A comparative study of herbage intake, ingestive behaviour and diet selection, and effects of condensed tannins upon body and wool growth in lambs grazing Yorkshire fog (Holcus lanatus) and annual ryegrass (Lolium multiflorum) dominant swards

An experiment was carried out from August to early November 1994 to examine differences in diet selection, herbage intake, grazing behaviour and animal performance between weaned lambs rotationally grazing swards of annual ryegrass (Lolium multiflorum)/white clover (Trifolium repens) and Yorkshire fog (Holcus lanatus)/T. repens with or without Lotus corniculatus. There were four replicate groups of six lambs per treatment. The effects of condensed tannins (CT) on lamb production were assessed by twice-daily oral administration of 10g polyethylene glycol (PEG; molecular weight 4000) to half the lambs on each sward. The Lotus content of all swards was very low, and results are presented here for main sward comparisons meaned over lotus treatments. Overall mean estimates of pre-grazing herbage mass and sward surface height for the annual ryegrass and Yorkshire fog swards respectively, were 5820 v. 4360 +/- 190 kg DM/ha (P , P < 0.01) and liveweight gain (141 v. 120 +/- 4.3 g per lamb per day, P < 0.01), although differences in carcass weight (17.9 v. 18.2 +/- 0.3 kg) and FEC transformed values (9.6 v. 11.0 +/- 06 eggs/g fresh faeces) were not significant. The effects of CT on animal performance were greater in Yorkshire fog swards. CT had no significant effects on diet selection, herbage intake and grazing behaviour patterns

Phosphorus, Sulphur and Micronutrients on Grassland Improvement with White Clover (\u3ci\u3eTrifolium repens\u3c/i\u3e L.) on Basaltic Soils in Uruguay

Grasslands improvement with legumes is a promising technology for increasing forage quality and productivity on basaltic soils, but requires the correction of nutrient deficiencies. Phosphorus is a key element, but usual techniques of soil analysis are not good predictors. An experimental work was conducted in the northern region of the country. Evaluating the response of an improvement with white clover to P. Citric Acid showed a good association between soil P status and legume behavior. In addition there was a positive trend in forage production, in relation to S application, even though this effect was only significant in legume yield during the second year. Neither Mo nor B resulted in significant effects on forage yield. Results should be considered as preliminary, due to climatic problems that limited the experimental work

A Control Plane Enabling Automated and Fully Adaptive Network Traffic Monitoring With eBPF

The extended Berkeley Packet Filter (eBPF) enables the dynamic injection of user-defined processing logic at run-time in the Linux networking stack without disrupting any active monitoring process. This enables the selective extraction of only the traffic features that are needed in a given instant of time, which is what we define fully adaptive network traffic monitoring. However, eBPF programs require ad-hoc control plane routines for each specific scenario in order to orchestrate the underlying data plane and export the required metrics, resulting in potentially duplicated source codes to maintain, and creating the risk of deploying, at runtime, unverified user-defined code that controls the devices running the monitoring process. This paper presents a control plane that automatically adapts both its management tasks and data extraction methodologies based on the underlying data plane provided by the user, who can merely focus on the monitoring logic definition. The paper evaluates the performance of the control plane's modules and demonstrates the advantages, in terms of processing speed and memory consumption, of a fully-adaptive monitoring approach with respect to nProbe (a state-of-the-art solution), an adaptive and a non-adaptive methodology in eBPF. Experiments prove that the control plane monitoring options do not significantly affect the underlying data plane (0.15% degraded throughput) and leverage the most efficient extraction primitives (20x faster execution time). Moreover, the fully-adaptive monitoring leads to a higher number of processed packets (10x) and significantly lower memory occupancy (10x) when extracting the smallest set of features

Network Virtual Machine (NetVM): A New Architecture for Efficient and Portable Packet Processing Applications

A challenge facing network device designers, besides increasing the speed of network gear, is improving its programmability in order to simplify the implementation of new applications (see for example, active networks, content networking, etc). This paper presents our work on designing and implementing a virtual network processor, called NetVM, which has an instruction set optimized for packet processing applications, i.e., for handling network traffic. Similarly to a Java Virtual Machine that virtualizes a CPU, a NetVM virtualizes a network processor. The NetVM is expected to provide a compatibility layer for networking tasks (e.g., packet filtering, packet counting, string matching) performed by various packet processing applications (firewalls, network monitors, intrusion detectors) so that they can be executed on any network device, ranging from expensive routers to small appliances (e.g. smart phones). Moreover, the NetVM will provide efficient mapping of the elementary functionalities used to realize the above mentioned networking tasks upon specific hardware functional units (e.g., ASICs, FPGAs, and network processing elements) included in special purpose hardware systems possibly deployed to implement network devices

