bluuebunny/crossref_metadata_2025 huggingface dataset:
Diurnal patterns of heat production and heart rate under thermoneutral conditions in Holstein Friesian cows differing in milk production
Authors: Purwanto B. P. , Abo Y. , Sakamoto R. , Furumoto F. , Yamamoto S.
Published: March 2009

Ten dairy cows were allocated into three groups according to milk productivity (four high, four intermediate and two dry cows, respectively). Heat production and heart rate, but not rectal temperature, were significantly different (P < 0·05) between groups. Heat production increased during feeding in the morning and in the afternoon and reached a peak 3 h later. Minimum heat production was observed in the early morning before feeding. The diurnal pattern for heart rate reflected that of heat production. These results suggest that cooling dairy cows during hot summer days is most effective at feeding time and 3 h afterwards.
Heritability of frost tolerance in white clover (Trifolium repens)
Authors: Caradus J. R. , Mackay A. C. , Bosch J. Van Den , Wewala S. , Greer D. H.
Published: March 2009

White clover genotypes selected for frost tolerance and susceptibility were pair-crossed in various combinations with unselected genotypes of Grasslands Huia. Progeny lines and parent genotypes were artificially frosted at −8°C and scored for percentage of leaves damaged. Progeny from crosses between frost-tolerant genotypes were less damaged by frost than progeny from crosses involving either susceptible genotypes or unselected Grasslands Huia genotypes. Heritability estimates for frost tolerance or susceptibility were high, ranging from 0·75 to 0·93, depending on method of calculation. Removal of leaf-size effects from scores of frost damage reduced heritability estimates to 0·54–0·73. It was concluded that, because heritability for frost tolerance was high, selection for this character and incorporation of frost tolerance into agronomically suitable but frost-sensitive cultivars by breeding would be successful.
Analysis of artificial mixtures of pure chemicals by near-infrared reflectance
Authors: Wetherill G. Z. , Murray I. , Glasbey C. A.
Published: March 2009

Compositional analysis of feeds and other materials by near-infrared reflectance (NIR) has been proposed as a cheap and rapid alternative to traditional wet chemical methods. A theoretical basis for NIR measurements is needed and may be obtained from the study of artificial mixtures of pure chemicals.

Mixtures of lactose, casein and sodium oleate, in widely differing concentrations, were analysed by NIR. Principal component analysis was used to study the variations between spectra, and multiple linear regressions gave predictors of sample compositions from the spectra. Optical densities at most combinations of wavelengths gave good predictions of sample compositions because there was much less unexplained variation between NIR spectra than would occur between natural samples.
Response to sowing time of three contrasting Australian cultivars of oilseed rape (Brassica napus)
Authors: Mendham N. J. , Russell J. , Jarosz N. K.
Published: March 2009

Serial sowings of three cultivars of oilseed rape were made from autumn (May) to spring (October) at two sites, one in the north and one in the south of Tasmania, in 1981. The highest seed yields at both sites exceeded 5 t/ha from early sowing, ranging down to c. 2 t/ha from late sowing at a site where irrigation was adequate and to < 1 t/ha where late-sown crops suffered from water stress. The midseason cultivar Marnoo gave the highest yields at both sites, resulting from a combination of substantial (800 g/m2) top growth before flowering, excellent seed survival, a long period for grain filling and high oil content. The early-flowering line RU1 made much less growth before flowering; while this was partly made up for in later growth, nearly as many seeds per pod being retained as in Marnoo, oil content was low. The later-flowering cultivar Wesbell made more growth before flowering than the other cultivars, but when sown early it tended to grow tall, lodge and lose many pods in the dense, tangled canopy. This, combined with generally fewer seeds per pod, resulted in a much less efficient crop in allocation of dry matter to seeds and oil. Wesbell failed to flower uniformly from the late sowings, indicating segregation for vernalization response. The many immature seeds at harvest gave a low overall oil content. All three cultivars responded to vernalization and longer photoperiod in a pot experiment. While photoperiod appeared to be the main factor controlling the development rate to flowering in the field, there were interactions with vernalization response andtemperature.
Effect of the developmental stage of potato seedlings on recovery after transplanting to the field and on tuber yield
Authors: Engels C. , Schwenkel J. , Bedewy R. El , Sattelmacher B.
Published: March 2009

Under the short-day conditions and cool temperatures prevailing from January to March in the Nile delta, Egypt, potato (Solatium tuberosum) seedlings grown from true potato seed formed tubers in the nursery when the plants were less than 5 cm in height. In order to examine the hypothesis that slow field establishment after transplanting and low tuber yields of these seedlings were caused by premature tuberization, different treatments to delay tuberization were applied in the nursery before transplanting.

Increasing the air and soil temperature in the nursery accelerated both the development of the above-ground and below-ground shoot organs, but did not improve field establishment of the seedlings after transplanting. Extension of the photoperiod with incandescent dim light, exogenous application of gibberellic acid (GA), and removal of the shoot apex to encourage the growth of lateral branches from the leaf buds increased biomass allocation to the above-ground shoot organs, decreased tuberization in the nursery and accelerated field establishment of transplanted seedlings. Extension of the photoperiod was the most effective treatment to delay tuberization, and doubled the final tuber yield from transplanted seedlings.

