Nutritional and management strategies for dairy cattle are designed to prepare the cow for lactation and to minimize the incidence of metabolic diseases around calving. However, strategies initiated during the dry period should also consider the potential effects on the calf prior to and after calving. Fetal requirements for energy and protein are significant, particularly during the last trimester of gestation. Energy requirements increase to 1.3 to 1.5 times maintenance in late pregnancy; therefore, the formulation of rations for dry cows must contain sufficient energy to support fetal growth plus maintenance. Protein requirements during pregnancy increase, particularly during the last 2 mo. Colostrum is a source of immune components and nutrients to the neonate and contains more protein, immunoglobulins (Ig), nonprotein nitrogen, fat, ash, vitamins, and minerals than does milk. Because some vitamins do not cross the placental barrier, colostrum is the primary source of these nutrients for the calf after birth. Colostrum from cows that are not supplemented with vitamin E during the dry period may provide inadequate vitamin E to calves after birth. The Ig concentration in colostrum is not markedly affected by prepartum protein nutrition; diets containing high crude protein (CP) generally increase the nonprotein fraction of colostrum, but low CP diets do not affect the CP or Ig concentration of colostrum. However, data from beef calves suggest that absorption of IgG may be impaired when low protein diets are fed during the dry period. Diets for dry cows may be balanced to reduce the cation to anion ratio, which may reduce the incidence of parturient paresis. Recent research also suggests that these diets might increase the incidence of calves born in respiratory acidosis, which may impair the acquisition of passive immunity.

This paper reviews animal treading and the associated effects on soil physical properties and pasture productivity from treading-induced soil compaction and pugging. Response curve relationships between soil physical properties (e.g. macroporosity, air-filled porosity, bulk density) and pasture and crop yield are reviewed. Optimum soil macroporosity for maximum pasture and crop yield ranges from 6 to 17% v/v, but there is a paucity of yield response curves for pastoral systems, particularly critical or optimum values of soil physical properties. There is little information available on the effects of cattle treading on soil physical properties and consequently pasture yield in seasons when soil pugging and poaching is minimised. Such information is needed to provide practical and rigorously tested decision support tools for land managers during grazing seasons. Knowledge of yield response curves, and critical or optimum values of soil physical properties for field pasture-based grazing systems, is required for improved farm-system production and economic decision support.

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This paper reviews knowledge of nitrogen and phosphorus generation from land use and export to waterways, including studies relevant to Australia. It provides a link between current and future modelling requirements, and the context for incorporation of this knowledge into catchment models for use by catchment managers. Selected catchment models used by catchment managers are reviewed, and factors limiting their application are addressed. The review highlights the importance of dissolved N and P for overland flow and groundwater pathways, for sheep, beef and dairy grazing land use. Consequently, the effectiveness of riparian buffers to remove N and P may not be adequate. Consideration of the effects of rainfall and hydrology, dissolved P and N losses from pastures and event-based catchment-scale loads are therefore important factors that should be incorporated into catchment models. The review shows that it is likely that nutrient losses under Australian dairying conditions have many similarities to worldwide studies. Catchment models need to represent the importance of event-based loads, intensively farmed land use, management and forms of nutrients. Otherwise there is a likelihood of either underestimating nutrient losses, or potentially overestimating the effectiveness of riparian buffers.

The concentration of immunoglobulin ( I g ) G in the blood of neonatal calves shortly after birth is a widely used criterion to determine the degree of acquisition of passive immunity. Another method used to determine the biological mechanisms of IgG absorption is calculation of the apparent efficiency of IgG absorption. Estimation of the efficiency of IgG absorption requires the estimation of plasma volume in neonatal calves. Previous estimates of plasma volume in a few calves of varying breeds have been made; the estimates ranged from 7 to 14.5% of body weight (BW). Holstein ( n = 97 from four farms) and Jersey ( n = 49 from one farm) calves were fed fresh maternal colostrum or colostrum that had been previously frozen. Calves were fed 2 L of colostrum at 4.1 h (SE = 0.2; range = 0.3 to 11.0 h ) and 12 h later. Plasma volume was measured by determining the concentration of Evans' blue dye in a jugular blood sample collected 10 min after injection of approximately 1.5 ml of 1.5% Evans' blue dye. Factors that affected plasma volume (milliliters) were BW, breed, and age at sampling; r 2 of the regression was 0.60. Factors that affected plasma volume (percentage of BW) were BW, breed, and age at sampling; r 2 of the regression was 0.08. Mean plasma volume for all calves was 3162 ml (SE = 79) and was 9.86% of birth BW (SE = 0.15%). Mean plasma volume was 2250 ml (9.71% of BW) and 3623 ml (9.94% of BW) for Jersey and Holstein calves, respectively. Body weight was the best predictor of plasma volume. (

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Treading by grazing animals can have a significant adverse effect on soil properties and plant growth, particularly under wet soil conditions. It may also affect water and nutrient movement over and through soil. It is difficult to assess treading with live animals under controlled conditions, when the field plots are small or where there are instruments installed. This paper describes a mechanical cow hoof device which can overcome these difficulties. The mechanical hoof consists of an artificial hoof made of mild steel mounted onto a compressed air ram, which, in turn, is driven by an air compressor system. Treading pressure, treading speed, duration of hoof-soil contact, and intensity and location of treading can all be controlled. Tests of the mechanical hoof in a simple field plot experiment showed that, over a 5-8-month period, treading increased bulk density (from 1.18 to 1.29 Mg m -3 ), decreased macroporosity (diam. > 30 µm) (from 16.5% to 10% v/v) in the top 10 cm soil, and reduced pasture yield (from 100 to 91% of relative dry matter yield). The mechanical hoof device can serve as a useful tool for studying the effect of treading on soil quality indicators, water and solute movement, and plant production under controlled conditions.