Forage Options for Dairy Cows

To remain competitive internationally, the Australian dairy industry will need to increase milk production per unit of land by producing and utilising more from home-grown feed. In the context of decreasing land availability but increasing feed cost per unit of land, increasing production and utilisation of home-grown feed is crucial to increase milk production in pasture-based dairy farms (Fariña et al., 2011). Pure pasture-based systems can achieve a maximum of ~20 t dry matter (DM)/ha/yr, although in practice top commercial farmers hardly exceed 15-16 t DM/ha. A strategy to increase productivity of forages is to select adequate combinations of forages alone or combined (intercropped) in a forage rotation. It was hypothesised that ≥25 t DM/ha may be achieved from a double-crop wholly grazeable forage rotation. Similarly, ≥40 t DM/ha may be achieved from a forage rotation using adequate forage options and intercropping management when grown for both grazing and conservation. The aim of this study was to investigate high yielding grazeable or a combination of grazeable and conserved double-crop forage options for dairy cows

Comparison of Two Systems of Pasture Allocation on Milking Intervals and Total Daily Milk Yield of Dairy Cows in a Pasture-Based Automatic Milking System

In pasture-based automatic milking systems (AMS), cows usually have a lower milking frequency (MF, the number of milking events in any 24 h period) than those reported in indoor housing systems (García and Fulkerson 2005). Moreover, milking intervals (MI, the interval between consecutive milking events, measured at every milking session in hours since the previous milking event) are higher, with up to 30% of milking events occurring with intervals above 16 h in grazing systems (NA Lyons unpublished data). Milking events occurring with long intervals have a negative effect on milk yield (Schmidt 1960) and udder health (Hammer et al. 2012). Recognising that feed is the main incentive to achieve voluntary cow traffic (Prescott et al. 1998), some initial reports have depicted the potential importance and effect of incentives put in place per day (Jago et al. 2007). Yet to date no research has been published that quantifies the actual impact of number of feed allocations, on animal performance in pasture-based systems. The aim of this study was to determine the impact of 2 different grazing treatments (2-way grazing [2WG] versus 3-way grazing [3WG] allocations of feed per 24 h period), on MI, MF and daily milk yield (DY, in kg milk/d). It was hypothesised that an increase in frequency of feed allocation would result in increased cow traffic, MF and DY

Animal Behaviour and Pasture Depletion in a Pasture-Based Automatic Milking System

In an automatic milking system (AMS) feed is used as an incentive to encourage voluntary and distributed cow traffic to the milking unit (Prescott et al. 1998). Therefore the timing, placement and size of feed allocations need to be managed in order to achieve targeted milking events per day. Behavioural studies allow the construction of time budgets (Gibb et al. 1998), and aid understanding of how cows modify their behaviour under different management regimes (Johansson et al. 1999). To date there are no published reports on how different location of feed incentives affect cows’ behaviour upon arrival at a pasture allocation in pasture-based AMS. A behavioural study was conducted in a pasture-based AMS where cows received supplementary feed either prior to (PRE), or immediately after (POST) milking. It was hypothesised that as PRE cows would have spent comparatively more time than POST cows since they ate their respective allocation of supplementary feed (at the time of exiting the dairy), they would be more motivated to go to the paddock in search of additional feed. Thus they would graze more intensively once they entered their pasture allocation

Drivers of distance-decay in bryophyte assemblages at multiple spatial scales: Dispersal limitations or environmental control?

Questions: Despite the increasing scientific interest in distance decay of compositional similarity in ecology, the scale dependence of geographical versus environmental control on distance decay of biological communities has not been properly addressed so far. The present work highlights the relative importance of niche-based processes versus dispersal limitations on distance decay patterns of epilithic bryophyte assemblages at different spatial scales. Location: Serra de Sintra, central Portugal. Methods: We adopted a nested sampling design with 32 selected sampling sites in each of which two clusters, each with five rocks, were surveyed. Each cluster was characterized by a set of 15 macroscale variables, which were divided into environmental and anthropogenic. For each rock eight microscale variables were recorded. Partial Mantel tests were used to assess the relative importance of geographical and environmental distance on community dissimilarity for each grain size (site, cluster, rock). Quantile regressions were used to describe the decay patterns of community similarity with respect to geographical and environmental distances. Ordination analyses and variation partitioning techniques were applied to assess the pure and shared effects of measured variables on bryophyte community composition. Results: Environmental distance based upon macroscale predictors was significantly correlated to community similarity, while no significant correlation was found for ecological distance calculated for microscale predictors, except at the largest grain size. The decrease of community similarity with geographical and environmental distance was thus consistently strengthened with increasing sample grain. Compositional variation was best explained by anthropogenic variables. Conclusions: The relative importance of environmental versus geographical distance on compositional similarity in epilithic bryophyte communities varies with the spatial scale of the predictors and with the sample grain. The decrease of similarity with increasing distance is related to changes in habitat features, especially those driven by human disturbance, while it is weakly affected by variations in substrate features

System Fitness of Grazeable Forages for Large Herds in Automatic Milking Systems

Automatic milking rotary (AMR) systems have the capacity to milk 800 cows. To maintain a pasture-based system whereby \u3e 50% of the total diet is pasture (Garcia and Fulkerson, 2005), large herds milked by AMR will be required to walk significant distances. Walking distances of greater than 1-km are associated with an increased incidence of undesirably long milking intervals and reduced milk yield (Lyons N, unpubl. data). The aim of this study was to investigate the total land area required and associated walking distance for large automatic milking system (AMS) herds when incorporating complementary forage rotations (CFR; Garcia et al., 2008) into the system

