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Factors that affect heat production in lactating Jersey cows
D L Morris1, T M Brown-Brandl2, P S Miller1
1Department of Animal Science, University of Nebraska-Lincoln, Lincoln 68583.
Journal of Dairy Science
|November 15, 2020
Summary
Understanding heat production (HP) in dairy cows is key for energy metabolism. Dry matter intake and metabolic body weight effectively predict HP, with milk protein and nutrient digestibility also significantly contributing.
Area of Science:
- Animal Science
- Nutritional Physiology
- Dairy Cattle Metabolism
Background:
- Heat production (HP) is a significant energy expenditure in lactating dairy cows.
- Understanding factors influencing HP is crucial for optimizing energy metabolism and improving animal health.
- Previous models have not fully elucidated the complex interplay of factors affecting HP in diverse feeding and production scenarios.
Purpose of the Study:
- To develop and validate predictive models for heat production (HP) in lactating Jersey cows.
- To identify key nutritional and physiological factors contributing to the variation in HP.
- To provide a more accurate understanding of energy partitioning and utilization in dairy cows.
Main Methods:
- Utilized individual animal-period data from 293 cows across 9 studies.
- Incorporated a wide range of lactation stages (44-410 days in milk) and milk yields (7.8-43.0 kg/d).
- Fitted eight distinct models, including dry matter intake (DMI), milk composition, nutrient digestibility, and urinary nitrogen excretion, while accounting for metabolic body weight and random effects (study, cow, period).
Main Results:
- Dry matter intake (DMI) and metabolic body weight adequately predicted HP (concordance correlation coefficient = 0.84).
- Models incorporating milk component yield, nutrient digestibility, or urinary nitrogen excretion showed similar predictive power (0.79-0.85).
- Heat production associated with milk protein yield and digestible protein supply was notably higher than other factors.
Conclusions:
- Heat production in lactating dairy cows can be reliably predicted using metabolic body weight and DMI.
- Milk protein yield, nutrient digestibility, and urinary nitrogen excretion explain significant variation in HP, comparable to DMI.
- Protein metabolism, including digestion, absorption, and milk protein synthesis, plays a substantial role in the overall heat production of dairy cows.
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