Sustainability & efficiency

The genetic background of fiber digestibility and nitrogen use efficiency in dairy cattle

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Abstract

Dairy cattle possess a unique ability to convert fiber-rich feed into highly nutritious food products, indicating their potential importance in future food production systems. However, nitrogen (N) losses from the dairy sector represent an environmental concern that may constrain the contribution of dairy production to sustainable food systems. Limited information is available on the genetic background of these traits, mainly due to challenges in large-scale phenotyping. This study aimed to quantify genetic variation in feed digestibility, N excretion and milk nitrogen use efficiency (N in milk divided by N intake; NUE) in dairy cows. Data were collected on four commercial dairy farms where the breeding company CRV routinely records individual feed intake. During seven sampling sessions, spot fecal and urinary samples were collected from about 500 Holstein-Friesian cows. To account for diurnal variation, six samples per cow were collected across six 4-h intervals, covering a 24-h cycle. Dry matter (DM), N and neutral detergent fiber (NDF) content were determined in pooled feces and feed samples. Furthermore, N content was determined in pooled urine. Acid-insoluble ash and creatinine were used as markers to estimate total fecal and urinary outputs, respectively. Based on these measurements, apparent total tract digestibility of DM, N, and NDF was determined. In addition, milk production traits, including milk urea, body weight, and 55K SNP genotypes were available. Heritability's were estimated using a genomic relationship matrix. Cows consumed on average 23.9 kg DM/d with a DM digestibility of 73.1%, NDF digestibility of 60.1% and N digestibility of 67.4%. Heritability estimates were 0.11 (± 0.08) for DM digestibility, 0.10 (± 0.08) for NDF digestibility, 0.14 (± 0.09) for N digestibility, 0.22 (± 0.10) for fecal N excretion (g/d), 0.36 (± 0.10) for urinary N excretion, and 0.21 (± 0.09) for milk NUE. These results indicate substantial variation among cows in digestibility and nitrogen use. Genetic factors explain a small fraction of the variation in feed digestibility, but explain 21% of the differences in milk nitrogen use efficiency. The phenotypic correlation between milk urea and milk nitrogen use efficiency was 0.04, suggesting that milk urea is not reliable indicator for selecting nitrogen-efficient dairy cattle.

Keywords: 2026

How to Cite:

Bovenhuis, H., Dijkstra, J., Edens, M., Gilbert, M. & Guennoc, E., (2026) “The genetic background of fiber digestibility and nitrogen use efficiency in dairy cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285484. doi: https://doi.org/10.31274/wcgalp.23722

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