Modelling beef cows' individual response to short nutrient restriction in different lactation stages

Area of Science:

• Animal Science
• Nutritional Physiology
• Ruminant Metabolism

Background:

• Short-term nutrient restrictions are common in extensive beef cattle systems.
• Understanding cow responses to feed challenges is crucial for optimizing production.

Purpose of the Study:

• To model milk yield, non-esterified fatty acids (NEFA), and β-hydroxybutyrate (BHB) responses to nutritional challenges.
• To identify distinct metabolic response (MR) profiles in beef cows.
• To analyze differences in response based on lactation stage and cluster.

Main Methods:

• Utilized data from 31 beef cows subjected to repeated 4-day feed restrictions over three months.
• Employed natural cubic splines to model milk yield, NEFA, and BHB.
• Clustered cows into Low MR and High MR groups based on metabolic response variables.

Main Results:

• Basal values for milk yield, NEFA, and BHB decreased as lactation advanced.
• High MR cows showed higher basal levels and more intense responses to feed restriction.
• Both clusters recovered baseline values during refeeding, with similar reaction times.

Conclusions:

• Cow response to nutritional challenges is primarily driven by milk production potential, not body reserves.
• High-responding cows effectively managed metabolic pathways to cope with and recover from feed restrictions.
• Individualized management strategies may be beneficial for beef cows facing nutritional variability.