bluuebunny/crossref_metadata_2025 huggingface dataset:
Ileal apparent digestibilities of amino acids, growth and tissue deposition in growing pigs fed low glucosinolate rapeseed meals
Authors: Rowan T. G. , Lawrence T. L. J.
Published: March 2009

A factorially designed growth and carcass dissection experiment was made in which a low glucosinolate rapeseed meal (cv. Tower, TRSM) was compared with soya-bean meal (SBM) as the sole protein supplement in simple diets, containing barley and a vitamin and mineral supplement (to give 18 mg copper/kg air-dry diet) only, which were fed individually on a restricted scale of feeding to 72 pigs. The diets were of similar digestible energy (DE) content and were formulated to contain in each kg of air-dry matter 150, 170 and 190 g crude protein. In each crude-protein level the total lysine content was similar. Also experiments using 35 pigs were made to determine the ileal apparent digestibilities of amino acids in barley-based diets containing SBM, the low glucosinolate rapeseed meals Erglu (ERSM) and TRSM and a high glucosinolate British rapeseed meal (BRSM) and either 20 mg or 200 mg copper/kg air-dry diet.

In the growth experiments there were no significant interactions for the variables considered. Pigs given TRSM diets, compared with those given SBM diets, had significantly poorer growth rates, conversion efficiencies and killing-out proportions but the proportions of lean and fat in carcasses and the backfat thicknesses (P2) were similar. There were no significant differences between protein levels in the killing-out proportions, the proportions of fat in carcasses and backfat thicknesses (P2) but pigs given diets containing 150 g, compared with 170 and 190 g, crude protein/kg air-dry diet had significantly lower growth rates and proportions of lean in the carcass and significantly poorer efficiencies of food conversion. The quantities of dietary crude protein used to produce units of live-weight gain, carcass weight and lean tissue increased progressively from the diets containing 150 to 170 to 190 g crude protein in each kg air-dry diet.

In the ileal digestibility studies the results indicated that amino acids were of a lower digestibility in the rapeseed meal diets than in those based on SBM and that the copper content of the diet may have been important in this context.
Growth, tissue deposition and metabolism studies in growing pigs given low glucosinolate rapeseed meal diets containing different amounts of copper and polyethylene glycol
Authors: Rowan G. , Lawrence T. L. J.
Published: March 2009

In three factorial growth experiments and a metabolism experiment pigs of approximately 25 kg initial live weight were given on a restricted scale of feeding simple diets, based on barley, a vitamin and mineral supplement and either soya-bean meal (SBM) or a low glucosinolate rapeseed meal (cv. Tower; TRSM). Variations in these two basic diets were produced by adding different quantities of tannic acid, polyethylene glycol (PEG) and copper (Cu).

Diets based on soya-bean meal were used in the first experiment. There were no significant interactions. Tannic acid added at 3·75 and 7·50 g/kg air-dry matter was without significant effect on performance compared with no tannic acid addition, but PEG at 17 g/kg air-dry matter significantly improved growth rate compared with no PEG addition to the diet (P < 0·05). In the second experiment TRSM-based diets were used. There were no significant interactions and no significant effects on performance from adding 0, 8·5 and 17·0 g PEG/kg air-dry matter. Increasing Cu from 17 to 54 mg/kg air-dry diet significantly improved growth rate (P < 0·05). In the third experiment TRSM and SBM based diets, of similar digestible energy (DE), crude protein and lysine content, and containing either 19 or 202 mg Cu/kg air-dry matter, were used. Pigs were slaughtered at 87·5 kg live weight and hand joints dissected. Pigs given the TRSM diet containing 19 mg Cu/kg grew significantly more slowly than pigs given the three other diets between which there were no significant differences. There were no other significant interactions and no significant differences between Cu concentrations for the growth, carcass and efficiency of conversion results. Compared with TRSM diets, SBM diets at similar slaughter weights gave significantly greater carcass weights, killingout proportions and backfat thicknesses. Also the efficiencies with which dietary protein and DE were used to promote units of carcass growth were significantly better for the SBM diets, but there were no significant differences in the estimated weights of lean in carcasses.

In the metabolism experiments the effects of adding PEG to diets similar to those used in the growth experiments were examined. The apparent digestibilities of dry matter, gross energy and nitrogen and the nitrogen retentions were significantly greater for the SBM diets than for the TRSM diets. The addition of PEG to the SBM and TRSM diets significantly decreased the apparent digestibilities of dry matter and gross energy, and significantly increased the apparent digestibility of nitrogen in the SBM diet but not in the TRSM diet.
The effect of density and nitrogen fertilizer on the growth and yield of maize (Zea maysL.) in Nigeria
Authors: Lucas E. O.
Published: March 2009

Summar

FARZ 27, a high-yield maize variety, was grown in 1984 and 1985 over a wide range of density treatments (1·9– 11·1 plants/m2) and with four rates of nitrogen application (0, 75, 100 and 150 kg N/ha) in Ibadan. south-western Nigeria.