The results are in agreement with the hypothesis that poor field establishment and low final tuber yields from potato transplants may be caused by the presence of strong tuber sinks at transplanting, which reduce assimilate partitioning towards the roots and above-ground shoots.
Relationships between body weight and scrotal characteristics, and between environmental effects and fertility in Ethiopian Horro rams
Authors: Gojjam Yohannes , Gizaw Solomon , Abegaz Solomon , Thwaites C. J.
Published: March 2009

The relationships between body weight, scrotal characteristics and environmental effects (year, birth type and age) and fertility were studied in a total of 254 Horro rams. Fertility varied between years (P < 0·01), but not with body weight at mating within the range (30–55 kg) observed, nor with type of birth (both P > 0·05).

Testicular diameter and circumference were strongly correlated to body weight (r = 0·95 and 0·89 respectively; both P < 0·001), but weight of testes only weakly so (r = 0–28; NS). Scrotal circumference was more highly correlated to body weight in ram lambs (r = 0–85; P < 0–001) than in adults (r = 0·51; p = 0·06).

It is concluded that adequate levels of fertility (82 ± 1·3%) are expressed by 30 kg Horro rams, and that when feed supplies are limited there are no benefits to be gained from maintaining rams of this breed at higher weights.
Effects of nitrogen and the plant growth regulator chlormequat on grain size, nitrogen content and amino acid composition of triticale
Authors: Naylor R. E. L. , Stephen N. H.
Published: March 2009

Field experiments were conducted in Scotland between 1985 and 1987 to examine the responses of mean grain weight and nitrogen content of triticale cultivars to levels of applied nitrogen from 0 to 180 kg N/ha and the plant growth regulator chlormequat. Cultivar differences were seen for both these characters. Mean grain weight generally declined as yield increased, whether with nitrogen or with chlormequat. Nitrogen content of the grain decreased as grain size increased. Nitrogen recovery (g/m2) generally increased with applied nitrogen and was unaffected by chlormequat application. Within a grain sample from an individual treatment, however, grain size was not related to nitrogen content.

The response of nitrogen content is interpreted as differential dilution of nitrogen in the grain by different amounts of carbohydrate. This is probably related to the frequent occurrence of shrivelled grain in triticale.
Heat stress during mid-pregnancy in sheep and the consequences for placental and fetal growth
Authors: McCrabb G. J. , McDonald B. J. , Hennoste L. M.
Published: March 2009

An experiment was conducted at Toorak Research Station, Julia Creek, in semi-arid northern Australia (141° E, 21° S) during 1990 to determine the relationship between placental and fetal weight in sheep after placental growth had been restricted by chronic heat stress during mid-pregnancy. Placental and fetal weight were measured in single bearing ewes housed either in a thermoneutral environment throughout pregnancy, or in a heated room between the 30th and 80th days of pregnancy followed by a thermoneutral environment until the 140th day of pregnancy. The placental weight of the heat-treated ewes was lower than that of the control ewes at the 80th (P< 0·05) and 140th (P< 0·01) days of pregnancy. Fetal weight and dimensions did not differ significantly between control and heat-treated ewes at the 80th day of pregnancy, although fetal weight (P< 0·01) and fetal dimensions (P< 0·05) for the previously heat-treated ewes were lower than those for the control ewes at the 140th day of pregnancy. Placental and fetal weight at the 140th day of pregnancy were correlated (P< 0·05) with the rectal temperature of ewes measured at 08.00 and 16.30 h during the period of heat-treatment, but not with the change in rectal temperature between 08.00 and 16.30 h. It was concluded that restricted placental growth in heat-treated ewes retarded fetal growth during late pregnancy even in the absence of heat treatment, and it is suggested that selection of ewes which can maintain normal rectal temperatures during periods of heat stress would produce lambs of normal birthweight in a hot climate.
The thermal response of sheep to a hot environment in different years
Authors: McCrabb G. J. , Bortolussi G. , Hennoste L. M. , McDonald B. J.
Published: March 2009

The aim of this experiment was to determine whether the thermal responses ofsheep exposed to a hot environment were similar in different years. Rectal temperaturesofsheep were measured during the hot months (between November and March) of three consecutive years (1990/91, 1991/92, 1992/93) in a flock of Merino sheep (n = 151) in the semi–arid tropics of northern Australia. Mean daily maximum temperatures in these months were 36±0·4, 39±0·3 and 37±0·3°C in Years 1, 2 and 3, respectively. In Year 1, rectal temperatures were measured on 3 consecutive days;the repeatability was 0·47 at 08·00 h and 0·64 at 16·00 h. In Year 1, two sub-groups were identified according to measurements of rectal temperature, low body temperature(LBT; n = 35) sheep, whose rectal temperature was ≤ 39·8°C at 16·00 h on each of the 3 consecutive measurement days, and high body temperature (HBT; n = 32) sheep, whose rectal temperature was ≥ 39·9°C. The rectal temperatures of LBT and HBT sheep were then measured during the subsequent 2 years. Rectal temperatures of HBT sheep were significantly higher than those of LBT sheep at both 08·00 and 16·00 h, in both Year 2 and Year 3. Rectal temperatures at 16·00 h in Year 1 were correlated (P < 0.001) with rectal temperatures at 16·00 h in both Year 2 (r = 0·79) and Year 3 (r = 0.82), respectively. It was concluded that measurement of rectal temperature in sheep exposed to a hot environment in any oneyear is an accurate index of their rectal temperatures during subsequent years.
Dehydrogenase and phosphatase activities in soil as influenced by the growth of arid-land crops
Authors: Rao A. V. , Bala K. , Tarafdar J. C.
Published: March 2009

