bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of the effects of liquid manure (urine and water) and nitrogen fertilizers applied to a grass-clover sward on soils of different pH value
Authors: Castle M. E. , Reid D.
Published: March 2009

In a 3-year plot experiment on a perennial ryegrass plus white clover sward the pH of the soil on the main plots was adjusted to, and maintained as nearly as possible at, target levels of 5·25, 6·00 and 6·75 by applying either sulphur or lime. Within the main plots the effects on herbage yield, clover content and crude-protein content of applying four fertilizers were compared at nitrogen rates of 225 and 450 kg/ha annually. The fertilizers were liquid manure (urine plus water), prilled urea, a urea solution and an ammonium-nitrate fertilizer. The applications of the urea and the ammonium-nitrate fertilizers were accompanied by dressings of a potassium fertilizer which supplied the same weights of potassium as in the liquid manure. On average the smallest yields of dry matter and crude protein were associated with the lowest soil pH with no significant interactions between pH and fertilizer treatment. The liquid manure gave slightly smaller total yields of mixed herbage dry matter than the other fertilizers, particularly at the low nitrogen rate. The herbage from the liquid manure treatment had a higher clover content and produced a greater total yield of clover dry matter. The effects of the liquid manure on the clover agree with those noted in previous experiments, but no evidence was found that these effects resulted from the liquid manure increasing the pH of the soil and improving the conditions for clover growth. Similarly, no proof was obtained that the clover effects were due to the nitrogen in the liquid manure being wholly in the ammonium form. However, the value of liquid manure as a fertilizer for grassland was demonstrated clearly.
Ecology of pastoralism in Ngorongoro Conservation Area, Tanzania
Authors: Homewood Katherine , Rodgers W. A. , Arhem K.
Published: March 2009

This management-oriented study of range, livestock and Maasai ecology in the wildlife conservation and pastoralist land use Ngorongoro Conservation Area (NCA) quantifies spatial and temporal variation in range resources for three main study sites over a 2-year period. Livestock response is analysed in terms of biomass densities, habitat and pasture utilization, activity, herd size, composition and dynamics. Milk production is investigated together with the main ecological factors influencing yields. A household survey of the Maasai food system suggests that pastoral products now provide an annual average of 40% dietary energy intake, the remainder being supplied by grain. These findings form the basis of our analysis of the growing friction between the Conservation Authority and the pastoralists. Pastoralist livestock closely resemble wild ungulate utilization of NCA range resources. A combination of disease interactions and administrative restrictions allow wildlife to establish preferential access to critical grazing resources. Our results in the context of other work suggest that contrary to popular opinion pastoralist land use is an ecologically appropriate and efficient form of livestock management. There is no adverse impact on the conservation values of NCA. Despite average fertility and mortality levels pastoralist herds show progressive decline due to offtake for grain purchase. Imposed policies restrict grazing, ban cultivation and maintain poor conditions for livestock trade and grain supply. Possible interventions and their potential impacts are considered and management compromises which could benefit both pastoralists and wildlife are proposed.
The effect of drinking frequency on some aspects of the productivity of zebu cattle
Authors: Nicholson M. J.
Published: March 2009

A 28-month trial was carried out under extensive grazing conditions to examine the effects of giving water to Boran cattle once daily, once every 2 days, and once every 3 days, with cattle having ad libitum access to water serving as the control. In the dry season, the weight and condition of lactating cows given water every 3 days declined more rapidly than that of cows given water daily. Calving rates and birth weights were unaffected by treatments although when compared with cows given water ad libitum, birth weights were depressed by 2·5 kg in all treatments. Thirty steers showed no treatment differences in 28-month weights despite a depression in dry-matter intake in the dry season by animals given water every 3rd day. In contrast, 210-day weaning weights were significantly depressed by 9 kg when cattle drank water every 2 days and 14 kg when they drank every 3 days compared with calves given water daily. Total water consumed was depressed in all classes of stock by 5–10% under the 2-day regime and by 25–34% under the 3-day regime when compared with cattle given water daily. The results show that giving water every 3 days can be carried out indefinitely with all classes of stock with only minor effects on cattle productivity under the climatic conditions in which the trial was held. The management implications of giving water every 2 or 3 days to cattle under extensive, pastoralist and ranching conditions are discussed.
The influence of sodium supplementation on the voluntary intake and digestibility of low-sodiumSetaria sphacelatacv. Nandi by cattle
Authors: Little D. A.
Published: March 2009

This study examines the effect of sodium (Na) supplementation on the intake and digestibility of Na-deficient feed by cattle, and the potential applicability of faecal analysis to the diagnosis of Na deficiency in the field. Mature cattle fitted with oesophageal fistulae were fed chaffedSetaria sphacelatacv. Nandi hayad libitumin metabolism cages, with and without a Na supplement (10 g Na daily as NaHCO3). In the first of two experiments the hay contained 0·44 g Na/kg D.M., and in the second, 1·05 g/kg. Prior to an unsupplemented treatment the animals were rapidly depleted of Na by removal of saliva via the fistula; Na status was assessed on the basis of the ratio Na/K in saliva.

When the feed contained 0·44 g Na/kg, Na supplementation increased voluntary intake by 28% (P < 0·01) and digestibility by 12% (P <0·05). No such responses were obtained in Expt 2, in which the feed contained 1·05 g Na/kg.

