Scale efficiency in Australian dairy farms

Data Envelope Analysis, (DEA), a linear programming technique, provides a more consistent measure of efficiency than the commonly cited partial measures of farm efficiency. It yields a relative measure of efficiency and identifies inputs or outputs that are under utilized.

In this paper, DEA is used to assess the technical efficiency of a sample of dairy farms across all dairy regions in Australia. Regions vary in size and scale of operation and are examined to see the relationship between farm size and technical efficiency, and to see if there is justification in the move towards bigger dairy production units than currently exist, given their factor mix.

Environmental efficiency : meaning and measurement and application to Australian dairy farms

Technical efficiency has been widely studied in the literature, but in its pursuit, many of the inputs used can impact on the environment. Environmental effects can be modelled as undesirable output or, as has been the case in more recent studies, as conventional inputs. This paper examines the concept of environmental efficiency and how it can be used to evaluate the performance of Australian dairy farming, using nitrogen surplus, arising from excessive applications of fertilizer, as a detrimental input. Farming promotes the image of clean and green production and if this image is to be maintained, there is a need to ensure activities are environmentally friendly.

Dietary approaches for weight loss with increased intakes of fruit, vegetables and dairy products

Aim: To assess the effectiveness of specific advice for increasing fruit, vegetable and dairy intake in free-living men participating in a weight loss study.

Methods: Subjects were randomised to one of two 12-week weight loss diets, either the WELL with daily targets of four serves of fruit, four serves of vegetables and three serves of dairy or a low fat diet (LF) with general advice to increase fruit and vegetable intake. Three-day food group diaries and a food frequency questionnaire assessed intake.

Results: Fifty-four overweight/obese male adults completed the study (WELL, n = 27; LF, n = 27; body mass index (mean ± standard deviation), 30.4 ± 2.5 kg/m²; age, 47.7 ± 9.5 years). There was no difference in mean weight change between groups (WELL, −4.8 ± 3.3 kg; LF, −4.6 ± 3.1 kg). Subjects on the WELL diet had greater (mean difference ± standard error) fruit (0.7 ± 0.2 serves/day), vegetable (1.2 ± 0.2 serves/day) and dairy (1.1 ± 0.1 serves/day) intakes than the LF group (measured by the food group diaries) (all P < 0.01). The WELL group reached the daily target for fruit from week 1 (4.7 ± 1.4 serves/day), vegetables by week 6 (4.1 ± 1.5 serves/day) and for dairy by week 8 (3.0 ± 0.8 serves/day).

Conclusions: Providing specific dietary targets to men for weight loss appears to promote greater consumption of fruit, vegetable and dairy foods than providing general dietary advice. Meeting dietary targets appears to require different adjustment periods depending on the food type.

Potential uses of ultrasound in the dairy ultrafiltration processes

There has been a growing interest in the industrial application of ultrasound, especially in the food industry. Power ultrasound can have a number of physical effects; it can increase turbulence through both the introduction of vibrational energy and through acoustic streaming, it can cause both particle agglomeration and particle dispersion and clean surfaces with a scouring action. Our work in this area has focused on the use of ultrasound to enhance membrane processing. Low frequency ultrasound has been used to facilitate cross flow ultrafiltration of dairy whey solutions for both during the ultrafiltration production cycle and the cleaning cycle. During the production cycle, the use of ultrasound reduces both pore blockage and the specific resistance of the fouling cake layer. This leads to higher flux rates and the potential for longer production cycles. During the cleaning cycle, ultrasound systematically increases cleaning efficiency, thus has the potential to reduce both total chemical consumption and system downtime. There was no deterioration in cleaning effectiveness or membrane condition which imples that sonication , has not damaged the membrane itself. Similarly, there was no change in the chemical nature of soluble proteins following sonication.

Functional dairy protein supplements for elite athletes

Elite athletes require a greater dietary protein intake than recreationally active people to maintain optimal muscular function. The timing of protein ingestion relative to exercise is critical to maximizing its physiological impact on skeletal muscles. Sports protein supplements provide a convenient means of supplying athletes with an adequate and timely source of quality dietary protein. There is now strong evidence that not all dietary proteins are equipotent in their effects on various aspects of athletic performance and specific protein isolates can provide benefits to athletes beyond simple supply of nutritional amino acids. Thus, there is an opportunity to develop new functional protein supplements to maximize athletic performance. This paper outlines the clinical evidence for the benefits of dairy proteins in sports performance and describes the development of new dairy protein supplements to build muscle strength, and to expedite recovery of strength following muscle-damaging eccentric exercise.

How farmers learn : different approaches to change

This paper presents findings of an Australian study that investigated how farm- management teams go about learning to manage their businesses, including how they learn in order to make strategic and tactical changes. The Australian farming context is one of increasing complexity and risk that demands greater sophistication and professionalism in farm management. Learning is related to increased capacity to manage successful change. Farm-management teams employ four different learning patterns when making changes to their management and marketing practices. Learning patterns are termed local focussed, people focussed, outward looking and extensive networking. These patterns appear to be related to ongoing learning practices of farm-management teams as well as to learning for change. Local focussed management teams learnt for change by accessing only local sources (including government extension services) or a single individual. People focussed farm-management teams preferred to learn for change principally by seeking information and advice on a one-to-one basis from more than one person, most frequently experts, but often other farmers. The remaining farm businesses accessed a variety of sources. The group classed as extensive networkers accessed a large number of varied sources in learning for change. Others who used a less extensive range were termed outward looking.

