UHPLC-MS/MS Uncovers Sheep Feed Efficiency Clues

Finding animals that convert feed into growth more efficiently can save money, cut environmental impact, and boost profits for livestock farmers. Earlier research showed that how animals process protein is closely tied to how efficiently they use their feed, at least in the Assaf sheep breed. Because of this link, it makes sense to look more closely at protein-related substances in the body as possible markers for identifying efficient animals—this could lead to a shorter, simpler list of markers that predict feed efficiency (FE).

Researchers at the Mountain Livestock Institute (Grulleros, León, Spain) studied 40 Assaf ewes to see how efficiently they used their feed, measuring this in two different ways. The sheep that consistently ranked at the top or bottom on both measurements were split into two groups: six "low efficiency" animals and six "high efficiency" animals. The team then analyzed blood samples using ultrahigh-performance liquid chromatography (UHPLC) with multiple reaction monitoring tandem mass spectrometry (MS/MS) with isotope-labeled target metabolites to measure specific protein-related substances, checking whether these substances could reliably tell the two groups apart and predict how efficiently an animal would use its feed. The results of this work were published in the journal JDS Communications.¹

Why Does Feed Efficiency Matter, and What Did This Study Set Out to Do About It?

As the global population rises, so does the demand for nutrient-rich food.²When it comes to raising livestock, feed is by far the biggest expense—making up around 66% of total costs on typical dairy sheep farms in Spain.³FE is basically a measure of how much feed it takes to produce a certain amount of meat, milk, or other output. By identifying and choosing animals that are naturally better at converting feed this way, farmers can lower costs, shrink their environmental footprint, and increase profits.^4,5

“However,” write the authors of the paper,¹ “estimating FE metrics, such as conversion ratios or residual-based traits, depends on individual feed intake records, which are costly and time consuming to obtain.”

As targeted metabolomics focusing on a specific set of candidate substances in the blood, rather than measuring everything at once, is a practical way to search for reliable biological markers,⁶ the researchers tested whether a smaller set of protein-related blood substances (ones already flagged as important in earlier work on Assaf sheep⁷) could reliably tell apart sheep with low versus high FE and predict actual FE numbers.
“In this context,” write the authors,¹ “this study aimed to evaluate whether a reduced panel of plasma metabolites related to protein metabolism in Assaf ewes could both discriminate animals with divergent FE phenotypes and predict quantitative FE metrics.”

Which Blood Substances are Linked to Feed Efficiency in Dairy Ewes, and How Well Do They Predict It?

The researchers were able to pinpoint nine substances in the blood that stood out as strongly linked to the difference between low- and high-efficiency sheep. They then combined information from these substances into a single overall score. When tested for accuracy, this score matched up closely with the animals' actual feed efficiency—fairly well for one measurement and very well for the other. This score was also used in a simpler prediction model, with similarly strong results. Overall, the substances that mattered most were closely tied to protein processing—particularly how the body transports and uses amino acids—confirming that protein handling plays a central role in why some dairy ewes use their feed more efficiently than others.¹

“These findings,” write the authors of the paper,¹ “enhance our understanding of protein metabolism signatures linked to FE and support the development of cost-effective tools (when compared with whole metabolomics) for selecting high-efficiency animals in ruminant production systems.”

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References

1. Fonseca, P. A. S.; Frutos, P.; Galucci, L. et al. Applicability of Targeted Metabolomics for the Prediction of Feed Efficiency Groups and Metrics in Dairy Sheep. JDS Commun. 2026, 7 (5), 557-562. DOI: 10.3168/jdsc.2025-0905
2. The Future of Food and Agriculture: Alternative Pathways to 2050. FAO (Food and Agriculture Organization of the United Nations) website. 2018. https://openknowledge.fao.org/server/api/core/bitstreams/2c6bd7b4-181e-4117-a90d-32a1bda8b27c/content
3. RENGRATI. 2021. Red Nacional de Granjas Típicas. Informe de Resultados Económicos de Ovino de Leche. https://www.mapa.gob.es/es/ganaderia/temas/produccion-y-mercados-ganaderos/sectores-ganaderos/red-de-granjas-tipicas/ovino-caprino
4. Connor, E. E. Invited Review: Improving Feed Efficiency in Dairy Production: Challenges and Possibilities. Animal 2015, 9 (3), 395-408. DOI: 10.1017/S1751731114002997
5. Madilindi, M. A.; Zishiri, O.T.; Dube, B. et al. Technological Advances in Genetic Improvement of Feed Efficiency in Dairy Cattle: A Review. Livest. Sci. 2022, 258, 104871. DOI: 10.1016/j.livsci.2022.104871
6. Griffiths, W. J.; Koal, T.; Wang, Y. et al. Targeted Metabolomics for Biomarker Discovery. Angew Chem Int Ed Engl. 2010, 49 (32), 5426-5445. DOI: DOI: 10.1002/anie.200905579
7. Toral, P. G.; Abecia, L.; Hervás, G. et al. Plasma and Milk Metabolomics in Lactating Sheep Divergent for Feed Efficiency. J Dairy Sci. 2023, 106 (6), 3947-3960. DOI: 10.3168/jds.2022-22609