The distribution of dehydrogenase activity (DHA) and the activities of phosphatases were studied in the rhizosphere of four varieties each of clusterbean (Cyamopsis tetragonoloba(L.) Taub.), mung bean (Vigna radiata(L.) Wilczek), moth bean (Vigna aconitifolia(Jacq.) Marechal) and pearl millet (Pennisetum americanum(L.) Leeke) grown in pots containing soil low in available P. Activities of dehydrogenase and phosphatases were greatest 25 days after sowing and remained constant from 50 days after sowing until crop maturity. Rhizosphere soils showed higher activities than other soils: 26–158% for acid phosphatase, 66–264% for alkaline phosphatase and up to 292% for DHA. Dehydrogenase and alkaline phosphatase activities were significantly higher in the rhizospheres of legumes than in those ofP. americanum.In general, the rhizospheres ofC. tetragonoloba‘HFG314’,V. radiata‘PDM62’,V. aconitifolia‘IPCMO344’ andP. americanum‘RCB2’ had higher activities than those of other varieties of the same species. Acid phosphatase activity was lower than alkaline phosphatase activity and differences between species and varieties were small and nonsignificant. The results suggest that the higher phosphatase activities in the rhizospheres of some crops may increase P availability and utilization from arid soils.
Activity of cytoplasmic acetyl-CoA hydrolase in sheep liver and its potential role in heat production
Authors: Jessop N. S. , Scollan N. D. , Souter M. J. , Crabtree B.
Published: March 2009

Acetyl-CoA hydrolase which is stimulated by adenosine-5′-triphosphate is present in the cytoplasm of ovine liver and, unlike in certain others species, is not inactivated by cold. It is suggested that this enzyme is involved in a substrate cycle between acetate and acetyl-CoA. The heat produced as a result of such cycling may be as much as 2·5% of basal heat production and may be partly responsible for the increased heat increment that often follows the ingestion of diets that provide large quantities of acetate.
Nutrient metabolism and rumen micro-organisms in sheep fed a poor-quality tropical grass hay supplemented with sulphate
Authors: Morrison M. , Murray R. M. , Boniface A. N.
Published: March 2009

A feeding trial was performed during 1986, in Townsville, Australia, to describe alterations in nutrient metabolism, and the coincident gross changes in rumen microbiology, when a sulphurdeficient diet was supplemented with inorganic sulphur. Eight Merino sheep were fedad libituma spear grass (Heteropogon contortus) hay of low sulphur content (0·4 g/kg DM), supplemented with all other essential minerals. Upon supplementation, daily sulphur intake was increased toc.0·75 g and four animals continued to be fedad libitum(group A) whilst the remaining animals were restricted in feed intake (group B). Sulphur supplementation caused a twofold increase in the feed intake of group A (P< 0·05). In both groups of animals, sulphur supplementation increased the fermentation of cotton thread cellulose (P< 0·05), as well as of ground plant dry matter (P< 0·05), suspended in the rumen in nylon bags for 24 and 48 h. The apparent digestibility of organic matter (AOMD) was also increased by sulphur supplementation; from 30·6 to 39·3% in group A (P< 0·05) and from 35·1 to 41·5% in group B (P> 0·05). The difference in AOMD between groups with sulphur supplementation was not significant, despite group B maintaining a longer retention of fluid digesta in the rumen (20·7 v. 25·3 h) with a significantly lowered rumen volume (4·68 v 3·67 litres,P< 0·05) and outflow of fluid digesta from this site (5·31 v 3·58 litres/day,P< 0·05). Sulphur supplementation increased the molar proportion of acetic acid in rumen fluid (P< 0·05) but lowered propionic and butyric acids in group A (P< 0·05). Only the molar proportion of propionic acid in rumen fluid was significantly lowered in group B (P< 0·05). In both groups of animals, counts of fluid-borne rumen bacteria, protozoa and sporangia of rumen anaerobic fungi (RAF) all increased significantly with sulphur supplementation (P< 0·05 in all instances), but no significant differences were observed between groups in microbial counts, despite the different feeding regimes. The increase in sporangial forms of RAF was most marked; no sporangial forms were detectable until the diet was supplemented with sulphate and measurable concentrations of rumen sulphide were observed. This is the first account of nondetectable concentrations of RAF brought about by the nutritional status of the diet.
Flowering and pod and seed development in pigeon pea (Cajanus cajan)
Authors: Togun A. O. , Tayo T. O.
Published: March 2009