On the Efficiency of Packet Telephony

This paper presents a study on the efficiency of packet switching in providing toll quality telephone services. Packet switching is appealing for the implementation of a commercial telephone network because it features lower cost and higher manageability than circuit switching, and enables integration of real-time and non real-time services. This work compares the real-time efficiency of packet switching and circuit switching, i.e., the volume of voice traffic being guaranteed deterministic quality related to the amount of network resources used. For this purpose, we developed a call level simulator which allows a general topology network to be studied. The simulator performs call admission control according to the availability of the resources required to provide a deterministic delay bound for each call. Statistical data on accepted and rejected calls are the simulation output. Results show that packet size - possibly constrained by the protocol in use - is a key factor in determining the real-time efficiency. The packet size which maximizes real-time efficiency is devised analytically

Creating disaggregated network services with eBPF: the Kubernetes network provider use case

The eBPF technology enables the creation of custom and highly efficient network services, running in the Linux kernel, tailored to the precise use case under consideration. However, the most prominent examples of such network services in eBPF follow a monolithic approach, in which all required code is created within the same program block. This makes the code hard to maintain, to extend, and difficult to reuse in other use cases. This paper leverages the Polycube framework to demonstrate that a disaggregated approach is feasible also with eBPF, with minimal overhead, introducing a larger degree of code reusability. This paper considers a complex network scenario, such as a complete network provider for Kubernetes, presenting the resulting architecture and a preliminary performance evaluation

Productivity and Composition of Two Improved Native Pastures under Different Grazing Managements in Uruguay

Two improved native pastures were established by phosphoric (P) fertilisation and oversowing of: white clover (Trifolium repens) mixed with birdsfoot trefoil (Lotus corniculatus) (TbL) and annual lotus (Lotus subbiflorus) (Rin). Such pastures were evaluated during 5 years with steers at two stocking rates (High and Low) and two grazing managements (Rotational and Alternate). Presence of legumes was high and botanical changes were favourable in both pastures that evidenced good persistence. Daily liveweight gains of steers and total animal production were high in both pastures, but significantly (P≤ 0.05) higher in TbL. No significant differences were found due to grazing management. High stocking rate resulted in superior (P≤ 0.05) animal production per hectare than Low. No significant interactions were detected

Participatory Plant Breeding in Uruguay

The introduction of forage legumes into the native pastures of Uruguay is considered an environmentally safe method with which to increase the level of production through the addition of biologically fixed nitrogen. An integrated plant breeding programme was initiated at INIA (National Agricultural Research Institute), Uruguay, with the aim of developing forage legumes able to persist and produce in co-existence with the native (grass dominant) vegetation under cattle and sheep grazing. The programme was conducted in parallel with rhizobial strain selection. During 1998 to 2001 at Glencoe Research Station (32o 01\u2732 S lat; 57o 00o 39 W long), 326 temperate and subtropical forage legume species were evaluated in the basaltic region of Uruguay. This study provided a set of data with which the legume species could be ranked according to their performance (Real et al., 2004) so that the best 10% could be selected for further evaluation and breeding. The best species according to objectively measured characters (i.e. forage and seed yield) could be very valuable to certain farming systems and farmers, but might be of little value for other farmers and their systems. A significant relationship between the farm decision making unit and the farming systems has been reported for this region (Ferreira, 1997). Participatory research has proved to be an effective way to include farmers\u27 local knowledge in plant breeding programmes (Dusseldorp & Box, 1993).Therefore, to aid the conventional plant breeding approach, a farmer participatory breeding group was formed

Multi-domain service orchestration over networks and clouds: a unified approach

End-to-end service delivery often includes transparently inserted Network Functions (NFs) in the path. Flexible service chaining will require dynamic instantiation of both NFs and traffic forwarding overlays. Virtualization techniques in compute and networking, like cloud and Software Defined Networking (SDN), promise such flexibility for service providers. However, patching together existing cloud and network control mechanisms necessarily puts one over the above, e.g., OpenDaylight under an OpenStack controller. We designed and implemented a joint cloud and network resource virtualization and programming API. In this demonstration, we show that our abstraction is capable for flexible service chaining control over any technology domain