# Social dominance and feed efficiency: Genetic analysis of latency to first meal after fresh feed delivery and residual feed intake in dairy cows

## TL;DR

The study finds that the time dairy cows take to eat after fresh feed is delivered is a measurable trait linked to social dominance and is heritable but not connected to feed efficiency.

## Contribution

This study introduces latency to first meal as a quantifiable and heritable phenotype for social dominance in dairy cows.

## Key findings

- Latency to first meal is heritable (0.17) and repeatable (0.43) when based on weekly averages.
- Latency to first meal is not genetically correlated with feed efficiency.
- Cows with longer latencies have fewer but longer feeding visits and eat at a faster rate.

## Abstract

Summary: Social dominance in dairy cattle housed in freestall barns is mainly expressed through competitive behavior to gain access to feed. However, measuring social dominance is extremely complex, as it involves dynamic interactions among cows. There is evidence that latency to eat may serve as a quantifiable phenotype for social dominance, given that shorter latencies are associated with more dominant cows. Here, latency to first meal was calculated as the time it takes for a cow to access the feed following the first feed delivery using data from automated feeding systems, which consisted of 6 million bunk visits from 1,770 mid-lactation Holstein cows. Feeding behavior and feed efficiency were also calculated. Overall, cows with longer latencies to eat had fewer but longer bunk visits, greater intake per visit, and ate at a faster rate. Latency to first meal, based on weekly averages, is heritable (0.17) and repeatable (0.43), and it is not correlated with feed efficiency. DMI = dry matter intake.

Summary: Social dominance in dairy cattle housed in freestall barns is mainly expressed through competitive behavior to gain access to feed. However, measuring social dominance is extremely complex, as it involves dynamic interactions among cows. There is evidence that latency to eat may serve as a quantifiable phenotype for social dominance, given that shorter latencies are associated with more dominant cows. Here, latency to first meal was calculated as the time it takes for a cow to access the feed following the first feed delivery using data from automated feeding systems, which consisted of 6 million bunk visits from 1,770 mid-lactation Holstein cows. Feeding behavior and feed efficiency were also calculated. Overall, cows with longer latencies to eat had fewer but longer bunk visits, greater intake per visit, and ate at a faster rate. Latency to first meal, based on weekly averages, is heritable (0.17) and repeatable (0.43), and it is not correlated with feed efficiency. DMI = dry matter intake.

•Latency to first meal is heritable and repeatable.•Latency to first meal is not genetically correlated with feed efficiency.•Cows with longer latencies have fewer bunk visits and eat at a faster rate.•Latency to first meal may be a quantifiable phenotype for social dominance.

Latency to first meal is heritable and repeatable.

Latency to first meal is not genetically correlated with feed efficiency.

Cows with longer latencies have fewer bunk visits and eat at a faster rate.

Latency to first meal may be a quantifiable phenotype for social dominance.

Social dominance is present in dairy production systems and affects performance, but it is difficult to measure. Latency to first meal after feed delivery may serve as a quantifiable phenotype for social dominance, given that dominant cows typically eat first. The goal of this study was to estimate the genetic variability of latency to first meal and evaluate its association with feed efficiency and feeding behavior in dairy cows. Data consisted of 6 million bunk visits from 1,770 mid-lactation Holstein cows collected from 2009 to 2024 at the University of Wisconsin–Madison using a roughage intake control system. Latency to first meal was calculated as the time it takes for a cow to access the feed following the feed delivery. The statistical model consisted of a repeatability animal model, with lactation and DIM as fixed effects, and cohort, animal, and permanent environment as random effects. Genetic parameters for latency to first meal were estimated using daily records and weekly averages. Heritability and repeatability of latency to first meal using daily records were 0.08 ± 0.01 and 0.22 ± 0.01, respectively. Heritability and repeatability of latency to first meal using weekly averages were 0.17 ± 0.03 and 0.43 ± 0.01, respectively. Genetic correlations between weekly averages of latency to first meal and DMI, milk energy, metabolic BW, and residual feed intake were −0.03 ± 0.08, −0.12 ± 0.08, 0.10 ± 0.06, and −0.08 ± 0.10, respectively. Latency to first meal was negatively correlated with number of visits at the feed bunk per day (−0.65 ± 0.06) and total duration of visits (−0.58 ± 0.05). Latency to first meal was positively correlated with duration of each visit (0.39 ± 0.07), intake per visit (0.65 ± 0.06), and feeding rate (0.51 ± 0.07). Overall, cows with longer latencies to eat had fewer but longer bunk visits, greater intake per visit, and ate at a faster rate. Latency to first meal may be a quantifiable phenotype for social dominance; it is both heritable and repeatable and is not correlated with feed efficiency.