Flower, pod and seed development were studied in the cultivars Cita-1 and Cita-2 in two field trials in 1985–86, in Ibadan, Nigeria. Flowering within any inflorescence was acropetal. On each plant the terminal inflorescence was the first to flower and, generally, inflorescences developed basipetally. A total of 569 flowers (mean of five plants) opened on Cita-1; of these, 20 were on the terminal inflorescence, 130 on axillary inflorescences and 419 on inflorescences on primary branches. For the 605 flowers (mean of five plants) which opened on Cita-2, the distribution was 19, 161 and 425, respectively.On Cita-1, 158 pods formed on average, of which 7 were on the terminal inflorescence, 33 on axillary inflorescences and 118 on inflorescences on primary branches lower down the plant. On Cita-2, for the 185 pods counted at maturity, the distribution was 8, 43 and 134, respectively. Some 72 and 69% of the total number of flowers which opened on Cita-1 and Cita-2, respectively, were aborted. In both cultivars, 99% of the mature pods were formed from flowers which opened within 24 days of the start of anthesis; the number of pods retained largely determined seed yield. The inflorescences which developed on the primary branches contributed 70% (Cita-1) and 66% (Cita-2) of the total seed yield. Early-formed pods were heavier than those formed later. Individual pods attained physiological maturity 35–42 days after successful pollination of the flower. At physiological maturity of the pod, the seed contained 3·72 % N, 0·45% P and 2·76% K, and the husk contained 1·98% N, 0·16% P and 1·96% K. The majority of open flowers which aborted were produced on primary branches, indicating that the primary branches have the greatest potential for increasing seed yield. A shorter flowering period might ensure greater retention of open flowers.
Seasonal changes of ingesta mean retention time and forestomach fluid volume in indigenous camels, cattle, sheep and goats grazing a thornbush savannah pasture in Kenya
Authors: Lechner-Doll M. , Rutagwenda T. , Schwartz H. J. , Schultka W. , Engelhardt W. V.
Published: March 2009

The study was carried out in northern Kenya in 1984–87. Forestomach volumes and digesta retention times were measured using Cr-EDTA or Co-EDTA as fluid markers and Ce-labelled particles or Cr-mordanted particles as paniculate phase markers.

Mean retention times of fluid and of particles were longer in the dry season than in the green season in all four animal species. The increase of particle mean retention time, as a percentage of the values in the green season, was highest in sheep (46%), followed by cattle (27%), goats (22%) and camels(18%). Forestomach volumes were also greater in the dry than in the green season; the increase was again highest in sheep (55%), followed by cattle (31%), goats (29%) and camels (28%). Outflow rates of fluid from the forestomach and the selectivity factor, by which small particles were retained longer in the forestomach than fluid, did not differ significantly between the seasons.

It is suggested that the increase of forestomach volumes is an effective adaptation to dry-season pasture conditions. It enables the animals to retain feed particles longer in the forestomach and so improve fibre digestion when feed quality is low. Cattle and sheep, which depend on a poor quality diet, improve fibre digestion in this way in the dry season more effectively than camels and goats. Camels and goats, on the other hand, were able to select a diet of such quality, even in the dry season, that their need to augment fibre digestion was reduced.
Changes in the baseline of the Crop Water Stress Index for lucerne (Medicago sativa) over 3 years
Authors: Rechel E. A. , DeTar W. R. , Ballard D.
Published: March 2009

The ability to detect and measure water stress accurately is critical for optimizing crop production. The Crop Water Stress Index (CWSI), the linear relationship of the difference between foliage and air temperatures as a function of the air vapour pressure deficit, is one widely used method. Under well-watered conditions, a ‘baseline’ is derived that is crop specific and presumed fairly constant, despite differences in development and physiology. This study reports changes in the baseline of the CWSI for lucerne crops not subjected to water shortage over 3 years. Studies of lucerne in California from April 1986 to October 1988 used the CWSI to plan irrigations. It was necessary to re-establish the baseline periodically throughout the experiment. In the first year it was similar to that reported in the literature, but in the second year it had a statistically significant steeper slope and higher intercept. In the third year, the regression equation was similar to that in the first year. The changes in the baseline are thought to be a result of crop age rather than year-to-year weather fluctuations. The baseline needs to be determined periodically as the crop matures, to ensure accurate interpretation of plant water stress.
Influence of autoclaved or irradiated Aspergillus oryzae fermentation extract on fermentation in the rumen simulation technique (Rusitec)
Authors: Newbold C. J. , Brock R. , Wallace R. J.
Published: March 2009

A rumen simulation device (Rusitec) was used to compare the effects of autoclaved and γ-irradiated Aspergillus oryzae fermentation extract (AO) with those of untreated AO on rumen fermentation. Each vessel received daily 18 g of a basal diet consisting of 500 g hay, 299·5 g rolled barley, 100 g molasses, 91 g fishmeal and 9·5 g of a minerals and vitamins mixture/kg dry matter. AO preparations (0·25 g/day) were added with the feed. Dry matter digestion increased at 24 h, but not at 48 h, after adding AO, suggesting that AO stimulated the rate of digestion but not the extent. AO increased the numbers of total and cellulolytic bacteria by 90 and 50%, respectively. Irradiated AO stimulated numbers of bacteria in the same way as AO, although to a slightly lesser extent. Autoclaved AO had no effect. Thus, the mode of action of AO on rumen fermentation depends on a heat-labile component, possibly a nutrient or an enzyme, or metabolic activity. Viable AO cells are not required to stimulate bacterial growth and activity.
Effects of bentonite on fermentation in the rumen simulation technique (Rusitec) and on rumen ciliate protozoa
Authors: Wallace R. J. , Newbold C. J.
Published: March 2009

