DSD 5.6 | Heat stress changes to the Mammary Gland

Dairy Science Digest

When your bulk tank volume takes a plunge through the last bout of heat, do you ever wonder exactly WHY?
What is it in the udder that changes to cause the decline? Why do we also commonly see elevated SCC in our tanks too?

To best understand the why, the Virgina Tech dairy team collected tissue samples from the mammary gland of cows in controlled environmental chambers. This month we invite Dr. Ben Corl to explain the cellular changes observed in the alveoli, epithelial and even immune cells of the mammary gland of cows undergoing a controlled heat stress challenge.

Additionally, he’ll describe the changes in gene expression in those same tissue samples that controls protein production and mammary health.

This continuation of our heat stress series features two papers titled:
(1) Cyclical heat stress during lactation influences the microstructure of the bovine mammary gland
(2) 2022: Heat stress increases mammary epithelial cells and reduces viable immune cells in milk of dairy cows

Topics of discussion

1:28 Introduction of Dr. Ben Corl
2:36 Describe the experimental design
3:58 Pair Feeding – Intake experimental design
7:14 Could the cows cool during the evening ?
8:47 Microscopic changes to the mammary
10:31 Cellular turnover in the alveoli
13:20 Increased losses of epithelial cells, a portion of the somatic cell population
16:39 Decline in viable Immune cell population in the mammary
19:38 Body temperature before and after milking
20:16 Number of alveoli
24:07 Gene & protein expression changes
24:56 Gene expression pathway for cellular health in the mammary
26:25 What do you want Boots on the ground dairyman to know

Background Information:
Temperature Humidity Index (THI)

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