There was no significant density or fertilizer effect on morphological characters of number of leaves per plant, height or stem diameter. For total dry-matter yield, the highest density of planting gave the highest yield although less dry matter was obtained in the 1985 experiment than in the 1984 experiment. Optimum density for grain production in both years was 8·8 plants/m2. There is an indication that there is no need to increase density of planting of maize beyond 80000 plants/ha in the south-western part of Nigeria. Plants without applied nitrogen fertilizer gave significantly lower total dry-matter and grain yields than plants with applied nitrogen. Highest grain yield was obtained with 150 kg N/ha in both years. By doubling the nitrogen application rate from the present recommended level of 75 kg N/ha to 150 kg N/ha an average increase of 0·42t/ha of maize was obtained in both years. With the present prices of fertilizer and maize, this increase is economical. It seems therefore that more revenue would accrue to the farmers by using 150 kg N/ha on the ‘FARZ series’ of maize instead of the present recommendation of 75 kg N/ha.
Endogenous losses of phosphorus by sheep
Authors: Ternouth J. H.
Published: March 2009

Twelve sheep were fed semisynthetic roughage diets at three rates to study the effects of intake of dry matter, concentration of phosphorus and the physical form of two low-P barley straws upon the faecal losses of P. The sheep were in negative P balance throughout the experiement. The absorption of dietary P increased with P intake and was unaffected by differences in the physical form of the roughage. For each barley straw diet, endogenous faecal P increased with dry matter intake, and was higher when the roughage was ground than chopped. Over the whole experiment, daily endogenous faecal P ranged from 8·5 to 31·5 mg/kg live weight. Endogenous faecal P was related to P intake or to dry matter intake and plasma inorganic P. The concentration of faecal endogenous P was negatively related to the intake of each diet. It is concluded that the concentration of inorganic plasma P and the rate of salivary secretion are responsible for the endogenous faecal excretion of P and the regulation of P balance in sheep fed low-P diets.
Effects of chlormequat chloride on yield and components of yield in six cultivars of spring barley (Hordeum vulgare)
Authors: White E. M.
Published: March 2009

The effects of chlormequat chloride on grain yield and its components in spring barley (Hordeum vulgare)cultivars were studied in five field experiments conducted at two sites near Belfast over 3 years (1982–84). Grain yield was significantly increased by chlormequat chloride treatment in only one experiment, where ear loss was less in the treated plots. Number of ears per plant was increased by treatment in another experiment but yield was unaffected. It was concluded that chlormequat chloride applications are unlikely to produce consistent yield increases in field crops of spring barley.
Effect of acidification with sulphuric acid on the volatilization of ammonia from cow and pig slurries
Authors: Stevens R. J. , Laughlin R. J. , Frost J. P.
Published: March 2009

Pig and cow slurries were applied to bare soil surfaces in the laboratory. Volatilization of NH3 was measured using ventilated enclosures for 3·25 days after slurry application. Slurries were acidified to pH values between 7 and 4 with 5 M H2SO4. Lowering cow slurry pH to 5·5 decreased NH2 volatilization by 95%, while lowering pig slurry pH to 6·0 decreased NH3 volatilization by 82%. A field experiment, measuring the volatilization of NH3 for 2 h after application to grassland stubble of slurry acidified to pH values between 7·5 and 5, gave similar results to the laboratory study.

Titration curves were constructed within the pH range of 9 to 4 with cow and pig slurries. There was a significant (P < 0·05) positive correlation between the NH4+-N content of the slurries and the volume of acid required to attain a target pH of 6·0 for pig slurries and a pH of 5·5 for cow slurries. One litre of slurry containing 2 g of NH4+-N required c. 20 ml of 5 M H2SO4 for acidification.
Performance of morphologically divergent plant types in dried peas (Pisum sativum)
Authors: Stelling D.
Published: March 2009

In 1991 and 1992, four sets of isogenic lines and eight released cultivars of pea (Pisum sativum L.) differing at the loci af (normal leaflets are converted to tendrils) and st (reduced stipule size) were grown in conventional plot stands at Göttingen, Germany. Crops were either supported by wire netting, to avoid the negative effects of lodging on yield, or were unsupported, thus permitting natural lodging, in order to study the effect of both genes on yield.

The conventional, normal-leafed plant type (AFAF STST) exhibited the highest yield potential, but also the largest yield reduction due to natural lodging. Yield potential of the ‘semi-leafless’ plant type (afaf STST) was less than that of the conventional type but, due to its better standing ability, the yield of the unsupported, ‘semi-leafless’ crop, on average, was less reduced by lodging than was the yield of the conventional one. With the additional reduction in stipule size by the gene st, the decrease in yield potential was too large to be counterbalanced by the positive effects of an improved standing ability. For the released cultivars, the effects of both genes on crop performance were smaller than for the isogenic lines.
Forage mixtures for dairy cows: the effect on dry matter intake and milk production of incorporating different proportions of maize silage into diets based on grass silages of differing energy value
Authors: Phipps R. H. , Weller R. F. , Rook A. J.
Published: March 2009