Bentonite (2 g/day) was added to four vessels in the rumen simulation technique (Rusitec) and the effects on the fermentation were compared with four control vessels over a 21-day period. Vessels in both groups were supplied with 20 g/day of a diet containing, per kg, 500 g hay, 299·5 g barley, 100 g molasses, 91 g fishmeal and 9·5 g of mineral/vitamin mix. Numbers of ciliate protozoa were reduced by 69% (40v. 12·8 ×103/ml) in vessels receiving bentonite. The viable count of bacteria was increased by one-third in these vessels (4·8v. 3·6 × 108/ml), and ammonia production was 54·7 and 76·7 mg/day in the bentonite and control vessels, respectively. Other effects on fermentation products and metabolic activities were minor, except that the rate of breakdown of [14C]leucine-labelledSelenomonas ruminantiumprotein was 47% lower in fluid taken from vessels receiving bentonite. Bentonite did not affect the rate of bacterial breakdown by protozoa immediately when it was added to rumen fluid invitro, although a decline in activity was becoming apparent after 4 h incubation. Microscopic examination of rumen fluid to which bentonite was added indicated that some bentonite was ingested by protozoa, but that its main toxic effect was at the cell surface, causing interference with the motion of cilia and thereby preventing motility of protozoa, particularly the holotrichs.
Ultrasonic scanning for determination of stage of pregnancy in the llama (Lama glama): a critical comparison of calibration techniques
Authors: Iason G. R. , Elston D. A. , Sim D. A.
Published: March 2009

Measurements of foetal head diameter (HD) and trunk diameter (TD) were made using ultrasonic scanning of 11 pregnant llamas (Lama glama). Each llama was scanned fortnightly to obtain measurements of HD and TD from c. 84–271 and 65–168 days since mating respectively. There were approximate linear relationships between TD and days after mating and between HD and the logarithm of days after mating.

Calibration equations for predicting the number of days after mating (d) from foetal measurements constructed using (i) the inverse method in whichdis regressed on HD or TD and (ii) the classical method in which HD or TD are regressed ond. These calibration methods were assessed by crossvalidation, treating each animal in turn as the individual for which predictions were required. Analysis of the prediction errors showed bias in the classical method, which consistently underestimateddat low values. A components of variance analysis indicated substantial variation between individuals which must be taken into account in calculating standard errors of prediction (S.E.P.) and confidence intervals. S.E.P. ofdfrom TD can be reduced from 12·5 to 10·4 days by increasing the number of observations on an individual from one to four at fortnightly intervals. For prediction from HD, the equivalent figures are size dependent: examples are from 8·3 to 5·6 days, and from 26 to 18 days, for HDs of 2 and 6 cm respectively. The effect of small positive correlations between residuals of successive fortnightly measurements on the same llamas had a negligible effect on S.E.P.S, increasing them byc. 0·2 days. Ultrasonic scanning is suitable for determination of stage of pregnancy of llamas providing S.E.P.S which are small in relation to their long gestation period (335–360 days).
Intake, rumen volume, retention time and digestibility of diets based on poultry litter and wheat straw in beef cows before and after calving
Authors: Brosh A. , Holzer Z. , Aharoni Y. , Levy D.
Published: March 2009

Beef cows in the 14 weeks before calving and during the first 12 weeks after calving were fed one of three diets based on 15, 30 and 45 % broilers poultry litter (PL), 20 % maize grain (MG) and 65, 50 and 35% wheat straw (WS) on a DM basis, respectively. They were housed from June to November in individual open pens. Four weeks before and 9 weeks after calving, in vivo digestibility, fibre and fluid mean retention time (MRT) were measured. The intake of all diets before calving was low. Nine weeks after calving the intake of DM increased 2·1 times on the 15% PL diet, and 1·6 times on the two other diets. The in vivo digestibility of the 15% PL diets was lower than that of the two other diets before calving, and increased after calving, in spite of the doubling of its intake, while that of the 45% PL diet decreased. The mean retention time of fibre in the digestive tract was not affected by the increase in DM intake after calving on the 15 % PL diet and was shortened on the two other diets. It seems that the combination of the volume taken up by the gravid uterus and the bulkiness of the 15% PL diets (65% WS) reduced the intake and impaired the digestibility of that diet before calving. After calving, the fibre pool increased considerably and consequently both intake and digestibility were increased.
Analysis of size-grouped potato yield data using a bivariate normal distribution of tuber size and weight
Authors: Hall J. E. , Glasbey C. A.
Published: March 2009

A bivariate normal model is proposed for the joint distribution of potato tuber size and weight. Parameters in the model are estimated from the yields and numbers of tubers in a range of riddle-size categories. The method is illustrated using data from a field experiment; parameters are estimated for each plot, and subjected to analysis of variance. The result is a more succinct summary of treatment effects than that produced in the traditional analysis, where data from each riddle size are analysed separately.
A method for calculating the population/yield relations of groundnut (Arachis hypogaea) in semi-arid climates
Authors: Azam-Ali S. N. , Nageswara Rao R. C. , Craigon J. , Wadia K. D. R. , Williams J. H.
Published: March 2009