Examination of available data suggests that a diagnosis of Na deficiency in cattle is indicated if the faecal Na concentration is below 1 g/kg D.M., and the ratio Na/K in faeces is less than 0·1. Further data are required to confirm these criteria, which should prove useful in the field when samples of saliva, the diagnostic criterion of choice, are not available.
Volatile fatty acids in the ruemen of sheep fed grass, unwilted and wilted silage, and barn-dried hay
Authors: Anderson B. K. , Jackson N.
Published: March 2009

Experiments were carried out to assess the effect of the following diets: unwilted and wilted silage, barn-dried hay and wilted silage and ensiled mixtures of grass and barley on the ruminal VFA patterns in sheep.

There was a tendency for the unwilted silage to result in a slightly higher level of rumen acetate and a lower level of propionate than grass, wilted silage or barn-dried hay. In two of the experiments (Exps. 2 and 4) significant direct relationships were found between rumen acetate and the crude-fibre content of the diets and significant inverse relationships were found between the rumen propionate and the crude-fibre content of the diets.

Significant relationships were also found between the rumen acids and the metabolizable energy content of the diets and in Exp. 2 there was a significant relationship between the rumen acetate and the water-soluble carbohydrate content of the diet.

The addition of barley meal to grass produced different ruminal VFA patterns in sheep fed the ensiled material and the resulting silage.
The productivity and nutritive value of tropical grass/legume pastures rotationally grazed by N'Dama cattle at Ibadan, Nigeria
Authors: Okorie I. I. , Hill D. H. , McIlroy R. J.
Published: March 2009

This study deals with the first 2 years of grazing trials on improved pastures of tropical grasses and legumes at Ibadan in Nigeria. The mixtures consisted of (i) Cynodon plectostachyus and Centrosema pubescens (legume), (ii) (i)+Chloris gayana and Digitaria decumbens, (iii) (ii) +Stylosanthes gracilis (legume). The mixtures were sown and planted in four blocks, the treatments being repeated four times, and were grazed rotationally by N'Dama cattle. During the first year's trial a uniform stocking rate of 1·7 steers/acre was adopted and a recovery period of 11 weeks was allowed. In the second year's trial the stocking rate was increased to 2·7 beasts/acre by the addition of nine yearling heifers and the recovery period was reduced to 5 weeks. Herbage yield and intake were measured by the clipping technique.
Effect of presence or absence of rumen ciliate protozoa on some blood components, nitrogen retention, and digestibility of food constituents in lambs
Authors: Akkada A. R. Abou , El-Shazly K.
Published: March 2009

1. The levels of blood reducing sugars, haemoglobin, protein N, NPN, ammonia N, and urea N in addition to the nitrogen retention and digestibility coefficients of food constituents, were studied in lambs with and without ciliate protozoa.

2. The inoculated lambs have higher blood haemoglobin, protein N, and lower reducing sugars, ammonia N, and urea N values than those of the uninoculated lambs.
The relationship between crop yield (or mean plant weight) of lettuce and plant density, length of growing period, and initial plant weight
Authors: Scaife M. A. , Jones D.
Published: March 2009

Lettuce obeys the Shinozaki–Kira relationship in which the reciprocal of plant weight is linearly related to plant density. The intercept (a) represents the reciprocal of the weight of an isolated plant and the slope (b) represents the reciprocal of yield/unit area at high densities (the ‘ceiling yield’). This work examines the time course of (a) and (b) in an ‘ideal environment’ in which water and nutrients are non-limiting, and the light/temperature regime is constant.

Two pot experiments are described: the first showed that the growth of isolated lettuces follows a logistic expression, which can therefore be substituted for a–1 in the Shinozaki-Kira equation. It was then hypothesized that b–1, the ‘ceiling yield’ would be constant over time. This was confirmed by the second experiment, giving the equation

w–1t = w–10 e1–kt × w–1max × bd,

in which wt is mean plant weight at time t, w0 and wmax are the initial and final weights of isolated plants, k is the early relative growth rate of such plants, b–1 is the constant ceiling yield, and d is the plant density.

Two examples of the use of the equation are given: one shows how it predicts the interaction between seed size and plant density within a species (subterranean clover): the other illustrates how it can be used to explain why lettuce growth appears to be log-linear against time whereas cereal growth is more nearly just linear.
The significance of crop residues to the maintenance of fertility under continuous cultivation at Samaru, Nigeria
Authors: Jones M. J.
Published: March 2009

The residues from a continuous millet–maize rotation, grown at two levels of phosphate and two levels of nitrogen fertilization, were either burned and the ash incorporated; chopped and incorporated unburned; or completely removed. After 3 years, differences in soil organic matter were small and largely non-significant, but the ash treatment had minimized the general fall in soil pH, and the ash and the unburned residue treatments had both conserved topsoil exchangeable K and Mg, which, where the residues had been removed, had declined by 44 and 12%, respectively. Fertilizer effects were also significant; single superphosphate had increased exchangeable Ca and lessened the fall in soil pH; calcium ammonium nitrate had depleted exchangeable Mg generally and had lowered pH and exchangeable Ca particularly where unburned residues had been returned.

A balance sheet of soil cations (0–30 cm), drawn up from soil and crop analyses and known fertilizer inputs shows, first, that whereas the calcium added in single superphosphate increased the exchangeable reserves of this nutrient, that added as calcium ammonium nitrate did not and must be presumed lost by leaching; secondly, the decline in exchangeable K where residues were removed was much less than the total crop removal, indicating a probable substantial release from non-exchangeable form.