During weeks 3–23 of lactation, 63 multiparous and 28 primiparous Friesian cows were offered ad libitum access to grass silage of either average (A)(ME 10·6 MJ/kg DM; CP 158 g/kg DM) or low (L)(ME 9·9 MJ/kg DM; CP 154 g/kg DM) energy value, either alone or in mixtures consisting of one of these grass silages with 25, 50 or 75% of the forage DM as maize silage. In addition, all cows received 7·2 kg DM/day of concentrate (ME 12·9 MJ/kg DM; CP 202 g/kg DM). There was a significant (P < 0·001) linear relationship between silage DM intake and percentage maize inclusion with grass silage. For grass silage A, DM intake of the mixture of grass and maize in a 1:1 DM ratio was significantly (P < 0·001) higher that at other inclusion levels. There was a significant (P < 0·05) overall linear effect of proportion of maize on milk yield, with a regression coefficient of 0·022 ± 0·009 kg/day per percentage maize proportion. Although milk composition was unaffected by treatment, there was a significant (P < 0·01) linear effect of maize proportion on protein yield for grass silage L, the regression coefficient being 0·8±0·03 g/day/percentage maize proportion. The mixture of grass silage A and maize silage in a 1:1 DM ratio produced the highest yield of milk protein.
Effect of sward height on herbage intake and production of ewes of different rearing rank during lactation
Authors: Parker W. J. , McCutcheon S. N.
Published: March 2009

Groups of six single- and six twin-rearing ewes were continuously stocked on five pastures with sward surface heights (SSHs) of 3·5, 5·0, 6·0, 7·0 and 8·5 cm from week l until week ll of lactation. Herbage intake, estimated from faecal chromium concentrations and thein vitrodigestibility of herbage samples collected from oesophageal-fistulated wethers, was lowest on the 3·5 cm sward but was not significantly different between SSH treatments during weeks 5, 8 and 9 of lactation. Twin-rearing ewes consumed 0·9–17·6% more herbage than single-rearing ewes did. By week ll, ewe liveweights showed increases of 2–4 kg/ewe on all except the 3·5 cm sward, where the ewes lost a similar amount of liveweight. From week 4 of lactation, twin-rearing ewes had a lower body condition than ewes raising a single lamb on all except the 3·5 cm sward, where the body condition of both rearing ranks was similar. Lamb growth rates during the first 6 weeks were similar for each SSH treatment but from days 46–76 of lactation, lambs on the 5·0 cm and longer swards grew faster (240 g/day) than those on the 3·5 cm sward (197 g/day). Lamb weight on day 76 ranged from 21·5 kg on the 3·5 cm sward to 23·0 kg on the 5·0 cm sward, but was not significantly affected by SSH. Similarly, midside wool growth of ewes and lambs was not significantly influenced by SSH during the period of continuous stocking. The results indicate that farmers should aim to provide swards of 5–7 cm height during lactation to maximize production in both single- and twin-rearing ewes.
Analysis of factors affecting superovulatory responses in ruminants
Authors: Woolliams J. A. , Luo Z. W. , Villanueva B. , Waddington D. , Broadbent P. J. , McKelvey W. A. C. , Robinson J. J.
Published: March 2009

Data on ovulation rate and numbers of ova and transferable embryos recovered from superovulated cattle and sheep were analysed using generalized linear models, quasi-likelihood, restricted maximum likelihood (REML) and generalized linear mixed models (GLMMS). The data pertained to the operation of nucleus breeding schemes in cattle and the commercial application of embryo transfer in sheep.

Results of the analyses showed that generalized linear models involving Poisson and Binomial distributions were inappropriate because of over-dispersion, and that analyses using quasi-likelihood to model negative binomial and β-binomial distributions were more suitable. Factors identified as important in determining the results in cattle were the number of previous superovulations (a higher proportion of transferable embryos were obtained in the initial flush compared to subsequent recoveries in two out of three sets of data), the donor (significant in all analyses with repeated recoveries) and its mate (significant in some analyses). In sheep, the use of pFSH or hMG for superovulation increased embryo yields above those obtained with PMSG + GnRH. Analyses of a further data set for sheep showed the effect of breed was ambiguous.

The effects of donors and their mates were treated as random effects in analyses involving REML and GLMMS. Results showed that the repeatability of the number of transferable embryos produced per donor ranged between 0·13 and 0·23 in three sets of data and was significant in all cases. In these analyses the variance among mates was not significantly different from zero.

The results of analyses were used to develop a random generator to simulate the numbers of ova and embryos recovered from a cow following superovulation. By sampling from negative binomial distributions where the scale factor used for each cow was a normally distributed deviate, distributions were obtained which had the same mean, variance and repeatability as those observed.
Ratios of plant to soil concentrations of strontium-85 and their relation to exchangeable bases for soils and crops of Greece
Authors: Papanicolaou E. P. , Apostolakis C. G. , Skarlou V. , Nobeli C. , Kritidis P.
Published: March 2009

The relationship between values of 85Sr concentration ratios (CRs) and exchangeable bases, expressed in absolute (mmol/kg) or relative (percentage of cation exchange capacity (CEC)) terms, was considered using the results of a glasshouse pot experiment conducted in 1989, for soils and crops of Greece. Exchangeable calcium, expressed in mmol/kg, presented, in most instances, a significant (P = 0·05–0·01) or highly significant (P < 0·01) negative correlation with the CRs of various crops or plant parts, while exchangeable calcium plus magnesium or total exchangeable bases (expressed also in mmol/kg) showed an even better correlation (higher values of r, lower variability). Expression of the amounts of exchangeable bases in relative terms further improved the correlation coefficient in each comparison. The correlations between the percentage of exchangeable (Ca + Mg) or exchangeable bases and CRs, which were always negative, were significant or highly significant for all tested crops or plant parts. The correlation between CRs and soil properties was greatest for exchangeable (Ca + Mg) expressed as a percentage of CEC (r = -0·92) and followed the order: Exchangeable (Ca + Mg) as % of CEC ≈ exchangeable bases as % of CEC ≈ exchangeable (Ca + Mg) in mmol/kg ≈ exchangeable bases in mmol/kg > exchangeable Ca as % of CEC > exchangeable Ca in mmol/kg.

