Australasian Dairy Science Symposium 2024
GreenFeed units are widely used globally to measure methane emissions. In grazing systems, cattle may decrease their visitation frequency to these units, leading to an increased number of measurement days or animals required to precisely determine greenhouse gas emissions. In total, 12–18 measurement days and 9–19 animals are required to estimate methane emissions in grazing cows and heifers.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
This study looked at the white clover inclusion in perennial ryegrass swards on a wetland soil type in the border midland and western region of Ireland. The focus of this study was to substitute chemical nitrogen (N) fertiliser applications with white clover as it can sufficiently support the N requirements of the sward due to its N fixation abilities. The results of the study found very successful clover establishment with significant savings in chemical N fertilier.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
Higher replacement rates in dairy herd lead to increased costs associated with rearing and/or purchasing replacement heifers and greater greenhouse gas emissions from the herd. Reducing the replacement rate has the potential to enhance farm milk solids production and reduce emission intensity. The findings of this study underscore the importance of considering both environmental factors, such as greenhouse gas emissions, and economic aspects, such as net farm income, when evaluating and implementing strategies for sustainable dairy farming.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
Understanding how cow–calf dairy systems can reduce the emotional impact of painful procedures such as disbudding is key to improving calf well-being. This research found that the behaviour of disbudded calves in attention bias tests (ABT) was unaffected by whether they were dam-reared or commercially reared, likely owing to compounded stress factors. Developing methods to assess dam-reared calf emotions within their natural environment will enhance our understanding of their experiences in pasture-based extended suckling systems.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
We determined climate change-driven heat stress risk for outdoor dairy cows in New Zealand’s pasture-based systems. Using climate projections from 2006 to 2098, we calculated temperature–humidity index and grazing heat-load index values, which indicated that THI may not fully capture outdoor heat stress dynamics, with solar radiation and wind speed playing critical roles. Key dairy regions in New Zealand already experience high heat stress risk and are projected to experience intensified risk in the future, necessitating adaptation strategies such as shade provision, genetic selection, and modified feeding practices.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
On pasture-based dairy farms, cows spend prolonged time away from pasture while in transit to and from the dairy and while waiting to be milked, which reduces the milk production of cows later in the milking order as shown in our research. This is likely to be linked to later-milked cows having access to less nutritious pasture. Implementing mitigation strategies that improve the nutrients available to later-milked cows, such as reserving fresh pasture, should be explored.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
Undigestible neutral detergent fibre (uNDF) has become a standard feed analysis overseas to properly quantify forage digestibility. However, this analysis is not available locally in New Zealand and the method implemented in our laboratory by using an alternative bag (F57) was not validated. The results of the current validation suggest that the F57 bag is suitable for uNDF determination, but that some further modifications to the protocol need to be made to improve the accuracy and precision of the uNDF determination.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
Ruminant milk components are increasingly recognised for human health benefits (e.g. functional fatty acid composition) or indicators of nutrient supply (e.g. milk urea). This experiment investigated the effect of including lucerne at 40% of the traditional diet of perennial ryegrass-white clover mix on milk production and composition. The findings showed that lucerne can improve dietary protein supply during periods of deficiency and increase the concentration of functional fatty acids in the milk of grazing dairy cattle.
This article belongs to the collection: Australasian Dairy Science Symposium 2024.
Calf-rearing practises can influence calf development and milk sales for the producer, and consumer demands for high animal-welfare practises may require changes to future rearing practises. The aim of this research was to compare calf growth and milk requirements by using conventional artificial rearing with calves reared with their dam in a pastoral dairy system.
This article belongs to the Collection Australasian Dairy Science Symposium 2024.
