bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological reasons for heterosis in growth ofBos indicus×Bos taurus
Authors: Frisch J. E.
Published: March 2009

By comparing growth rates of Brahman (B), Hereford × Shorthorn (HS), their reciprocal F1, hybrid (F1BX), their Fnhybrid (FnBX) and an F1Charolais × Brahman hybrid (FlCH 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 F1BX 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 F1BX 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 FnBX. Thus, although previous selection for increased live-weight gain should have favoured the FnBX, they realized lower live-weight gains than the FlBX 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 F1BX had similar values to the better parent (HS) for both scrotal circumference and plasma testosterone concentrations. However, the FnBX 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 F1BX.
Response of three potato genotypes to density and method of cultivation
Authors: Adetuyi F. C.
Published: March 2009

Potato (Solanum tuberosum L.) is propagated vegetatively using the tuber because it rarely survives from the true seed. Under normal conditions, potatoes left in the air or dry soil will produce sprouts but not roots. Large and vigorous sprouts are indicators of rapid emergence and relatively early maturity.
The effect of increased energy demand through walking exercise on intake and ruminal characteristics of sheep fed a roughage diet
Authors: Henning P. H.
Published: March 2009

Sheep were exercised on a treadmill to study the effect of increased energy demand on roughage intake and ruminal characteristics.

The experiment consisted of a pre-exercise period during which exercise sheep walked for 30 min/day at 2 km/h against a gradient of 0° followed by a full exercise period during which they walked a total of 9 km/day at 3 km/h against a 10°gradient during six daily sessions of 30 min each. Control sheep received no exercise but were treated similarly to exercise sheep in all other respects.

The mean values obtained during the pre-exercise period for the exercise and control groups and during the full exercise period for the exercise and control groups respectively were 1347, 1125; 1177 and 1114 g/day for organic matter (OM) intake; 956, 921; 803 and 848 g for rumen OM contents; 11·8, 13·6; 12·2 and 12·3 h for rumen retention time of water; 17·5, 20·2; 16·8 and 17·6 h for rumen retention time of fermentable OM; 27·3, 28·2; 26·4 and 26·7 h for rumen retention time of unfermentable OM and 46·9, 48·1, 44·4 and 45·9 kg for empty body weight. Only the decline in OM intake from pre-exercise to full exercise period differed significantly between exercise and control groups.

It is concluded from these results that an increase in the difference between energy demand and supply per se is not responsible for the apparent increase in the upper limit to OM accumulation in the rumen and concomitant increase in roughage intake observed during other situations of increased energy output such as lactation and severe cold.
Effects of harvesting programme and sowing date on the forage yield, digestibility, nitrogen concentration, tillers and crop fractions of barley in Cyprus
Authors: Droushiotis D. N. , Wilman D.
Published: March 2009

All combinations of four harvesting treatments and two sowing dates were comparedin each of 3 years in field experiments near Nicosia. In two of the years, different levels of applied nitrogen were compared. The harvesting treatments were: (1) a milk-stage cut,(2) a boot-stage cut and a regrowth cut, (3) a grazing-stage cut and a regrowth cut, and(4) three grazing-stage cuts and a regrowth cut. The sowing dates were (1) normal (12 November) and (2) early (15 October), with sufficient irrigation to ensure establishment. There was almost no response to applied nitrogen, evidently because of high reserves of available nitrogen in the soil. Early sowing reduced by 20 days the time taken to reach the stage at which the first node appeared, but increased, by 36 days, the length of time between the first node and the milk stage. Early sowing increased yield when the firstcut was at the grazing stage, but reduced yield when the first cut was at the boot or milk stage. At the grazing stage, the proportion of green leaf blade and the concentrations of nitrogen and nitrate-N were relatively high (means 74, 4·0 and 0·13% respectively) and digestibility was moderate (mean D-value 61). By the boot stage, green leaf, nitrogen and nitrate-N, but not digestibility, had declined (means 21, 1·8, 0·02 and 63 respectively). By the milk stage, green leaf, nitrogen and digestibility, but not nitrate-N, had declined further (means 3, 1·5, 48 and 0·05 respectively). Fully dead leaf blades were 28 units less digestible and 3·2 percentage units lower in nitrogen concentration than emerging leaves. Half dead leaf blades were higher in nitrate-N than fully expanded, fully green blades. 'Stem’ declined greatly in nitrogen concentration, but relatively little in digestibility, between the grazing and the boot stage.

Crops cut once or three times at a grazing stage recovered well, although theretended to be some reduction in the number of tillers compared with an undefoliated crop.
An analysis of primordium initiation in Avalon winter wheat crops with different sowing dates and at nine sites in England and Scotland
Authors: Kirby E. J. M. , Porter J. R. , Day W. , Adam Jill S. , Appleyard Margaret , Ayling Sarah , Baker C. K. , Belford R. K. , Biscoe P. V. , Chapman Anne , Fuller M. P. , Hampson Janice , Hay R. K. M. , Matthews S. , Thompson W. J. , Weir A. H. , Willington V. B. Anne , Wood D. W.
Published: March 2009

The initiation of leaf and spikelet primordia was studied at sites ranging in latitude from Newton Abbot (50·6°N) to Aberdeen (57·2°N) in crops sown in the middle of September, October and November 1983. The rate of primordium initiation tended to decrease from south to north but there were also marked differences between quite close sites.

