Degree Type

Thesis

Date of Award

2014

Degree Name

Master of Science

Department

Animal Science

First Advisor

Diane M. Spurlock

Abstract

Dry matter intake (DMI) is an important topic of research in dairy cattle. It is often studied relative to feed efficiency and disease. However, there are gaps in the current knowledge of DMI that remain to be filled. The objectives of the current study aimed to fill these gaps by estimating genetic parameters for DMI during the pre-fresh transition period, as well as examining the impact of lameness on DMI and milk production. In the current study, DMI during the dry period was moderately heritable, and had a high genetic correlation with lactating intake. This finding indicates DMI may be under similar genetic regulation during the dry period and lactation. Also, a low genetic correlation was found between the magnitude of intake depression before calving and other DMI traits, suggesting that the decline in DMI at parturition would be minimally affected by selection for DMI at other time points. It was confirmed that lameness has a negative effect on milk production and feed intake in lactating dairy cattle. Milk production decreased earlier than intake when comparing daily averages in the days before treatment, suggesting that decreased intake may not be the cause of decreased production surrounding a lameness event. Milk production also did not return to pre-treatment levels, indicating a lasting effect of lameness. When compared to the average of healthy cows, lame cows deviated in both intake and milk production for the days surrounding treatment for lameness. After treatment, milk production of multiparous cows gradually returned to pre-treatment levels, whereas primiparous cows recovered more quickly. The effects of lameness can be seen for at least two months after treatment for both DMI and milk production.

Copyright Owner

Brittany Nicole Shonka

Language

en

File Format

application/pdf

File Size

66 pages

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