Quantitative relationships between CRs of the tested crops or plant parts and exchangeable calcium plus magnesium (% of CEC) of soils are also presented.
Effects of pre-mating undernutrition on oestrus, ovulation and prenatal mortality in Merino ewes
Authors: Mackenzie A. J. , Edey T. N.
Published: March 2009

Oestrus, ovulation rate and prenatal mortality were studied in 114 mature Merino ewes of high and low body weight at mating. Three nutritional treatments were imposed over 8 weeks prior to hand mating to fertile rams; high plane (HH), low plane (LL) and 7 weeks of high plane followed by 1 week of fasting immediately prior to mating (HL). Ovarian activity, ovulation rate and the extent and timing of prenatal loss were assessed by the appropriate use of direct ovarian observations, pregnancy diagnosis, returns to service and lambing records.

While both prolonged undernutrition (LL) and acute nutritional restriction (HL) were associated with some suppression of behavioural oestrus, neither had any appreciable effect on ovulation rate or prenatal mortality. In all groups the right ovary was more active in producing ova than the left, and the HH group had more ovarian follicles (≥ 4 mm diameter) than the other two groups. Large unruptured ovarian follicles (6—15 mm diameter) were observed in nine ewes. Significantly more ova shed in multiple ovulations were lost, and multiple-ovulating ewes were more likely to suffer complete rather than partial loss of both embryos. Impaired fertility was evident when ewes that returned to service at an extended cycle length were re-mated.
Voluntary feed intake by sheep and digestibility of shadedStenotaphrum secundatumandPennisetum clandestinumherbage
Authors: Samarakoon S. P. , Shelton H. M. , Wilson J. R.
Published: March 2009

The effects of shade (50% of ambient light transmission) on the quality of established swards of buffalo grass (Stenotaphrum secundatum) and kikuyu grass (Pennisetum clandestinum) were examined at Wollongbar Research Station, northern New South Wales. Sarlon cloth was used to shade plots of the two species, after cutting to 8 cm, from November 1985 to March 1986. Herbage was harvested from shaded and adjacent unshaded plots for chemical analyses and for feeding as dry chaff to penned sheep at the University of Queensland research farm at Mt Cotton.

Shade markedly decreased the voluntary feed intake (VI) ofP. dandestinumby 30·7% over the two harvests while VI ofS. secundatumwas not significantly affected. Shade had no effect on thein vitroandin vivodigestibility ofP. clandestinumherbage but marginally increased that ofS. secundatum. These shade effects resulted in a 14·2% increase forS. secundatumand a 34% decrease forP. clandestinumin the intake of digestible dry matter of shaded compared with unshaded herbage.

The reduced VI of the shade-grown herbage ofP. clandestinumwas associated with a higher proportion of stem (21v. 8% for unshaded herbage), a lower proportion of leaf (48v. 54%), and a lower concentration of total nonstructural carbohydrates (TNC) (0.9v. 2.1%). InS. secundatum, there were similar, but smaller, changes in proportion of stem and TNC percentage in shade-grown herbage but, in contrast toP. clandestinum, these potential detriments to VI were offset by an increase in proportion of leaf and a decrease in the proportion of dead material. Average moisture content of shaded herbage (76%) was higher than that of unshaded herbage (70%). Nitrogen and potassium concentrations in plant tissue were higher in the shaded herbage.

The higher yielding capacity and maintenance of nutritive quality of shadedS. secundatumcompared with shadedP. clandestinumindicates the potential usefulness ofS. secundatumfor plantation agriculture.
Efficiency of urea-based fertilizers for wetland rice (Oryza sativa)
Authors: Mahapatra P. , Panda D. , Mohanty S. K.
Published: March 2009

Field experiments were conducted in two wet and two dry seasons in 1984–86 to evaluate efficiencies of different urea-based fertilizers, and methods of application, for irrigated rice. Response to applied N was significant in all seasons. In the wet season, use of dhaincha (Sesbania aculeata) green manure and urea (Dh + U), reduced zone placement of urea supergranules (USG), surface application of laccoated urea (LCU) and prilled urea in three split doses (PU-split) gave similar results, and all were better than basal broadcast application of urea coated with neem (Azadirachta indica) cake (NCU) or prilled urea (PU-basal). In the dry season, USG was significantly superior to PU-basal, NCU and (Dh + U). Nitrogen uptake by rice was greatest 15–30 days after transplanting (DAT), followed by a second peak during the reproductive phase of the crop. Ammonium-N in the soil decreased sharply up to 30 DAT, more slowly up to 60 DAT and then increased slightly. Ammonium-N in the soil was higher with USG, (Dh + U) and PU split than with other treatments, especially in uncropped conditions.
Effects of autumn sowing dates on growth and yield of indeterminate and determinate field beans (Vicia faba)
Authors: Pilbeam C. J. , Hebblethwaite P. D. , Ricketts H. E. , Hassan O. A.
Published: March 2009

Determinate forms of field bean (Vicia faba L.), because of their altered growth habit, may differ in phenology from indeterminate cultivars and so their responses to environmental conditions may necessitate different optimum sowing dates. This was studied in autumn-sown field beans at the University of Nottingham at Sutton Bonington by standard growth analysis techniques, final yield components and monitoring of crop growth stages in an indeterminate cultivar, Bourdon, and two determinate populations, 858 and 796 (provided by Plant Breeding International, Cambridge), in three consecutive seasons beginning in 1985/86.