The application of ultrasound to dairy ultrafiltration : the influence of operating conditions

Work previously presented has shown that ultrasound can be effective in enhancing both the production and cleaning cycles of dairy membrane  processes. In this present work we extend these previous results to consider the effect of ultrasonic frequency and the use of intermittent ultrasound. These results show that the use of continuous low frequency (50 kHz) ultrasound is most effective in both the fouling and cleaning cycles. The application of intermittent high frequency (1 MHz) ultrasound is less effective. At higher transmembrane pressure, high frequency pulsed sonication can indeed lead to a reduction in steady state membrane flux. The benefits of ultrasound arise from a reduction in both concentration polarization and in the resistance provided by the more labile protein deposits that are removed during a water wash. Conversely, the loss of membrane flux when high frequency pulsed sonication is used arises from a significant increase in the more tenacious ‘irreversible’ fouling deposit.

The optimisation of ultrasonic cleaning procedures for dairy fouled ultrafiltration membranes

Ultrafiltration (UF) of whey is a major membrane based process in the dairy industry. However, commercialization of this application has been limited by membrane fouling, which has a detrimental influence on the permeation rate. There are a number of different chemical and physical cleaning methods currently used for cleaning a fouled membrane. It has been suggested that the cleaning frequency and the severity of such cleaning procedures control the membrane lifetime. The development of an optimal cleaning strategy should therefore have a direct implication on the process economics. Recently, the use of ultrasound has attracted considerable interest as an alternative approach to the conventional methods. In the present study, we have studied the ultrasonic cleaning of polysulfone ultrafiltration membranes fouled with dairy whey solutions. The effects of a number of cleaning process parameters have been examined in the presence of ultrasound and results compared with the conventional operation. Experiments were conducted using a small single sheet membrane unit that was immersed totally within an ultrasonic bath. Results show that ultrasonic cleaning improves the cleaning efficiency under all experimental conditions. The ultrasonic effect is more significant in the absence of surfactant, but is less influenced by temperature and transmembrane pressure. Our results suggest that the ultrasonic energy acts primarily by increasing the turbulence within the cleaning solution.

Mechanisms for the ultrasonic enhancement of dairy whey ultrafiltration

Low frequency ultrasound has been used to facilitate cross-flow ultrafiltration of dairy whey solutions. Experimental results show that ultrasonic irradiation at low power levels can significantly enhance the permeate flux with an enhancement factor of between 1.2 and 1.7. The use of turbulence promoters (spacers) in combination with ultrasound can lead to a doubling in the permeate flux. The application of a combined pore blockage/cake resistance model to the observed experimental data suggests that the use of ultrasound acts to lower the compressibility of both the initial protein deposit and the growing cake. Conversely, the pore blockage parameter is not significantly affected. The use of a gel polarization model shows that the ultrasonic irradiation increases the mass transfer coefficient within the concentration polarization layer. Electron microscopy results showed no evidence that the ultrasonic irradiation altered the membrane integrity. HPLC analysis of the whey proteins in the feed solution before and after sonication showed that the concentration profile of the whey proteins was also not affected by the sonication process.

The use of ultrasonic cleaning for ultrafiltration membranes in the dairy industry

The ultrafiltration of whey solutions is a common feature of dairy processes. However, the frequent fouling of ultrafiltration membranes and the subsequent cleaning cycle significantly affect the economics of such a process. In this work, we investigated the effect of ultrasonics on the cleaning of whey-fouled membranes and examined the variables that influence this effect. Experiments were conducted using a small single sheet membrane unit that was immersed totally within an ultrasonic bath.

Results show that the use of ultrasonics enhances the flux recovery following fouling. The extent of flux recovery is independent of the length of sonication time and increases with ultrasonic power. The use of surfactants in combination with ultrasonic irradiation shows a synergistic effect, providing a better efficiency than either cleaning process alone. Repetitive use of ultrasonic cleaning over a 1 month period does not result in any significant change in the permeate flux of a cleaned membrane, indicating that the ultrasonic treatment does not appear to damage the membrane structure itself.

Power ultrasound offers an environmentally friendly approach to cleaning dairy UF membranes

Flat sheet polymeric UF membranes of 30000 MWCO were obtained from Millipore Inc. Polypropylene spacers of a 50 mil (1.3 mm) thickness were obtained from KOCH membrane systems. A single 30 cm^sup 2^ membrane sheet was sandwiched with a spacer on the feed side of a cross flow Minitan S unit (Millipore Inc). The unit was immersed in a 50 kHz ultrasonic bath that was switched on as required. All experiments used re-constituted spray-dried whey powder to foul the membrane.