bluuebunny/crossref_metadata_2025 huggingface dataset:
The utilization of irrigated pastures by dairy cows II. The effect of stocking rate
Authors: Freer M.
Published: March 2009

1. An experiment was carried out over 2 years to study the effect of stocking rate on the efficiency of pasture utilization by dairy cows on irrigated perennial pasture.

2. Two matched groups of milking cows grazed throughout the experiment on two unequal areas of pasture at stocking rates of 1·0 and 1·7 cows/acre during the first season and 1·2 and 2·0 cows/acre during the second season (L and H groups, respectively). The same rotational grazing technique was used on both areas.

3. In each season the experimental period lasted 249 days. During the first 200 days and 215 days of this period in the first and second seasons, respectively, pasture, grazed or conserved (from the same proportion of both areas), comprised the entire ration.

4. The H group produced 57 and 59% more milk per acre than the L group during the first and second seasons, respectively. Milk production per cow in the H group was not significantly depressed. The solids-not-fat content of the milk in both seasons, and the butterfat content in the first season, were significantly depressed at the higher stocking rate.

5. The body-weight gain of the cowa in the H group, relative to those in the L group, was depressed by 68% (from 170 to 55 lb./cow) and 88% (from 172 to 20 lb./cow) in the first and second seasons, respectively.

6. The yield per acre of utilized pasture, based on the nutrient requirements of the cows, was 39 and 38% higher at the higher stocking rate in the first and second seasons, respectively. The estimated individual intake of these cows in the two seasons was depressed by 14 and 20%, respectively. The estimated yield per acre of utilized pasture ranged from 4092 lb. s.e. at 1·0 cows/acre to 6519 lb. s.e. at 2·0 cows/acre.

7. The mean daily herbage intake during the second season, estimated by a herbage clipping technique, was 29·5 and 22·9 lb. dry matter per cow for the L and H treatments, respectively. The cows in the H group ate, at each grazing, all the herbage that had grown since the previous grazing, whereas the estimated intake of the L group was equivalent to only 80% of this regrowth. However, the estimated rate of regrowth of the swards on the two treatments was the same.

8. Herbage intake estimates derived from a faecal-indicator technique, and observations of the grazing behaviour of the cows provided more detailed information on the pattern of herbage availability on successive days during the grazing of paddocks at each stocking rate.

9. The results of this experiment are discussed in relation to the design of grazing experiments and to farming practice.
Effects of different patterns of allocation of a restricted quantity of food upon the growth and development of cockerels
Authors: Osbourn D. F. , Wilson P. N.
Published: March 2009

1. The live-weight gains and food consumption of groups of chickens subjected to two different patterns, (A) and (B), of allocation of a restricted quantity of food, were compared with the live-weight gains and food consumption of a control group (C), fed ad lib. throughout the experiment.

2. Group B (compensatory growth regime), showed a greater relative growth rate after re-alimentation than group A (mild restriction followed by ad lib. feeding). The growth rate of group B was shown to be significantly greater than that of the control group at equivalent live weights. In addition, it was shown that the increased growth rate, induced by periods of restriction of similar severity and duration, was very similar for birds within the ranges of 200–300 g. live weight and 750–1100 g. live weight.

3. The differences, due to treatment, in the growth rate after re-alimentation were in part caused by a concurrent increase in appetite. The severity and duration of the undernutrition immediately prior to re-alimentation would appear to affect appetite during re-alimentation more than the total restriction imposed. Measured in terms of food consumed, the restriction imposed upon groups A and B was the same, but in terms of live weight gain group B was very slightly more retarded than group A.
Observations on the effect of hexoestrol on earthworms and other soil invertebrates
Authors: Raw F.
Published: March 2009

1. Activity of Lumbricus terrestris, Allolobophora caliginosa and A. chlorotica was unaffected by 15 mg. hexoestrol in solution in 500 g. soil.

2. Activity and reproduction of A. caliginosa was unaffected by 10 mg. hexoestrol in 500 g. soil, but 100 mg. and over affected activity and stopped reproduction.

3. Egg capsules of A. caliginosa and A. chlorotica developed normally in a saturated aqueous solution of hexoestrol.

4. No effect on the soil fauna of grass plots due to grazing with implanted bullocks was observed.
Studies in beef production II. The estimation of live weight of beef steers from chest girth and other body measurements
Authors: Brookes A. J. , Harrington G.
Published: March 2009

1. Records collected on the steers reared during the long-term experiment on beef production on the Cambridge University Farm from 1946 to 1955 have been analysed to examine the relation of live weight to various body measurements and the dependence of these relations on breed, treatment and age.

2. Among the measurements considered singly, chest girth was most closely related to live weight.

3. There were marked differences in the slopes of the regression lines relating log live weight to log chest girth during the two phases of the experiment—from birth to 8 months of age and from 8 months to slaughter.

4. The regression coefficients in the first period were affected by the treatment on which the calves were being reared. Those in the second period were affected both by the level of feeding the steers were receiving during that period and by the manner in which they had been reared to 8 months.

