Management of semi-domesticated reindeer (Rangifer tarandus tarandus) in the northern regions have historically focused on reindeer vegetation interactions. while few data on the food intake of these animals exist. Dry matter intake (DMI) was therefore estimated successively during winter in reindeer calves fed (i) ad libitum pelleted reindeer feed (RF-80; n = 6), (ii) fed ad libitum mixed lichens (n = 6) and (iii) in free-ranging reindeer calves (n = 3) on natural winter pasture (March/April; 69degreesN). Faecal output, determined with faeces collection bags, was 24 +/- 4, 6 +/- 3 and 22 +/- 3 g DM/day/kg BM0.75 in reindeer fed RF-80, mixed lichens and on winter pasture, respectively. Actual DMI of reindeer in captivity fed RF-80 and mixed lichens was 70 +/- 10 g DM/day/kg BM0.75 and 27 +/- 8 g DM/day/kg BM0.75 respectively. The DMI of the captive reindeer calves was accurately estimated on both diets on the basis of the digestibility of their diet and their faecal output. Using the same method, the DMI of free-rangeing reindeer calves on natural winter pastures in northern Norway was estimated to be 34-61 g DM/day/kg BM0.75. The present study discusses tractors that influence the food intake of reindeer in winter with emphasis on the seasonal regulation of appetite and DMI in these Arctic ruminants.
Morphological description based on features of the olive stone, such as its surface and shape, can help to determine an olive cultivar's identity. The description, however, is based on visual examination and is thus affected by the examiner's expertise. Although the eye has the capacity to discern texture and shape, the values that are assigned to score different levels or descriptor states, such as a highly scabrous to smooth surface or a circular to elliptic shape, are categorical values. Studies on scoring methodology have shown that the assignment to categories or classes is problematic. The purpose of the present work was to classify olive cultivars by computer-image analysis of olive stone characteristics using mathematical tools, such as fractal geometry and moments. Fractals were used to extract texture information, and moments were used to extract shape information. The results revealed an overall classification accuracy of more than 90% using a Mahalanobis distance. The fractals and moments calculated for stones from genetically identical trees of the same cultivar did not show any statistically significant differences. As environmentally independent and robust morphological descriptors, both fractals and moments showed potential for accurate and efficient classification of olive cultivars and eventual description of olive diversity.
The water-insoluble phosphorus (P) component ('residue source') was separated from four commercial triple superphosphate (TSP) products and its agronomic effectiveness evaluated. Two of the TSP products were sourced from the USA and two from the UK. Effectiveness was measured using a pot trial technique with ryegrass as the test crop. The residue sources were evaluated on 13 soils varying in key properties: readily plant-available P, texture, pH and organic matter content. Four of the soils were from Germany, one from Spain, five from the UK and three from France. Grass dry-matter yield and P offtake were measured at every cut on every soil. For both of these variables, significant responses to applied P were obtained on all soils. Mono-calcium phosphate (MCP) was used as the comparative P Source and effectiveness of the residue sources was estimated relative to that of MCP. Using dry-matter data, the residue sources were 44-87 % as effective as MCP; P offtake data provided corresponding estimates of 35-79 %. Both methods of estimation indicated the same ranking of residue sources in terms of relative effectiveness, those derived from USA products being more effective than those derived from UK products. The ranking was the same for all soils. The effectiveness of the residue sources relative to that of MCP appeared little affected by measured soil properties: texture, pH, available P or organic carbon content. The results indicate there is little difference in agronomic effectiveness of TSP products with water solubility greater than 85 %.
