Studies on restricted suckling in dual purpose and dairy breed cattle in Mexico

The aim of this thesis was to investigate the effects of rearing calves by restricted suckling (RS) compared to artificial rearing (AR) in dual purpose and dairy breed cattle in Mexico, milked once or three times a day, respectively. The following parameters were recorded during the first eight weeks after calving: social, abnormal and general behaviours and weight gain of Zebu crossbred and dairy calves; and milk yield, milk composition and udder health in the Zebu crossbred dams and udder health and milk let-down in the Holstein dams. RS reduced the abnormal behaviours of the calves and resulted in less foraging behaviours compared to AR. AR dairy calves consumed four-fold as much concentrate as RS dairy calves, whereas the amount of milk ingested was similar in the two treatments. A higher fat content in the milk ingested by RS calves compared to whole milk fed to AR calves, resulted in similar total ME intake from milk and concentrate in both treatments. Irrespective of type of animals RS resulted in similar weight gain in comparison to AR. Cow-calf separation five days after calving induced fewer indications of physiological stress in RS cows and calves. RS further increased the saleable and total (saleable and suckled) milk yield and decreased the fat content in saleable milk. RS improved udder health of the Zebu crossbred cows as judged according to elevated CMT scores and lower lactose content in AR cows. RS of Holstein dairy cows did not impair milk let-down and udder health tended to be improved according to the CMT. RS calves showed a front teat preference, which did not impair udder health according to similar CMT scores of front and rear teats. These studies indicate that RS is economically viable for the farmer as once daily milking combined with twice daily suckling considerably increased the saleable and total milk yield of Zebu crossbred cows and improved animal well-being

Practical Distributed Control Synthesis

Classic distributed control problems have an interesting dichotomy: they are either trivial or undecidable. If we allow the controllers to fully synchronize, then synthesis is trivial. In this case, controllers can effectively act as a single controller with complete information, resulting in a trivial control problem. But when we eliminate communication and restrict the supervisors to locally available information, the problem becomes undecidable. In this paper we argue in favor of a middle way. Communication is, in most applications, expensive, and should hence be minimized. We therefore study a solution that tries to communicate only scarcely and, while allowing communication in order to make joint decision, favors local decisions over joint decisions that require communication.Comment: In Proceedings INFINITY 2011, arXiv:1111.267

Feeding Techniques To Increase Calf Growth In The First Two Months Of Life

End of project reportData from Cornell University and the University of Illinois in the USA suggested that average daily liveweight gains of 900 to 1000 g/calf/day could be achieved from birth to weaning provided the calf milk replacer (CMR) is formulated to meet the calf’s amino acid requirements for such a rate of gain. Their findings suggested a daily milk replacer DM allowance of 1250 to 1500 g/d with a crude protein content of 26 to 30%. A series of studies were undertaken, at ARINI with home born dairy calves and at Grange Beef Research Centre with purchased dairy calves, to determine the effect of increasing the daily milk replacer DM allowance and or increasing the crude protein content of the CMR on calf performance.The main outcomes of these studies were There was no growth or intake response in any of the studies to increasing the crude protein content of the CMP from 23% to 28%. Calf growth rates responded to increasing the dailymilk replacer allowance from 600 to 1200 g/day for both home bred and purchased calves. However, the effect was not significant post-weaning in any of the studies. In all of the studies (for both home reared and purchased calves) feeding a high level of CMRdecreased concentrate DM intake. However, the calves concentrate intakes were similar post-weaning. The home bred calves with free access to the milk replacer feeders failed to consume their 1200 g/day allowance. Calves offered 600 or 1200 g of CMR/day had average consumption of 554 and 944 g/d, respectively, in the milk feeding period. Feeding a high (1200 g/d) compared to a low level (600 g/d) CMRdiet for the first 56 days had no significant effect on carcass weight or carcass characteristics when purchased male calves were slaughtered off an ad libitum concentrate diet after 388 days. The final carcass weights were 231 and 240 kg for the respective 600 and 1200 g/d CMR. Reducing the fat content of the CMRfrom 18% to 12% did not have any effect on concentrate intake or liveweight gain

The performance of heifers reared in a suckling system

In this study the effects on the performance of heifers reared in a suckling system (suckled heifers) compared to heifers reared in a bucket system (bucket heifers) were investigated. Heifers are young dairy cows that started first lactation. Focus was on the following parameters: age and live weight at first calving, milk production, and mastitis incidence. Also, attention was given to Paratuberculosis since suckling systems might increase the risks on its occurrence

Correlated mesoscopic fluctuations in integer quantum Hall transitions

We investigate the origin of the resistance fluctuations of mesoscopic samples, near transitions between Quantum Hall plateaus. These fluctuations have been recently observed experimentally by E. Peled et al. [Phys. Rev. Lett. 90, 246802 (2003); ibid 90, 236802 (2003); Phys. Rev. B 69, R241305 (2004)]. We perform realistic first-principles simulations using a six-terminal geometry and sample sizes similar to those of real devices, to model the actual experiment. We present the theory and implementation of these simulations, which are based on the linear response theory for non-interacting electrons. The Hall and longitudinal resistances extracted from the Landauer formula exhibit all the observed experimental features. We give a unified explanation for the three regimes with distinct types of fluctuations observed experimentally, based on a simple generalization of the Landauer-Buttiker model. The transport is shown to be determined by the interplay between tunneling and chiral currents. We identify the central part of the transition, at intermediate filling factors, as the critical region where the localization length is larger than the sample size.Comment: 18 pages 17 figure

Rapid Recovery for Systems with Scarce Faults

Our goal is to achieve a high degree of fault tolerance through the control of a safety critical systems. This reduces to solving a game between a malicious environment that injects failures and a controller who tries to establish a correct behavior. We suggest a new control objective for such systems that offers a better balance between complexity and precision: we seek systems that are k-resilient. In order to be k-resilient, a system needs to be able to rapidly recover from a small number, up to k, of local faults infinitely many times, provided that blocks of up to k faults are separated by short recovery periods in which no fault occurs. k-resilience is a simple but powerful abstraction from the precise distribution of local faults, but much more refined than the traditional objective to maximize the number of local faults. We argue why we believe this to be the right level of abstraction for safety critical systems when local faults are few and far between. We show that the computational complexity of constructing optimal control with respect to resilience is low and demonstrate the feasibility through an implementation and experimental results.Comment: In Proceedings GandALF 2012, arXiv:1210.202