5. Height at shoulder was the measurement which, as a second variate in the regression equations, led to the greatest increases in the accuracy of prediction of live weight. However, the relation of this measurement to live weight was also affected by the treatment.

6. It was considered that these measurements show little promise as estimators of live weight which could be generally applied, since their relations to live weight were affected by the treatment of the animal.
Seasonal variations in blood composition in high and low potassium type Marwari sheep
Authors: Taneja G. C. , Ghosh P. K. , Abichandani R. K. , Goyal D.
Published: March 2009

Blood samples were obtained at monthly intervals for 12 months from 8 HK and 8 LK wethers of the Marwari breed maintained at Jodhpur (26° 05′ N, 73° 01′ E). The samples were analysed for packed cell volume (PCV), red blood cell count (RBC), haemoglobin concentration (Hb), mean cell volume (MCV), mean cell haemoglobin concentration (MCHC), plasma inorganic phosphorus and plasma specific conductance.

The HK animals, on average, had significantly higher PCV, RBC, Hb, MCHC and plasma inorganic phosphorus values than the LK animals but the MCV was significantly higher in the LK group. There was no difference in the plasma specific conductance.

PCV, RBC and Hb values differed considerably from animal to animal within each group. These individual variations could help the breed to survive in a desert environment.

No particular tendency or pattern in the effect of season on the blood characters studied has been observed. This indicates that the animals of both groups responded in a similar way to the environmental changes.
Uptake of magnesium and other fertilizer elements by sugar beet grown on sandy soils
Authors: Durrant M. J. , Draycott A. P.
Published: March 2009

Ten experiments (1967–9) on sandy soil in East Anglia measured the effect of magnesium fertilizer on yield and cations in sugar beet. Magnesium fertilizer increased sugar yield by up to 0·80 t/ha and on the three most responsive fields it consistently increased top and root dry·matter yields throughout the growing period.

On average, without magnesium fertilizer, the concentration of magnesium in tops progressively decreased from 0·33% at singling to 0·15% at harvest, and in roots from 0·39% to 0·09%. The corresponding decreases with magnesium fertilizer were (tops) from 0·68% to 0·20% and (roots) from 0·48% to 0·10%. Yield was increased by magnesium fertilizers when tops contained less than 0·35% Mg during May, 0·30% during June, 0·22% during July and 0·17% during August. Deficiency symptoms were not visible until the concentration in tops averaged less than 0·2% – the percentage of plants with symptoms increased rapidly at smaller concentrations. Magnesium fertilizer decreased the concentration of calcium in tops and roots but did not affect the concentration of potassium or sodium.

The maximum amount of magnesium, potassium, sodium and calcium in tops (August–September) was 11, 218, 75 and 62 kg/ha respectively; these decreased to 8, 168, 55 and 50 kg/ha at harvesting, showing that only about 75% of the largest amount in tops was present at harvest. The amounts removed in roots at harvest were 9 kg/ha Mg, 75 kg/ha K, 11 kg/ha Na and 26 kg/ha Ca. A dressing of 100 kg/ha magnesium increased the amount of magnesium in the crop at harvest by only 4·5 kg/ha.
Use of the marker 51Cr-EDTA in the ovine caecum
Authors: Hecker J. F.
Published: March 2009

Experiments were done on three sheep fed several diets to determine the usefulness of the marker 51Cr-EDTA in the caecum of the sheep to study changes in weight of digesta and its turnover time. The activity of the marker decreased exponentially with time, indicating that it had mixed with a pool of digesta. Variation in the results was attributed mainly to the slowness of mixing and to the periodic nature of filling with digesta from the ileum.

Most estimates of weight of digesta were compatible with the digesta being contained in the caecum and the proximal colon but in one sheep some estimates obtained by one method of calculation were so large as to be unrealistic. Both the estimated weight and the rate of turnover of digesta varied with the weight of the sheep and the level of food intake.
Applying nitrogen fertilizers for spring barley
Authors: Widdowson F. V. , Penny A. , Williams R. J. B.
Published: March 2009

1. Fifteen experiments on spring barley (mainly Proctor), done from 1957 to 1959, compared alternative alternative methods of applying 0·3, 0·6 and 0·9 cwt. N/acre.

2. Combine-drilling 0·3 or 0·6 cwt. N/acre as ammonium sulphate produced higher mean yields than broadcasting, but drilling 0·9 cwt. N/acre checked early growth and reduced mean yields in two of the three seasons.
Nitrogen studies in a coffee soil III. The comparative efficiency of ammonium sulphate and urea fertilizers in the presence and absence of an organic mulch measured in terms of crop yield
Authors: Robinson J. B. D.
Published: March 2009

The work reported in two previous papers, Robinson (1960a, b) led to certain conclusions which required evaluation in terms of coffee yields (Coffee arabica Linn). The work describes changes in nitrate and ammonia-N in the Kikuyu red loam coffee topsoil, both natural and fertilizer derived, in the presence and absence of mulches.