The rate of leaf initiation increased with temperature but photoperiod had little effect; the rate of spikelet initiation was affected both by temperature and by photoperiod. There were differences in the total number of leaves initiated which were only partlyexplained by differences in vernalization.

Expressing leaf and spikelet initiation rates in terms of thermal and photo-thermal time respectively showed a constant rate of leaf initiation and a constant and more rapid rate of spikelet initiation.
Effects of infrequent drinking on the nitrogen metabolism of Bedouin goats maintained on different diets
Authors: Brosh A. , Shkolnik A. , Choshniak I.
Published: March 2009

summary

The effect of infrequent drinking on nitrogen metabolism was studied in Bedouin goats, a breed herded in the extreme deserts of the Middle East. The goats were given water either daily or only once every 4 days, while being maintained on roughages of different quality: lucerne hay (19% protein), Rhodes grass (10% protein) or wheat straw (3·7%). On lucerne hay and Rhodes grass the goats kept their body mass constant, whether given water daily or only once every 4 days. When on wheat straw the body mass was maintained constant only when given water once every 4 days. Infrequent drinking was found to hamper considerably the food intake of the goats when fed on high quality roughage. When on the wheat straw, the nitrogen intake of the goats (only 12% of that recorded when fed lucerne hay and given water daily) was, however, not affected by the drinking regime. Infrequent drinking improved nitrogen digestibility on all the diets, but more so on those of low quality than on the lucerne hay.

When tested on the low quality feeds, urea excretion was low and urea retention and recycling were maintained at high rates. Infrequent drinking had no adverse effect on these capacities.
Determination of the volatilization of ammonia from surface-applied cattle slurry by the micrometeorological mass balance method
Authors: Stevens R. J. , Logan H. J.
Published: March 2009

Agronomic experiments have shown that nitrogen applied in organic manures gives variable responses in grass growth (van Dijk & Sturm, 1983; Smith, Unwin & Williams, 1985). In a series of field trials in southern England, the average apparent recovery in herbage of the nitrogen from cow slurry was only 13% (Unwin, Pain & Whinham, 1986). The volatilization of ammonia from spread slurry is one possible mechanism for the nitrogen inefficiency (Freney, Simpson & Denmead, 1983; Ryden, 1984). Direct measurements of ammonia loss from land surfaces can be made by micrometeorological methods (Denmead, 1983) and, using the micrometeorological mass balance technique, high rates of ammonia loss were recorded after the land spreading of liquid dairy cattle manure in Canada (Beauchamp, Kidd & Thurtell, 1982). The micrometeorological mass balance method has been used in England to measure ammonia loss from a grazed sward (Ryden & McNeill, 1984). This paper presents the results of an experiment where the same method was used to measure the ammonia loss after land-spreading cattle slurry in Northern Ireland.
Dry-matter intake of Hereford and first-cross cows measured by controlled release of chromic oxide on three pasture systems
Authors: Barlow R. , Ellis K. J. , Williamson P. J. , Costigan P. , Stephenson P. D. , Rose G. , Mears P. T.
Published: March 2009

Faecal output of 287 beef cows consisting of Hereford (H × H), Simmental × Hereford (S × H), Friesian × Hereford (F × H) and Brahman × Hereford (B × H) breeding was estimated using controlled release of chromic oxide (Cr2O3). All cows were from 6 to 10 years of age and had grazed on one of three pasture systems in the subtropics of New South Wales since they were 7–8 months of age. These pastures were designated as being of high, medium and low nutritive value. Faecal organic matter output (FOMO) was estimated in each of four periods (early lactation, mid lactation, late lactation, and non-lactating) during one annual production cycle.

Herbage mass exceeded 2 t/ha on all pasture systems, but estimates of organic-matter digestibility, nitrogen content and pasture composition indicated large differences in pasture quality (high > medium > low). Live weight of cows averaged 604, 488 and 393 kg live weight on the high, medium and low pastures, respectively. There were significant differences in live weight between genotypes on the medium (B × H > F × H and H × H) and low (S × H ≡ F × H ≡ B × H > H × H) pastures but not on the high pasture).

FOMO and dry-matter intake (DMI) differed significantly between genotypes among lactating cows on all pasture systems. Rankings on high pastures were reasonably consistent in all periods: S × H ≡ F × H ≥ B × H ≥ H × H, as were those on low pastures, B × H ≥ S × H ≡ F × H ≥ H × H. Differences on medium pastures were significant only during mid-lactation when B × H ≡ S × H ≡ F × H > H × H. Significant differences between genotypes were observed among non-lactating cows on high pastures only, where H × H ≡ S × H ≡ F × H > B × H. Lactating females had significantly higher FOMO and DMI than non-lactating females when compared across genotypes during early lactation on all pastures.
Growth of sugar-beet crops including the influence of synthetic plant growth regulators
Authors: Green C. F. , Vaidyanathan L. V. , Ivins J. D.
Published: March 2009

J. agric. Sci., Camb. (1986), 107, 285–297

The authors regret that Fig. 9 relating sucrose weight to total dry weight contained a few misplotted measurements. The sixth group of bivariate observations (five data points) were plotted a factor of 10 g/plant too light in the y-direction (sucrose weight). This error was not present in curve fitting, thus the fitted relationship (Fig. 9; Table 2) is correct fitted relationships on Figs 5 and 9 and thus also remain unchanged. Figure 9 should be presented as
Evaluation of polyethylene glycol test of measuring cell membrane stability as a drought tolerance test in wheat
Authors: Premachandra G. S. , Shimada T.
Published: March 2009

Effectiveness of the polyethylene glycol (PEG) test for measuring cell membrane stability (CMS) to select drought-tolerant genotypes in wheat was investigated. PEG test was compared with two other tests. Genetic variability of CMS was also investigated.