Between 1980 and 1986, six field experiments were conducted to investigate the relations between planting density, total dry matter and pod yield of groundnut (Arachis hypogaeaL. cv. TMV2) grown at different levels of irrigation and rainfall at two sites in central India. In general, the relationship between total dry matter and planting density for most treatments was well described by the function:

where W is the crop dry weight per unit ground area,wmis the maximum weight per plant, Wmis the maximum crop weight per unit ground area and P is the plant population. Because the harvest index,h, was constant for each treatment irrespective of plant population, a similar equation described the relationship between pod yield and planting density. When nine of the eleven treatments planted in a square (i.e. 1:1) arrangement were compared, the asymptotic value Wmvaried between treatments depending on available soil water and atmospheric demand. To quantify the effects of plant and environmental factors on crop productivity, a ‘transpiration equivalent’ (ωw; (g/kg)/kPa), i.e. the product of the dry matter/water ratio and mean seasonal saturation deficit D, was used as a crop constant to calculate productivity at each site or season from a knowledge of seasonal rainfall and/or irrigation and soil water-holding capacity. Thus, total crop productivity, W'8, was calculated using the equation W'8= ωwS/D where S (mm) is a soil supply term dependent on soil water-holding capacity and monthly values of rainfall and/or irrigation. When values for Wmand W'8were plotted against each other, a linear regression was obtained with a slope = 1·02 (R2= 0·78). The mean harvest index of 0·38 was used to predict pod yield from a knowledge of W'8. It was concluded that of all the climatic, soil and management factors that influence crop growth in semi-arid situations, it is the interaction between the supply of and demand for water that ultimately determines total productivity, pod yield and optimum plant population.
Proceedings of the Twenty-Third Meeting of the AFRC Modellers' Group
Authors: France J.
Published: March 2009

This group, which is concerned with the applications of mathematics to agricultural science, is sponsored by the Agricultural and Food Research Council. It was formed in 1970, and has since met at approximately yearly intervals in London for one-day meetings. The twenty-third meeting of the group, chaired by P. H. Nye of the Department of Plant Sciences at the University of Oxford, was held in the Wellcome Meeting Room at the Royal Society, 6 Carlton House Terrace, London on Friday, 7 May 1993, when the following papers were read.
Potential of immunization for increasing animal production
Authors: Holder A. T. , Aston R. , Flint D. J.
Published: March 2009

The use of exogenous hormone treatment as a means of increasing the efficiency of animal production has, in general, been rather poorly received by both the public and government agencies. This antipathy towards hormone treatment has tended to direct research effort into finding less contentious ‘hormonefree’ methods of improving animal production. Over the last 10 years, immunological manipulation of the endocrine system has emerged as an attractive possibility in this search. In this review we briefly outline three approaches under current consideration, whereby growth hormone (GH) concentrations or activity are modified. These methods involve immunological manipulation of GH release, use of antibodies as GH mimics and antibody-mediated enhancement of GH action.
Effects of cultivation and nitrification inhibitor on soil nitrogen availability after a grass ley and on the response of the following cereal crop to fertilizer nitrogen
Authors: Webb J. , Froment M. , Sylvester-Bradley R.
Published: March 2009

Three experiments carried out at Bridget's Experimental Husbandry Farm, Hampshire between 1984 and 1987 on clay loam and silty clay loam soils over chalk investigated the response of winter wheat grown after grass to spring-applied fertilizer nitrogen. The influence of method of establishment and the use of a nitrification inhibitor were also studied. Yields were similar whether the crops were established by direct drilling or following ploughing. Crops required between 88 and 209 kg N/ha nitrogen fertilizer for optimum yield. There was no consistent difference in nitrogen requirement nor were there consistent differences in nitrogen offtake (which is the amount of N in kg/ha removed in harvested grain) or apparent fertilizer recovery following ploughing or direct drilling. The use of a nitrification inhibitor increased grain yield when applied in the autumn without fertilizer, but not when applied with fertilizer in the spring.
Effect of insect pollination on seed production in linseed (Linum usitatissimum)
Authors: Williams I. H. , Simpkins J. R. , Martin A. P.
Published: March 2009

The effect of bee visits to the flowers on flower longevity and capsule, seed and oil production in linseed (Linum usitatissimum L.) cv. Antares, was investigated in two very different growing seasons (1988 and 1989); plots caged to exclude insects, plots caged with a honeybee colony and plots uncaged and open-pollinated by honeybees and bumblebees were compared. The experiments were conducted at Rothamsted Experimental Station Farm in Hertfordshire.

Although honeybee visits to the flowers resulted in earlier petal fall, they did not increase capsule or seed production. It is concluded that the crop is self-fertile, self-pollinates well, and that inadequate pollination is not a factor limiting yield.
A method of assessing the yield stability of crop genotypes
Authors: Westcott B.
Published: March 2009

A method of assessing genotypic stability is proposed in the case where genotype yields are measured across environments but no concomitant environment data are available. The method is introduced in a practical context and two examples of its use with actual data are presented.