An experiment was designed to test the response of growing pullets to two changes in photoperiod (an increase from 8 to 14 h followed 5 weeks later by the reverse change, or a decrease from 14 to 8 h followed by an increase). The first change was made either at 35 days or at 56 days of age, to test the influence of age on the responses observed. Control groups were kept oil constant 8-h and constant 14-h photoperiods and the responses to appropriate single changes were also tested. Mean age at first egg varied from 111 days for birds given a single increment at 56 days to 166 days for pullets given an increase in photoperiod at 35 days followed by a reduction at 70 days. Responses to the single changes confirmed earlier reports that sensitivity to change in photoperiod varies with age ill a manner that is quantitatively predictable. Responses to the double changes could be explained by Postulating that the initial change altered the 'physiological age' of the bird to all extent that was also quantitatively predictable. An early increase in photoperiod advances sexual development and makes the bird more sensitive to a subsequent decrease than would be expected by reference to its chronological age. An early decrease in photoperiod delays sexual development, which can have the effect of making the bird more or less sensitive to a subsequent increase since, ill layer-strain pullets, sensitivity to an increment in photoperiod normally increases Lip to about 9 weeks of age but decreases thereafter. Mean age at first egg predicted using these concepts was very highly correlated with observed age at first egg. The results provide a rational basis for constructing a model to predict age at first egg for any combination of increases and decreases in photoperiod applied to growing pullets.
This Study was conducted to determine the effects of plastic film mulch on percentage of abortive tillers and harvest index (HI) in two spring wheat populations, and to explore its mechanism in relation to size inequality and life-history strategies theory. Field-grown spring wheat mulched with plastic film shows a remarkable increase in grain yield (an average increase of 38.5% over non-mulched control), which mainly results from the significant increase in above-ground biomass (+44.7%). At the same time, however, reproductive allocation (spike weight/above-ground biomass, -5.2%) and harvest index (-4.5%) were significantly lower (P<0.05) in mulched than unmulched populations in both of the two cultivars used. Meanwhile, the number and weight of barren shoots and the ratio of barren shoot biomass to total shoot biomass were significantly greater in mulched populations than unmulched controls both at booting, flowering and ripening stages. From tillering to ripening stages, the tendency of G (Gini coefficient) shows obvious differences between mulched populations ('Lambda' type with the peak of G at booting stages) and non-mulched controls ('V' type with the lowest G at flowering and rebounded at ripening stage). At booting and flowering, the G was significantly higher in mulched populations than unmulched controls, and it was just contrary at ripening. Reproductive allocation and HI were both negatively correlated to average G of the populations, which indicated that resource use efficiency of a crop is inversely related to plant-to-plant variability and also provided further evidence for the views that stand uniformity of field crops is an important aspect of high yield formation. From these results, it was concluded that appreciable growth redundancy occurred in spring wheat populations mulched with plastic film, which may result from the exacerbated inter-plant competition and self-thinning (evidenced by the increased degree of Gini coefficient at booting and flowering stages). Thus, spring wheat cultivation with plastic film mulching does not always mean efficiency, although there is a remarkable increase in grain yields.
The gastrointestinal tract (gut) contents of male Zebu cattle (Bos indicus) were studied in the southern Sahelian zone of Mali. Measurements were carried out on 39 animals in mid-dry season (MDS) and 15 at the end of the dry season (late dry season, LDS). After overnight fasting, the animals were weighed and then slaughtered. The different gut compartments were emptied and representative samples of their fill were analysed for contents of dry matter (all) and NDF (reticulo-rumen only). Related to fasted live weight (FLW), gut fresh matter (FM) fill (g FM/kg FLW) increased from 165(.)7+/-4(.)81 g in MDS to 227(.)5+/-3(.)05 g in LDS (Pless than or equal to0(.)001), liquid gut contents (g fluid/kg FLW) increased from 138(.)9+/-4(.)65 to 193(.)5+/-2(.)49g (Pless than or equal to0(.)001) and gut dry matter fill (g DM/kg FLW) increased from 26(.)8+/-0(.)88 to 34(.)0+/-0(.)97 g (Pless than or equal to0.001). Fresh matter content of the reticulo-rumen accounted for 77% and 80% of the entire gut FM fill in MDS and LDS, respectively. While the NDF component in reticulo-rumen fill (g NDF/kg DM) increased from 778(.)5+/-5(.)63 g in MDS to 836(.)6+/-6(.)37g in LDS (Pless than or equal to0(.)001), the ratio between dry matter and fluid in the reticulo-rumen (g DM/g fluid) decreased from 193(.)2+/-10(.)17 g in MDS to 169(.)0+/-5(.)54 g in LDS (Pless than or equal to0.05). The data support the notion that African breeds of Zebu cattle adjust to deteriorating feeding conditions by increasing reticulo-rumen dry matter and fluid contents. In-depth studies are needed to quantify the physiological benefits resulting from this strategy.