Drought was induced artificially in pot-grown plants and in excised leaves, and percentage injury in leaf tissues by drought stress as measured by CMS was compared with that by PEG test. Percentage injury in leaf tissues of pot-grown plants was not correlated significantly with that by PEG test. However, percentage injury in excised leaves was well correlated with that in PEG test. The results suggest that the PEG test has merit in measuring drought tolerance in wheat. Frequency distribution of CMS in winter wheat lines was closely related to the characteristic pattern of quantitative inheritance and therefore CMS of wheat seems to be controlled by polygene action.
Inheritance of three agronomic characters in Lycopersicon interspecific crosses
Authors: Yassin T. E.
Published: March 2009

Crosses between two cultivars of tomato (Lycopersicon esculentum Mill.), and two accessions of the wild species L. pimpinellifolium (Jusl.) Mill, were made and F1, F2 and backcross generations were developed and studied. Significant differences in number of fruits per plant, yield per plant and fruit weight were found between means of the different generations. Variation in number of fruits per plant and yield was also found between plants within generations. Number of fruits per plant was a highly heritable character (average h2 = 73·6%) and closely correlated with yield per plant, indicating that it may be a suitable selection criterion for yield improvement in tomato crosses.
Water requirements and metabolism in Egyptian Barki and Rahmani sheep and Baladi goats during spring, summer and winter seasons
Authors: El-Nouty F. D. , Hassan G. A. , Taher T. H. , Samak M. A. , Abo-Elezz Zahraa , Salem M. H.
Published: March 2009

Water requirements and metabolism were studied in eight each of Barki and Rahmani sheep and eight Baladi goats. The animals were individually housed in the shade in semi-open pens that were located in a non-desert area. The experiments were carried out during spring, summer and winter seasons, and each experiment lasted for 3 weeks during each season. After a preliminary period of 1 week, an 8-day period was then followed during which body weight, daily feed intake and daily drinking water were recorded. Rectal temperature and respiration rate were also recorded in the early morning and late afternoon. Four animals from each group were then weighed and injected intravenously with tritiated water, TOH (001 mCi/kg body weight) and blood samples were collected during a 4-day period to estimate total body water (TBW) and water turnover rate (WTR).

In all seasons studied, the Rahmani sheep had higher TOH disappearance rate (^-values) and WTR and consequently shorter biological half-time (1½) than the Barki. Moreover, the Barki sheep showed less thermal discomfort than the Rahmani particularly during the summer. Although the Rahmani sheep ingested more water than the Barki sheep during the summer, the Rahmani sheep had a lower percentage of TBW and their calculated water loss revealed that they were in negative water balance during this season. Accordingly, the Barki sheep seem to perform better than the Rahmani in newlyreclaimed desert areas. Baladi goats appear to be more adapted to unfavourable environmental conditions than sheep. This is based upon the findings that they had lower k-values, lower WTR, longer tiand higher TBW, than the two breeds of sheep.
Organic and chemical sources of nitrogen: its effect on nitrogen transformation and rice productivity under submerged conditions
Authors: Chakraborty P. K. , Mandal L. N. , Majumdar Anup
Published: March 2009

A field experiment was carried out in three wet seasons of 1982, 1983 and 1984 with various combinations of urea and organic nitrogen sources to investigate the nitrogen transformation and productivity of rice crop in a waterlogged situation. The treatments used were: (i) control (No), (ii) FYM + urea, (iii)Sesbania+ urea, (iv) urea, the levels of nitrogen being 60 and 90 kg/ha and the proportion being 50:50 between organic and chemical sources where such combination was used. The soil samples were analysed for ammonium, hydrolysable and non-hydrolysable forms of nitrogen at 15, 30 and 45 days after transplanting. The release of hydrolysable and non-hydrolysable nitrogen was superior in theurea-Sesbaniacombination while the release of NH4·N was slightly better in FYM-urea combination. Yield of rice and apparent nitrogen use efficiency were highest in sole urea treatment and almost similar in FYM-urea andSesbania+ urea combinations. A statistical nitrogen-transformation model outlined the relationship among the various forms of soil nitrogen under submergence. The model suggested a strong correlation among the different forms of nitrogen during the earlier period of submergence.
Influence of salinity, rice straw and water regime on nitrogen fixation in paddy soils
Authors: Jena P. K. , Rajaramamohan Rao V.
Published: March 2009

