Pensarnau, Cross Inn, Llandysul, Ceredigion

Focus Site Project: Investigation into whether high crude protein levels in the ration may be associated with a depression in dairy cow fertility

Introduction to project: 

Cows at Pensarnau farm are housed for most of the year and fed a TMR ration based on three cuts of grass silages. The farmer has noticed that when cows are moved to pasture or silages of higher crude protein levels, milk urea levels become higher and there is an associated drop in fertility with regard to cows holding to service at this time.

A review carried out by Cornell University of studies relating to high protein rations and fertility in dairy cows noted that although high dietary protein stimulates milk production, high protein has often been associated with decreased reproductive performance. Most high producing cows are encouraged to consume protein in excess of requirements, and blood urea concentrations can be increased.

Milk urea nitrogen provides a rapid, non-invasive, and less expensive means of assessing blood urea nitrogen and of monitoring overall protein metabolism in lactating cows. Measurements of blood and milk urea levels can provide a useful index for studying the association between metabolism of dietary protein and reproductive efficiency. Across many studies, increased blood or milk urea concentrations have been correlated with decreased fertility in dairy cows both in confinement and in grazing herds.  

Project Objectives:

  • To gather information on milk urea levels, blood urea levels, ration crude protein levels and fertility records
  • To analyse this information to see if any associations are exhibited 
  • To provide guidance on reformulating cow rations on the farm to provide a better outcome for conception rates  

Key Performance Indicators Set:

  1. To provide a better outcome for conception rates by using milk and blood urea levels as an early warning system of ration imbalance
  2. To provide guidelines on using milk urea levels as a source of information regarding ration protein metabolism by the cow

Timeline and Milestones:

May 2019 Analyse fertility records captured by NMR milk recording, bulk milk urea levels and rations fed from Jan 2018

Jun-Sep 2019 Analyse forage samples and take monthly blood samples from 9 cows due for service for urea, Beta-hydroxybutyrate (BHB) and non-esterified fatty acids (NEFA)

Aug-Dec 2019 Monitor conception rates by carrying out pregnancy diagnoses using milk samples collected at NMR milk recording 

Feb 2020 Open event on farm to deliver results


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