Submitted to: Journal of Dairy Science
Publication Type: Abstract only
Publication Acceptance Date: 5/2/2011
Publication Date: 7/11/2011
Citation: Lopes, F., Esser, N.M., Hoffman, P.C., Coblentz, W.K., Combs, D.K. 2011. Effect of prior grazing experiences on grazing behavior and performance of lactating cows. Journal of Dairy Science. 94:464. Interpretive Summary:
Technical Abstract: The impact of grazing experiences early in life on grazing behavior and performance of lactating dairy heifers was evaluated in a 3-year study. Sixty-four Holstein and Holstein x Jersey calves were randomly assigned to one of 4 treatments (n = 16) in 2008. Treatments were combinations of managing heifers in confinement or on pasture: T1, grazed 2008 and 2009; T2, grazed 2008 and confined in 2009; T3, confined in 2008 and grazed in 2009; T4, confined in 2008 and 2009. All animals grazed as lactating cows in 2010. In 2008, T1 and T2 heifers were on pasture from August through October, and T3 and T4 were housed in bedded pack pens. In year 2, T1 and T3 grazed from June–September, 2009, while T2 and T4 remained in confinement. All 4 treatment groups calved between January and April, 2010, and grazed as primiparous cows from May through July. In 2009 and 2010 grazing activities were assessed by visual observations (9h/d) and by measuring movements with GPS units attached to each animal. Daily milk was also recorded in 2010. All data were analyzed using proc mixed (SAS) as a completely randomized design, with treatment and day as fixed effects. Paddock was the random effect. In 2009 on d1, heifers that had grazed in 2008 spent more time grazing than heifers with no grazing experience (78 vs. 35% of the time, P < 0.05). In 2010 on d1, time spent grazing was 62, 59, 76, and 13% for T1, T2, T3 and T4, respectively, with T4 ranking lowest (P < 0.05). In 2009 and 2010 on d 1–3, experienced heifers walked a greater distance in the pasture than inexperienced animals. Milk production was lowest initially for cows with no previous grazing experience (T4). Animals that had not grazed in 2009 (T2 and T4) produced less milk than those that had grazed in 2009 (T 1 and T3) on d 1–3. However, average (61d) daily milk over the entire experiment was not significantly different (P > 0.05) (30.5, 30.1, 31.5 and 29.6 kg for T1, T2, T3 and T4). Results indicate that previous grazing experience can impact behavior and milk production during the first 3 d on pasture. After that, no behavioral differences (P > 0.05) were noted in after d-3 in either study.