The method depends ultimately on the choice of a suitable measure of similarity between genotypes. Most of the stability information appears in a sequence of plots, where stable genotypes are immediately highlighted as consistently more remote points.
The growth and yield of winter wheat following 10 years of continuous ploughing, shallow-tine cultivation or direct drilling on a non-calcareous clay soil
Authors: Ayling Sarah M. , Bacon E. , Christian D. G. , Goss M. J.
Published: March 2009

The growth and grain yield of winter wheat were measured in plots which had been direct drilled, mouldboard ploughed or shallow-tine cultivated for 10 consecutive years. The experiment was carried out on a non-calcareous clay soil prone to winter waterlogging. In 1985 the crop grew well on all cultivations and grain yield, average 7–2 t/ha, was similar in all treatments and no adverse effects on wheat growth or on grain and straw yield were observed.
A study of field drain ochre deposits. 2. The distribution of micro-organisms
Authors: Dbwi I. Ap , Johnson D. B. , Kelso W. I.
Published: March 2009

Sheathed filamentous bacteria,Leptothrixspp. andGallionellaspp., were observed in ochre samples from sites in England and Wales.Thiobacillus ferrooxidanswas found in acidic samples (pH < 4·0) and in ochre from drainage water of near neutral pH suggesting that it can contribute to ochre formation over a wide range of drainage water pH, Heterotrophic bacteria capable of growing in artificial media of low pH and complexdegrading heterotrophic bacteria were also isolated. Some ochre deposits could be described as either pyritic or filamentous but the majority of samples fell between these extremes and had various combinations ofT. ferrooxidans, sheathed filamentous bacteria and other heterotrophic bacteria.
A comparative in vitro digestion trial using inocula of livestock from South Turkana and Kitale, Kenya
Authors: Coppock D. L. , Ellis J. E. , Waweru S. K.
Published: March 2009

The dry-matter digestibilities of 13 important herbaceous and browse forages from an arid rangeland in north-western Kenya were evaluated in a comparative in vitro trial using rumen fluid from indigenous sheep, goats, a camel, and Merino sheep kept at an agricultural laboratory. All inoculum donors had varied diets preceding the experiment, but little substantial difference was observed in the ability of each fluid to digest test materials. Tt was concluded that the Merino sheep inoculum provided an adequate substitute for inocula from indigenous animals for studies of the nutritional ecology of free-ranging livestock.
Observations on resistance in white clover (Trifolium repens L.) to the stem nematode (Ditylenchus dipsaci (Kühn) Filipjev)
Authors: Cook R. , Evans D. R.
Published: March 2009

The expression of symptoms of stem nematode reproduction on a total of 53 white clovers (26 cultivars, 14 genepools and 13 introductions from plant collections) was studied in a series of field and glasshouse experiments. Seedlings or stolon-tip cuttings were inoculated with nematodes and the clovers classified by the proportion of plants which developed symptoms. Significant differences were found between varieties although in each test the majority was intermediate between more resistant and susceptible extremes. There was significant positive correlation between tests, in spite of different inoculation methods and different average levels of susceptibility. Very large-leaved cv. Aran was more resistant than most other clovers tested, and small-leaved cv. S. 184 was more susceptible. There was no general correlation of leaf size with reaction to stemnematode. Small-leaved cv. Pronitro was also resistant while several large-leaved cultivars were susceptible. In observations of plants exposed to nematodes over a long period, either by sequential inoculations or through perpetuating latent infections, apparently resistant plants eventually succumbed and supported nematode reproduction. It has not been determined whether this was because selection for virulence in the nematodes had occurred.
Genetic and phenotypic aspects of doe productivity in four breeds of rabbits
Authors: Khalil M. H. , Afifi E. A. , Emara M. E. , Owen J. B.
Published: March 2009

Data on 841 purebred Bauscat, White Flander, Giza White and Baladi Red litters provided estimates of genetic, phenotypic and environmental parameters for gestation length, litter size at birth and at weaning, mortality and sex ratio at weaning. A total of 170 daughters (paternal half-sisters) of 76 sires were available for the analysis. No important differences were detected among breeds for litter traits studied except litter size at weaning (P< 0·001). Year of kindling affected (P< 0·001) gestation length, litter size at birth and mortality percentage. No clear patterns of the effect of parity and month of kindling on litter traits were observed. The sire of the doe and doe within sire affected most of the traits studied. Estimates of heritability indicated that the sire's genetic contribution to litter traits are much higher during the pre-natal period than for the suckling period. Estimates of repeatability for litter traits studied were relatively low. Genetic and phenotypic correlations between gestation length and other litter traits were relatively low. Litter size traits were positively correlated both genetically and phenotypically. Estimates of genetic and phenotypic correlation between litter size traits and preweaning mortality were generally negative. Phenotypic and environmental correlations were generally very similar in size and sign. Predicted direct selection was shown to give greater improvement in litter size at birth than indirect selection through litter size at weaning.
Use of soluble glass rumen boluses to provide a supplement of copper for suckled calves
Authors: Givens D. I. , Zervas G. , Simpson V. R. , Telfer S. B.
Published: March 2009

An experiment was carried out on a site where the copper content of herbage was relatively low (4·7–6·2 mg/kg d.m.) to examine the value of copper contained in soluble glass rumen boluses as a means of providing supplementary copper to calves.

