PSX-B-20 - Effect of shifting from forage to high grain diet on chewing, feed sorting and lying behavior of cows supplemented with or without a phytogenic additive

The aim was to evaluate the effect of changing from forage to a high grain diet on chewing, feed sorting and lying behavior of cows supplemented with or without a phytogenic feed additive. Nine cows were blocked in two groups and used in a change-over design. Each experimental run consisted of one week of forage feeding, one week of diet transition, and four weeks of high grain feeding (65% concentrate). During the washout period of 10 weeks between the two runs, cows grazed on pasture. Cows were fed either a control diet (CON) or a diet with a phytogenic additive (PHY) based on menthol, thymol and eugenol. Data on chewing, feed sorting and lying behavior were analyzed using SAS with week of feeding and supplementation as fixed effects, and cow as random effect. Data across weeks from the same cow were processed using a first order variance-covariance structure matrix taking into account that the covariance decays with time. We found a reduction (P < 0.01) in rumination time by 53% with diet change. Within the high grain feeding, rumination reached lowest value in the second week (160 min/d). The high grain diet increased (P < 0.01) selection for long size particles by 20%. Although lying time was not affected immediately after diet change, it increased (P < 0.01) by 8% from the second week of high grain consumption. In the fourth week of grain feeding, there was a tendency for PHY to increase rumination (P = 0.07) and total chewing time (P = 0.10), but with no effect on sorting for fiber or lying time. The high grain diet decreased chewing and standing time, and increased sorting for fibrous ingredients especially after one week of feeding. The phytogenic feed additive may contribute to stimulate chewing in long term supplementation.