In the fourth season, treatment-induced soil differences, in particular the ratios between exchangeable cations, significantly affected the chemical composition of the maize test crop but not its final yield.
Influence of doe age on incidence of multiple births and perinatal reproductive wastage in West African Dwarf goats
Authors: Osuagwuh A. I. A.
Published: March 2009

Breeding records over 12 years (1977–89), involving 455 West African Dwarf does derived from an original population of 133 breeding does, were used to examine the influence of dam age on the incidence of multiple births and perinatal reproductive wastage due to abortion and neonatal deaths. The animals were semi-intensively managed in two goat research units at the University of Ibadan Teaching and Research Farm.

The regression results showed that the variable component, multiple births, increased (P < 0·01) linearly with advancing age of the doe, while the incidence of abortionsand neonatal deaths increased (P < 0·01) exponentially with doe age. Graphs plotted from the regression results indicated a sharp increase in the incidence of abortion and neonatal deaths between the ages of 6 and 7 years. This suggests that the practice of keeping these animals for longer than necessary, especially in rural areas of the country where they are mostly reared and kept for prestigious reasons, should be re-evaluated. Therefore it is recommended that to maintain an economically viable production system, does should be culled between the ages of 6 and 7 years and the provision of replacements planned accordingly.
Prediction of body composition of live cattle using two ultrasonic machines of differing complexity: a report of four separate trials
Authors: Kempster A. J. , Cuthbertson A. , Jones D. W. , Owen M. G.
Published: March 2009

Results are reported from four separate trials carried out to determine the precision of the Sonatest (simple A-mode ultrasonic machine) and the Scanogram (modified linear scanner) for predicting the body composition of live cattle. Cattle in the four trials differed in breed, sex and origin, and the data provided an opportunity to determine the consistency of results in different circumstances. A total of 210 cattle were involved.

Fat thickness measurements (Sonatest and Scanogram) and fat and M. longissimus areas (Scanogram only) were taken at the 10th and 13th ribs and at the position of the 3rd lumbar vertebra. Their precision as predictors of carcass tissues percentages was examined when they were used in addition to live weight at evaluation.

There was little consistency between trials in the positions and measurements which gave the most precise prediction. The lowest within-breed residual standard deviations of carcass lean percentage obtained with fat thickness measurements taken by Sonatest were in the range 2·5–2·7 and there was little advantage in using additional measurements in multiple regression.

Fat areas taken by Scanogram were more precise predictors (within-breed residual standard deviations were close to 2·0). Precision was improved marginally to about 1·8 by using combinations of fat areas but M. longissimus areas were of little additional value.
The evaluation under grazing of legumes associated with Andropogon gayanus in a tropical savannah environment on the central plateau of Brazil
Authors: Thomas D. , de Andrade R. P.
Published: March 2009

The persistence and productivity under grazing of seven accessions of Stylosanthes macrocephala, Zornia latifolia and Zornia brasiliensis in combination with Andropogon gayanus (cv. Planaltina) were investigated in small plots at two stocking rates on a low fertility, acid oxisol in the tropical savannah of the centre-west region of Brazil.

Two new accessions of S. macrocephala CIAT 2039 (CPAC 1033) and CIAT 2053 (CPAC 1034) were more productive and persistent than the control cultivar Pioneiro. After 4 years there were no differences in dry-matter yield between the two accessions. No anthracnose (Colletotrichum gloeosporioides) problems were noted in these accessions. Animals refused to graze Z. brasiliensis accessions at any time during the trial. Stocking rate effects became pronounced over time and legume contents were highest in the treatment grazed at 3·0 animals/ha. The advantages of the small-plot grazing method used in the experiment are discussed.
Forms of nitrogen in waterlogged soils and their contribution to yield and nitrogen uptake by rice
Authors: Prasad S. S. , Sarkar A. K. , Sinha N. P.
Published: March 2009

The major portion of nitrogen nutrition of flooded rice is met through the mineralization of organic forms of N present in soil. This is true even when fertilizer nitrogen is added. The mineralization of organic matter under waterlogged conditions is governed mainly by the prevailing chemical and biological conditions. In recent years, attempts have been made to characterize the products of hydrolysis of soil organic nitrogen (Asami & Hara, 1970; Shinde, 1978; Subba Rao & Ghosh, 1981). Information on different fractions of nitrogen in waterlogged rice soils is scanty.
Progress achieved by breeding open-pollinated cultivars as compared with landraces of sorghum
Authors: Blum A. , Golan G. , Mayer J.
Published: March 2009

To assess the progress made in modern breeding of open-pollinated sorghum cultivars, 24 contemporary and improved sorghum cultivars from ICRISAT (International Crops Research Institute for the Semi-Arid Tropics, India) were compared with 40 sorghum landraces collected in Ethiopia. The experiment was performed at Bet Dagan, Israel, in 1988 under near-potential (dripirrigated) and dryland (stored soil moisture) growing conditions. Data on phenology, biomass, harvest index, grain yield and its components were collected. ‘Drought susceptibility index’ (S) was calculated for each genotype as the reduction in yield from irrigated to dryland conditions relative to the mean reduction for all genotypes.

