Enhancing production and reproductive performance of heat stressed dairy cattle

Project Director
Pantoja, J.

Recipient Organization
UNIVERSITY OF PUERTO RICO AT MAYAGUEZ
P. O. BOX 9000
MAYAGUEZ,PR 00681

Performing Department
ANIMAL INDUSTRY

Non Technical Summary
Heat stress is responsible for large decline in pregnancy rates and lowered milk production of dairy cows in the tropics and subtropics, especially during the hot months of the year. Since the summer depression in fertility is greater for high producing than for low producing cows, the continual improvement in milk yield per cow expected over time means that problems with heat stress will be exacerbated in the future. Despite its importance, there are few effective strategies for reducing the effects of heat stress in dairy cows. The major strategy of providing elaborate housing involving shades, sprinklers and fans is capital intensive and of limited use for small and medium size dairies as well as for alternate production systems using grazing. For this reason, feeding strategies involving the use of exogenous enzymes, diet modifications, grazing management, and the evaluation of the genetic diversity among local dairy cattle will be evaluated for their potential to improve milk production and reproductive performance under heat stress conditions in the tropics.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

100%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
301	3410	1010	15%
302	3499	1010	25%
305	3410	1020	15%
306	3410	1020	25%
307	3499	1010	20%

Knowledge Area
305 - Animal Physiological Processes; 307 - Animal Management Systems; 301 - Reproductive Performance of Animals; 302 - Nutrient Utilization in Animals; 306 - Environmental Stress in Animals;

Subject Of Investigation
3499 - Dairy cattle, general/other; 3410 - Dairy cattle, live animal;

Field Of Science
1020 - Physiology; 1010 - Nutrition and metabolism;

Keywords

heat stress

feed consumption

reproduction

Goals / Objectives
To Define the physiological characteristics of the heat stressed dairy cow. To improve milk production of heat stressed dairy cows without decreasing fertility.

Project Methods
Evaluate the physiological characteristics of the heat stressed dairy cow and the relationship between secondary cow characteristics (coat color, coat density, and body size) on production and the ability of the cow to tolerate heat stress. Several exogenous enzyme concentrations and types of diets will be evaluated on conserved forages to increase feed intake. Evaluation of individuals with the short-hair gene will be conducted under grazing conditions to evaluate and compare their performance to normal hair individuals.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: No progress up to this point because the experimental condition of the Lajas Experimental Station Dairy unit are not yet adequate to start the trial. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
It is expected that this research bring about conclusive applied recommendations related to the behavior and performance of heat stressed dairy cows.

Publications

No publications reported this period

Progress 01/01/07 to 12/31/07

Outputs
The digestion trial evaluating the use of exogenous enzymes was completed August 2006. Preliminary data showed no differences for dry matter intake (14.69,15.18, 15.28 and 14.84 kg for the control, Biocellulase A, Promote and Combo, respectively) or milk production (14.94, 15.76, 15.04, 15.84 kg for the control, Biocellulase A, Promote and Combo, respectively). The information on milk composition, diet digestibility and environmental effects are still not available due to problems with the use of the Nutrition Laboratory at Mayaguez.

Impacts
It is expected that this research bring about conclusive recommendations for the use of feed supplemente that can improve digestibility and reduce heat stress of lactating dairy cows.

Publications

No publications reported this period