The pathophysiology of distal renal tubular acidosis

The kidneys have a central role in the control of acid-base homeostasis owing to bicarbonate reabsorption and production of ammonia and ammonium in the proximal tubule and active acid secretion along the collecting duct. Impaired acid excretion by the collecting duct system causes distal renal tubular acidosis (dRTA), which is characterized by the failure to acidify urine below pH 5.5. This defect originates from reduced function of acid-secretory type A intercalated cells. Inherited forms of dRTA are caused by variants in SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, WDR72 and probably in other genes that are yet to be discovered. Inheritance of dRTA follows autosomal-dominant and -recessive patterns. Acquired forms of dRTA are caused by various types of autoimmune diseases or adverse effects of some drugs. Incomplete dRTA is frequently found in patients with and without kidney stone disease. These patients fail to appropriately acidify their urine when challenged, suggesting that incomplete dRTA may represent an intermediate state in the spectrum of the ability to excrete acids. Unrecognized or insufficiently treated dRTA can cause rickets and failure to thrive in children, osteomalacia in adults, nephrolithiasis and nephrocalcinosis. Electrolyte disorders are also often present and poorly controlled dRTA can increase the risk of developing chronic kidney disease

Incomplete milkings in automatic milking systems

Ponencia presentada en 2nd International Conference on Precision Dairy Farming. Rochester, Minnesota, 18 al 20 de junio de 2019.Fil: Masía, Fernando Miguel. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Cátedra de Producción de Leche; Argentina.Fil: Masía, Fernando Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Lyons, Nicolas A. NSW Government. Department of Primary Industries; Australia.Fil: Piccardi, Mónica Belén. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.Fil: Piccardi, Mónica Belén. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Balzarini, Mónica Graciela. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Cátedra de Estadística y Biometría; Argentina.Fil: Balzarini, Mónica Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro Científico Tecnológico (CCT Córdoba); Argentina.Fil: Hovey, Russell C. University of California, Davis. Department of Animal Science; Estados Unidos de América.Fil: Garcia, Sergio C. The University of Sydney. School of Life and Environmental Sciences; Australia.Fil: Garcia, Sergio C. The University of Sydney. Sydney Institute of Agriculture; Australia.Automatic milking systems (AMS) rely on voluntary and distributed attendance of cows to the dairy facility throughout lactation. This generates variation in milking intervals (MI), defined as the period of time that elapses between two consecutive milking events, measured in hours. Farmers operating AMS need to manage variation in MI within and between cows. In AMS a robotic arm locates and attaches a cup onto each individual teat. Success of this task depends on several cow and equipment factors, including localisation and insertion of the teats, which is related to the amount of milk in the udder. Unsuccessful attachment of the cups to one or more teats, and premature cup removal, are some of the causes of incomplete milkings (Lyons et al., 2014). The aim of this work was to cluster cows according to the risk of having incomplete milkings and to characterize the groups regarding MI, peak yield (Lpeak) and days to peak yield (Dpeak).http://www.precisiondairyfarming.com/wp-content/uploads/2019/07/PrecisionDairy2019_Proceedings.pdfFil: Masía, Fernando Miguel. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Cátedra de Producción de Leche; Argentina.Fil: Masía, Fernando Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Lyons, Nicolas A. NSW Government. Department of Primary Industries; Australia.Fil: Piccardi, Mónica Belén. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.Fil: Piccardi, Mónica Belén. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Balzarini, Mónica Graciela. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Cátedra de Estadística y Biometría; Argentina.Fil: Balzarini, Mónica Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro Científico Tecnológico (CCT Córdoba); Argentina.Fil: Hovey, Russell C. University of California, Davis. Department of Animal Science; Estados Unidos de América.Fil: Garcia, Sergio C. The University of Sydney. School of Life and Environmental Sciences; Australia.Fil: Garcia, Sergio C. The University of Sydney. Sydney Institute of Agriculture; Australia

Random insights into the complexity of two-dimensional tensor network calculations

Projected entangled pair states (PEPS) offer memory-efficient representations of some quantum many-body states that obey an entanglement area law, and are the basis for classical simulations of ground states in two-dimensional (2d) condensed matter systems. However, rigorous results show that exactly computing observables from a 2d PEPS state is generically a computationally hard problem. Yet approximation schemes for computing properties of 2d PEPS are regularly used, and empirically seen to succeed, for a large subclass of (not too entangled) condensed matter ground states. Adopting the philosophy of random matrix theory, in this work we analyze the complexity of approximately contracting a 2d random PEPS by exploiting an analytic mapping to an effective replicated statistical mechanics model that permits a controlled analysis at large bond dimension. Through this statistical-mechanics lens, we argue that: i) although approximately sampling wave-function amplitudes of random PEPS faces a computational-complexity phase transition above a critical bond dimension, ii) one can generically efficiently estimate the norm and correlation functions for any finite bond dimension. These results are supported numerically for various bond-dimension regimes. It is an important open question whether the above results for random PEPS apply more generally also to PEPS representing physically relevant ground state