A method for quantifying treatment comparisons for a situation in which there are too many zeros in the dataset for a conventional analysis of variance to be valid is presented. The method assumes the existence of a latent variable such that zero observations correspond to values below a threshold, and non-zero observations are transformed to fit the part of the distribution above the threshold. The method is known as Tobit analysis in econometrics. Parameters are estimated by maximum likelihood and standard errors obtained, all using standard numerical routines. Use of the method is demonstrated by analysis of a dataset of crop lodging, and it is anticipated to be widely applicable to other types of data for which high numbers of zeros prevent conventional analysis.
A comparative slaughter experiment was carried out to examine the effects of feeding either grass silage alone or a mixed diet of silage and concentrate on animal performance and the partitioning of nutrients between lean and fat deposition in steers. Eighteen Hereford x Friesian steers were randomly assigned to two dietary treatments; grass silage only (S) or a mixture of grass silage and a barley/soya bean meat concentrate (80:20 on fresh basis) in the ratio of 60:40 (on a metabolizable energy basis ; SC), and to one of three target slaughter liveweights, 250, 350 or 500 kg. Metabolizable energy (ME) intake was maintained at 800 kJ ME per kg metabolic liveweight (kg(0.75)) per day. The relationships between chemical composition and empty body weight (EBW) at slaughter were assessed using allometric equations (log(e)gamma = log(e)a + b log(e) EBW). When assessed across the slaughter weights, supplementing silage with concentrates resulted in higher rates of liveweight (P<0.001), carcass fat (P<0(.)05) and protein (P<0(.)01) gains and a reduction in time taken to reach the average slaughter weight by 57 days (P<0(.)001). Carcass protein deposition was relatively linear across the slaughter weights (250-500 kg) and the relationship with EBW was Y= 0(.)2372X(0.8831) across treatments and did not differ between the diets. The rate at which carcass fat was deposited in relation to weight across all steers was Y=0(.)0004X(1.9648) and was not different between the two diets. Hence, ratios of carcass fat: protein and carcass fat: protein gain ratios were not different. The results suggest that the main effect of feeding grass silage compared with grass silage-concentrate at similar levels of ME intake was to increase the rate of tissue accretion, but nutrient partitioning between fat and protein deposition was unchanged. There was no evidence of increased carcass fat: protein deposition in silaLye-fed animals, which suggests that there is no problem of greater fat and reduced protein deposition in animals fed higher quality grass silage.
An experiment was carried out to determine endogenous excretion of allantoin (AN) in lambs and kids fasted and fed on a purine-free diet (milk replacer: MR). After weaning (40-50 days after birth), the animals were reared by feeding on MR until they were 120 days old. At 8 months of age, they were fasted for 8 days, and then re-fed on MR for 13 days. After weaning, AN excretion gradually decreased almost to a constant level at 80-120 days after birth (mean 0.14 mmol/kgW(0.75)/day). In goat kids, there was variation but no definite trend in urinary AN excretion in the period 40-120 days (mean 0.35 mmol/kgW(0.75)/day). Urinary AN excretion was very low after fasting for 8 days, mean values (per kgW(0.75)/day) being 0.13 mmoles for lambs and 0.17 mmoles for goat kids. In lambs, urinary AN excretion did not increase following subsequent re-feeding of MR, and for goat kids the increase was small. Changes in plasma AN concentration after fasting and re-feeding showed a similar response to that of urinary AN excretion for both sheep and goats so that there was a high positive correlation between the plasma AN and urinary AN excretion (r = 0.881 for lambs and r = 0.853 for kids). It is concluded that, in these young animals, urinary AN excretion rapidly responds to changes in plasma AN and is therefore likely to be a useful practical indication of endogenous PD excretion.