This paper presents early coffee yield results which have been obtained from field trials laid down on the Coffee Research Station, Ruiru, Kenya, to measure the effect of treatments based on the conclusions drawn from the soil studies.
Thein vitroproduction, by rumen micro-organisms, of volatile fatty acids from cellulose and hemicellulose labelled with14C
Authors: Bath I. H. , Head M. J.
Published: March 2009

1. A new technique has been used to study the fermentation of hemicellulose and α-cellulosein vitro. This involved the use of14C-labelled carbohydrates fermented in the presence of normal herbage material in an artificial rumen.

2. A method of growing grass in an atmosphere of14CO2, its fractionation into hemicellulose and α-cellulose and the analysis of the labelled V.F.A. end-products are described.
The growth and performance of cotton in a desert environment: II. Dry matter production
Authors: Hearn A. B.
Published: March 2009

Variety, water and spacing were treatments in two experiments with cotton in 1963 and 1964 in which fruiting points, flowers and bolls were counted and the dry weights and leaf areas of plants were measured at intervals during the season.

Until leaf-area index, L, started to decrease, the equation described how dry weight, W, changed. The equation gave smoothed estimates of crop growth rate, C, which were consistent with estimates of photosynthesis made with de Wit's (1965) model. The relationship between G and L conformed to , derived from Beer's Law, rather than C = aL — bL2 derived from the linear regression of E on L. When L > 3 the crop appeared to use most of the available light, so that C approached a maximum. Treatments initially affected dry-matter production through the numbers and types of branches and nodes, which in turn affected the sinks available and thus the proportion of dry matter reinvested in new leaf. This initial period, when growth was simple to describe in conventional terms, was denned as the vegetative phase of growth.

The start of the reproductive phase of growth overlapped the vegetative phase. The change from one to the other was completed when the rate of dry weight increase of the bolls, CB, equalled C. This indicated that the sink formed by the bolls had increased sufficiently in size to use all the assimilates available for growth. Sink size increased as the crop flowered and was estimated from the product of the number of bolls and the growth rate of a single boll.

When CB equalled C, bolls were shed which prevented the size of the sink to increase beyond the ability of the plant to supply it with assimilates. This agrees with Mason's nutritional theory of boll shedding. Because of the crop's morphology and because age decreased the photosynthesis of the crop, the size of the sink inevitably increased out of phase with the supply of assimilates. The extent to which this was so determined when CB equalled C. It is postulated that environment, genotype and agronomic practice affect yield according to whether they increase or decrease the extent to which the sink size and the supply of assimilates are out of phase.
The growth and performance of cotton in a desert environment: III. Crop performance
Authors: Hearn A. B.
Published: March 2009

The biological and economic performance of a cotton crop are examined. The effects of variety, water, sowing date and spacing on crop performance are considered in relation to their effects on crop growth, which had been studied previously, or noted in the literature. Suitable varieties and agronomic practices are discussed. An empirical relationship between available water, dry matter production and yield of seed cotton is evaluated physically and biologically on the basis of Penman's and de Wit's work, and practically in the light of commercial yields and rates of watering.
The assessment of herbage legume varieties: IV. The potential of 64-chromosome white clover
Authors: Davies W. Ellis
Published: March 2009

Colchicine induced 64-chromosome white clover was compared at a number of centres with control material (2n = 32), as spaced plants and in broadcast plots with and without companion grasses.

The chromosome-doubled material generally conformed to the well-known reaction of polyploids; the plants were later flowering, had thicker petioles and stolons, broader leaflets and spread less vigorously. Yield of green matter of spaced plants was much less, and in broadcast plots the gross yield (grass + clover) and that of the clover fraction was 7% less than in comparable S. 100 plots. The Finlay-Wilkinson analysis indicated that the chromosome-doubled form did not respond to improved conditions to the same extent as did the control varieties. The presence of grass in the mixture partly compensated for low clover yield, but was insufficient to increase total yields to that of S. 100 controls.
The moisture characteristics of some Rothamsted, Woburn and Saxmundham soils
Authors: Salter P. J. , Williams J. B.
Published: March 2009

Determinations were made of the available-water capacities and moisture release characteristics of six soils of different texture from Rothamsted, Woburn and Saxmundham. The amount of available water retained in the surface foot of soil ranged from 1·59 in in a sandy loam to 2·75 in in a silt loam under permanent grass. With one exception soils which had received additions of farmyard manure had significantly higher available-water capacities than unmanured soils.
Preliminary trials on the intercropping of maize with different tropical legumes in Western Nigeria
Authors: Agboola Akinola A. , Fayemi Adeboyejo A.
Published: March 2009

A preliminary investigation on interplanting of maize with nine different tropical legumes in the rain-forest zone of the Western State of Nigeria at Ibadan indicated that Popondo (Phaseolus lunatus) and Mucuna (Mucuna utilis) lowered maize yield, while calopo (Calopogonium tnucunoides) Cowpea (Vigna sinensis) and greengram (Phaseolus aureus) had much less effect on maize and were themselves tolerant to maize shade. These three legumes were interplanted with maize continuously for four growing seasons, during which there was a significant response of maize to fertilizer treatment only in the control (no legume) treatment. Maize interplanted with the legumes gave no response to applications of 50 lb N per acre.