In a laboratory incubation study, the effect of natural and artificial soil salinity on the soil N2fixation, nitrogenase (C2H2reduction) and N2-fixing populations was evaluated in rice soils under two water regimes. N2fixation was less pronounced in two saline soils and in a normal non-saline soil amended with salt mixture (salinity level of 4 and 30 dS/m) than in a non-saline soil under flooded and nonflooded conditions. Flooded soils amended with rice straw showed higher N2-fixing activity than the non-flooded soils at all salinity levels used in the study. Leaching the saline soil improved N2fixation. An increase in the soil salinity led to a decrease in the populations of at least three groups of N2-fixing micro-organisms. The population density of anaerobic N2fixers and Azospirillum in a saline soil increased considerably after leaching or after addition of rice straw. Azotobacter populations were little affected by the salinity levels used in this study. Results indicate that soil amelioration for salinity with leaching and organic matter addition would improve the implicated microbial populations and N2fixation in salt-affected rice soils.
Predicting sodification of calcium-saturated soil columns on leaching with sodic waters
Authors: Siyag R. S. , Lamba M. S. , Pal Raj , Poonia S. R.
Published: March 2009

Depth accumulation of exchangeable Na+ was measured in Ca-saturated sandy loam soil columns (length 50 cm; diameter 5 cm) after percolating 500, 1000, 1500 and 2000 ml of 013 M Na+, as NaCl, NaHCO3, Na2SO4 and Na2CO3 solutions. The values of exchangeable sodium percentage (ESP) increased gradually with the increase in the volumes of the solution percolated. Two conceptual layer models, based on whether solutions were added to the topmost soil layer in one lot (M-I) or in splits equal to the saturation deficit (M-II), were used to predict the depth distribution of ESP of soil. The chemical processes considered in the models were the formation of ion pairs and the exchange equilibria of Na+ and Ca2+. The predicted values of ESP were considerably higher for model M-II than model M-I. The consideration of ion-pair formation and the accompanying anion had only negligible effect on the predicted ESP. The model M-II over-predicted the experimental ESP throughout the soil columns, whereas the model M-I under-predicted it for the upper layer(s) and over-predicted for the lower layers. On the basis of average ESP of the whole columns, the less realistic model M-I predicted experimental results better than model M-II. This was attributed to the presence of mobile and immobile zones for the flowing solutions.
The effect of level and type of concentrate and type of conserved forage on dry matter intake and milk production of lactating dairy cows
Authors: Phipps R. H. , Weller R. F. , Elliott R. J. , Sutton J. D.
Published: March 2009

Between weeks 3 and 16 of lactation 191 British Friesians received a basal ration ad libitum of either grass silage (GS), grass and maize silage (GS/MS) blended in a ratio of 1:2 or grass silage and 4% NaOH-treated barley straw (GS/TS) blended in a 4:1 ratio. The grass silage, which was not well preserved, had an estimated metabolizable energy (ME) content of 9–9 MJ/kg D.M., while corresponding values for the GS/MS and GS/TS mixtures were 106 and 9–5 MJ/kg D.M., respectively. A conventional concentrate (CC) based on barley and soyabean meal was fed at three levels (9, 6 and 3 kg fresh weight/day). Although the 9 kg level was only used in conjunction with GS, the two lower levels were fed with all three forage types. Concentrate composition was also varied at the 6 and 3 kg levels by replacing, in each case, 2 kg CC with a special concentrate (SC) which, in addition to barley, wheat and soyabean meal contained, on an air-dry basis, 25 % fishmeal and 25 % protected fat in the form of Megalac
Monensin induced metabolic changes in cattle fed a restricted intake of lucerne hay
Authors: O'Kelly J. C. , Spiers W. G.
Published: March 2009

O'Kelly (1985) has presented evidence which suggests that at the same feed intake Brahman cross cattle synthesize more microbial lipid than British cattle with a resultant increased efficiency of utilization of metabolizable energy for maintenance. The lipid content of bacteria associated with both liquid and solid fractions of rumen contents is also higher in Brahman than in Hereford cattle (J. C. O'Kelly & W. G. Spiers, unpublished). The reasons for these breed differences are unknown. A step in investigating the problem could be to determine whether microbial lipid content in Hereford cattle can be increased by altering rumen fermentation patterns in association with changes in the microbial population. Ionophores alter rumen fermentation by increasing the production of propionic acid relative to other volatile fatty acids and also inhibit Gram-positive bacteria by facilitating the formation and transport across cell membranes of lipid-soluble complexes with various cations (Bergen & Bates, 1984). However, there are no reports on the effects of ionophores on microbial lipid metabolism in cattle on restricted feed intakes typical of those in tropical areas.
Studies on the effect of green manuring in nitrogen economy in a rice–wheat rotation using a 15N technique
Authors: Goswami N. N. , Prasad R. , Sarkar M. C. , Singh S.
Published: March 2009

A field experiment using 15N was carried out at the Indian Agricultural Research Institute, New Delhi during the crop year 1985–1986 to investigate the possible economy in fertilizer nitrogen applied to rice and succeeding wheat by growing a summer leguminous green manure (Sesbania aculeata) and incorporating it in soil before transplanting rice. Grain and straw yields of rice with 60 kg N/ha after green manuring were slightly greater than with 120 kg N/ha after summer fallow. Thus summer green manuring can lead to an economy of 60 kg N/ha in rice. 15N analysis showed that green manuring contributed 4·7–5·6% N of the total taken up by rice and 1·9–4·8% of that taken up by the succeeding wheat, depending upon the rate of fertilizer N applied to rice.