On average, cultivars produced about three- to fourfold more grain than landraces. Cultivars had the same mean growth duration and biomass but were 40% (irrigated) to 27% (dryland) shorter in mean plant height than landraces. This yield advantage was fully accounted for by a proportionately greater mean kernel number per panicle and harvest index, irrespective of the water regime. ‘Drought susceptibility index’ was near average for all cultivars and much more variable among landraces. Dryland yield became progressively dependent on the yield potential as the yield potential was genetically improved in the cultivars.

It was concluded that, irrespective of the water regime, the large yield improvement in modern open-pollinated cultivars of sorghum, as compared with landraces, has been achieved only through greater dry matter partitioning to the panicle accompanied by a reduction in plant height. The genetic improvement of yield in open-pollinated cultivars and hybrids of sorghum is discussed.
Effect of green manuring with dhaincha (Sesbania aculeata) on growth and yield of direct-sown and transplanted rice under intermediate deepwater conditions (0–50 cm)
Authors: Sharma A. R. , Das K. C.
Published: March 2009

In intermediate deepwater conditions (0–50 cm) at Cuttack, India during 1990 and 1991, rice and dhaincha (Sesbania aculeata) were either mixed-sown in different arrangements (parallel lines and mixed broadcasting) in dry soil by the end of May or rice seedlings were transplanted in plots grown with pure dhaincha after the accumulation of water in the field by mid-July. Incorporation of dhaincha in situ after 48 and 54 days of growth added 60·8–65·2 and 72·9–76·9 kg N/ha in the mixed stands compared with 81·3 and 85·1 kg N/ha in the pure stand in 1990 and 1991 respectively. Although the growth of rice when sown simultaneously with dhaincha was affected initially due to the more vigorous growth and shading by the latter, tillering of rice increased after the incorporation of green manure following an increase in inter-row spacings. The performance of the direct-sown and transplanted rice was similar in 1990, when the water level rose relatively slowly, but in 1991 the transplanted crop yielded significantly less due to the sudden accumulation of water to higher depths (48 cm), resulting in greater mortality of seedlings at planting. However, the grain yield of both directsown and transplanted crops increased with dhaincha green manuring compared with the control (no application of dhaincha) and was equal to the application of 40 kg N/ha applied as urea fertilizer. The highest yield was obtained when rice and dhaincha were grown at a 2:1 ratio in 20 cm wide rows and the clonal tillers uprooted from the adjoining rice rows were planted in lines vacated by dhaincha. The yield was, however, equal to that from treatments where rice and dhaincha were grown in alternate rows at 15 cm spacing or mixed broadcasting. Increase in yield under green manuring was due to greater panicle weight, which was probably due to a continued supply of N following decomposition of organic matter added through dhaincha. Therefore, green manuring of direct-sown rice with dhaincha was beneficial for higher crop productivity under excess water conditions.
Evaluation of fatty acids in oil as reaping indices for Caribbean-grown groundnut (Arachis hypogaea)
Authors: Hinds M. J. , Singh B.
Published: March 2009

Studies were conducted to evaluate amounts of fatty acids in the oil as possible indicators of crop maturity in the groundnut, cultivar NC2, grown in St Vincent, Eastern Caribbean. Percentage fatty acids in oil of the composite samples of seeds collected between 99 and 141 days after planting for a period of 3 years (1985–87) was determined by gas-liquid chromatography. Results indicated variation in the amounts of individual fatty acids with crop maturity. There were definite trends, however, with respect to oleic and linoleic acids. As seeds matured, percentage oleic acid increased and percentage linoleic acid decreased, and consequently, the oleic:linoleic acid ratio in oil of the composite seeds increased significantly. The percentage oleic acid peaked significantly at a value of 55.8 ± 0.59 at optimum harvest dates. The results clearly suggested therefore that percentage oleic acid in oil could be used as a reliable reaping index for groundnut.
The effects of limestone, N, K and Mg fertilizers on Mg absorption by oats and barley
Authors: Alston A. M.
Published: March 2009

Oats grown in a pot experiment on two sandy loams were sampled at four stages of growth. Neither KC1 nor MgSO4.7H2O had any effect on yield but % Mg and total Mg uptake were consistently decreased by applying K and increased by applying Mg.Ca(NO3)2 increased % Mg more than did (NH4)2SO4, but yield and total Mg uptake were higher where (NH4)2SO4 was applied. The effects of fertilizers were similar on both soils.

The effects of applying (NH4)2SO4 and NaNO3 to the soil on % Mg in barley were compared in a field experiment on an acid loam to which several rates of limestone had been applied. Treatments had no effect on the % Mg in grain or straw at maturity. At four earlier stages of growth (NH4)2SO4 increased % Mg in the plants more than did NaNO3. Limestone slightly increased % Mg. Nitrification of NH4 in the soil was rapid.
The effects of grazing intensity on herbage consumption and animal production. I. Short-term effects in strip-grazed dairy cows
Authors: Greenhalgh J. F. D. , Reid G. W. , Aitken J. N. , Florence E.
Published: March 2009

1. The object of the experiment was to determine the effects of varying the quantities of herbage available to cows on their diet and milk production.

2. Four groups of five Ayrshire cows were strip grazed for three periods of 3-4 weeks on areas calculated from sample cuts to supply (A) 25, (B) 35, (C) 45 or (D) 55 lb. dry matter per cow per day. These periods were interspersed between four standard periods of 2-3 weeks, in which all the cows were strip grazed on 50-60 lb. dry matter per head per day.