High yields of maize were maintained during the four growing seasons in both the fertilized control plots and those interplanted with different legumes without fertilizer, whereas the yield of maize in plots with neither legume nor fertilizer was reduced to half of the yield of the first maize crop.

Starting from the third cropping season, there was a significant interaction between the presence or absence of legume and fertilizer.

The planting pattern of the maize and legumes (intercropping or growing maize after the legume harvest) did not affect the yield of maize.

Legumes tended to compete with maize during the late cropping season. This did not affect the maize yield seriously during the investigation, but legume yield was significantly suppressed by maize shade.
Weed control in irrigated groundnuts (Arachis hypogaeaL.) in the Sudan Gezira
Authors: Ishag Hassan M.
Published: March 2009

Experiments were conducted at Gezira Research Station during the 1964 and 1965 seasons to determine the effect of time and number of weedings on pod yield of Ashford groundnuts.

Natural stands of annual weeds, mainlyIpomoea cordofanaandRhynchosia memnonia, reduced the pod yield by an average of 80%. Results showed that groundnuts must be weeded at least once after the first 30 days from sowing. Groundnut pod yield was increased from 986 kg/ha in the unweeded plots to 4690 kg/ha in the plots weeded 30 and 60 days after sowing. Three weedings, i. e. 15, 30 and 45 days from sowing, yielded less than 30 and 60 days from sowing because weeding stopped too soon. For practical purposes weeding at 30 and 60 days only was adequate.

Number of pods per plant was the most important factor determining yield. Maximum pod yield was obtained from 15–20 pods per plant, and the earlier the 20 flowers produced, the higher was the pod yield.

Weeds decreased number of branches per plant and consequently number of pods per plant. Weight of 1000 seeds, shelling percentage and harvest index was also affected by weeds.

Ipomoea cordofanawas the most noxious weed because it emerged about the same time as the groundnut plants and also the seeds germinated throughout the growing season.
Factors influencing the role of clover in grass-clover leys fertilized with nitrogen at different rates I. The effects of the variety of companion grass on the yields of total herbage and of clover
Authors: Reid D.
Published: March 2009

1. A study has been made of some of the factors influencing the role of clover in grass-clover swards fertilized with nitrogen at different rates.

2. From 1955 to 1957 inclusive three nitrogen treatments, 0, 4 and 10 cwt. ‘Nitro-Chalk’ (15·5% N)/acre/season, were applied to twentyone grass-clover mixtures sown in the spring of 1954. The mixtures contained either S 184, S100 or Kersey white clover alone or in association with one of the following grasses, S 23 or S 24 perennial ryegrass, S143 or S37 cocksfoot, S48 timothy or S53 meadow fescue.
Factors influencing the role of clover in grass-clover leys fertilized with nitrogen at different rates II. The effects of the variety of white clover on the yields of total herbage and of clover
Authors: Reid D.
Published: March 2009

1. A brief description is given of an experiment in which some of the factors influencing the role of clover in grass—clover swards fertilized with nitrogen at different rates were studied.

2. Reference is made to a previous paper detailing the experimental methods and reporting the results pertaining to the effects of the grass varieties included in the seeds mixture on the yields of mixed herbage and of clover. The effects of the clover varieties on these yields are discussed in the present paper.
Studies on the adaptability of three breeds of sheep to a tropical environment modified by altitude V. The annual fluctuation in breeding ability of rams maintained on Rhodesian highveld
Authors: Symington R. B.
Published: March 2009

Semen characteristics and libido were observed for 34 months in German Merino, Persian Blackhead and indigenous ‘Native’ rams maintained on Rhodesian highveld. Birth rate from controlled service was determined during 23 of these months.

1. Breeding ability, as judged by semen production and libido, was continuous in all rams. A fluctuation in birth rate from controlled service was due more likely to seasonal variation in female fertility than in seminal fertilizing capacity.

2. Monthly changes occurred in all seminal characteristics but only those in sperm concentration were consistent between years. In all breeds spermatogenic activity was high in spring and mid-summer, low in late summer and autumn.
The nutrition of zebu cattle Part IV. The intake of dry matter by cattle with some notes on the digestibility of Rhodes grass and Star grass hays
Authors: Marshall B. , Bredon R. M. , Juko C. D.
Published: March 2009

The daily intake of dry matter by zebu steers between 400 and 600 lb. live weight when fed hay and hay-concentrate mixture was investigated and found to be 2·0–2·2% of body weight.

Preliminary results of the nutritional values of Rhodes grass and Star grass hays are discussed and these suggest that the local zebu cattle require less starch equivalent for maintenance than do European cattle in temperate climates.
The effect of light-dark sequences on wool growth
Authors: Hart D. S.
Published: March 2009

Corriedale ewes in New Zealand on a constant ration throughout the year were subjected to various light treatments and their monthly growth of wool compared with controls having normal daylight hours.