15N analysis showed that at 60 kg N/ha applied to rice, 35·4% was recovered by rice, 41% by the succeeding wheat and 16·7% was left in the 0–45 cm soil layer after summer fallow; after green manuring 32·8% N was recovered by rice, 3·0% by succeeding wheat and 22·6% was left in the soil. Thus 56·2 and 58·4% of applied N could be accounted for after summer fallow and green manuring, respectively. At 120 kg N/ha about 60–61% of applied N could be accounted for. Thus about 40–44% of N applied to rice was lost by the various loss mechanisms operating in rice fields.
The effects of fertilizers on the bulking of Majestic potatoes
Authors: Hanley F. , Jarvis R. H. , Ridgman W. J.
Published: March 2009

1. Four experiments designed to investigate the effect of fertilizers on the rate of bulking of Majestic potatoes are described and the results discussed.

2. Irrespective of fertilizer application yield increased until the haulm died and then decreased slightly.

3. Sulphate of ammonia increased the yield by increasing the number of tubers and increasing the yield in all size-grades. Thus its effect was seen throughout the season, no matter what grades yield was based on. It also increased dry-matter percentage.
Carbohydrate levels and regrowth in perennial rye-grass
Authors: Davies Alison
Published: March 2009

In a series of experiments in which variations in the level of carbohydrates in the plant have been brought about by means of short-term exposures to darkness and raised temperatures, it has been shown that:

1. The yield of leaf material after cutting is affected by pretreatments. This effect seems to be at least partly associated with the level of carbohydrates present in the stubble at the time of cutting.

2. The rate of growth of the plants is independent of the pretreatments imposed once growth is fully established.
Unsaturated water transmission characteristics of soils in relation to texture, aggregate size and initial moisture content
Authors: Mundra M. C. , Pal Raj , Siyag R. S. , Poonia S. R.
Published: March 2009

To study the effect of soil texture, aggregate size and initial moisture content on soil water diffusivity, D(θ), and unsaturated hydraulic conductivity, K(θ), horizontal absorption experiments were conducted on samples of loamy sand, sandy loam and clay–loam soils as well as on artificially prepared water-stable aggregates of a clay–loam sample (sizes 0.·25–0–25, 0·25–0·5, 0·5–1, 1–2, and 2–4 mm). For comparable moisture contents, D(θ) followed the order loamy sand > sandy loam > clay–loam. The effect of initial moisture content on D(θ) varied with soil texture. K(θ), which was evaluated using D(θ) for air-dry initial moisture content and the slopes of the water retention curves, also varied with soil texture.

The D(θ) function for air-dry initial moisture content increased with the decrease in aggregate size, the increase being more pronounced below a size of 1 mm. Values of D(θ) obtained from initially airdry soil and at 10% of saturation moisture content did not differ greatly from one another. The K(θ) function was almost the same for aggregate sizes 1–2 and 2–4 mm. In the size ranges of < 1 mm, K(θ) increased with the decrease in aggregate size. The particle/aggregate size range of 0·1–0·5 mm was the most conducive to unsaturated water flow.
The effects of grassland management on nitrogen losses from grazed swards through ammonia volatilization; the relationship to excretal N returns from cattle
Authors: Jarvis S. C. , Hatch D. J. , Roberts Daphne H.
Published: March 2009

Ammonia (NH3)-N fluxes from three swards, grazed by cattle and with different N managements, were measured using the mass balance micrometeorological method after a 7-day grazing period in the spring of 2 years. At the same time the impact of the sward managements on N returns in dung and urine was examined in housed animals and the effects of the changes in excreted returns on NH3-N losses examined. The treatments were ryegrass swards receiving either 420 or 210 kg N/ha per year, and a mixed ryegrass/white clover sward receiving no mineral N. There was little difference in the faecal N returns between treatments but there were differences in the N returned in urine, thus 74, 60 and 56% of the excreted returns from 420 N, 210 N or grass/clover treatments, respectively, were in urine. The fluxes of NH3-N from the grazed swards were greatest whilst the animals were present and there were large differences between treatments, the ratio of total NH3losses from 420 N grass to those from 210 N grass and grass/lover being 7·8:1. The NH3-N losses were equivalent (i) to 12,5 and 7 % of the urinary N returns to 420 N, 210 N grass and grass/clover swards, or alternatively (ii) to 9 and 3% of the fertilizer addition to 420 and 210 N swards and 3% of the estimated rate of N2fixation in the grass/clover sward. Throughout the investigation there was little difference between the effects with the 210 N grass swards and those with grass/clover.
Evaluation of winter hardiness in Romanian introductions of Lolium perenne
Authors: Tcacenco F. A. , Eagles C. F. , Tyler B. F.
Published: March 2009

Characterization of accessions of Lolium perenne collected in Romania, using naturally hardened tillers in an artificial freezing test, is described. Accessions showed contrasting hardening response to variation in the winter environment at Aberystwyth. Cold tolerance of the accessions, measured as lethal temperature for 50% of the tillers (LT50), was positively correlated with the mean temperature of the coldest month at the sites of origin and with persistence in swards after three winters. Superior populations were identified within this collection and are being used as a source of winter hardiness in a breeding programme.

The role of temperature and irradiance in the contrasting hardening responses of three accessions was investigated in controlled-environment studies with seedlings.