3. Measurements of milk production and of herbage consumption, by the chromic oxide-faecal nitrogen technique, were made for the last 12 or 16 days of experimental and last 8 days of standard periods. The observations made in the standard periods were used as covariates in the analyses of those made in the experimental periods.
Soyabeans in Tanzania. I. The exploitation of hybridization for the improvement of soyabeans
Authors: Auckland A. K.
Published: March 2009

1. The main objectives of the breeding programme were to develop two types of soyabeans:

(a) High yielding, non-shattering, resistant to lodging, determinate in habit, with pods formed 5-6 in. from ground level, for mechanical harvesting.

(b) High yielding, non-shattering but with no qualifications as to habit, for hand harvesting by African farmers.

An account of the breeding programme carried out on twelve crosses is given. The breeding method used was a combination of the bulk and pedigree methods.
Effects of leaf shear breaking load on the feeding value of perennial ryegrass (Lolium pevenne) for sheep. II. Effects on feed intake, particle breakdown, rumen digesta outflow and animal performance
Authors: Inoué T. , Brookes I. M. , John A. , Kolver E. S. , Barry T. N.
Published: March 2009

A series of experiments was conducted at Palmerston North, New Zealand, during 1988–91 to compare the efficiency of chewing during eating and rumination, rumen fractional outflow rate (FOR), voluntary organic matter intake, liveweight gain and wool production in sheep fed either low (LS) or high (HS) leaf shear breaking load perennial ryegrass (PRG). The LS ryegrass had a 13% lower mean leaf shear breaking load and ingestion rates tended to be higher than for HS PRG, but no consistent significant treatment differences were observed in rate of particle breakdown, rumen FOR, voluntary intake or animal performance. It was concluded that selection for reduced leaf shear breaking loadper sedid not improve feeding value. The total shear load required to reduce a unit dry weight of PRG leaf to < 1 mm particles (index of masticatory load; IML) differed by only 3% between LS and HS PRG in this study, due to higher leaf length:dry weight ratios for LS PRG. It is therefore suggested that IML, which takes into account both leaf shear breaking load and associated changes in leaf morphology may be a better criterion for selection than leaf shear breaking load alone in breeding programmes to improve the feeding value of perennial ryegrass.
Effect of non-uniform distribution of particle-associated markers on the measurement of duodenal digesta flow by the double-marker technique
Authors: Faichney G. J.
Published: March 2009

Simulating changes in the distribution of the particle marker between particle-phase and fluid-phase dry matter by ±40% resulted in calculated flows of dry matter to the duodenum that differed from the ideal of uniform distribution by 1 to 2%; true digesta flow values were virtually unaffected. These errors are small and can probably be ignored.
Hatchability of layers' eggs stored and incubated in different positions at 5500 altitude
Authors: Arif M. , Joshi K. L. , Shah P. , Kumar A. , Joshi M. C.
Published: March 2009

The hatchability of layers' eggs stored and incubated in different positions was examined at the Defence Agricultural Research Laboratory, Almora, India (5500' above sea level) in 1990. Hatchability was found to be highest in the eggs stored and incubated with their narrow end up and lowest in eggs stored and incubated horizontally.
Further studies of water use by irrigated and unirrigated Arabica coffee in Kenya
Authors: Blore T. W. D.
Published: March 2009

1. Frequent soil sampling to 10 ft. depth was carried out on irrigated and unirrigated plots and, with the assistance of rainfall data, fairly accurate measurements of water uso were obtained unless the soil was at, or near to, field capacity. Evapotranspiration could then not bo distinguished from drainage beyond the root range.

2. A previous method of relating the water uso of unirrigated coffee to the readings of a sunken evaporation pan was shown to be reliable. The relationships between the water use of unirrigated coffee and meteorological factors (Penman's Eo, sunken pan evaporation or solar radiation) were shown to be dependent on soil-moisturo deficit, and on this basis a more precise method of predicting water use from sunken pan evaporation is proposed. When this method was applied to meteorological data from earlier years, good agreement was obtained between measured and estimated quantities of water in a 10 ft. profile.
Grazed pasture parameters. II. Pasture dry-matter use in a stocking rate and grazing management experiment with dairy cows
Authors: Campbell A. G.
Published: March 2009

1. Dry-matter intake, pasture utilization and grazing pressure were studied over 3 years on a small-scale replica of a dairy cow grazing management x stocking rate trial.

2. The four treatments were:

(i) Controlled rotational grazing, light stocking rate (0.95 cow/acre).

(ii) Controlled rotational grazing, heavy stocking rate (1.19 cow/acre).

(iii) Uncontrolled, set stocked grazing, light stocking rate (0.95 cow/acre).

(iv) Uncontrolled, set stocked grazing, heavy stocking rate (1.19 cows/acre).

3. Mean D.M. intakes were: (i) 29, (ii) 21, (iii) 28 and (iv) 21 lb./cow per day. D.M. intake was reduced on average by 7 ± 2.1 lb./cow per day at the higher level of stocking.
White clover investigations. III. Effect of irrigation on seed production
Authors: Zaleski A.
Published: March 2009

During 1962-65 investigation was carried out at Cambridge on the effect of irrigation combined with cutting treatments on vegetative growth, inflorescence formation and yield of seed of S184 white clover sown on gravelly loam of poor waterholding capacity.

