53 research outputs found
Nutrition-induced Changes of Growth from Birth to First Calving and Its Impact on Mammary Development and First-lactation Milk Yield in Dairy Heifers: A Review
This review focuses on the nutritional effects from birth until age at first calving on growth, mammary developmental changes, and first-lactation milk yield in heifer calves. The advancement in the genetic potential and the nutritional requirements of the animals has hastened the growth rate. Genetic selection for high milk yield has suggested higher growth capacity and hence increasing nutritional inputs are required. Rapid rearing by feeding high energy or high concentrate diets not only reduces the age of sexual maturity but also lowers the time period of attaining the age of first calving. However, high energy diets may cause undesirable fat deposition thereby affecting future milk yield potential. Discrepancies exist whether overfed or overweight heifers at puberty can influence the mammary development and future milk yield potential and performance. The data on post-pubertal nutritional management suggested that body weight at calving and post-pubertal growth rate is important in first lactation milk yield. There is a continuous research need for strategic feeding that accelerates growth of dairy heifers without reduction in subsequent production. Nutritional management from birth, across puberty and during pregnancy is critical for mammary growth and for producing a successful cow. This review will mostly highlight studies carried out on dairy breeds and possible available opportunities to manipulate nutritional status from birth until age at first calving
Comparative investigations on digestion in grazing (Ceratotherium simum) and browsing (Diceros bicornis) rhinoceroses
Rhinoceroses represent the largest extant herbivores with extensive dietary specialization for plant groups like browse (black rhino Diceros bicornis) or grass (white rhino Ceratotherium simum). However, it is not clear to what extent such diet selection patterns are reflected in adaptations of digestive physiology of the respective feeding types. In this study, feeding trials with four black and five white rhinos were conducted in four zoos. The animals had ad libitum access to the same batch of grass hay (second cut; neutral detergent fiber (NDF) 63% dry matter (DM), crude protein 10.2% DM). Total intake, fecal N content, in vitro digestibility of NDF residues of feces, fecal particle size and mean retention time (MRT) of particles (Cr-mordanted fiber; 1–2 mm) and fluid (Co-EDTA) were quantified. The average daily DM intake was 70±12 g/kg BW0.75 for white and 73±10 g/kg BW0.75 for black rhinos. In the in vitro fermentation test fecal NDF residues of black rhinos resulted in higher gas productions at fermentation times of 12 to 24 h, indicating that white rhinos have a superior capacity to digest NDF. Average MRT for fluids and particles was 28±4 h and 43±5 h in white and 34±4 h and 39±4 h in black rhinos. The selectivity factor (SF=MRTparticle /MRTfluid) was higher for white (1.5±0.2) than for black rhinos (1.2±0.1) (p=0.016). In a comparison of 12 ruminant and 3 rhino species, SF was correlated to percentage of grass in diet (R=0.75). Mean fecal particle size was higher in white (9.1±1.94 mm) than in black rhinos (6.1±0.79 mm) (p=0.016). The results demonstrate differences between white and black rhinos in terms of retention times and fiber digestibility. The more selective retention of particles by the white rhino corresponds with the higher digestion of fiber measured indirectly. Furthermore there is indication for a general pattern of high SF in grazing ruminants and rhinos. The difference in fecal particle size between both rhino species might be due to the considerable difference in body weight
Recommended from our members
Influence of ruminal methane on digesta retention and digestive physiology in non-lactating dairy cattle
Enteric methane (CH4) production is a side-effect of herbivore digestion, but it is unknown whether CH4 itself influences digestive physiology.
