The effects of grass and grass-birdsfoot trefoil pastures on Jersey heifer development: Heifer growth, performance, and economic impact

Authors: HADFIELD, JACOB - Utah State University; Waldron, Blair; ISOM, S. - Utah State University; FEUZ, R - Utah State University; LARSEN, R - Utah State University; CREECH, J. - Utah State University; ROSE, MARCUS - Utah State University; LONG, JENNIFER - Utah State University; Peel, Michael; MILLER, RHONDA - Utah State University; ROOD, KERRY - Utah State University; YOUNG, ALLEN - Utah State University; STOTT, RUSTY - Utah State University; SWEAT, ALEXIS - Utah State University; THORNTON, KARA - Utah State University

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2021
Publication Date: 8/11/2021
Citation: Hadfield, J.A., Waldron, B.L., Isom, S.C., Feuz, R., Larsen, R., Creech, J.E., Rose, M.F., Long, J., Peel, M., Miller, R.L., Rood, K.A., Young, A., Stott, R., Sweat, A., Thornton, K.J. 2021. The effects of grass and grass-birdsfoot trefoil pastures on Jersey heifer development: Heifer growth, performance, and economic impact. Journal of Dairy Science. 104(10):10863-10878. https://doi.org/10.3168/jds.2020-19524.
DOI: https://doi.org/10.3168/jds.2020-19524

Interpretive Summary: Dairy heifers developed on pasture have decreased performance compared to those in a conventional confinement setting. As the number of organic dairies increases, it is important that new strategies are developed to improve performance, since these animals are required to, at least partially, consume pasture. This research indicates that Jersey heifers developed on grass pastures interseeded with the legume birdsfoot trefoil have similar performance to heifers raised in a conventional confinement setting and improved performance compared to heifers on grass monoculture pastures. These findings provide a potential solution for producers to improve performance of heifers in pasture-based settings.

Technical Abstract: Dairy heifers developed in certified organic programs, especially those utilizing pasture-based management schemes, have lower rates of gain than heifers raised in confinement production systems. This study investigates the effects that different forages in a rotational grazing system have on development of organically raised dairy heifers. Over three years, 210 yearling Jersey heifers were assigned to one of nine treatments, including a conventional confinement control (TMR) or one of eight pasture treatments: Cache Meadow bromegrass (Bromus riparius Rehmann; MB), QuickDraw orchard grass (Dactylis glomerata L,; OG), Amazon perennial ryegrass (Lolium perenne L.; PR), or Fawn tall fescue (Schendonorus arundinaceus [Schreb.] Dumort; TF) and each individual grass interseeded with birdsfoot trefoil (Lotus corniculatus L., BFT). Every 35 d, over a 105 d period, heifers were weighed, measured for hip height, and blood samples were collected to determine serum insulin-like growth factor-1 (IGF-1) and blood urea nitrogen (BUN) concentrations. Fecal egg counts (FEC) were also assessed. Heifer body weights (BW), BUN, and IGF-1 concentrations were affected by treatment when analyzed over time. Heifers on grass-BFT pastures (MIX) had increased BW compared to heifers on monoculture grass pastures (MONO). Heifers receiving TMR or PR+BFT had increased BW gain over the 105 d period compared to heifers grazing TF+BFT, OG, PR, MB, or TF. Whereas, individually for all grass species, heifers grazing +BFT pastures had greater ending BW and weight gain than heifers grazing the respective grass monocultures. Furthermore, weight gain for heifers on PR+BFT, MB+BFT, and OG+BFT were not different from those on TMR. Heifers grazing MIX pastures had increased BUN compared to heifers grazing MONO pastures. Heifer hip-height, conception rate, and FEC were not affected by treatment. These results show that the addition of BFT to pasture improves growth of grazing replacement heifers. Grass pastures interseeded with BFT may be a sustainable option to achieve adequate growth of dairy heifers raised in a pasture scenario.