Effect of synchronizing, access to supplement, and grazing session on grazing behavior of early lactating dairy cows

• Published in: Journal of animal science 2016-10, Vol.94, p.614-614
• Main Authors: Chilibroste, P, Marchelli, J P, Mattiauda, D A
• Format: Article
• Language: English
• Subjects: Cattle; Corn; Covariance; Cow's milk; Dairy cattle; Eating behavior; Feeding; Feeds; Grazing; Pasture; Studies; Supplements; Synchronism
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jam2016-1272

An experiment was performed to study the effect of two contrasting feeding strategies involving TMR and grazing, during the first 60 d in milk of Holstein dairy cows. Twenty four multiparous dairy cows were blocked according to parity, expected calving date, body condition score (BCS; 3.2 ± 0.35) and BW (688 ± 60.7 kg) before calving, and were randomly allocated to follow 1 of 2 feeding strategies: GR-one = 1 grazing session (AM: 800 to 1400 h) supplemented with a total mixed ratio (TMR corn silage/concentrate mix 40/60; respectively) out of the grazing plot orGR-two = 2 grazing sessions (AM: 0800 to 1400 h; PM: 1800 to 400 h) supplemented with TMR into the grazing plot. The 2 treatments were based on the same offer of energy (50 Mcal ENL/cow/d), differing in the synchrony or not between the access to pasture and to TMR (50% each of the total energy on offer). In both treatments TMR supplementation was offered once a day at 1700 h on feed troughs (0.6 m lineal access per cow). On Days 10, 13, 30, and 33 of the experiment the number of cows grazing or idling were determined every 15 min during the first 4 h of the AM and 3 h of the PM grazing session. The PROC GLIMMIX of SAS (SAS 9.2, 2010) with a binomial response distribution and with Logit as a link function was used to determine the probability of the different events. A first order autoregressive heterogeneous (AR1) covariance structure was selected. The probability of cows grazing (approximately 0.5) during the AM grazing session was not different between treatments. There was a significant effect of time with higher probability of grazing during the first hour than in the following ones (0.84a, 0.32b, 0.36b and 0.41b for the first, second, third and fourth h, respectively; p < 0.01). A significant interaction between treatment and time was detected: GR-one cows grazed longer than GR-two cows during the first h (0.89 vs. 0.75; p < 0.05) but shorter during the third hour (0.26 vs. 0.47; p < 0.05) of the grazing session. During the PM grazing session the GR-two cows expended a large proportion of time either around the feed troughs (0.83, 0.57 and 0.50) or idling (0.10, 0.19 and 0.17) during the first, second and 3rdh, respectively. The changes observed on grazing behavior were no reflected on productive performance (companion abstract).