We investigated the effect of adding CH4 to, or reducing it in, the reticulorumen (RR) in a 4 × 4 Latin square experiment with rumen-fistulated,
non-lactating cows, with four treatments: (i) control, (ii) insufflation of CH4 (iCH4), (iii) N via rumen fistula, (iv) reduction of CH4 via
administration of bromochloromethane (BCM). DM intake (DMI), apparent total tract digestibility, digesta mean retention times (MRT), rumen
motility and chewing activity, spot breath CH4 emission (CH4exhal, litre/kg DMI) as well as CH4 dissolved in rumen fluid (CH4RRf, μg/ml)
were measured. Data were analysed using mixed models, including treatment (or, alternatively, CH4exhal or CH4RRf) and DMI relative to
body mass0·85 (rDMI) as covariates. rDMI was the lowest on the BCM treatment. CH4exhal was highest for iCH4 and lowest for BCM
treatments, whereas only BCM affected (reduced) CH4RRf. After adjusting for rDMI, CH4RRf had a negative association with MRT in the
gastrointestinal tract but not in the RR, and negative associations with fibre digestibility and measures of rumination activity. Adjusting for
rDMI, CH4exhal had additionally a negative association with particle MRT in the RR and a positive association with rumen motility. Thus,
higher rumen levels of CH4 (CH4exhal or CH4RRf) were associated with shorter MRT and increased motility. These findings are tentatively
interpreted as a feedback mechanism in the ruminant digestive tract that aims at mitigating CH4 losses by shortening MRT at higher CH4
Optimization clustering techniques on register unemployment data
An important strategy for data classification consists in organising data
points in clusters. The k-means is a traditional optimisation method applied to
cluster data points. Using a labour market database, aiming the segmentation of this
market taking into account the heterogeneity resulting from different unemployment
characteristics observed along the Portuguese geographical space, we suggest the
application of an alternative method based on the computation of the dominant
eigenvalue of a matrix related with the distance among data points. This approach
presents results consistent with the results obtained by the k-means.info:eu-repo/semantics/publishedVersio
Gesundheit und Leistungsfähigkeit von Milchkühen im ökologischen Landbau interdisziplinär betrachtet – eine (Interventions-) Studie zu Stoffwechselstörungen und Eutererkrankungen unter Berücksichtigung von Grundfuttererzeugung, Fütterungsmanagement und Tierhaltung
Im Mittelpunkt des Projektes stand die Stoffwechsel- und Eutergesundheit von ökologisch gehaltenen Milchkühen im prä- und peripartalen Zeitraum sowie in den ersten 100 Laktationstagen und deren Beeinflussung durch die Futter- und Nährstoffversorgung und die Haltungsumwelt im umfassenden Sinn. In einer bundesweiten Feldstudie auf 106 ökologisch wirtschaftenden Milchviehbetrieben erfolgten Erhebungen mit dem Ziel einer Risikomodellierung zu Stoffwechsel- und Eutererkrankungen. Vor diesem Hintergrund wurden die Produktionssysteme von der Pflanzenzusammensetzung im Grünland und im Ackerfutter über die Grobfutterproduktion, Futterqualität und Rationsgestaltung, Haltungsumwelt bis hin zur Tiergesundheit und Milchqualität analysiert, um hier einzelbetriebliche Risikoeinschätzungen vorzunehmen, Optimierungspotenziale aufzuzeigen und Handlungsempfehlungen abzuleiten, die anschließend betriebsindividuell implementiert wurden. Die Effektivität des so geschaffenen präventiv orientierten Tiergesundheitsmanagements wurde anhand der Entwicklung ausgewählter Kennzahlen der Euter- und Stoffwechselgesundheit geprüft. Es konnte gezeigt werden, dass sich mit dieser Vorgehensweise auch unter Praxisbedingungen die Tiergesundheitssituation signifikant verbes-sern lässt. Die Feldstudie wurde mit experimentellen Untersuchungen ergänzt, die sich speziellen Fragen der Analyse von nXP in Grasprodukten, des Kraftfuttereinsatzes, der Wahl der geeigneten Rasse, dem Infektionsgeschehen, der Nutzung von Haltungstechniken im Fütterungsmanagement und der Verbesserung der Grasnarbe widmeten. Die im Projekt generierten, aufgrund ihrer Ableitung aus der Praxis widerspruchsarmen Erkenntnisse wurden über vielfältige Formen des Wissenstransfers an die Akteure in der Ökologischen Milchviehhaltung vermittelt. Ein Merkblatt zur Euter- und Stoffwechselgesundheit bei Biomilchkühen und ein modular aufgebautes Wissenstransferkonzept wurden erarbeitet, um die Projektergebnisse nachhaltig nutzen zu können
Location patterns of urban industry in Shanghai and implications for sustainability
