Effects of incorporating dry matter intake and residual feed intake into a selection index for dairy cattle using deterministic modeling

Authors: HOULAHAN, KERRY - University Of Guelph; SCHENKEL, FLAVIO - University Of Guelph; HAILEMARIAM, DAGNACHEW - University Of Alberta; LASSEN, JAN - Collaborator; KARGO, MORTEN - Aarhus University; Cole, John; CONNOR, ERIN - University Of Delaware; WEGMANN, SILVIA - Collaborator; OLIVEIRA JR, GERSON - University Of Guelph; MIGLIOR, FILIPPO - University Of Guelph; FLEMING, ALLISON - Collaborator; CHUD, TATIANE - University Of Guelph; BAES, CHRISTINE - University Of Guelph

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2021
Publication Date: 4/17/2021
Citation: Houlahan, K., Schenkel, F.S., Hailemariam, D., Lassen, J., Kargo, M., Cole, J.B., Connor, E.E., Wegmann, S., Oliveira Jr, G.A., Miglior, F., Fleming, A., Chud, T.C., Baes, C.F. 2021. Effects of incorporating dry matter intake and residual feed intake into a selection index for dairy cattle using deterministic modeling. Animals. 11(4):1157. https://doi.org/10.3390/ani11041157.
DOI: https://doi.org/10.3390/ani11041157

Interpretive Summary: Feed costs represent one of the major expenses on a dairy farm. With the increasing demand for high-quality dairy products, the efficiency of dairy farms is one of the most important topics of current discussion. The potential impacts of selecting cows to be more efficient at converting feed to milk was assessed through simulation. This simulation study allows for recommendations to the industry for a potential methodology to improve the feed efficiency of dairy cows, and overall farm efficiency.

Technical Abstract: The inclusion of feed efficiency into the breeding goal for dairy cattle has been discussed for many years. The effects of incorporating dry matter intake or residual feed intake into a selection index were assessed using a deterministic modeling program. Both traits were investigated in four ways: 1) applying no selection pressure; 2) restricting the trait genetic gain to zero; 3) applying negative selection pressure, and 4) applying positive selection pressure. The scenarios considered as improving feed efficiency were restricting the genetic gain of dry matter intake (2), while increasing production and applying negative selection pressure on residual feed intake (3). Changes in response to selection in annual monetary genetic gain and genetic gain in standard deviation units were used to evaluate the impact of including either dry matter intake or residual feed intake into a selection index that included, fat and protein yield, stature, body condition score, age at first service, first service to conception, clinical ketosis and displaced abomasum. Restricting the genetic gain for dry matter intake while improving fat and protein yield showed an annual genetic gain of 0.27 standard deviation units more efficiently using dry matter in a 305-d lactation. Incorporating residual feed intake to improve efficiency led to an annual genetic gain of 0.06 standard deviation units more efficiently using dry matter in a 305-d lactation. Improving efficiency through dry matter intake led to a reduction in the rate of genetic gain for production traits, while improving efficiency through residual feed intake had a slight negative impact on body condition score (0.10 standard deviation units). Overall, both feed efficiency traits could improve the rate at which dairy cows convert feed to milk and could be used in a national selection index without detrimental effect on conformation, health, and fertility. Further work is necessary to determine the optimal manner of including either trait in a selection program.