Extent and economic effect of heat loads on dairy cattle production in Australia

Objective To investigate the extent of heat load problems, caused by the combination of excessive temperature and humidity, in Holstein-Friesian cows in Australia. Also, to outline how milk production losses and consequent costs from this can be estimated and minimised. Procedures Long-term meteorological data for Australia were analysed to determine the distribution of hot conditions over space and time. Fifteen dairy production regions were identified for higher-resolution data analysis. Both the raw meteorological data and their integration into a temperature-humidity thermal index were compiled onto a computer program. This mapping software displays the distribution of climatic patterns, both Australia-wide and within the selected dairying regions. Graphical displays of the variation in historical records for 200 locations in the 15 dairying regions are also available. As a separate study, production data from research stations, on-farm trials and milk factory records were statistically analysed and correlated with the climatic indices, to estimate production losses due to hot conditions. Results Both milk yields and milk constituents declined with increases in the temperature-humidity index. The onset and rate of this decline are dependent on a number of factors, including location, level of production, adaptation, and management regime. These results have been integrated into a farm-level economic analysis for managers of dairy properties. Conclusion By considering the historical patterns of hot conditions over time and space, along with expected production losses, managers of dairy farms can now conduct an economic evaluation of investment strategies to alleviate heat loads. These strategies include the provision of sprinklers, shade structures, or combinations of these.

Assessing the influence and distribution of shrimp pond effluent in a tidal mangrove creek in north-east Australia

Effluent from a land based shrimp farm was detected in a receiving creek as changes in physical, chemical and biological parameters. The extent and severity of these changes depended on farm operations. This assessment was conducted at three different stages of shrimp-pond maturity, including (1) when the ponds were empty, (2) full and (3) being harvested. Methods for assessing farm effluent in receiving waters included physical/chemical analyses of the water column, phytoplankton bioassays and nitrogen isotope signatures of marine flora. Comparisons were made with an adjacent creek that served as the farms intake creek and did not directly receive effluent. Physical/chemical parameters identified distinct changes in the receiving creek with respect to farm operations. Elevated water column NH4+ (18.5+/-8.0 muM) and chlorophyll a concentrations (5.5+/-1.9 mug/l) were measured when the farm was in operation, in contrast to when the farm was inactive (1.3+/-0.3 muM and 1.2+/-0.6 mug/l, respectively). At all times, physically chemical parameters at the mouth of the effluent creek, were equivalent to control values, indicating effluent was contained within the effluent-receiving creek. However, elevated delta(15)N signatures of mangroves (up to similar to8parts per thousand) and macroalgae (up to similar to5parts per thousand) indicated a broader influence of shrimp farm effluent, extending to the lower regions of the farms intake creek. Bioassays at upstream sites close to the location of farm effluent discharge indicated that phytoplankton at these sites did not respond to further nutrient additions, however downstream sites showed large growth responses. This suggested that further nutrient loading from the shrimp farm, resulting in greater nutrient dispersal, will increase the extent of phytoplankton blooms downstream from the site of effluent discharge. When shrimp ponds were empty water quality in the effluent and intake creeks was comparable. This indicated that observed elevated nutrient and phytoplankton concentrations were directly attributable to farm operations. (C) 2003 Elsevier Ltd. All rights reserved.

Improving drought tolerance in rainfed lowland rice: An example from Thailand

A large portion of the world's poor farm in rainfed systems where the water supply is unpredictable and droughts are common. In Thailand there are approximately 6.2 million ha of rain fed lowland rice, which account for 67% of the country's total rice-growing area. This rice system is often characterised by too much and too little water in the same season. Farmers' estimates of their annual losses to drought are as high as 45% in the upper parts of the toposequence. In contrast to irrigated rice systems, gains from crop improvement of rainfed rice have been modest, in part because there has been little effort to breed and select for drought tolerance for the target rainfed environments. The crop improvement strategy being used in Thailand considers three mechanisms that influence yield in the drought prone targets: yield potential as an important mechanism for mild drought (where yield loss is less than 50%), drought escape (appropriate phenology) and drought tolerance traits of leaf water potential, sterility, flower delay and drought response index for more severe drought conditions. Genotypes are exposed to managed drought environments for selection of drought tolerant genotypes. A marker assisted selection (MAS) scheme has been developed and applied for selection of progenies in the backcrossing program. The plant breeding program uses rapid generation advance techniques that enable early yield testing in the target population of environments (TPE) through inter-station (multi-location yield testing) and on-farm trials. A farmer participatory approach has been used to identify the TPE for the breeding program. Four terrace paddy levels have been identified, upper (drought), middle (drought prone to favorable) and lower (flooded). This paper reports the change in the breeding program for the drought prone tainted lowland rice environments of North and Northeast Thailand by incorporating our knowledge on adaptation and on response of rice to drought. (c) 2005 Elsevier B.V. All rights reserved.

