Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Smith, Trent

Committee Member

Rude, Brian J.

Committee Member

Lemley, Caleb O.

Committee Member

Burnett, Derris D.

Date of Degree

12-10-2021

Document Type

Dissertation - Open Access

Major

Animal and Dairy Sciences

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Agriculture and Life Sciences

Department

Department of Animal and Dairy Sciences

Abstract

Winter hair coat shedding ability in southern U.S. cattle production has previously been associated with differences in adjusted birth and weaning weights of calves from dams that shed by June or later (Gray et al., 2011; Cauble et al., 2019). This study was developed to research possible avenues of why these relationships exist with winter hair coat shedding ability. The primary objectives of the following experiments were to: 1) evaluate how mineral status relates to winter hair coat shedding ability, 2) evaluate how winter hair coat shedding ability relates to apparent digestibility of forage, 3) evaluate winter hair coat shedding ability’s association with uterine artery hemodynamics during gestation, 4) evaluate how winter hair coat shedding ability is associated with growth performance and development of calves from birth until weaning, and 5) evaluate how winter hair coat shedding ability relates to loin muscle (LM) relative gene expression of dams’ calves from birth until weaning. Results indicated that plasma Cu and Zn levels were greatest for dams during the grazing month of March that reach MFS by April compared to all other groups; dams that reached MFS by July had greatest forage digestibility for DM, Ash, NDF, ADF, and CP for the grazing month of May compared to all other shedding groups; winter hair coat shedding ability had a relation with ipsilateral uterine artery pulsatility at d 150 of gestation while also influencing the growth and development of the uterine artery diameter from d 150 through 210 of gestation; dams that shed by July produced calves that had shorter hip height when measured at 120 d of age and at weaning when compared to calves of dams that reached MFS in April, May, and June; and calves of dams’ that shed by July had increased expression of IGF2 compared to calves of dams’ that shed by April, May, and June, with differing results for IGF1 having the greatest expression for calves produced from dams that shed by April compared to May and June. These results may begin to explain the existing differences in adjusted birth and weaning weight of those calves.

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