Alley cropping is a prototype agro-forestry system practiced in many parts of the humid tropics. It is one of the established, promising and sustainable low-input soil management ventures. An improved understanding of the eco-physiological relationships between the arable and perennials in this system could contribute to solving issues of sustainability for nutrient use and system productivity. Field experiments were conducted in Alabata and Ajibode, located in the derived savannah zone of Nigeria, to evaluate the comparative effects of an alley cropping system, arbuscular mycorrhizal fungi inoculation and cassava intercropping on maize yield. These on-farms trials (research managed and farmer managed) were conducted in the 1993/94 and 1995/96 growing seasons, in Rhodic Kandiustalf soil type with low nutrients. Each trial was a split-plot factorial arranged in randomized complete blocks with three replications. Biomass productions of maize and cassava tuber yield were determined. The results obtained at Alabata indicated that the maize plants were heavily infected with AM fungi whether inoculated or not. The hedgerow trees did not have a significant effect on maize yield. The increase in yield brought about by the alley cropping system was generally less than 15 %, except in one farm where increases of 34.6 and 46.5 %, were recorded in AM-inoculated and non-inoculated plots respectively. The introduced AM fungi did not significantly enhance maize yield at Alabata; the percentage increase was not more than 24 %. This trend was also observed at Ajibode. Cassava tuber yield was found to be suppressed by the alley cropping system irrespective of the cultivar. The decrease in yield ranged from 2.6 to 150.8 %. However, inoculation of the cassava with exotic AM fungi brought about an enhancement of its tuber production. The increase ranged from 20.7 to 189.8% depending on the treatment combination. It is therefore necessary to encourage adoption of the improved alley cropping system integrated with mycorrhizal technology.
Extending the duration of the late reproductive phase in wheat has been proposed as a possible avenue to improve spike fertility. There is a positive correlation between the number of fertile florets and the duration of the stem elongation phase when this phase is varied by extended photoperiod. Photoperiod treatments imposed during the vegetative period also influence the duration of stem elongation. The present study analysed the effect of long photoperiod (19 h) of different duration (10, 12, 14, 18 or 22 d) imposed before the onset of stem elongation on floret fertility in wheat. It was found that the length of the stem elongation phase was modified by earlier 'historic' photoperiod treatments imposed during previous phases. However, neither the number of fertile florets per spike nor the spikelet fertility was affected significantly by these historic treatments. The results of the study therefore showed that an increased duration of the late reproductive phase was ineffective in increasing the number of fertile florets, unless the length of that phase was directly altered by current photoperiod.
The origin and significance of an indent on laminae of wheat is unknown. The constancy, position and emergence of a leaf indent was recorded on a range of winter wheat cultivars sown on two dates in 1998/99 and three dates in 1999/2000. The time when the indent developed was also examined in 1999/2000. The indent appeared to be caused by tissue in the region of the ligule on the previous leaf swelling as the ligule formed. The synchrony between a ligule on one leaf and an indent on the next generally lasted until the ligule appeared from within the previous leaf sheath. The date of plant emergence influenced the pattern of tip to indent length throughout the life of the plant and different varieties also showed different patterns. There was strong correlation between the length of a leaf sheath and the length of the next (younger) lamina from the ligule to the indent.
Lentil (Lens culinaris Medik.) cultivars (Jordan 1 and Jordan 2) were sensitized to chlorsulfuron herbicide. Both cultivars were subjected to three doses of gamma-irradiation (90, 100 and 110 Gray) to develop plants tolerant/resistant to this herbicide. The herbicide-tolerant plants as well as the sensitized plants were subjected to acetolactate synthase (ALS) enzyme assay to reveal the biochemical basis of plant tolerance. The results indicated that as the radiation dose increased, the tolerance to the herbicide application decreased in both lentil cultivars. Cultivar Jordan 1 showed sensitivity to chlorsulfuron herbicide at all treatments compared with that of Jordan 2. ALS enzyme activity in the two lentil cultivars was inhibited by chlorsulfuron. The irradiated plants (90 Gray) in both treated seeds plants (M1) and seeds of tolerant plants (M2) showed a lower level of inhibition to high concentration (250 mug/l) of chlorsulfuron herbicide. The results suggested an alteration of the expression system of ALS gene(s) leading to overproduction of altered ALS enzyme at the herbicide binding site of the enzyme in lentil plant.
