mo supplementation and before any of the other clinical signs were evident, suggesting that Mo may be affecting puberty by altering the release of luteinizing hormone either directly or indirectly.

Mo supplementation significantly reduced the percentage conception rate to 12–33% compared with 57–80% in control and Fe-supplemented animals. This effect was not dependent on the rate of live-weight gain which was standardized across the different treatments at approximately 0·6 kg/day. Within 12 weeks of the replacement of dietary Fe by Mo a lower conception rate occurred; replacing dietary Mo by Fe led to a normal conception rate within 12 weeks without any accompanying changes in Cu status or in the rate of live-weight gain. The plasma Mo concentrations, however, changed significantly during these alterations in dietary supplementation. The pre-ovulatory peak height of luteinizing hormone was significantly lower in animals on the Mo-supplemented diet compared with control and Fe-supplemented animals, but the administration of LHRH did not alter the conception rate.

More Mo-supplemented animals failed to ovulate following prostaglandin induced synchronization in comparison with the other treatments, and by the 84th week a significantly greater number of Mo-supplemented animals (12/18) had become anoestrous compared with the other groups (2/30). Cu repletion of these anoestrous Mo animals for a period of 20 weeks did not result in resumption of normal oestrous cycles, but ovulation and oestrus were induced by progesterone and LHRH treatment. Results in the latter part of the study indicated that Mo caused superovulation.

These data show that Mo supplementation delayed the onset of puberty, decreased the conception rate and caused anovulation and anoestrus in cattle without accompanying changes in Cu status or in live-weight gain. It is suggested that these effects of Mo are associated with a decreased release of luteinizing hormone that might be due to an altered ovarian steroid secretion.

Ninety-nine lactating British Friesian cows, in their second and subsequent lactations, were divided into two groups receiving ad libitum grass silage. The cows in group A were offered silage individually through Calan Broadbent gates while those in group B were given 24 h/day access to a self-feed silage clamp. The crude protein (CP), acid-detergent fibre (ADF), neutral-detergent fibre (NDF), in vitro digestible organic matter and estimated metabolizable energy (ME) values in the D.M. of the silage were 140, 373, 584, 610g/kg D.M. and 9·7 MJ/kg D.M. respectively. The cows in each group received either 11kg/day fresh weight of concentrate S in which the principal energy source was cereal starch or 9 kg/day fresh weight of concentrate F containing mixed high quality fibre sources plus 2 kg/day fresh weight of concentrate S. The CP, ADF, NDF, starch and sugar concentrations in concentrates S and F were 203, 71, 204, 444, and 44 and 202, 147, 329, 116 and 149g/kg D.M., respectively.

The only significant difference produced by method of silage allocation was that groupfed cows gained more live weight (P < 0·01) than those fed individually.

Over the whole experimental period the mean silage D.M. intake of cows fed concentrate F in group A was 0–5 kg/day higher than those fed concentrate S. However, in early lactation the benefit to silage intake in favour of concentrate F was 1 kg D.M./day.

In group A estimated intakes derived from calculated ME inputs and outputs were markedly lower than the observed intakes, but were similar to correspondingly derived estimates for group B.

Although concentrate type did not affect milk yield, concentrate F was associated with a higher fat concentration and yield (P <0–05) but a lower protein concentration (P < 0·001) and a slightly lower yield.

The in vivo digestibility coefficients for D.M. and organic matter determined in lactating dairy cows given concentrates S and F respectively were similar (0·724 v. 0·716 and 0·749 v. 0·742) but that for ADF was significantly (P < 0·001) higher (0·565 v. 0·673) in the ration containing concentrate F than in that containing concentrate S.

Estimates of the mean efficiency of utilization of the production ME made on a weekly basis were unaffected by concentrate type.