1. In the controls the peak of wool growth occurred during November–January with long daylight hours and the minimum during June–August with short daylight hours.
The effect of sodium and potassium on sugar beet on the Lincolnshire limestone soils
Authors: Adams S. N.
Published: March 2009

1. Seventeen experiments in 1957–59 on the Lincolnshire Limestone soils tested the response of sugar beet to 2·5 cwt. potassium chloride per acre (as commercial muriate of potash, 60% K2O) and its chemical equivalent in sodium chloride: 1·8 cwt. per acre. Average response of sugar yield to sodium was higher than to potassium, especially in the wet summer of 1958. There was a negative interaction between sodium and potassium; in the presence of sodium it was uneconomic to apply potassium.
The tillering pattern in barley varieties: I. Production, survival and contribution to yield by component tillers
Authors: Cannell R. Q.
Published: March 2009

Two field experiments have been conducted to investigate the pattern of tillering, ear emergence and survival of the component tillers of three barley varieties, representing old and new varieties. The varieties were grown under contrasting nitrogen fertilizer levels and plant spacings. The results reported are for the variety means and variety x nitrogen and variety x spacing interactions. After the main stem (M) the most frequently occurring tiller was the tiller appearing in the axil of the first true leaf (T2), followed by the coleoptile node tiller (T1) and the tiller in the axil of the second true leaf (T3). The T1 tiller occurred most frequently in the newest variety, Deba Abed, and least in the oldest one, Spratt Archer. Survival rates of the shoots were highest in M, followed by T2, T1 and T3. Higher-order tillers occurred relatively infrequently and had low survival rates. M contributed the largest percentage of the grain yield, followed by T2, T1 and T3. The 13% grain yield advantage of Deba Abed over Spratt Archer was mainly accounted for by the difference in production by the T1 tiller. The results are discussed in. relation to the only other known paper on component tillers in barley.
The non-protein nitrogen composition of grass silages: I. The estimation of the basic amino acids and non-volatile amines by chromatography on a weak cation exchange resin
Authors: Hughes A. D.
Published: March 2009

Investigations into the non-protein nitrogen composition of grass silages using the 50 cm strong cation-exchange column of Spackman, Stein & Moore (1958) to determine the basic amino acids led to difficulties in the determination of ethanolamine in the presence of high concentrations of ammonia, and of histidine in the presence of δ amino-n-valeric acid. An alternative technique for the ion exchange chromatography and estimation of histidine, lysine, ornithine, ethanolamine, arginine and ammonia on a weak cation-exchange resin has been developed. This method enables small amounts of ethanolamine to be determined in the presence of large amounts of ammonia and values for the ethanolamine content of a number of silage samples are presented. When used in conjunction with the technique of Spackmanet al.(1958) the δ-amino-n-valeric acid content of grass silages could also be determined in the presence of histidine.

The estimation of amines produced by the microbial decomposition of herbage proteins during ensiling has previously involved their initial separation from the amino acids followed by quantitative partition chromatography. An alternative method for the estimation of these amines by ion-exchange chromatography on a weak cation-exchange resin is described. This method permits the colorimetric determination of β-phenylethylamine, tyramine, tryptamine, 5-hydroxytryptamine, putrescine, cadaverine and histamine without interference from the amino acids. The efficiency of this technique has been investigated using standard solutions of the naturally occurring amines and samples of good quality and of high pH spoilt silages.
The growth and development of some barley varieties in response to irrigation and nitrogen fertilizer
Authors: Kirby E. J. M.
Published: March 2009

In an experiment to investigate growth in relation to nitrogen concentration and nitrogen uptake, Proctor was compared with four other varieties of barley at two levels of irrigation and two levels of nitrogen fertilizer by means of weekly samples throughout the growing season. The varieties were Deba Abed, a new variety recommended for high fertility conditions where feeding quality grain is required, and three exotic varieties, chosen for their high concentration of nitrogen in the grain.

Irrigation stimulated tillering, although certain varieties responded more strongly than others; irrigation also led to a higher specific growth rate. Certain of the exotic varieties had high growth rates early in the season but growth fell off earlier due to earlier ear emergence. Maximum leaf area index was greater in the irrigated treatment at the high nitrogen fertilizer level. The adapted varieties had higher maximum leaf area indices than the exotic varieties, although some of the exotics had higher rates of leaf area growth early in the season; there were also differences in the way in which the varieties responded to irrigation. Irrigation and variety both affected the rate at which the percentage nitrogen in the shoot fell with time.

Analysis of these data indicates that nitrogen uptake early in the season was an important factor determining the total amount of nitrogen taken up by the plant. It was also shown that the relative rate of decline of the specific growth rate and the specific rate of nitrogen uptake differed between varieties. Analysis of the specific growth rate indicated that differences in leaf growth, rather than net assimilation rate, led to the varietal differences. The differential response to irrigation is discussed with reference to drought resistance.
The efficiency of utilization of proteins contained in roughages, soya bean oil meal or mixtures of both, by sheep
Authors: Dror Y. , Tagari H. , Bondi A.
Published: March 2009

In two feeding experiments the effects of different sources of protein on nitrogen utilization were studied. Three protein sources were examined in both experiments; (a) soya-bean oil meal; (b) lucerne hay or vetch oat hay, and (c) a mixture of soyabean oil meal and hay. The first experiment was carried out with nine adult rams and the second with twelve growing rams.