Under the conditions described, irrigation was beneficial for seed production when it was applied between the period of shutting-up and the start of clover flowering. An excess of water either from natural precipitation or irrigation during the flowering period had, however, a harmful effect on seed production.

Apart from the first year, the effect of differential cuttings up to the early bud stage was insignificant on the seed yield. The interaction cutting x irrigation was not significant.

The author is grateful to Mr F. R. Home, Director of the National Institute of Agricultural Botany, for opportunities and facilities provided for this experiment.
Competitive ability of maize and common bean (Phaseolus vulgaris) cultivars intercropped in different environments
Authors: Rezende G. D. S. P. , Ramalho M. A. P.
Published: March 2009

Sixteen common bean (Phaseolus vulgaris L.) cultivars with different life cycles and growth habits were intercropped with four maize cultivars, to evaluate the competitive ability of each yield component, following a methodology similar to that used for diallel crosses. The experiments were done in 1991 at two sites in Brazil. The intercropping combinations were evaluated using an 8 × 8 quadratic lattice design with three replications. Two other experiments were done on monocultures, using a randomized complete block design with three replications. The variable considered was ‘maize equivalent yield’, obtained by adjusting for the price difference between the species. The method used showed that the differences in performance of the many intercropped combinations can be explained by ‘general complementing ability’ (gĉa) of each cultivar, since there was no significant effect of ‘specific complementing ability’ (sĉa). The best maize cultivars to be intercropped with common bean (indicated by high gĉa values) were BR–201 and C–525, which produced high grain yields when intercropped without detrimental effects on legume yields. FT–84–292, Carioca 300V and ESAL506 were the common bean cultivars with the highest yields when intercropped, which was also reflected in their good performance in monoculture. Significant cultivar × location interactions occurred only in monocultures, supporting the belief that intercropping is a more stable cropping system.
Inhibition of iron precipitation by humic substances in field drains
Authors: Vaughan D. , Ord B. G.
Published: March 2009

Ferrous iron is oxidized and precipitated as iron ochre in field drains. In drainage waters taken from an ochre-producing site near Aberdeen, Scotland in 1987, iron deposition was inhibited by the addition of humic and fulvic acids, which form complexes with Fe(II). The inhibition was dependent on the concentrations of soluble humic materials and the proportion of Fe complexed. Iron deposition in the presence of humic substances is discussed in relation to the amount of the cation which is complexed and its oxidation state.
The effect of energy and protein intake on the excretion of purine derivatives
Authors: Susmel P. , Stefanon B. , Plazzotta E. , Spanghero M. , Mills C. R.
Published: March 2009

In three separate experiments, groups of four, three and six mature, rumen-cannulated Simmental cows were fed diets designed to supply different quantities of energy (E) and nitrogen (N) to the rumen microbes. Experiment 1 (straw plus concentrate plus urea) had balanced E and N supplies; Expt 2 (hay and four levels of soyabean meal) had different sub-optimum N levels at the same intake as Expt 1; and Expt 3 (hay plus maize plus two levels of urea) reproduced the N shortage in Expt 2 at a higher level of intake.

The amount of total N excreted in the urine (TUN) was 574 mg/kg LW0·75in Expt 1 and 420 mg/kg LW0·75of this N was excreted as total purine nitrogen (TPN). In Expt 2, TUN increased significantly (P< 0·05) with increasing soyabean levels; TPN also increased, reaching the level observed in Expt 1 when soyabean meal supplementation was highest. In Expt 3, TUN and TPN increased with increasing dietary urea concentrations; TUN and TPN were always higher than in Expts 1 and 2.

Estimated microbial nitrogen supply (EMNS, based on TPN) was always considerably lower than estimates based on fermentable non-protein OM and crude protein (EMNR-EN) or an assumed yield of microbial N per kg OM apparently digested in the rumen (EMNR-OM). Regression analyses of EMNS on EMNR-EN, EMNR-OM or OM intake had moderater2values (0·76, 0·65 and 0·62 respectively) but the constant terms were significantly different from zero. The regressions of EMNR-EN and EMNR-OM on TPN gave angular coefficients of 15·81 and 11·47 respectively.

The correlation between rumen liquid parameters (total count, bacterial DM, ATP and nitrogen) and OM intake, EMNS or EMNR increased with sampling time (from 09.00 to 16.00 h). The EMNR-OM produced correlation coefficients similar to those obtained with OM intake; these correlations were numerically higher than those obtained with EMNS or EMNR-EN.
Influence of dietary supplementation and partial suckling on body weight and on lactation and reproductive performance of primiparous Boran (Bos indicus) cows in Ethiopia
Authors: Tegegne A. , Geleto A. , Osuji P.O. , Kassa T. , Franceschini R.
Published: March 2009