The advantages of environmental simulation techniques for characterization of genetic resources are discussed.
The effects of diets deficient in phosphorus, phosphorus and vitamin D, or calcium, on the skeleton and teeth of the growing sheep III. The composition and structure of the teeth. III. The composition and structure of the teeth
Authors: McRoberts M. R. , Hill R. , Dalgarno A. C.
Published: March 2009

1. The teeth of sheep that had been fed from 6 months of age for 12 months on diets low in calcium or in phosphorus and vitamin D content were compared with those of similar animals fed a control diet.

2. The low calcium diet depressed the development of both dentine and enamel but had a greater effect on enamel than dentine, while the low phosphorus and vitamin D diet depressed dentine development slightly and had practically no effect on enamel.

3. The percentages of ash of the dentine and enamel were not significantly affected by the diets fed.
Effects of autumn harvest date on the performance of white clover/grass mixtures in Nova Scotia
Authors: Fraser J. , Sutherland K. , Martin R. C.
Published: March 2009

White clover (Trifolium repens L.) is well adapted to the cool moist climate of Atlantic Canada, where it improves digestibility and protein content in pastures, but little is known about its role in pasture stockpiled for autumn grazing in this region. The objectives of this study were to determine the effect of autumn harvest dates on dry matter yield and clover content in herbage mixtures. Two experiments conducted in Nova Scotia between 1985 and 1991 on two different soil types showed that the effects of autumn harvest dates were inconsistent from year to year. Herbage growth rates ranged from 11 to 41 kg/ha per day between early September and mid-October. Clover content was generally lower in August–early September than in November harvests and declined in subsequent years irrespective of harvest date or forage species. Kersey White and Sonja white clovers were the highest yielding cultivars. Crude protein declined in late autumn harvests whereas acid detergent fibre tended to increase, and there were differences between years. Forage quality was significantly better in tall fescue (Festuca arundinacea Schreb.) than orchardgrass (Dactylis glomerata L.)/white clover mixtures.
Soil properties and mineralogy in relation to land use on a sedimentary toposequence in south-eastern Nigeria
Authors: Eshett E. T. , Omueti J. A. I. , Juo A. S. R.
Published: March 2009

The mineralogy of the clay fraction (<2 μm) of nine soil samples representing three physiographic positions of a toposequence in Ochon, south-eastern Nigeria, was determined by transmission electron microscopy and X-ray diffraction.

Soils in the crest and middle slopes (pedons TE1 and TE2, respectively) of the toposequence, formed over fine-grained sandstone, were coarse-textured, well-drained and acidic and had low effective cation exchange capacity and percentage base saturation. Kaolinite, mica, quartz, goethite and gibbsite were the principal minerals identified in the clay fraction of these soils. Soils in the valley bottom (pedon TE3) formed over arenaceous shale were, on the other hand, fine-textured, poorly drained and weakly acidic with higher cation exchange capacity and percentage base saturation. Their clay fraction mineralogy was similar to that of the well-drained upland soils but additionally included feldspar and smectite/vermiculite mixed layer minerals.

Mixed cropping of yam, cassava, maize and other annuals under traditional methods was carried out on the drier, well-drained crest and upper slopes while sole cropping of lowland rice occurred in the poorly drained, more fertile valley-bottom site. The valley-bottom soils show greater potential for improvement in agricultural productivity under good management than the upland soils.
Gene for resistance to bean common mosaic virus in cvs Seafarer and Aurora of Phaseolus vulgaris
Authors: Innes N. L. , Walkey D. G. A.
Published: March 2009

Resistance to bean common mosaic virus in the cultivars Seafarer and Aurora from the U.S.A. is controlled by the dominant gene I originally found in the cv. Corbett Refugee.
The utilization of phosphorus and nitrogen in wheat offal by growing pigs
Authors: Frape D. L. , Wayman B. J. , Tuck Mary G.
Published: March 2009

Two experiments with growing pigs grouped in pens and three with growing pigs kept in metabolism crates were undertaken in order to determine young growing pigs'dietary requirement for phosphorus of vegetable origin, the relative potency and true digestibility of that source and the effect of dietary Ca concentration on its utilization. Much of the P was contained in wheat offal, and of this 900 g/kg total P was phytin-P.

In the first two experiments the responses to vegetable P were measured by pig live-weight gain, gain: feed ratio, several conventional carcass measurements and the weight, length and density, and the ash, Ca and P contents of the fourth left metacarpal, and also by the alkaline phosphatase activity of blood serum. No significant differences were found between treatments in terms of body-weight gain, gain: feed ratio, or the commercially important carcass characteristics. The requirement of pork pigs for P was measured by bone and serum enzyme characteristics when all the dietary P was of plant origin, apart from 0·3 g P/kg from casein. Under the conditions of this experiment this P requirement appeared to be met when the diet contained 5–6 g P/kg. The potency of vegetable P in Expts 1 and 2 and of wheat offal P in Expt 3 relative to feed grade dicalcium phosphate was 0·77, equivalent to a net retention of 0·4–0·5 as a proportion of that consumed estimated from growth and digestibility measurements. A true digestibility coefficient of 0·53±0·01 for wheat offal P was obtained in Expts 4 and 5. The effect of variation in dietary N and energy, associated with variation in dietary offal concentration, on the reliability of the potency estimates is discussed.

