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Developing technologies to improve the fertility of dairy cows - AC0205

Description
The number of cows in the national herd is the main driver for environmental impact of dairy farming. Genetic increases in milk yield are predicted to continue, so cow numbers and environmental impact might be expected to continue falling. However, poor fertility is hampering progress by reducing lifetime yield per cow. In addition, outputs of methane, nitrogen and phosphorus during the rearing phase are spread over fewer units of lifetime milk production. Thus, it is important that the fertility issue is addressed urgently.

We provided strategic information on nutritional and genetic tools for improving fertility in our previous Defra/LINK funded studies of fertility. In the interim programme proposed here we aim to accelerate uptake of outputs from previous research by providing additional tools that can be used by nutritionists, breeders and producers to improve fertility. The objective is to provide new information that builds on previous research into dairy cow fertility and links to other fields, with a view to developing appropriate technologies for implementation. This information will also provide guidelines to help identify future research requirements to address Defra policies.

The objectives of our Defra nutrition contract (LS3306) were to identify nutritional factors that influence oocyte quality and blastocyst development. Dietary starch, fibre and fatty acids were shown to affect these parameters and this information was used in LK0646.

The objectives of our LINK nutrition contract (LK0646) were to quantify effects of diet on metabolic hormones; to identify dietary factors that affect conception rate; and to test optimum diets under commercial conditions. Dietary starch, fibre, amino acids and fatty acids affected metabolic hormones and follicle numbers. Using this information, together with information on oocyte quality from LS3306, dietary strategies were designed that improved pregnancy rate in an initial experiment.

Although these preliminary results indicated that dietary strategies may affect pregnancy rate, it is not known how they affect cow metabolism and health status. We will measure indicators of fatty acid transport and liver function in these cows to provide a more complete picture. Additionally, we will assess the impact of these diets on rumen methane.

Modelling highlights the importance of oestrous detection rate in determining overall pregnancy rates in dairy herds. We will therefore investigate relationships between appetite, milk yield, body condition, energy balance and expression of oestrus.

The objectives of the LINK genetic contract (LK0639) were to calculate sire breeding values for fertility traits, and to identify polymorphisms associated with fertility characteristics. These objectives were achieved. However more needs to be done, particularly in the area of polymorphisms. We now aim to use SNP analysis to search for polymorphisms in genes associated with expression of oestrus.

The scientific objectives of this project are:
• To determine how diets that influence fertility affect fatty acid transport, liver function and methane production.
• To quantify the relationship between energy balance and expression of oestrus.
• To identify additional molecular markers for traits associated with fertility and expression of oestrus.

These deliverables will enhance the tools provided by our previous research, thus strengthening the ability of the industry to slow the decline in fertility. By relating enhancements in fertility to the environmental impact of dairy farming, we will provide Defra with information to guide its policy objectives. It is anticipated that this project will also provide guidelines for the establishment of a longer-term research programme.
Objective
Overall Objective: To provide new information that builds on previous research into dairy cow fertility and links to other fields, with a view to developing appropriate technologies for implementation.

Objective 1 – Nutrition: To determine how diets that influence fertility affect fatty acid transport, liver function and methane inhibition.

Objective 2 – Genetics: To identify molecular markers for traits associated with fertility and expression of oestrous.

Objective 3 – Oestrus: To quantify the relationship between energy balance and expression of oestrus.
Project Documents
• Final Report : Tools for reducing the environmental impact of the UK dairy herd: Improvement of dairy cow fertility through studies of liver metabolism, molecular markers and oestrous expression   (371k)
• Final Report - Annex : AC0205 annex   (417k)
Time-Scale and Cost
From: 2006

To: 2008

Cost: £200,000
Contractor / Funded Organisations
University - Nottingham
Keywords
Agriculture and Climate Change              
Air Pollution              
Animal              
Animal Production              
Dairy              
Farming              
Genetics              
Livestock Farming              
Reproduction              
Fields of Study
Agriculture and Climate Change