The results of N balance experiments showed clearly the superiority of the hay ration over the soya-bean meal ration. N retention when the mixed ration was given was greater than on hay alone. No parallel trend was found between the protein digestibility of any of the diets and its efficiency for N retention.

With adult sheep a negative correlation between the extent of N retention and blood urea concentration was found; this agreed with our earlier findings. No such negative correlation was found with growing animals.

The highest concentrations of the various forms of soluble N compounds such as soluble a-amino N, diffusible N and diffusible peptide N were found in the rumen liquor taken from the sheep kept on the hay diet. The lowest amounts were observed when the soya-bean oil meal diet was given and intermediate amounts with the mixed diet. These trend sappeared to be related to the NPN (non-protein nitrogen) content of the diet, but the amounts of soluble N compounds present in rumen liquor were not directly correlated with the extent of N retention.

Concentrations of VFA present in rumen liquor depended primarily on the carbohydrate composition in the diet. The type of protein ingested exerted some influence, particularly on the concentrations of caproic and iso-caproic acid. The ratios of concentrations of the individual fatty acids in blood to the concentrations of the same acids in rumen liquor were found to increase with lengthening of the fatty acid chain.
Effects of soil compaction on yield and fertilizer requirement of sugar beet
Authors: Draycott A. P. , Hull R. , Messem A. B. , Webb D. J.
Published: March 2009

Five experiments (1967–9) on soils formed from calcareous drift examined the effects of soil compaction on seedling emergence and yield of sugar beet, also the interaction between compaction and response to nitrogen fertilizer (N) and phosphate fertilizer (P2O5). Some seedbeds were compacted in winter, others in spring and others prepared with the minimum of compaction; each was tested with 0·6, 1·2 and 1·8 cwt/acre N plus 0·8 cwt/acre additional P2O5. All plots were given a basal dressing of 0–8 cwt/acre P2O6and enough of other major nutrients.

Compaction decreased seedling populations in four experiments but increased it in one year, when the weather was dry while the seeds were germinating. However, in every experiment compaction significantly decreased yield of roots and sugar. It also interacted with the fertilizer treatments, significantly on average, increasing nitrogen requirement and decreasing phosphate requirement. On average, 0·6 cwt/acre N and 1·6 cwt/acre P2O5gave the greatest yield without compaction and 1·2 cwt/acre N and 0·8 cwt/acre P2O6with compaction.
Embryo mortality in Scottish Blackface ewes as influenced by body condition at mating and by post-mating nutrition
Authors: Gunn R. G. , Doney J. M. , Russel A. J. F.
Published: March 2009

One hundred and forty-nine Scottish Blackface ewes (aged 5 and 6 years), from two different farm sources, were group-fed over 6 weeks in such a manner that at 3 weeks before mating there were approximately equal numbers from each source in two widely different levels of subjectively assessed body condition (scores 1·5 and 3 on a scale ranging from 0 = emaciated to 5 = very fat). The majority of ewes were maintained in these levels of condition until mating after which they were allocated alternately to high and low planes of post-mating nutrition for 26±2 days.

Half the ewes in each group were killed on day 26±2, or earlier return-to-service, for ovulation and viable embryo counts. Surviving ewes were fed at or above maintenance until parturition and the number of lambs recorded.

Condition at mating had a significant, positive effect on both ovulation and lambing rates and had an apparent negative effect on embryo mortality up to day 26±2, although this was influenced by differences in the distributions of single and multiple shed ova. Post-mating nutrition had no effect on embryo mortality up to day 26±2. Neither condition at mating nor post-mating nutrition had any effect on embryo mortality from day 26±2 to parturition.

Source of ewe had a significant effect on both ovulation rate and embryo mortality at both levels of body, condition.
Competition and yield compensation in relation to breeding sugar beet
Authors: Curtis Godfrey J. , Hornsey Kenneth G.
Published: March 2009

Samples were prepared to simulate the populations which would be obtained from the random interpollination of known numbers of inbred lines. This was done by mixing together seed of a vigorous and a less vigorous genotype in calculated proportions. The less vigorous represented the inbred component which would result from selling and sibbing within the constituent lines, while the more vigorous represented the hybrid fraction. The difference in yield between the two genotypes was comparable with the level of enhancement which could be expected in the hybrids as a result of heterosis. Root yields of these populations in the field suggest that depression due to the presence of inbred individuals in a synthetic variety may be predicted by a mathematical model. Yields calculated from the model to allow for various levels of compensation enabled the order of magnitude of the compensation to be estimated. However, the presence of quite small numbers of less vigorous individuals was detectable. Given the limitations imposed by the assumptions necessary to simulate these varieties, the optimal number of lines for an open-pollinated variety may be predicted.
Effects of pregnancy and lactation in sheep on the metabolism of propionate by the ruminal mucosa and on some enzymic activities in the ruminal mucosa
Authors: Weekes T. E. C.
Published: March 2009

Ruminal papillae were removed at slaughter from pregnant, lactating and nonbreeding control ewes. The amounts of lactate and pyruvate formed per unit dry weight of papillae during incubationin vitrowith added propionate were not significantly affected by breeding state.