Seventy-one small-framed Angus and seventy-four Holstein steers were chosen to represent small and large mature types in a study designed to provide quantitative information on the effect of breed, diet and housing type on composition of carcasses from cattle slaughtered serially over a wide weight range. Within breed, steers were individually fed ad libitum either a maize-grain or a maize-silage diet and assigned randomly to one of two housing types. The effects of treatments on response variables with increasing carcass weight were tested by covariance analysis.

The rate of change of soft tissue chemical composition with increasing carcass weight was not influenced by diet, breed mature size or housing type except for ash which decreased at a faster rate in Angus than in Holstein steers. Percentages of water, protein and ash decreased while lipid increased with increasing carcass weight. At any carcass weight, Angus had more lipid and less water in soft tissue. Percentages of soft tissue protein and ash were affected by diet within breed. The energy content of soft tissue increased with weight and was affected only by breed. Angus soft tissue had more energy than that of Holsteins. Similar results were obtained when the entire carcass was analysed.

Cattle fed grain had slightly more water and less ash in bone than cattle fed silage. Angus steers had more protein and ash in bone than Holsteins. Although there was a diet × breed × housing type interaction for lipid content of bone, Holstein bone had higher lipid content than Angus bone for either diet or type of housing. All percentages of chemical components in bone, except water, increased with increasing carcass weight.

The experiment showed that large mature-size breeds have the ability to transform a high-energy diet into protein for human consumption. The percentage changes in ash, protein and lipid with increasing carcass weight appeared to follow a pattern of development similar to bone, muscle and fat, respectively, suggesting that Hammond's theory of differential growth holds also for chemical components of bovine carcasses. Bone chemical components, however, had a slightly different developmental pattern. The quantitative information on bone presented herein could be used to exploit bone as a source of human food, dietary supplements and products for bone remodelling surgery.

Kinetic studies of Ca metabolism, using 45CaCl32, were carried out on two mature red deer stags during the period of maximum rate of Ca deposition in the antlers. They were offered green-feed oats to provide energy for maintenance; the diet provided approximately 42mg Ca/kg W per day.

Ca appeared to be irreversibly lost from the circulation into the antlers and could be treated for kinetic purposes in the same way as loss of Ca from the body in milk. The size of the rapidly exchangeable Ca pool in the body, excluding the antlers, was 0·21 g/kg W, similar to estimates for lactating cattle. Rates of Ca deposition in the antlers of the two stags, calculated from the model of Ca metabolism, were 58·4 and 38·6 mg Ca/kg W per day. Net endogenous loss was 6–7 mg Ca/kg W per day, much lower than estimates available for other ruminant species. Only 25–40% of Ca requirement or 11–24 mg Ca/kg W per day was derived from the diet, suggesting that the availability of Ca in greenfeed oats is much lower than current estimates for forages. Bones removed on completion of the experiment showed evidence of considerable skeletal demineralization.

In other stags subjected to stable Ca balances at the same stage of antler growth, while consuming ryegrass-white clover forage, 60–80% of Ca requirement was derived from the diet, with calculated rates of true absorption of 32–46 mg Ca/kg W per day. These rates of Ca absorption are low compared with values observed in other ruminants at times of high Ca demand such as during lactation.

The effects of sowing date on leaf appearance, spikelet initiation and mainstem apical development in spring barley cv. Triumph were investigated in field experiments involving 13 sowings made during the period 22 February to 1 July over the years 1982–1985. Delaying sowing was associated with faster rates and shorter durations of leaf appearance and spikelet initiation and earlier attainment of all stages of apex development. The rates of leaf appearance and spikelet initiation were correlated with daylength at crop emergence although there was evidence that the latter process was also influenced by temperature. The derivation of three models relating the duration of developmental phases to temperature and/or daylength is described. In these models the attainment of successive stages of apical development was assumed to require the perception by the crop of a ‘threshold amount’ (THR) of accumulated temperature (THR(ΣT)) and/or daylength (THR(ΣPT), THR(ΣP)) above certain base values (TbPb). The base values of temperature and/or daylength for each phase were derived as those values which minimized the coefficient of variation of the amounts of accumulated temperature and/or daylength experienced by all 13 sowings. For various developmental phases the model based on temperature gave base values between 0 and 3 °C. The model based on daylength gave base values between 11 and 13 h. In both these models there was a highly significant correlation between observed and expected dates of attainment of various stages of apex development. It is suggested that the derived relationships between temperature, daylength and apical development could be used as an aid in the forward planning of crop management. The model based on temperature and daylength (photothermal time) gave no useful base values and it is concluded that more precise methods of relating development to these factors must be sought.