A significant genotype-environment interaction can limit gains in selecting superior genotypes since the best genotype in one locality may not be the best one in another locality. The efficiency of indirect selection is related to the heritability of the trait and to the genetic correlation between localities. Since a major objective of Eragrostis curvula (lovegrass) breeding programmes in Argentina is to select superior genotypes from new cultivar introductions, research on the relative effectiveness of direct and indirect selection is necessary in order to identify localities under which the efficiency of indirect selection could be maximized. To do this, experiments using a set of 18 hybrids were carried out in three localities from the semi-arid region of Argentina. Aerial biomass yield, leaf length, crown diameter, panicle number and panicle length were measured and an analysis of variance and covariance were performed. The high genetic correlation obtained suggests that the genetic mechanisms involved in the expression of these traits would be the same, or at least very similar, in Rio Cuarto, Villa Mercedes and Bahia Blanca environments where the hybrids showed a stable performance. In general, the heritability obtained was higher in Villa Mercedes and Bahia Blanca than in Rio Cuarto. For a given selection intensity the expected correlated response in Villa Mercedes and Bahia Blanca to indirect selection was compared with the expected gain with direct response to selection in Rio Cuarto. For dry matter yield, indirect selection in Bahia Blanca did not differ from selection done in Rio Cuarto (-3%). However, for performance in Villa Mercedes indirect selection was shown to be less efficient (-29%). For the other traits considered, indirect selection was variable and less efficient, ranging from -18 to -34%. The estimated decrease in efficiency of selection for all the traits considered in the locality of Rio Cuarto was higher than in the other localities, suggesting that this place was not a good choice for carrying out indirect selection. Conversely, genetic progress would be faster if selection was carried out in Villa Mercedes, because the evaluations provide higher and more accurate estimates of the heritabilities than in the other localities.
An experiment combining a hyperinsulinaemic euglycaemic clamp approach and an isotope dilution method determined the effects of cold exposure and time relative to feeding on blood glucose metabolism in four sheep. The sheep, fed 20 g/kg body-weight (BW) of lucerne hay cubes and 5 g/kg BW of maize-based concentrates once daily, were exposed in turn to a thermoneutral environment (20 degreesC) and a cold environment (0 degreesC) for 20 days. The combined experiments were performed at four different times relative to feeding, i.e. 3 to 2 h, 2 to 1 h and 1 to 0 h before, and 1 to 2 h after the initiation of feeding for the basal periods, and 1 to 0 h before, and 0 to 1 h, 1 to 2 h and 3 to 4 It after the initiation of feeding for the glucose clamp periods in both environments. [U-C-13]Glucose was continuously infused for 6 h after a priming injection. Insulin was continuously infused at 6.0 mU/kg BW per min for 2 h, which corresponded to the last 2 h of the [U-C-13]glucose infusion. Blood glucose concentrations were maintained euglycaemic during the insulin infusion by concomitant variable glucose infusion. Blood glucose turnover rate (GTR) during the basal period was enhanced by cold exposure (P=0.01) and feeding (P=0.04). Blood GTR increased (P<0.01) with the glucose clamp. During the glucose clamp, blood GTR and glucose infusion rate (GIR) were greater (P=0.003 and P=0.001, respectively) during cold exposure than in the thermoneutral environment. Time relative to feeding influenced (P=0.003) the GIR, whereas changes in blood GTR and endogenous glucose production rate were not significant. No significant cold x feeding interaction was observed in these variables. It was suggested that, in sheep, glucose metabolism was enhanced by cold exposure and the glucose clamp. It was probable that blood glucose metabolism during the glucose clamp was influenced by cold exposure and feeding, but the combined effect of cold exposure and feeding was not significant.