Increasing dietary Ca concentration caused a slight decrease in the digestion of wheat offal-P. The soaking of wheat offal in water for an average of 11 h before feeding increased P digestion in one of two experiments.In vitroevidence indicated that soaking initiated the hydrolysis of insoluble P compounds.
The relationship between mean temperature and accumulated temperature totals for maize in the central lowlands of England
Authors: Bunting E. S.
Published: March 2009

In northern areas of maize production in Europe and America, increasing use is being made of the association between accumulated temperature and stage of crop development. Temperature is accumulated either in terms of day-degrees above a given base temperature, taken to be 10 °CC in the U.K., or in terms of developmental units (‘Ontario Units’). Formulae for obtaining the daily contribution from recorded maximum and minimum air temperatures are available for compiling accumulated temperature totals for each of these methods, but the processing of long series of data is tedious, even with the assistance of computer programs. Results are presented from several locations in the central lowlands of England to suggest that very close approximations to the true monthly or seasonal totals can be obtained from the regression relations with corresponding mean monthly or seasonal temperatures.

For the sites considered the regression equations were sufficiently close to make joint, ‘regional’, regression equations appropriate. It is believed that the results will be applicable to other areas of England, and that the methods suggested might provide a suitable basis for supplementing the information available on accumulated temperatures elsewhere in northern Europe.
Effect of a duodenal infusion of methionine on erythrocyte reduced glutathione of sheep
Authors: Sumner R. M. W. , Peter D. W. , Board P. G.
Published: March 2009

Reduced glutathione (GSH) is synthesized within blood erythrocytes from the constituent nonessential amino acids, glutamic acid, cysteine and glycine. The concentration of GSH in. erythrocytes can therefore be affected by the permeability of erythrocyte membranes to certain of these amino acids and their availability within the erythrocyte (Young, Ellory & Tucker, 1976; Smith, 1977). Alterations in the activity of the two enzymes responsible for GSH synthesis, γ-glutamyl cysteine synthetase and glutathione synthetase can likewise influence GSH concentration (Smith, Lee & Mia, 1973; Blume, Paniker & Beutler, 1974; Wellneret al.1974; Board, Morris & Peter, 1976).
Effect of N, P and K fertilizers on the availability of native and applied manganese to wheat
Authors: Mishra B. , Tripathi B. R.
Published: March 2009

The influence of three rates of each of N, P and K fertilizers on the availability of native and applied Mn to wheat was studied in a field experiment on an alluvial soil of the Indo-Gangetic plain. Increasing dressings of N as ammonium sulphate resulted in consistently higher yields and Mn uptake by the crop. Concentration of Mn in the grain increased with increasing N dressings when native Mn and Mn fertilizer supplied this nutrient but it was unaffected inplants sprayed with Mn. Adding P as superphosphate tended to lower the concentration of Mn in the grain when relying on native or applied Mn but it significantly enhanced the crop yield and total Mn uptake. Applying K as muriate of potash slightly depressed Mn uptake by plants. Potassium had a more pronounced effect in the absence of P fertilizer. The concentration of Mn in thestraw was not significantly affected by N, P and K fertilization.
The response of pastures in Northern Ireland to N, P and K fertilizers and to animal slurries: I. Effects on dry-matter yield
Authors: Adams S. N.
Published: March 2009

Sixteen factorial experiments made from 1969 to 1971 on Northern Ireland pastures measured effects on yield of 0, 180 or 360 kg of N, 0, 30 or 60 kg of P and 0, 150 or 300 kg of K/ha/year both with and without 138,000 1 of slurry/ha.

Without slurry, pasture yield was almost always substantially increased by nitrogen, slightly by potassium and hardly at all by phosphorus. There was a slight positive interaction between nitrogen and potassium, but no other interactions. Response to nitrogen was not linear and therefore was lower than has been obtained in many British trials.

Slurry sharply reduced response to nitrogen and virtually eliminated response to phosphorus and potassium. The NH4-nitrogen content of slurry gave an adequate measure of its effect on pasture yield. The nitrogen, phosphorus and potassium contents of the most concentrated slurries were 15, 29 and 36 times respectively those of the most dilute batches. Hence considerable imprecision is brought into a fertilizer programme when slurry is applied.

As manuring on individual fields can never be precise, the fertilizer phosphorus and potassium needed for grassland is best assessed by considering the farm as a whole. A nutrient balance can show if the farming system is gaining or losing phosphorus and potassium. The amounts of fertilizer phosphorus and potassium needed are those which cover any deficits on the farm as a whole.
Digestion by sheep of ground and unground dried molassed sugarbeet pulp diets and the effect of partially replacing the beet pulp with barley
Authors: Rymer C. , Armstrong D. G.
Published: March 2009

A 4 x 4 Latin square design experiment was performed at the Ruminant Research Centre, Cockle Park Farm, University of Newcastle upon Tyne, in 1986 to determine the effect of grinding molassed sugarbeet pulp (MSBP) to varying degrees of fineness on overall apparent digestibility in wether sheep when the product constituted 90% of dry matter intake. A product (designatedS) consisting of the pelleted screenings of unground MSBP was significantly less digestible than the other three products. No significant difference in overall apparent digestibility was observed between unground, coarsely ground and finely ground MSBP prepared from the same batch.

