1. BODY GROWTH RATES AND FIRST LACTATION MILK
PRODUCTION OF PREGNANT HOLSTEIN HEIFERS
REARED ON PASTURE OR CONVENTIONAL DIETS
Fultz, Peters, *S.W. 1,
Semler, R.R.
and Erdman, 2, J.W. 1, R.A. 2
University of Maryland Extension1 , University of Maryland, College Park2
Abstract Materials and Methods Results
Objective was to compare body growth rates and first •Between March 25 and June 30, 2010, pregnant heifers Growth and lactation Pasture Conventional SEM P value
lactation milk production of pregnant heifers on intensively- were alternately assigned to either P or C diets based on measure
grazed pasture (P) to those fed conventional (C) diets. breeding dates.
Pregnant Holstein heifers were assigned to P (n=15) or C ADG, lb/d 1.98 1.58 0.765 0.043
•Both P (n=15) and C (n= 15) fed heifers were located in
(n=15) using breeding dates. Control heifers were fed a TMR
adjacent areas.
including corn and rye silages, grass hay, and monensin-
supplemented grain mix. Pastured heifers were fed one • Heifers fed conventional TMR included corn and rye
lb/animal/day of ground shelled corn with minerals and silage, grass hay, and a monensin supplemented grain
WH gain, in/d 0.0177 0.0169 0.0016 0.854
monensin. Grazing ran from March 25 to June 30. Pasture mix.
consisted primarily of endophyte-infected tall fescue.
• Pasture reared heifers received one pound/animal/day
Pasture-fed heifers were rotated daily to a new paddock of Mean HH gain, in/d 0.0134 0.0189 0.0012 0.060
of ground shelled corn with minerals and monensin.
0.25 to 0.75 acre, based on available dry matter. Biweekly
measurements included: body weight (BW), whither height • Unimproved permanent pasture consisted primarily of
(WH), hip height (HH), body condition score (BCS). Growth endophyte-infected tall fescue.
measurements were fitted by quadratic regression to
BCS 2.82 3.02 0.030 0.001
•Heifers were rotated daily to a new paddock of
generate growth curves for individual animals. First
approximately 0.25 to 0.75 ac, based on available DM.
derivatives of individual regression equations were used to
estimate average daily growth rates for BW, WH, and HH. •Measurements included body weight (BW), whither Projected 305 d milk, lb 18781 17666 1036 0.105
Growth rates and projected first lactation 305 day actual milk, height (WH), hip height (HH), and body condition score
fat, and protein production from DHI records were analyzed (BCS) taken every 2 weeks.
using analysis of variance. Pastured heifers had increased
•Growth measurements were fitted by quadratic
(P = 0.043) average daily gain (ADG), reduced (P = 0.001)
regression to generate growth curves by individual
Projected 305 d fat, lb 1678 1554 23.8 0.117
BCS, a trend for decreased (P = 0.06) HH gain and no
animal.
differences in WH gain as compared to C heifers. Projected
milk and fat yields did not differ while protein yields were •First derivatives of regression equations were used to
increased (P = 0.043) by P. While P reduces BCS, it can be estimate average growth rates for BW, WH, and HH. Projected 305 d protein, lb 595 551 14.6 0.043
used in pregnant heifers without detrimental effects on
•Growth rates and projected first lactation 305 day actual
skeletal development or milk production.
milk, fat, and protein production from DHI records were
analyzed using analysis of variance.
Heifers on pasture had increased (P < 0.05) ADG, reduced (P<0.01)
BCS, increased projected 305 day protein (P<0.05 ) while skeletal
growth rates (WH, HH) and projected milk and fat were similar to heifers
Introduction fed conventional diet.
• Since 1995, University of Maryland Extension field faculty
has been promoting the idea of Management Intensive
Grazing on dairy farms. Conclusion
• In 2006, five case studies were published of Maryland dairy We conclude that pasture could be used
producers that transitioned to Management Intensive Grazing without detrimental effect on skeletal
(1). The advantages that these producers found included development or first lactation milk
greater profitability, reduced feed costs, improved ability to production, but it did have an impact on
manage soil and soil nutrients, and improved quality of life. BCS.
• A 2006 statewide dairy Extension needs assessment survey
(2) taken in Maryland indicated approximately 30% of the
respondents considered themselves a grazing dairy farm. References
1. Peters, R. R., K. M. Wilson, M. R. Bell, R.
• These findings prompted University of Maryland dairy
A. Erdman, S. W. Fultz, J. E. Hall, R. A.
scientists to initiate a grazing study with Holstein heifers at
Kohn, W. D. Lantz, J. W. Semler, and M.
the University of Maryland dairy farm to gain experience and
A. Varner. 2007 Trends in Maryland
expertise in evaluating growth responses using Management
dairying and future prospects. J. Anim.
Intensive Grazing.
Sci. 85 (Suppl. 1)/ J. Dairy Sci. 90 (Suppl.
1)/ Poult. Sci. 86 (Suppl. 1): 26.
Acknowledgement 2. Johnson, D .M., S. W. Fultz, and M. R.
Objective Bell. 2006. Dairy success through
The authors thank Mike Dwyer, Facility Manager, management-intensive grazing. USDA,
To compare body growth and first lactation milk production of and Brian Spielman, Dairy Program Manager, at University of Maryland Extension programs are
Natural Resource Conservation Service,
pregnant Holstein heifers on pasture (P) vs. conventional (C) the Central Maryland Research and Education open to all citizens without regard to race, color,
Annapolis, MD.
diets. Center, Clarksville, for their technical assistance. gender, disability, religion, age, sexual orientation,
marital or parental status, or national origin.