Bourdon yielded significantly more (2·4 t/ha, on average) than the determinate selections as a result of more pod-bearing nodes per stem and seeds per pod and a greater individual seed weight. There was, however, no correlation between seed yield and canopy size, either in total or during pod filling. Determinacy, contrary to expectation, did not increase harvest index. In fact, the reproductive stems of Bourdon had higher harvest indices than those of 858. The yield disadvantage of determinates was therefore exacerbated by the existence of reproductive stems, which, by prolonging the maturation phase, may also detract from a further potential benefit of the determinate habit, namely an increase in yield stability.

There seemed to be no cultivar differences in the temperature requirement for the initiation of developmental processes. An average accumulation of 1239 °C days was required from sowing to flowering. Differences between this and other work in the calculated base temperature for flowering were cautiously explained by the lack of data distinguishing day and night temperature in this experiment and by the use of autumn-sown rather than spring-sown cultivars. It is also suggested that photoperiod may be important in initiating flowering.

Both determinate and indeterminate forms gave the greatest seed yields from the earliest sowing dates.
Land evaluation modelling to assess the effects of climate change on winter wheat potential in England and Wales
Authors: Brignall A. P. , Rounsevel M. D. A.
Published: March 2009

The effects of climate change on crop suitability in England and Wales were estimatedby systematically adjusting agroclimatic data inputs to a land evaluation model. Mean temperature risesof 1 and 2°C increased drought risk and reduced the length of time whe soil was at field capacity over-winter by raising potential evapotranspiration. In eastern England, this change had a detrimental effect on the potential for cultivating winter wheat because of drought stress. In northern and western England and Wales, drier conditions promoted greater opportunities for soil tillage, especially when temperature rises wereassociated with decreased precipitation. The effect of increased temperature was offset by increased precipitation. The magnitude of the drought stress and length of field capacity periods are similar to current mean conditions when a + 1 °C temperature change is coupled with a 10% increase in precipitation. This demonstrates that winter wheat suitability in England and Wales is affected more by changes in precipitation than by changes in temperature. The local limitations of soils and relief notwithstanding, it appears that the northern and western areas of England and Wales are most likely to gain from a warmer, drier climate.
Effect of herbage rejection by steers on white clover (Trifolium repens) branching and development in continuously stocked grass–clover swards
Authors: Teuber N. , Laidlaw A. S.
Published: March 2009

The proportion of sward area rejected for grazing under different stocking intensities in grass-white clover (Trifolium repens L.) swards continuously grazed by steers toconstant sward height was determined and the effect of these areas on clover stolon developmentwas investigated.

In a randomized block field experiment, grazing treatments imposed from 1988 to 1991 comprised target sward surface heights (SSH) of 5, 7 or 9 cm from April to July followed by 7 or 9 cm from July to October (i.e. six treatments). The percentage area rejected was higher in 9 cm than in the shorter swards, the proportion of the total areas rejected increasing generally over the year. Within the rejected areas in spring the number of branches on the main axes of white clover plants was only 17% and the mean number of nodes per branch was 14% of those in grazed areas. Corresponding percentages in summer in rejected areas were 56 and 46% compared with grazed areas.

In a glasshouse experiment involving stolons grown for 18–21 days, the difference between those from grazed and rejected areas in branch number per stolon and mean node number per branch was much reduced. Branching and rate of branch development (node number) were slower in stolons maintained under dark conditions.

Mean growing point density over six sampling dates from summer 1990 to autumn 1991 was significantly higher in the 5 cm than in the 9 cm spring SSH treatment. Although rejected areashad only 34% of the growing point density of grazed areas in autumn, the latter comprised the majority of the total area in most sward height treatments and so reduced the overall effect of rejected areas on growing point density.
An approach to determining optimum tuber planting densities in early potato varieties
Authors: Wurr D. C. E. , Fellows J. R. , Allen E. J.
Published: March 2009

Thirteen experiments conducted near Tenby, Dyfed, between 1973 and 1980, examined the effects of seed-tuber weight and within-row spacing on tuber yields of seven potato varieties grown for early production. These data have been used in an attempt to develop an approach to the determination of optimum tuber planting densities in early crops which will provide agronomists with logically applicable principles. Tuber planting densities, which maximized the net crop return (ware value minus seed cost), were estimated for eight ratios of seed cost to ware value ranging from 0·25 to 8·0. Optimum tuber planting densities decreased with the use of higher ratios of seed cost: ware value and heavier seed, except for ratios of 0·25 and 0·50 applied to yields of tubers > 25 mm harvested in June. In general, later harvesting together with the use of larger riddle sizes give a lower optimum density with ratios < 2·2·0. Optimum densities for Red Craigs Royal, Ulster Sceptre and Vanessa were higher than for the other varieties.

