Date of Graduation

5-2021

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Animal Science

Advisor/Mentor

Kegley, Lafferty

Committee Member/Reader

Powell, Jeremy G.

Committee Member/Second Reader

Littlejohn, Brittni

Abstract

This study will focus on how maternal phosphorus status of beef heifers affects the growth and performance of their calves. Heifers have been offered free-choice mineral with either 0 or 4% supplemental phosphorus from 30 days after weaning until calving. A study by H. Hilfiker, a University of Arkansas honors student, investigated the effects of these treatments from 30 days after weaning until 60 days after the breeding season when heifers were confirmed to be bred or open. For this developing heifer project 64 crossbred Angus heifers were assigned randomly into 8 groups (8 heifers/ group) before assigning each group to one of the two dietary treatments – 1) supplemented with phosphorus or 2) not supplemented. Heifers were synchronized and bred in November of 2019. In February of 2020, heifers confirmed to be pregnant continued onto this trial. Heifers remained on their previous treatments but were stratified by body weight and reassigned to pasture groups (to equalize group numbers) within treatment (4 groups: 2 groups/treatment with 9 heifers/group). At time of birth, colostrum samples were collected from a subset of 12 heifers/treatment (6 heifers/group) and evaluated for colostrum phosphorus and immunoglobulin concentrations. Serum samples were collected from calves at 48 hours postpartum to evaluate calf immunoglobulin concentrations. Data were analyzed using the MIXED (for continuous data) and GLIMMIX (for scoring data) procedures of SAS using group as the experimental unit. Cows grazed mixed grass pastures; monthly forage samples ranged from 0.28 to 0.36% phosphorus. There were no differences (P > 0.10) for heifer body weight during gestation, calf birth weight, calf viability scores at birth, or calf weight at an average age of 21 days. There were also no differences (P > 0.10) in colostrum components: fat, protein, lactose, and immunoglobulin G (IgG), or in the serum IgG or plasma mineral concentrations for both cows and calves 48 hours after parturition. All calves were sampled at approximately 21 days of age and there were no treatment differences (P > 0.10) in serum IgG concentrations. With no significant findings, research concludes that there are no benefits to supplementing gestating heifers with phosphorus when they graze pasture with a history of fertilization with livestock manure.

Keywords

Beef; cattle; phosphorus; supplement; nutrition

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