This study was conducted in the central highlands of Ethiopia during 1990–92 to examine the effects of diet and partial suckling on lactation and reproductive performance of Boran (Bos indicus) cows. Primiparous Boran cows were allocated to dietary supplementation or no supplementation with either milking or partial suckling based on body weight at calving. All cows received grass hay ad libitum and the supplemented groups were provided with additional concentrate feed which supplied 222 g/kg DM crude protein and 10 MJ/kg DM energy. Calves were weaned at 8 weeks of age. Mean (±S.E.) dam calving and calf birth weights were 314±11·4 and 25±0·6 kg. Body weights at first postpartum oestrus and at conception were not affected by suckling. Supplemented cows however, were heavier at first oestrus (P = 0·06) and at conception (P < 0·01) than non-supplemented cows. Lactation length was longer (P < 0·01) and mean daily milk yield higher (P < 0·001) in suckled than in milked cows. Diet, however, did not influence either lactation length or daily milk yield. In suckled cows, mean daily milk yield declined sharply after weaning (week 9) and was lower by 38 and 43% of week 8 production in the supplemented and non-supplemented groups, respectively. The overall mean lactation yield was 212·4±64·6 litres; with a significant (P < 0·05) diet × suckling interaction effect. Concentrations of milk fat, total protein and total solids were not affected by either diet or suckling treatment. The postpartum anoestrus interval was longer (P < 0·01) in non-supplemented than in supplemented cows, but did not differ between suckled and milked cows. The percentage of cows cycling by 150 days postpartum was higher (P < 0·05) in supplemented than in nonsupplemented and in milked than in suckled (P > 0·05) cows. By this interval, a higher (P < 0·05) percentage of supplemented-milked (90%) cows cycled than in the other three treatment groups (48·5%). Pregnancy from the first insemination ranged from 45·5 to 63·6% in the four treatment groups. It was concluded that although partial suckling extended the postpartum anoestrus interval, lactation length and milk yield were improved. The negative effects of partial suckling on postpartum reproduction could be overcome with the appropriate dietary supplementation. The economic tradeoff between dietary supplementation, milk yield and reproduction has to be determined in partially suckled cows.
The response to selection of different procedures for the analysis of early generation variety trials
Authors: Cullis B. R. , Gleeson A. C. , Thomson F. M.
Published: March 2009

A simulation study was conducted to determine the relative response to selection of a one-dimensional spatial analysis of field experiments (SAFE) specifically adapted for early generation trials. The primary purpose of the analysis in these trials is to obtain accurate estimates of genotypic effects of the unreplicated test lines by adjusting for local variation, using either the yields of all neighbouring plots or the yields of neighbouring plots of (replicated) check varieties. The response to selection of the SAFE analysis, relative to the use of unadjusted yields of test line plots, was consistently greater than the relative response to selection of check-plot-only analyses. The relative response to selection of SAFE increased as the percentage of trend variance increased.
An evaluation of small seed for ware-potato production
Authors: Allen E. J. , O'Brien P. J. , Firman D.
Published: March 2009

Sixteen experiments over six seasons (1981–87) compared the growth and yield of up to 16 seed-tuber weights, ranging from 1–5 to 110–120 g, in one second-early and four maincrop varieties. Four of the experiments (1986–87) examined effects in seed tubers from seed crops planted in July; the remaining experiments used seed from crops planted at the normal time, April–May. Effects were similar for seed from the different planting dates. Plants from seed < 5 g (and occasionally up to 15 g) emerged slightly later and produced a smaller crop canopy that those from larger seed. The later emergence from the smallest seed was a consequence of a slower rate of sprout elongation. There were no effects of seed weight above 15 g on stem emergence or growth of the canopy. In 1982, a severe frost completely defoliated all plants in four experiments but within 2 weeks complete plant emergence was re-achieved from all seed weights except the smallest (1–5 g). The results suggest few differences between seed weights > 5 or 10 g in emergence from similar depths of planting or in recovery from frost damage.

Tuber yields were little affected by seed weight > 5 or 10 g, even at constant within-row spacings. Consequently, seed rates from 0·59 to 5·4 t/ha produced similar yields and the results suggest considerable economic benefits and potential for using seed tubers of much smaller weight than may be sold under current legislation. The use of small seed tubers from late-planted crops may result in further economies in production costs and reduction in disease in seed tubers.
The effects of seed size and spacing on growth and yield of lesser yam (Dioscorea esculenta)
Authors: Enyi B. A. C.
Published: March 2009

The effects of seed size and spacing on growth, development and yield of lesser yam and the relationship between growth, development and yield in this yam variety were investigated in the 1967 and 1968 growing seasons. Larger seeds outyielded smaller ones both in the total and ware tuber yields. The seed size effect was associated with a difference in tuber number, leaf area duration and bulking rate. Mean tuber weight at harvest, decreased with the decrease in seed size. Total and ware tuber yields increased with the decrease in spacing distance. The spacing effect was associated with differences in leaf area duration and bulking rate per unit area. Final total dry matter produced per plant increased with the increase in both seed size and spacing distance but the dry matter produced per unit area decreased with the increase in spacing distance. Leaf area index and leaf area duration increased with an increase in seed size and decreased with increase in spacing distance. There was a greater positive relationship between total tuber yield and leaf area duration between tuber initiation and the final sampling period than that between it and absolute leaf area duration.
The effects of crossing Merino with Ossimi and Barki sheep on some productive traits
Authors: Aboul-Naga A. , Eltawil E. E. , Galal E. Salah E. , Labban F. , Khishest S. S.
Published: March 2009

A total number of 5949 birth records collected over a period of 9 years from a crossbreeding experiment at Sakha Animal Research Station were used in this study. The following breeding groups were included: Fleisch Merino (M), native Ossimi (0) and Barki (B) breeds, MO, MB, ¾M ¼ O, ¾ M ¾ B and the inter se mating groups of the backcrosses (’¾ M ¼O’ and ‘¾ M ¼B’). Productive traits studied were birth, 4-month and yearling weight, lamb liveability at 4 months of age; and first fleece weight (at 10 months of age).

