Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 6/24/2010
Publication Date: 7/11/2010
Citation: Lopes, F., Combs, D.K., Hoffman, P.C., Esser, N.M., Coblentz, W.K. 2010. Assessment of Prior Grazing Experiences on Adaption to Pasture and Performance of Dairy Heifers. Joint Meeting of the ADSA, AMSA, ASAS and PSA. 93:79. Interpretive Summary:
Technical Abstract: The objective of this study was to evaluate how previous grazing experience affects animal behavior on pasture. Animal behavior was monitored in 32 Holstein (n = 21) and Holstein-Jersey (n = 11) yearlings. Two heifer groups (n = 8 per group) had been exposed to pasture from August through October 2008, while the other 2 groups had been continuously housed in a bedding pack barn since weaning. All 4 groups were housed in the same bedding pack barn from November 2008 until the start of the experiment. In June 2009, heifers were assigned to one of 4 Italian ryegrass pastures. The experimental unit was paddock and the experimental design was a randomized complete block. Each group was allocated approximately 50kg pasture DM/head initially. Animal activity was assessed by visual observation. The same person recorded the activity of each heifer every 15 min from 0700h to 1600h during the first 5 d of the study. Heifer’s activities were categorized as: walking, drinking water, grazing, lying down or standing but not grazing. Behavior of heifers that grazed in 2008 initially differed from those with no previous grazing experience. During the first day, heifers with grazing experience spent more time grazing than heifers that had no prior grazing experience (57 vs. 43% of the time, P < 0.05). By the fourth day no difference between treatments group was observed. After the first week, behavior was monitored every 2 weeks through August 2009 (7 periods, 2 consecutive days per period). After the initial week on pasture, both groups spent approximately 60 percent of the time grazing (60 vs. 59% of the time, P > 0.05). At the end of the grazing season animal body weight was not different between experienced and inexperienced animals (451 vs. 442 kg, P > 0.05). The data suggests that prior grazing experience initially affected animal behavior on pasture. Time spent grazing increased for both experienced and inexperienced heifers over the first few days of the grazing period. Both groups of heifers adapted to the pastures within one week and there was no evidence that grazing behavior or weight gain were affected after the first week of pasture adaptation.