In a 4 x 6 randomized block design experiment, mature wethers equipped with rumen, duodenal and ileal cannulae were fed, in two meals, 1000 g concentrates and 100 g chopped hay per day. The concentrates consisted of 820 g mixture of barley and MSBP, 167·5 g soyabean meal, 10 g vitamins and minerals and 2·5 g chromic oxide per kg (fresh weight). The ratio of MSBP: barley was 1:3, 1:1 or 3:1 and the MSBP was either unground or finely ground. The aim was to determine the effect of replacing MSBP with barley on the nature of the rumen fermentation, overall apparent digestibility of the diet and the efficiency of rumen microbial protein synthesis (using 35S as a microbial marker).

There were no significant differences between the six diets in overall apparent digestibility of dry matter and organic matter, but N digestibility increased significantly (P > 0·05) as barley replaced MSBP in the diet. As before, the particle size of MSBP had no effect on overall apparent digestibility of the diet. The quantity of microbial N was reduced (nonsignificantly) and the efficiency of rumen microbial protein synthesis decreased (P> 0·05) compared with the other treatments when sheep were fed diets in which the ratio of MSBP: barley was 1:1. The particle size of MSBP had no effect on these factors.

As barley replaced MSBP in the diet, the mean pH of rumen fluid, calculated over 24 h, tended to decrease and there was a significant increase (P> 0·05) in the length of time that the rumen fluid was below pH 6. There were no significant differences between treatments in the concentration of ammonia-N in the rumen fluid. The dilution rate of rumen fluid (measured using14C-Cr EDTA and Co EDTA as markers) decreased (P> 0·05) when MSBP replaced barley in the diet, and ground MSBP gave rise to lower (P> 0·05) dilution rates than unground MSBP. There were no significant differences between treatments in the ruminal concentration of total volatile fatty acids (VFAs) or the proportions of individual VFAs.
Comparative studies on different methods of Azolla utilization in rice culture
Authors: Singh A. L. , Singh P. K.
Published: March 2009

Inoculation of 3·0 t of fresh Azolla pinnata (Bangkok) per hectare 15 days before transplanting, 10 and 30 days after transplanting produced Azolla mats on the water surface 10, 12 and 15 days after inoculation, respectively. The Azolla growth and N2-fixation before transplanting were more than that after transplanting. Growing Azolla once before transplanting and twice after transplanting produced a total of 51·0–52·8 t fresh Azolla/ha, which fixed 92·8–96·0 kg nitrogen, whereas growing it once before transplanting plus once after transplanting and twice after transplanting produced 35·0–40·0 and 29·0–37·5 t fresh Azolla/h, and fixed 660·–72·4 and 52·5–66·1 kg N, respectively.

Application of Azolla increased the plant height, tillering, grain and straw yields of rice and also the fertility of the soil at harvest. Growing and incorporating Azolla once before transplanting and twice after transplanting of rice increased the grain and straw yields significantly more than applying 60 kg N/ha as urea and showed greater effect on soil fertility.

Growing Azolla before or after transplanting the rice in combination with 30 kg N/ha as urea and Azolla once before transplanting and once after transplanting without incorporation gave responses similar to that obtained by a divided application of 60 kg N/ha as urea. Growing and incorporating Azolla twice after transplanting showed slightly less response than growing it once before and once after transplanting and giving 60 kg N/ha as urea but slightly more than giving 45 kg N/ha as urea. The Azolla pinnata collected from Bangkok and Vietnam when used once before transplanting at equal biomass (15·0 t/ha fresh Azolla) together with a top dressing of 30 kg N/ha as urea showed a similar response in the rice crop.
The interaction of seed rate and pesticide on the tiller density, herbage yield and frit fly population of newly sown grass
Authors: Ellis S. A. , Clements R. O. , Bale J. S.
Published: March 2009

The relationship between seed rate and use of pesticide (chlorpyrifos and aldicarb) on tiller density and herbage yield of a conventionally established autumn re-seed (i.e. grass sown after a previous grass crop) of Italian ryegrass (cv. RvP) was investigated in small plot trials at three sites in Yorkshire, Berkshire and Devon in August 1984. Plots were also sampled for pests and earthworms. Pesticide enhanced yield at all sites at the first harvest in October 1984, particularly at the low seed rates, but this effect did not persist until the spring harvest in 1985. Tiller density and herbage dry-matter yield increased logarithmically with increasing seed rate. Frit fly was the major pest and the proportion of infested tillers increased linearly with seed rate. Low seed rate in combination with appropriate insecticide was more cost effective than untreated higher seed rates in the establishment of autumn re-seeded Italian ryegrass.
The effect of concentrate supplementation on high-yielding dairy cows under two systems of grazing
Authors: Arriaga-Jordan C. M. , Holmes W.
Published: March 2009

An experiment with 36 high-yielding spring-calving cows studied the effect of 1 or 6 kg/day of concentrates offered to cows on either continuously stocked grazing or rotational strip grazing. A 4 × 4 latin-square design with periods of 3 weeks duration was adopted.

Mean yield was 29 kg/day of fat corrected milk (FCM). The continuously stocked cows had higher milk yields, consumed more herbage organic matter, grazed longer, with bites of smaller size and responded less in total intake to the higher level of concentrates than the strip-grazed cows. The higher concentrate treatment increased milk yields but reduced fat contents so that the average response was 0·26 kg FCM/kg concentrate. There was no difference in response to concentrate allowance between grazing treatments.

The differences recorded between grazing systems were attributable mainly to differences in green herbage allowance, which was greater with continuous grazing.