Predicting nitrogen use efficiency of individual dairy cows by mid-infrared spectra

Reducing the environmental impact of dairy production

Milk production takes place all around the world. Today, dairy products such as milk, butter, cheese and ice cream are consumed by more than 6 billion people worldwide, and and global demand for dairy continues to grow. Unfortunately however, this increasing demand for dairy has negative impacts on natural resources and on the environment.

One of these negative impacts is that the nitrogen (N) in the dairy cows’ manure can contribute to the pollution of ground- and surface water. Liquid dairy cattle manure - a mixture of cow urine and faeces - emits ammonia is a particularly environmentally unfriendly nitrogen fertilizer source.

Predicting NUE by mid-infrared spectra

Thus, a more efficient and environmentally friendly production system is needed, a system in which NUE of dairy cows plays a key role. The results of the study “Predicting nitrogen use efficiency of individual dairy cows by mid-infrared spectra” can be viewed as a step towards this new and improved system. The objectives of the study were 1) to develop an optimal prediction model of NUE, dry matter intake and nitrogen loss for individual dairy cows in China, and 2) to investigate the contribution of input variables and their underlying relationship with N related traits.

Rui Shi, first author, states that the results of the study show real potential for large-scale genetic evaluation of NUE: “We used MIR spectra of milk to predict the NUE of 56 Chinese Holstein cows. We found that milk yield is highly correlated with N output, which means that it contributes significantly to the prediction of NUE. The development of prediction models for N related traits is important, because this knowledge can be used by dairy farmers to significantly reduce the environmental impact of their cows.”

Mid-infrared (MIR) spectroscopy is an analytical technique that can be used to characterize new materials or identify and verify known and unknown samples. It is used to study and identify chemical substances based on the interactions of molecules with electromagnetic radiation in the mid-infrared region.

Rui Shi and the other researchers developed powerful prediction models for N related traits of Chinese Holstein cows in the hope that these models can also be applied to large-scale data to further investigate the genetic architecture of N efficiency.

Note: this paper was presented during the WIAS Annual Conference 2022. A new, full-length paper has recently been submitted to the Journal of Animal Science and Biotechnology for publication.