China’s economy has undergone rapid transition and industrial restructuring. The term “urban industry” describes a particular type of industry within Chinese cities experiencing restructuring. Given the high percentage of industrial firms that have either closed or relocated from city centres to the urban fringe and beyond, emergent global cities such as Shanghai, are implementing strategies for local economic and urban development, which involve urban industrial upgrading numerous firms in the city centre and urban fringe. This study aims to analyze the location patterns of seven urban industrial sectors within the Shanghai urban region using 2008 micro-geography data. To avoid Modifiable Areal Unit Problem (MAUP) issue, four distance-based measures including nearest neighbourhood analysis, Kernel density estimation, K-function and co-location quotient have been extensively applied to analyze and compare the concentration and co-location between the seven sectors. The results reveal disparate patterns varying with distance and interesting co-location as well. The results are as follows: the city centre and the urban fringe have the highest intensity of urban industrial firms, but the zones with 20–30 km from the city centre is a watershed for most categories; the degree of concentration varies with distance, weaker at shorter distance, increasing up to the maximum distance of 30 km and then decreasing until 50 km; for all urban industries, there are three types of patterns, mixture of clustered, random and dispersed distribution at a varied range of distances. Consequently, this paper argues that the location pattern of urban industry reflects the stage-specific industrial restructuring and spatial transformation, conditioned by sustainability objectives
Trade, wages and productivity
We develop a new general equilibrium model of monopolistic competition with heterogeneous firms, variable demand elasticity and multiple asymmetric regions, in which trade integration induces wage and productivity changes. Using Canada-US interregional trade data, we structurally estimate a theory-based gravity equation system featuring endogenous wages and productivity. Given the estimated parameter values, we first decompose border effects into a pure border effect, relative and absolute wage effects, and a selection effect. We then quantify the impacts of removing the trade distortions generated by the Canada-US border on regional market aggregates such as wages, productivity, markups, the mass of varieties produced and consumed, as well as welfare. Last, we extend the counterfactual analysis to the firm level by generating productivity distributions and their changes via simulation
Trade, wages and productivity
We develop a new general equilibrium model of monopolistic competition with heterogeneous firms, variable demand elasticity and multiple asymmetric regions, in which trade integration induces wage and productivity changes. Using Canada-US interregional trade data, we structurally estimate a theory-based gravity equation system featuring endogenous wages and productivity. Given the estimated parameter values, we first decompose border effects into a pure border effect, relative and absolute wage effects, and a selection effect. We then quantify the impacts of removing the trade distortions generated by the Canada-US border on regional market aggregates such as wages, productivity, markups, the mass of varieties produced and consumed, as well as welfare. Last, we extend the counterfactual analysis to the firm level by generating productivity distributions and their changes via simulation
Physical characteristics of rumen contents in four large ruminants of different feeding type, the addax (Addax nasomaculatus), bison (Bison bison), red deer (Cervus elaphus) and moose (Alces alces)
Based on morphological and physiological observations, it has been suggested that differences exist in the degree that reticuloruminal (RR) contents are stratified have been suspected between various ruminant species. However, the occurrence of stratification has hardly been measured in non-domestic species. Forestomach contents of free-ranging moose (n=22) and red deer (24) shot during regular hunting procedures, and of captive (but 100% forage fed) addax (6) and bison (10) culled for commercial or management purposes were investigated. There was no difference between the species in the degree by which RR ingesta separated according to size due to buoyancy characteristics in vitro. However, RR fluid of moose was more viscous than that of the other species, and no difference in moisture content was evident between the dorsal and the ventral rumen in moose, in contrast to the other species. Hence, the RR milieu in moose appears less favourable for gas or particle separation due to buoyancy characteristics. These findings are in accord with notable differences in RR papillation between the species. In moose, particle separation is most likely restricted to the reticulum, whereas in the other species, the whole rumen may pre-sort particles in varying degrees; a possible explanation for this pattern is a hypothetically lesser saliva production and fluid throughput in moose. The results suggest that differences in RR physiology may occur across ruminant species. However, RR contents stratification probably has to be considered a dynamic process that is best measured by its result – the significantly smaller particle size in the distal digestive tract when compared to the RR – than by regional differences in particle size within the RR
- …