Twenty-four Friesian cows were allocated to one of four diets for weeks 3–14 of lactation following 2 weeks on a common diet. The diets (kg air-dry feed/day) were 7–2 kg hay and 10·8 kg either starchy or fibrous concentrates (60S and 60F) or 3·5 kg hay and 14·0 kg either starchy or fibrous concentrates (80S and 80F). Rumen samples were taken by stomach tube in weeks 10 and 12 of lactation and the digestibility of the diets was measured with four cows per treatment during weeks 13 and 14. The digestibility of the same feeds was also measured in sheep at maintenance.

The principal carbohydrate constituents of the concentrates were barley, wheat and cassava in the starchy concentrates and citrus pulp, sugar-beet pulp and wheat feed in the fibrous concentrates. The concentrates were designed to have similar concentrations of metabolizable energy (ME) and the diets were planned to provide similar intakes of digestible energy and crude protein.

Milk yield and composition were very similar for treatments 60S and 60F. With the higher proportion of starchy concentrates (80S), milk yield was about 20% greater than on 60S, fat concentration fell severely but protein and lactose concentrations were unaffected. With the higher proportion of fibrous concentrates (80F), milk yield and the protein and lactose concentration were similar to values on 60F but fat concentration was lower, though not nearly so low as on 80S. Milk energy yield was reduced by the higher proportion of concentrates but was unaffected by type of carbohydrates. Live-weight changes were small.

In both the sheep, consuming at maintenance, and the lactating cows consuming at about 3 times maintenance, digestibility of dry matter, organic matter and energy was higher with the higher concentrate diets but was unaffected by type of concentrate. The digestibility of fibre was greater with the fibrous concentrates but the effect of level of concentrate inclusion was inconsistent. Digestibility coefficients were consistently lower for the lactating cows than for the sheep.

The proportion of acetic acid in the rumen volatile fatty acids in the cows was higher and the proportion of propionic acid was lower with the fibrous concentrates. The differences were much greater with the higher proportion of concentrates.

During weeks 15–22 of lactation the cows were reallocated to concentrate treatments and given hay ad libitum. Hay intake was about 1 kg/day higher with the fibrous concentrates but the difference was not significant. Hay intake fell by about 0·6 kg/kg concentrate intake for both concentrate types. No significant differences in milk yield or composition were established, probably because of incomplete adaptation even after 8 weeks.

It is concluded that at concentrate intakes of about 10 kg/day, the source of carbohydrate in the concentrates has little effect on milk production when the concentrates are of similar ME concentration. However, at higher levels of concentrate inclusion, although the diets may have similar ME concentrations, important differences in the yields of fat, protein and lactose occur due to carbohydrate source and these can be related to differences in rumen fermentation.

The results of four field experiments conducted for 2 or 3 years on two soils, loamy sand (Typic Ustipsamments) and silty clay loam (Natric Ustochrept) showed that in rice, application of N in three equal amounts was more efficient than one or two applications, irrespective of source of N and type of soil. The results further showed that application of the first dose of N 7 days after transplanting rice was more beneficial than its application at transplanting. Calcium ammonium nitrate was significantly inferior to urea and/or ammonium sulphate for rice in both soils. There were no significant differences in wheat yield, N concentration or uptake due to time and source of N application.