Location: Forage and Range ResearchTitle: Dry matter intake and feed efficiency of heifers from 4 dairy breed types grazing organic grass and grass-birdsfoot trefoil mixed pastures
|GREENLAND, MICHAEL - Utah State University|
|ISOM, S. - Utah State University|
|FONNESBECK, SAWYER - Utah State University|
|ROOD, KERRY - Utah State University|
|THORNTON, KARA - Utah State University|
|MILLER, RHONDA - Utah State University|
|HADFIELD, JACOB - Utah State University|
|HENDERSON, BRACKEN - University Of Idaho|
|CREECH, J. EARL - Utah State University|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2022
Publication Date: 4/25/2023
Citation: Greenland, M.S., Waldron, B.L., Isom, S.C., Fonnesbeck, S.D., Peel, M., Rood, K.A., Thornton, K.J., Miller, R.L., Hadfield, J.A., Henderson, B., Creech, J. 2023. Dry matter intake and feed efficiency of heifers from 4 dairy breed types grazing organic grass and grass-birdsfoot trefoil mixed pastures. Journal of Dairy Science. 106(6):3918-3921. https://doi.org/10.3168/jds.2022-22858.
Interpretive Summary: Decreased intake (DMI) of pasture by dairy cattle limits growth and milk production, however, some dairy breeds may be more efficient grazers than others. In a comparison of four dairy breeds, heifers grazing grass-legume mixtures had greater DMI than those grazing grass-only pastures, but heifers on grass-only pastures were twice as efficient at converting the feed to growth. Holsteins had the greatest overall DMI, but Jerseys had the most favorable feed efficiency. However, the lack of interactions between breed and pasture-type indicated that no breed was better adapted to pastures with contrasting levels of nutritive value.
Technical Abstract: Insufficient dry matter intake (DMI) of pasture by dairy cows is a major factor limiting growth and milk production, however, it has been hypothesized that some dairy breeds may be more efficient grazers than others. This study was conducted to determine whether dairy breeds differ in DMI and feed efficiency when grazing either grass monoculture or grass-legume mixed pastures. The experiment compared four levels of dairy breed (Jersey, Holstein, Holstein-Jersey crossbreds, and Montbéliarde-Swedish Red-Holstein 3-breed crossbreds) and two levels of pasture-type (grass monoculture [MONO] and grass-birdsfoot trefoil [BFT] mixture [MIXED]) for a total of 8 treatments. Pastures were rotationally stocked with pre-pubertal heifers for 105 days for three years, and DMI determined from herbage disappearance. Feed conversion efficiency (FCE) and residual feed intake (RFI) were then derived from DMI and heifer body weights (BW) and normalized to 40% metabolic mature BW of the corresponding dairy breed to account for inherent differences in size and growth. We observed differences in DMI and feed efficiency among breeds and between pasture-types. On average, Holsteins had the greatest overall DMI (4.4 kg/AU), then intermediate DMI by the crossbreds (4.0 kg/AU), and Jerseys had the least DMI (3.6 kg/AU). Heifers grazing grass-BFT pastures had on average 2% greater DMI than those grazing grass monocultures, but heifers on grass monocultures were twice as efficient (i.e., RFI/AU of 0.27 and -0.27, respectively). Overall, Jerseys had the most favorable feed efficiency, however, ranking of Holsteins and crossbreds depended upon the feed efficiency metric. This study is the one of the first to compare the interaction of dairy breed and pasture quality on grazing efficiency. However, the lack of a breed × pasture-type interaction for DMI, FCE, or RFI indicated that none of these dairy breeds were better adapted than another breed to pastures with contrasting levels of nutritive value.