The results provide an illustration of how to approach the problem of selecting tuber planting densities in order to maximize net crop returns in early potato varieties.
Use of prolonged-release bovine somatotropin for milk production in British Friesian dairy cows. 3. Effect on manufacturing properties and quality of Cheddar, Wensleydale and Cheshire cheese
Authors: Phipps R. H. , Bines V. , Adriaens F.
Published: March 2009

Manufacturing properties and quality of Cheddar, Wensleydale and Cheshire cheeses made either with milk from cows treated with Sometribove, methionyl bovine somatotropin (BST), or with milk from untreated control cows were compared.

The source of milk did not affect manufacturing properties in terms of processing time. Renneting times for Cheddar cheese made from control milk and that made from milk produced by cows treated with BST were 57 and 55 min, respectively. Corresponding values for Wensleydale and Cheshire cheeses were 50 and 53 min and 49 and 46 min, respectively. The source of milk did not influence cheese composition in terms of moisture, fat, protein and salt. When cheeses were submitted to the National Grading Service, those made from milk produced by BST-treated cows were indistinguishable from those made from control milk. The total points scored (maximum 100) for Cheddar, Wensleydale and Cheshire cheeses made with milk from control and BST-treated cows were 89 and 88, 85 and 85, and 86 and 86, respectively.
Whole-body and tissue protein synthesis in steers losing weight on a low-protein roughage diet: the effect of trenbolone acetate
Authors: Hunter R. A. , Magner T.
Published: March 2009

Six Brahman (Bos indicus) steers implanted with 300 mg trenbolone acetate and six similar nonimplanted steers were fed a low-quality, low-protein roughage diet at 10 g dry matter/kg live weight. They were housed in individual pens for 27 days in 1987 before being placed in metabolism crates for measurement of digestibility, nitrogen retention, and the rate of protein synthesis in the whole body and fractional rate in three muscles and hide.

The rate of weight loss of steers treated with trenbolone acetate was significantly (P < 0·05) less than that of controls (–0·34 v. –0·56 kg/day). Treated steers excreted significantly (P < 0·05) less 3-methylhistidine (128 v. 202 μmol) and urea N (0·5 v. 1·6 g/day) in urine. There was a more favourable nitrogen retention in animals implanted with trenbolone acetate (–10 v. –12g/day) but this difference was not significant.

Whole-body protein synthesis, calculated from plasma leucine flux, was 511 and 508 g/day in treated and control steers, respectively. Treatment also had no significant effect on the fractional rate of protein synthesis, in skeletal muscle or in hide. The fractional rate of synthesis in muscle was < 1%/day and in hide < 2%/day. These results are discussed in relation to the protein and energy metabolism of undernourished cattle.
Effect of storage temperature and time on viability of rhizobia on lime-coated alsike clover (Trifolium hybridum) seed
Authors: Stout D. G. , Hall J. W. , Brooke B. M. , Baalim G. , Thompson D. J.
Published: March 2009

Seed is often stored in warehouses where the temperature may drop below freezing or increase to 40°C depending on the time of year. Survival of rhizobia on lime-coated alsike clover (Trifolium hybridumL.) seed stored in polypropylene bags was monitored under various temperature regimes ranging from –10 to 35 °C at Agriculture Canada Range Research Station, Kamloops, British Columbia, Canada during 1990 and 1991. Rhizobia were applied ata range of initial concentrations. Seed was inoculated with a peat-based clover inoculant (‘B’ inoculant, Nitragin Ltd, Milwaukee, Wisconsin, USA), and then given a commercial polymer-based lime coat (GNR™, Grow Tec Ltd, Nisku, Alberta, Canada). Rhizobia died continuously at all temperatures within the range —10 to 35°C. The dependence of Iog10(number of viable rhizobia/seed) on storage time was best described by a linear equation: Iog10(viable rhizobia/seed) =a+b(time). Coefficientaprovidedan estimate of the initial concentration of rhizobia. Coefficientbprovided a measure of how rapidly rhizobia died. The death rate of rhizobia was the same during storage at 5 or 20 °C, but increased at a storage temperature of 35 °C. Storage at freezing temperatures did not increase the rate of rhizobial death but repeated freezing and thawing resulted in an increase. As the rate of rhizobial death was similar at constant temperatures from — 10 to 20 °C, temperature requirements are not stringent. Nevertheless, some temperature control is required to maximize the legal storage life of preinoculated coated seed, which in this study was estimated to be 96 days.
Quantitative selection for compact, high-yielding maize hybrids
Authors: Zhang J. H. , Luo Y. N. , Wang Z. X. , Gao X. Z.
Published: March 2009

Maize (Zea mays L.) hybrids with different productivity per unit approximate leaf projected area (ALPA) were compared in China, 1990–92. The results showed that the selection index (SI) values of all the hybrids tested decreased with an increase in population density. Nevertheless, the hybrids with high SI values at low plant densities also had relatively high SI values at high plant densities. Thus, high SI hybrids could be selected at any of these densities. Although no significant yield increase was obtained by using high SI hybrids at plant densities of 52500 plants/ha or lower; significant increases in yield were obtained for high SI hybrids at > 67 500 plants/ha. Leaf area was one of the parameters necessary for determining SI, and this could be predicted with a skewed bell-shaped function simply by measuring the length and breadth of the largest leaf and counting the total number of leaves per plant.
Potassium depletion under long-term fertilization in a semi-arid soil in India
Authors: Mittal S. B. , Singh Raghbir , Mehta S. C. , Singh Mahendra
Published: March 2009

