Performance of dairy heifers on contrasting meadow fescue grazing systems

Authors: LIMA, LAIS - University Of Florida; NINO DE GUZMAN, CARLOS - University Of Florida; Jaramillo, David; VYAS, DIWAKAR - University Of Florida

Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2024
Publication Date: 6/16/2024
Citation: Lima, L., Nino De Guzman, C., Jaramillo, D.M., Vyas, D. 2024. Performance of dairy heifers on contrasting meadow fescue grazing systems. American Dairy Science Association Abstracts. June 25-28, 2023.

Interpretive Summary:

Technical Abstract: This study explored the potential of clover as a nitrogen (N) fertilizer alternative in meadow fescue pastures, assessing key pasture and animal productive parameters. The experiment was conducted at UW Marshfield Agricultural Research Station, in Stratford, WI, from May to October 2023. The study will be replicated in 2024. The experiment utilized a randomized complete block design with three treatments and three replications, yielding nine pastures (experimental units). The treatments comprised Meadow Fescue + N fertilizer (MF+N; 157 kg N/ha/yr.), Meadow Fescue without N fertilizer (MF), and Meadow Fescue + Clover (MF+C). Eighteen 'tester' heifers, two per pasture, were allocated to each pasture and remained in treatment throughout the experimental period. Stocking rates (SR) were adjusted bi-weekly using put-and-take animals, to obtain target herbage allowance of 2.2 kg DM/kg BW. Average daily gain (ADG) assessments occurred every 28 days, with fasted bodyweights obtained after a minimum 12-hour feed and water withdrawal. All pastures were rotationally stocked, following a 27-day rest period per paddock, allocating animals to new paddocks every 3-4 days across ten paddocks per pasture. Data were analyzed using PROC GLIMMIX of SAS. Pre-graze herbage mass was greater for MF+N (P = 0.02), across most weeks. While ADG and gain per area showed no significant differences among treatments (0.63kg/d, 218 kg/ha, respectively; P > 0.05), SR was greater for MF+N and MF+C than MF (4.1, 4.0, 3.1 animal units/ha [1 animal unit = 300 kg]; P = 0.038). There was also a treatment by time of evaluation interaction for in vitro digestible OM concentrations (P = 0.01), where these decreased as the season progressed, ranging from 79 to 65% from May to September, respectively. However, IVDOM concentrations decreased at a faster rate for MF, relative to other treatments. The MF+N treatment displayed no substantial divergence compared to other treatments, suggesting that strategic grazing management and legume integration offer viable alternatives for sustaining grazing systems without compromising productivity.