Generally, the cross-bred lambs were heavier in body weights and sheared more wool than the pure breds, with the differences being almost significant. In liveability, native breeds showed significantly higher estimates than the cross-breds where the Merino breed was the poorest in this respect.

Merino × Ossimi first cross was the best breed group showing a high heterosis estimate of 0·9, 5·2, 10·3, 7·6, 0·9 and 0·7 kg in birth, 4-month, yearling males and females body weights and first fleece weight, respectively. They were followed by ¾ M ¼ O with a corresponding heterosis value of 0·8, 3·9, 7·4, 4·2, 0·5 and 0·5 kg respectively. Merino x Barki and their backcrosses to Merino are ranked second to the Ossimi crosses. Heterosis in the Barki backcross was 0·8, 2·9, 4·8, 2·1, 0·4 and 0·4 kg compared with 0·5, 2·5, 3·1, 2·7, 0·5, 0·4 kg for MB, on different traits, respectively. The interbreeding of the backcrosses caused a diminishing in hybrid vigour. Heterosis estimates in ‘¾ M ¼ O’ were 0·3, 0·9, 4·6, 2·3, 0·3 and 0·3 kg, whereas it was 0·1, 0·3, –0·1, –0·3, 0·0 and 0·1 kg for ‘¾ M ¼B’, in different traits respectively. All cross-breds showed negligible or/and negative heterosis in lamb liveability up to 4 months.

The effects of breed group, year of birth, age of dam, sex and type of birth were found to be highly significant on all traits except the effect of type of birth on lamb liveability.
Influence of air humidity on the partition of heat exchanges of cattle
Authors: McLean J. A. , Calvert D. T.
Published: March 2009

The balance between heat production and heat loss and the partition of heat exchanges of cattle in relation to air humidity has been studied at two different air temperatures using a direct (gradient-layer) calorimeter.

Increasing humidity at 35 °C air temperature caused no significant change in heat production or in the level of total heat loss finally attained, but body temperature and respiratory activity were both increased.

Increasing humidity at 15 °C air temperature caused a small reduction in heat loss by evaporation but had no effect on sensible heat loss, body temperature or respiratory frequency.

Heat loss by evaporation amounted to 18% of the total heat loss at 15 °C and to 84% at 35 °C.

Heat loss by respiratory evaporation amounted to 54% of the total evaporative heat loss at 15 °C and to 38% at 35 °C.
Intravaginal stilboestrol-progestagen treatments in the induction of early breeding in sheep
Authors: Gordon I. , Maher P. G.
Published: March 2009

Ninety-eight sheep in three farm flocks were treated in July (period of late anoestrus) with intravaginal sponges impregnated with 30 mg ‘Cronolone’ (9α-fluoro-11βhydroxy 17α-acetoxy-progesterone; G. D. Searle) or ‘Cronolone’ plus 400 mg progesterone and incorporating doses of 0–800 μg diethyl stilboestrol. Treatment was for 12 days; a single dose of 500 i.u. PMS (Burroughs Wellcome) was injected at pessary withdrawal. Ten rams bred the ewes at the induced and subsequent heats.

Of the ninety-five ewes retaining pessaries, ninety-three (98%) were bred in the 3 days following treatment. Sixty-three sheep (68·5%) conceived at the controlled oestrus, producing an average of 1·54 lambs/conception. In the thirty-four ewes failing to conceive at that time, twenty-seven (80%) showed oestrus after one cycle interval; twenty of these (74%) conceived and produced 1·3 lambs/conception. Lambing outcome toservices at the controlled oestrus was lowest in sheep treated with 800 μg stilboestrol, but the reduction was not significant.
Effects of defoliation on populations of Festuca arundinacea Schreb. sown in spring and autumn
Authors: Thomas W. D. , Lazenby Alec
Published: March 2009

The effects of defoliation regime on seasonal and total yields of spring- and autumnsown material of three populations Festuca arundinacea(syn. 1 and syn. 2 from North Africa and the British cultivar S. 170) were examined at Cambridge from the period June 1963 to April 1965.

A micro-plot technique was used in which defoliation treatments were defined by vertical height above soil level. The vertical growth intervals between successive defoliations were, for the summer cutting regimes 7.5–25 cm and 2.5–12.5 cm, and for the winter regimes 7.5–20 cm, 2.5–20 cm, 7.5–12.5 cm, and 2.5–7.5 cm.

In summer 1963 mean yields of all populations were very similar, being equivalent to approximately 12000 kg/ha. Mean population yields for the following three 6-month periods were equivalent to (in kg/ha): syn. 11519, 14740, 3385; syn. 2 2194,17669, 5523; S. 170 1656, 19832,3696.

Variety x treatment interactions were found in every season. In particular, S. 170 winter production was reduced by severe defoliations in the preceding summer, and syn. 1 and syn. 2 summer production by severe defoliations in the preceding winter. It is suggested that such interactions may have been responsible for conflicting assessments of the relative potential production of these populations.

Syn. 1 appeared to offer no advantage over S. 170, and syn. 2 only to outyield S. 170 where spring sowing was followed by infrequent or lax defoliations in all seasons. Agronomic implications are discussed.