When results were expressed relative to the total weight of mueosa in the rumen, the amounts of lactate and pyruvate formed were significantly greater for ewes slaughtered during the final two thirds of a 10-week period of lactation in comparison with unmated ewes slaughtered at the same time.

The calculated extent of conversion of propionate absorbed from the rumen into lactate and pyruvate was small, averaging 3·0%.

When results were expressed per unit weight of mucosa, breeding state did not significantly affect the activity of four of the enzymes involved in the conversion of propionate into lactate and pyruvate, namely propionyl-CoA synthetase, propionyl-CoA carboxylase, NADP-malic dehydrogenase and lactic dehydrogenase, or of aspartate aminotransferase.

When results were expressed relative to the total weight of ruminal mucosa, the activities of all these enzymes and also of alanine aminotransferase were significantly greater during lactation than in control sheep slaughtered at the same time. The activities in ewes slaughtered during the last 50 days of pregnancy, however, were not significantly different from the control values.

Glutamic dehydrogenase activity per unit weight of tissue was higher after the lambs had been weaned than during lactation. Alanine aminotransferase activity per unit weight of mucosa decreased during the last 50 days of pregnancy.
An assessment of chromic oxide as an indigestible marker for digestion studies in sheep
Authors: Faichney G. J.
Published: March 2009

Fistulated cross-bred sheep were given, by means of continuous feeders, concentrate diets containing chromic oxide (Cr2O3). Dry-matter digestibility coefficients predicted from the faecal concentration of Cr2O3 were compared with those obtained by total collection of faeces, and the concentration of Cr2O3 in spot samples of faeces taken at different times of day was compared with that in faeces bulked over an 8-day collection period. The rate of flow of digesta from the abomasum and the partition of digestion between the stomach and intestines, calculated from the concentration of Cr2O3 in samples of abomasal digesta, were compared with values obtained using two markers, one of which remained in solution while the other was adsorbed by particulate matter.

Récovery of Cr2O3 in the faeces ranged from 91 to 101% and predicted dry-matter digestibilities were similar to those obtained by total collection. There was no diurnal variation but there was marked random variation in the concentration of Cr2O3 in spot samples of faeces. Cr2O3 was shown to behave independently of the particulate matter in digesta and, as a single marker, it significantly underestimated the flow of digesta from the abomasum relative to the double marker method. Cr2O3 thus overestimated digestion in the stomach and underestimated digestion in the intestines. It was concluded that Cr2O3 was not a satisfactory marker for studies of the flow of digesta and hence the partition of digestion within the gastro-intestinal tract when digesta samples are taken from a simple cannula.
The nutrition of the early weaned lamb:II. The effect of dietary protein concentration, feeding level and sex on body composition at two live weights
Authors: Andrews R. P. , Ørskov E. R.
Published: March 2009

1. In an experiment with ninety-nine lambs the effects on the body composition of male and female lambs were examined when five diets containing different concentrations of crude protein (in the range 10–20%) were given at three levels of feeding and lambs were slaughtered at two live weights (27·5 and 40 kg).

2. With lambs slaughtered at 27·5 kg there were significant increases in the rate of both nitrogen and fat retention with increases in levels of feeding. There were also linear increases in the rate of protein deposition and decreases in fat deposition with increases in the concentration of crude protein. This effect was particularly marked at the high level of feeding.

3. With lambs slaughtered at 40 kg live weight there were also linear increases in fat and in nitrogen deposition with increasing feeding level but the effect of increasing the protein concentration on increases in nitrogen retention departed from linearity.

4. While at 27·5 kg there were no significant effects of feeding level on nitrogen and ether-extract content of the bodies at slaughter, with animals slaughtered at 40 kg there was a significant linear decrease in ether-extract content with increasing feeding level and a corresponding linear increase in nitrogen content with increased level of feeding.

5. Male lambs deposited more nitrogen and less fat than females. This was true of both rate of deposition and of carcass composition at 40 kg live weight.
The utilization of dietary fats by ruminants:I. The digestibility of some commercially available fats
Authors: Andrews R. J. , Lewis D.
Published: March 2009

The digestibility of some fats (beef tallow, HEF, herring oil, soyabean oil and maize oil) were studied in balance trials with sheep which had been maintained on the diets for a 35 day period of acclimatization to establish ‘steady state’ conditions. Corrected digestibility coefficients for the individual fats were calculated from a knowledge of the intake and output of lipid on a low-fat basal ration. The difference between the intake of fat and the corrected lipid output (total lipid output minus lipid output on basal ration) expressed as a percentage gave the corrected digestibility coefficients.