Multivariate cluster and canonical variate analyses were undertaken for 10 genotypes of linseed (Linum usitatissimum L.) that were tested in a four-times replicated randomized block design across 18 environments (six localities by 3 years) of Ethiopia. The main aims of this study were to determine the similarities and differences of the genotypes and their testing environments, and to compare applicability of the two statistical methods. Cluster analysis grouped the genotypes into five classes in accordance with their original sources. The six locations and 18 environments were stratified into four and seven clusters, respectively. Three sites (Bekoji, Kulumsa and Sinana) were separately stratified, while three other ones (Holetta, Asasa and Adet) showed closer similarity. Canonical variate analysis indicated that 'D33C' and 'D24C' were distinguished from the other genotypes by their high oil contents. 'N10D' and 'Norlin' had closer values and were thus preferred for their good seed yield and earliness. Days to flowering and maturity, oil contents and lodging per cent played major roles in discriminating the genotypes. Comparison of the two methods showed clearer differentiation by cluster analysis than canonical variate analysis. Canonical variate analysis also contributed information on how each variable discriminated the genotypes and their test environments. Thus, both methods complement each other in providing useful information for more efficient variety development programmes.
A collection of 112 accessions of common beans from the north of Spain has been evaluated for 24 characters during 2 years. A combination of cluster plus canonical discriminant analysis using morphological traits to generate canonical functions was able to separate landraces from different geographic areas of northern Spain, assigning them to germplasm groups related to their centres of origin. The accessions were clustered in three groups in both years. Two groups were related to races with South American origins (races 'Chile', 'Peru' and 'Nueva Granada'), the other group was related to races with Mesoamerican origins (races 'Mesoamerica' and 'Durango'). The variation found was higher in the west of the geographic area studied decreasing toward the east. These results will permit a more efficient management and conservation of these resources, and their efficient use in breeding programmes.
The paper investigates the effect of controlled seasonal breeding on milk production in a herd of Small East African (SEA) goats. Polynomial growth Curve models were fitted to both daily and cumulative milk yield data obtained from an experiment conducted over a period of 4 years (1984-88) under simulated pastoral herd management in Isiolo District, northern Kenya. The experimental treatment consisted of six different mating seasons per year, which were replicated three times over the course of the experiment. Milk yields in the first 2 weeks of lactation were negatively affected ( < 400 g/day) when kidding took place between June and September, whereas maximum initial yields of about 450 to 550 g/day were achieved at the onset and during the long rainy season. Multiple peaks in milk yield curves were observed when a rainy season occurred after about the first half of the lactation period. In terms of total amount of milk produced until 28 weeks of lactation, the production system could benefit from the introduction of a restricted breeding management allowing does to be bred in the period from June to November, with total milk yields being estimated at approximately 60 kg of milk. Maximum milk production until weaning can be expected to be achieved by does mated between October and January (between 46 and 48 kg of milk). The present experiment has revealed that mating just prior to or during the long rainy season leads to low milk yields until weaning and significantly increases the incidence of early kid deaths. It is concluded that evaluating milk production in goat herds exposed to strong seasonal changes in forage supply is perhaps best carried out in terms of cumulative milk yields, instead of average daily yields, which are subject to large fluctuations. Furthermore, under these conditions fitting polynomial growth curves to longitudinal milk yield data using the general linear mixed model appears to be more appropriate than the estimation of non-linear algebraic lactation curves.
This group, which is concerned with the applications of mathematics to agricultural science, was formed in 1970 and has since met at approximately yearly intervals in London for one-day meetings. The thirty-fifth meeting of the group, chaired by Dr David Parsons of Silsoe Research Institute, was held in the Kohn Centre at the Royal Society, 6 Carlton House Terrace, London on Friday, 11 April 2003 when the following papers were read. [PUBLICATION ABSTRACT