In 12-year (1975–87) fertilizer trial on a pearl millet-wheat rotation, there were no responses to applied K and exchangeable K decreased from 620 to 200 kg/ha. In spite of progressively diminishing exchangeable K, removal of K by crops was independent of soil K status, indicating that exchangeable K had no relation to K uptake in this soil. Thus, nonexchangeable K made a major contribution to plant K, up to 90% in untreated plots and > 70% in K-treated plots. A significant (r = -·708) relationship between nonexchangeable K and K fixation capacity was found. Nonexchangeable K was also significantly but negatively correlated (r = -0·583) with free energy exchange (ΔGr). Potassium supply values, expressed by pK-½p (Ca + Mg), were positively and significantly correlated with K removal by crops in 1987 and with the K saturation values of the exchange phase, so that both these measures can be successfully used to test soil K availability. The results of this study suggested that on this soil, under a pearl millet-wheat crop system, inclusion of K in the fertilizer programme may soon be needed.
In vivo and in sacco digestibility and rumen microbial degradation of cell walls of soyabean and rape integuments and of dehydrated beet pulp in sheep, observed by scanning electron microscopy
Authors: Grenet E. , Barry P.
Published: March 2009

The in vivo digestibility of soyabean integuments, rape integuments and dehydrated beet pulp was determined in sheep in the Centre de Recherches de Clermont-Ferrand-Theix, in 1985. Organic matter digestibility was 83·5, 59·6 and 85·0%, respectively, for the three feeds. The nylon bag method was used to determine the disappearance of dry matter (DM) in the rumen. After 72 h, 89 and 96% DM had disappeared for soyabean integuments and beet pulp, respectively, but only 61% for rape integuments. The DM disappearance rate was slowest (P < 0·05) for soyabean integuments. Microscopic examination showed that the different layers of the soyabean integument could be ranked in increasing order of resistance to microbial degradation as follows: parenchyma, aleurone layer, column cell layer, palisade layer and epidermis. The hilum area was the most resistant and the only one lignified. The cell layers of the rape integument could be ranked in increasing order of resistance as follows: epidermis, aleurone layer and palisade layer. The last was highly lignified and not degradable. Degradation of beet pulp was fast, occurring first in the parenchyma. The vessels resisted degradation but were only a small part of the feed. This study shows why beet pulp has a low fill value and allows high intake. The soyabean integument is very digestible and is degraded slowly, whereas almost half of the rape integument is made up of a cell layer that is not degradable.
Tillage and irrigation effects on root growth, soil water depletion and yield of wheat following rice
Authors: Chaudhary M. R. , Khera R. , Singh C. J.
Published: March 2009

The effects of deep tillage and no-tillage on soil physical properties and wheat yield following rice were compared with conventional tillage at three irrigation rates (irrigation water:open pan evaporation ratios of 0·6, 0·9 and 1·2) in 1982–85 at the experimental station of the Punjab Agricultural University, Ludhiana. Deep tillage decreased soil bulk density and penetrometer resistance, and increased depth of rooting, profile water use and wheat yield. No-tillage adversely affected all these variables. The tillage effects varied with amount and distribution of rain during the cropping season.
Use of successional sowing in evaluating cowpea (Vigna unguiculata) adaptation to drought in the Sudan savannah zone. 2. Response of reproductive traits
Authors: Muleba N. , Mwanke M. , Drabo I.
Published: March 2009

Two sets of experiments on cowpea sowing date were conducted in 1983–85 at Ouagadougou, Burkina Faso. One set tested six daylength-insensitive (DI) cultivars and the other compared four or five daylength-sensitive (DS) cultivars with one or two DI cultivars as controls. Sowing after inadequate rainfall, particularly when followed by drought stress, impeded seedling establishment and growth. Severe drought stress during the reproductive growth stages and prolonged drought stress throughout the crop season adversely affected flowering, flowering intensity and subsequent yield. Cultivar differences in ability to withstand drought damage were observed. The ability of cultivars to (i) branch profusely, to compensate for stands lost by drought during seedling growth and (ii) flower at such a time that pod set and fill coincide with favourable climatic conditions appears to be a prerequisite for satisfactory adaptation to the Sudan savannah zone of semi-arid West Africa. Daylength-sensitivity and early maturity per se were inadequate to prevent yield losses under drought conditions.
Seasonal changes in leaf water potential components in two almond cultivars
Authors: Ruíz-Sánchez M. C. , Sánchez-Blanco M. J. , Planes J. , Alarcón J. J. , Torrecillas A.
Published: March 2009

Almond trees (Amygdalus communisL. cvs Garrigues and Ramillete) were grown in the field under non-irrigated conditions in Murcia, Spain. Seasonal variations in leaf water potential components were studied in 1989. Predawn leaf water potential showed high values in both cultivars, due to the absence of soil water stress. Pressure-volume curve analysis indicated that the leaf osmotic potential at full saturation (Ψo(sat)) for cv. Garrigues remained fairly constant throughout the season. Bulk modulus of elasticity (E) showed, in both cultivars, a tendency to decrease as the season progressed. E values were higher in Ramillete than in Garrigues. The relative water content at the turgor loss point (RWCtlp) seemed to be controlled by E values. The larger relative apoplastic water content (RWCafound in Ramillete might have allowed it to retain more water at low leaf water potentials than Garrigues. These facts would support the suggestion that Ramillete is a more drought-resistant cultivar than Garrigues.
Effects of cutting height on the growth of leaves and stolons in perennial ryegrass–white clover swards
Authors: Wilman D. , Acuña G. H. p.
Published: March 2009

All combinations of five cutting heights (2, 4, 6, 8 and 10 cm) were compared, for 3 years (1986–88), on field plots sown with a mixture of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) in Wales. The plots were cut at 4-week intervals from April to October each year.