Forty-five spring-born suckled calves (mean live weight 91 kg) were divided into three groups on the basis of body weight. Animals in group GB were given two boluses initially, those in group CI each received copper injections at approximately monthly intervals and those in group C remained as controls throughout. Group C calves became progressively hypocupraemic (minimum mean plasma copper 8·5 μmol/1) compared with those in groups GB and CI which showed an increase in plasma copper concentration. In addition measurements of plasma caeruloplasmin activity, blood haemoglobin concentration and erythrocyte superoxide dismutase activity all showed significant increases due to treatment. No response in live-weight gain was observed but overall live-weight gain was approximately 1·05 kg/day. Although the initial response in plasma copper was quicker with copper injections, measurements of erythrocyte superoxide dismutase activity and haemoglobin showed advantages of glass boluses not shared by copper injections. This possibly resulted from the slow release nature of copper in the glass. Under the conditions of the experiment where herbage molybdenum values were relatively low (1·2–1·9 mg/kg d.m.), copper contained in soluble glass boluses appeared to prevent hypocupraemia in calves as effectively as regular copper injections.
Comparative influence of soil and management on barley yield in the Vale of Whitehorse, England
Authors: Ogunkunle A. O. , Beckett P. H. T.
Published: March 2009

The reliability of the soil series as a basis for crop yield prediction was examined by comparing the influence of soil and management (inter-farmer differences) on the variance of barley grain yield. Yields of barley were measured from farmers' fields for 2 years and in undisturbed soil cores for 5 years. Fields on different soil series within farms and on the same soil series across farms were used. Linear stepwise regressions of yield on a number of soil properties were also examined to assess the relative influence of soil and management on the properties that were significant to yield.

The results show that generally, soil classification has a strong influence on yield variance, but there is clear evidence that the influence of management, specifically the cumulative effect of P and K fertilizer applications, is considerable. Thus in an undisturbed core, for the first 3 years when N, P, K and Mg were applied, the influence of soil was stronger than that of management, but this was reversed in the 4th year when P and K were not applied. Similarly in the field, the influence of soil was stronger in the 1st year, but this was reversed in the 2nd year, although on different field-farm combinations. In all cases, the influence of neither soil nor management was significantly stronger than the other.

The results of the regression studies also confirmed those of yield variance in that in general, neither soil nor management has exclusive control of the yield variance. The soil was significantly stronger than management in the control of only coarse sand content at 0–15 cm out of the four soil properties (including Mg and pH (0–15 cm) and K (15–30 cm)) which were significant to yield in the cores. On the other hand, management was significantly stronger than soil in the control of only available P at O–15 cm out of the three soil properties (including Cu and Mg both at 0–15 cm) that were significant to field yield.

It is concluded that for soil classification to be a reliable basis for yield prediction and/or agrotechnology transfer, the effect of management must be emphasized.
The effects of optimum heading date and its stability on yield and consistency of performance of barley and durum wheat in dry areas
Authors: Hadjichristodoulou A.
Published: March 2009

Data from several trials with large numbers of barley and durum wheat varieties conducted mainly under dryland conditions in a Mediterranean climate were used to study the effects of heading date and its stability on consistency of performance.

Heading date was expressed in relation to one or more control varieties, because of the significant genotype × environment interactions. Data from trials during 1969–85 were used to determine optimum heading date in order to aid selection for consistently high-yielding varieties. For rainfed barley in Cyprus this optimum range was between 2 days after and 5–8 days before heading of Kantara barley and for rainfed wheat 1 day after to 4 days before heading of Karpasia durum wheat. It is suggested that by selecting at one environment single plants from segregating populations or lines from nurseries and yield trials, having heading date within the optimum range, the chances of selecting consistently high-yielding lines are increased.

The genotype and environment significantly affected heading date. Stability of heading date was genetically controlled. Early varieties tended to be more variable than late varieties of both barley and durum wheat. Lines with the lowest values for variance of heading date gave low yields under variable conditions because they were very late. The consistently high-yielding lines of barley and durum wheat had variance of log transformed heading (s2log2) 0·025–0·050.

In durum wheat, lines with the lowest variance were later in heading date than the optimum for Cyprus environments. The absolute values of variance of heading date of varieties varied with year, but significant positive correlations were obtained between years (r = 0·84 for durum wheat and r = 0·55 for barley, P < 0·01).

Barley, which is considered a safer crop for the driest parts of the Mediterranean countries, heads a few days earlier than durum wheat but its better performance may be attributed also to its ability to grow faster than wheat in the winter months.
Blossom-end rot of watermelon in the southern region of Oman (Dhofar)
Authors: Hammouda A. M.
Published: March 2009

Blossom-end rot, a non-parasitic disease, was found to occur widely on some oblong varieties of watermelon, causing much damage in the southern region of Oman (Dhofar). Fruit contact with soil surface seems to be the major agent of blossom-end rot of watermelon, especially in the early stage. Incidence of watermelon blossom-end rot was apparently reduced by mulch using a mixture of dried grasses or coconut leaves.