It was found that the corrected digestibility coefficients for beef tallow was 85%; HEF, 74%; herring oil, 84%; soyabean oil, 83%; and maize oil, 70%. The values for beef tallow and HEF were comparable to similar estimates in pigs. The digestibility of the highly unsaturated soyabean and maize oil were markedly lower in comparison with non-ruminant species. Extensive hydrogenation of dietary unsaturated fatty acids was confirmed. For soyabean and maize oil the corrected output of stearic acid exceeded the dietary intake.
Woburn irrigation, 1960–8:IV. Design and interpretation
Authors: Penman H. L.
Published: March 2009

Results are given for a second period of 9 years, 6 on the pattern of 1951–9, with the last 3 years used for ad hoc management experiments. The meteorological specification of a year of ‘irrigation need’ was satisfied in 4 years: there were good responses in 5 years. During the first 6 years, out of twenty-four sets of crop yields (from eight different crops), very good responses were obtained on nine, good responses on eight, and zero or very slightly negative responses on the other seven.

A general theory of the inter-relationships of growth and water, and of growth and radiation, leads to an expression

k = 39ε t ha−1 cm−1,

as the maximum possible response to irrigation in terms of total dry matter produced, where ɛ is the fraction of solar radiation fixed by the crop (ɛ has a range 50–100 × 10−4 for good to very good farming) when irrigation is needed. The ‘need’ is defined through

Y = k(ET + De − Dm),

where Y is the yield, ET is the total potential evaporation, De is a limiting deficit up to which there is no check to growth, and beyond there is no growth, and Dm is the maximum deficit experienced by the crop at the time of measuring Y. The agronomic object of the experiments is to determine De, i.e. what reserve of soil water can be used by the crop before irrigation is necessary.
Relationship between body weight and testicular size in buffalo bulls
Authors: Yassen A. M. , Mahmoud M. N.
Published: March 2009

The relationship between body weight, testes volume and circumference as computed for 42 slaughterhouse buffalo bulls (Bos bubalis). Animals ranged in body weight from 290 to 610 kg, testes volume (testes plus epididymides without scrota) from 102·5 to 296·7 ml and testes circumference (testes with scrota intact) from 21·31 cm. Relationships between body weight and testes volume, body weight and testes circumference, testes circumference and testes volume were all linear and correlations (r) were, 0·986, 0·932, 0·951 and were highly significant. Regression equations were calculated and it was clearly shown that buffalo bull testes volume is a function of body weight and could be easily predicted either from body weight or from testes circumference.

Comparisons between the testicular size of the buffalo bull (B. bubalis) and domestic bull (B. taurus) based on calculations from prediction equations showed that the testes size of the buffalo bull was half that of a domestic bull of similar body weight.
Milk-fed calves: 1. The effect of milk intake upon the herbage intake and performance of grazing calves
Authors: Baker R. D. , Le Du Y. L. P. , Barker J. M.
Published: March 2009

Two trials were conducted, using 18 and 30 castrated male calves respectively, to investigate the importance of milk in the diet of calves during the first 8 months of life and its effect on herbage intake and live-weight change. Reconstituted milk substitute was fed in a manner that simulated the supply of milk for lactation, yields of 2101, 1635 and 1165 kg (Expt 1) and 1906, 1609, 1304, 1005 and 701 kg (Expt 2) over a 240-day period. Calves were purchased in mid-February, when approximately 1 week old, and housed individually until turned out to graze at 10 weeks of age. At pasture, the calves were strip grazed on swards of Lolium perenne cv. S. 23 or S. 24 and given a daily herbage allowance of 60 g D.m./kg live weight.

The live-weight gain response to milk consumption was 81 g/kg milk fed during the housed period and 50 g during the grazing season. Herbage and milk intake per unit live weight were inversely related but because the grazing season responses were confounded with the treatments during the housed periods, it was not possible to determine true replacement rates. Herbage intake per head increased with time but there was no general trend when intake was expressed per unit live weight.
Nitrogen response and stocking rate of Pennisetum clandestinum pastures: II. Cattle growth
Authors: Mears P. T. , Humphreys L. R.
Published: March 2009

Individual live-weight gain (LWG) of Angus weaner cattle continuously grazing (Pennisetum clandestinum) pasture was negatively and linearly related to stocking rate (SR) and independent of ammonium nitrate (N) application rate at similar grazing pressures.

Live-weight gain varied from 380 to 1056 kg/ha according to N rate in 1970–1 and from 637 to 1477 kg/ha in 1971–2. Calculated SR giving maximum LWG/ha was 3·4, 4·7, 7·6 and 9·8 animals/ha for the 0, 134, 336 and 672kg N/ha treatments respectively in 1970–1 and 6·1, 5·7, 9·1 and 10·6 animals/ha for the same treatments in 1971–2. Highest response to applied N (1·9 and 3·4 kg LWG/kg additional N in successive years) occurred between N131 and N336; response was greater at low and intermediate SR than at high SR. Carcass weight, quality score, depth of subcutaneous fat and area of eye muscle were negatively related to SR; SR's giving maximum output per unit area caused a reduction of ca.25% in production per head and adversely affected carcass quality at 18 months of age.

LWG/head was independent of feed availability in spring and summer and was positively related to availability of green kikuyu up to 600 kg D.M./head in the autumn/winter period.