A reduction in cutting height reduced the length, width and weight of clover leaflets, petiole length, stolon diameter, the length of stolon internodes and the height of stolons above ground level, but increased the length of clover stolon/m2, the number of stolon nodes/m2 and the proportion of stolon nodes which produced branches. The latter factors out-weighed the former, leading to the inverse relationship between cutting height and the proportion of clover in the sward previously reported (Acuñia & Wilman 1993).

A reduction in cutting height reduced the following attributes of ryegrass: the height of the shoot apex, the length and width of leaf blades, sheath length, leaf extension rate, the death rate of leaves and the net gain in blade length.

Cutting height had little effect on either the thickness of clover leaflets or the rates of leaf emergence in clover and ryegrass.
Nitrogen in the excreta of dairy cattle: changes during short-term storage
Authors: Whitehead D. C. , Raistrick N.
Published: March 2009

The concentration of N in samples of urine from dairy cattle fed on grass herbage, or grass or maize silage, sometimes with additional concentrate feeds, ranged from 6·0 to 13·8 mg N/l with 67–91% of the total N being present as urea. The concentration of N in 11 samples of dung was 0·32–0·52% on a fresh weight basis (2·74–3·82% N in dry weight). About 18% of the dung N was contained in particulate material of > 0·2 mm diameter,c.72% in fine particulate plus colloidal material, andc.10% was soluble in the presence of A12(SO4)3.

When urine was stored for 3 weeks, the urea component was hydrolysed with the formation of ammonium. The rate at which hydrolysis occurred was greatly influenced by temperature. Hydrolysis of urea was complete within 2 days at 35 °C, within 7 days at 20 °C and within 21 days at 10 °C, but was onlyc.90% complete after 21 days at 5 °C. The rate of hydrolysis of urinary urea-N at 20 °C was increased slightly by inoculation with slurry, dung or soil, and was also increased slightly by the greater aeration resulting from a continuous stream of bubbled air. No nitrification was detected, even in urine that was aerated for 6 weeks, probably because the process was inhibited under the conditions of high pH (9–10) and high concentrations of ammoniacal N.

When dung was stored for 3 weeks at 5 or 10 °C, there was little change in the amount of organic matter or in the form of N. However, at higher temperatures, some mineralization occurred and the amount of organic matter declined by 8% at 20 °C and by 17% at 35 °C. About 10% of the organic N was converted to ammonium during 3 weeks at 20 °C, andc.18% at 35 °C.

With a slurry prepared from approximately equal amounts of urine, dung and water, more of the dung material was mineralized than with the dung stored alone:c.15% of the organic matter was lost during 3 weeks at 5 °C and c. 34% at 35 °C. Despite this loss of organic matter, there was net immobilization of soluble N during the 3-week period by the solid fractions of the slurry, at all four temperatures.
Effects of intraruminal infusions of urea, sucrose or urea plus sucrose on plasma urea and glucose kinetics in sheep fed chopped lucerne hay
Authors: Obara Y. , Dellow D. W.
Published: March 2009

The effect of rumen fermentation on the relationship between urea and glucose kinetics was examined in sheep fed chopped lucerne hay with intraruminal infusions of water, urea, sucrose, or urea plus sucrose at Palmerston North, New Zealand in 1986. Sheep were fed hourly and infused intraruminally with water (1200 m1/day), or a similar volume containing either urea alone (13·7g/day), sucrose alone (178·2 g/day) or urea (14·6 g/day) plus sucrose (175·0 g/day). The added sucrose resulted in a lower rumen ammonia concentration (P< 0·05), lower plasma urea concentration (P< 0·05) and reduced urinary urea excretion (P< 0·05). Urea recycled to the gut tended to increase with the sucrose, urea or sucrose plus urea treatments compared with the water treatment. The fermentation of sucrose in the rumen resulted in decreases in ruminal pH (P< 0·05) and in the ratio of acetate to propionate (A:P) (P< 0·05). The infusion of sucrose also increased the concentration of propionate in rumen fluid (P< 0·05), tended to increase the plasma glucose level and increased plasma glucose irreversible loss (P< 0·05). The infusion of urea resulted in an increase in the plasma urea level (P< 0·05), urea pool size (P< 0·05) and urea irreversible loss (P< 0·01). However, urea infusion did not affect glucose metabolism or volatile fatty acid (VFA) fermentation. The effects of sucrose infusion on glucose and urea kinetics were broadly similar when given alone or with urea, apart from changes in the urea degradation rate. It was concluded that the additional fermentative activity resulting from sucrose increased propionate production which, in turn, was available for glucose production, thus ‘sparing’ amino acids for tissue protein utilization and reducing urea excretion.