BODY GROWTH RATES AND FIRST LACTATION MILK PRODUCTION OF PREGNANT HOLSTEIN HEIFERS REARED ON PASTURE OR CONVENTIONAL DIETS
Applied Research
Stanley Fultz
Principal Agent Emeritus
University of Maryland Extension
Jacksonville
Abstract
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\r\n Objective was to compare body growth rates and first lactation milk production of pregnant heifers on intensively-grazed pasture (P) to those fed conventional (C) diets. Pregnant Holstein heifers were assigned to P (n=15) or C (n=15) using breeding dates. Control heifers were fed a TMR including corn and rye silages, grass hay, and monensin-supplemented grain mix. Pastured heifers were fed one lb/animal/day of ground shelled corn with minerals and monensin. Grazing ran from March 25 to June 30. Pasture consisted primarily of endophyte-infected tall fescue. Pasture-fed heifers were rotated daily to a new paddock of 0.25 to 0.75 acre, based on available dry matter. Biweekly measurements included: body weight (BW), whither height (WH), hip height (HH), body condition score (BCS). Growth measurements were fitted by quadratic regression to generate growth curves for individual animals. First derivatives of individual regression equations were used to estimate average daily growth rates for BW, WH, and HH. Growth rates and projected first lactation 305 day actual milk, fat, and protein production from DHI records were analyzed using analysis of variance. Pastured heifers had increased (P = 0.043) average daily gain (ADG), reduced (P = 0.001) BCS, a trend for decreased (P = 0.06) HH gain and no differences in WH gain as compared to C heifers. Projected milk and fat yields did not differ while protein yields were increased (P = 0.043) by P. While P reduces BCS, it can be used in pregnant heifers without detrimental effects on skeletal development or milk production.
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Poster has NOT been presented at any previous NACAA AM/PIC
This poster is being submitted for judging. It will be displayed at the AM/PIC if not selected as a State winner. The abstract will be published in the proceedings.
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Authors: S.W. Fultz, R.R. Peters, J.W. Semler, R.A. Erdman
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Fultz, S. Extension Agent, Dairy Science, University of Maryland Extension, Frederick County, Maryland, 21702
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Peters, R. Extension Specialist, Dairy Management, University of Maryland, Maryland, 20742
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Semler, J. Extension Agent, Agriculture and Natural Resources, University of Maryland Extension, Washington County, Maryland, 21713
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Erdman, R. Professor, University of Maryland, Maryland, 20742