Long-term persistence of multi-drug-resistant Salmonella enterica serovar Newport in two dairy herds

Objective - To evaluate the association between maintaining joint hospital and maternity pens;and persistence of multi-drug-resistant (MDR) Salmonella enterica serovar Newport on 2 dairy farms. Design - Observational study. Sample Population - Feces and environmental samples from 2 dairy herds. Procedure - Herds were monitored for fecal shedding of S enterica Newport after outbreaks of clinical disease. Fecal and environmental samples were collected approximately monthly from pens housing sick cows and calving cows and from pens containing lactating cows. Cattle shedding the organism were tested serially on subsequent visits to determine carrier status. One farm was resampled after initiation of interventional procedures, including separation of hospital and maternity pens. Isolates were characterized via serotyping, determination of antimicrobial resistance phenotype, detection of the CMY-2 gene, and DNA fingerprinting. Results - The prevalence (32.4% and 33.3% on farms A and B, respectively) of isolating Salmonella from samples from joint hospital-maternity pens was significantly higher than the prevalence in samples from pens housing preparturient cows (0.8%, both farms) and postparturient cows on Farm B (8.8%). Multi-drug-resistant Salmonella Newport was isolated in high numbers from bedding material, feed refusals, lagoon slurry, and milk filters. One cow excreted the organism for 190 days. Interventional procedures yielded significant reductions in the prevalences of isolating the organism from fecal and environmental samples. Most isolates were of the C2 serogroup and were resistant to third-generation cephalosporins. Conclusions and Clinical Relevance - Management practices may be effective at reducing the persistence of MDR Salmonella spp in dairy herds, thus mitigating animal and public health risk.

Peanut farmers experience with FARMSCAPE in peninsular India

Researchers and extension officers collaborated with farmers in addressing peanut cropping and sowing decisions using on-farm experiments and cropping systems simulation in the Pollachi region of Tamil Nadu, India. The most influential variable affecting the peanut productivity in this irrigated region regard sowing date. During the 1998-1999 rabi (post rainy) season, three farmers fields in villages in Pollachi region were selected and monitored. The APSIM model was used to simulate the effect of sowing date. The APSIM-Peanut module simulation demonstrated close correspondence with the field observation in predicting yield. The model predicted that December sowing resulted in higher yield than January sowing due to longer pod filling period, and this was confirmed by farmer experience. The farmers and extension officers became comfortable with their role as owners of the collaborative experiments and custodians of the learning environment.

Improving drought tolerance in rainfed lowland rice: an example from Thailand

A large portion of the world’s poor farm in rainfed systems where the water supply is unpredictable and droughts are common. In Thailand there are approximately 6.2 million ha of rain fed lowland rice which account for 67% of the country’s total rice-growing area. This rice system is often characterised by too much and too little water in the same season. Farmers’ estimates of their annual losses to drought are as high as 45% in the upper parts of the toposequence. In contrast to irrigated rice systems, gains from crop improvement of rainfed rice have been modest, in part because there has been little effort to breed and select for drought tolerance for the target rainfed environments. The crop improvement strategy being used in Thailand considers three mechanisms that influence yield in the drought prone targets: yield potential as an important mechanism for mild drought (where yield loss is less than 50%), drought escape (appropriate phenology) and drought tolerance traits of leaf water potential, sterility, flower delay and drought response index for more severe drought conditions. Genotypes are exposed to managed drought environments for selection of drought tolerant genotypes. A marker assisted selection (MAS) scheme has been developed and applied for selection of progenies in the backcrossing program. The plant breeding program uses rapid generation advance techniques that enable early yield testing in the target population of environments (TPE) through inter-station (multi-location yield testing) and on-farm trials. A farmer participatory approach has been used to identify the TPE for the breeding program. Four terrace paddy levels have been identified, upper (drought), middle (drought prone to favorable) and lower (flooded). This paper reports the change in the breeding program for the drought prone rainfed lowland rice environments of North and Northeast Thailand by incorporating our knowledge on adaptation and on response of rice to drought.

The evaluation of the spatial and temporal stability of sugarcane farm performance based on yield and commercial cane sugar

In broader catchment scale investigations, there is a need to understand and ultimately exploit the spatial variation of agricultural crops for an improved economic return. In many instances, this spatial variation is temporally unstable and may be different for various crop attributes and crop species. In the Australian sugar industry, the opportunity arose to evaluate the performance of 231 farms in the Tully Mill area in far north Queensland using production information on cane yield (t/ha) and CCS ( a fresh weight measure of sucrose content in the cane) accumulated over a 12-year period. Such an arrangement of data can be expressed as a 3-way array where a farm x attribute x year matrix can be evaluated and interactions considered. Two multivariate techniques, the 3-way mixture method of clustering and the 3-mode principal component analysis, were employed to identify meaningful relationships between farms that performed similarly for both cane yield and CCS. In this context, farm has a spatial component and the aim of this analysis was to determine if systematic patterns in farm performance expressed by cane yield and CCS persisted over time. There was no spatial relationship between cane yield and CCS. However, the analysis revealed that the relationship between farms was remarkably stable from one year to the next for both attributes and there was some spatial aggregation of farm performance in parts of the mill area. This finding is important, since temporally consistent spatial variation may be exploited to improve regional production. Alternatively, the putative causes of the spatial variation may be explored to enhance the understanding of sugarcane production in the wet tropics of Australia.