Intake estimation in dairy cows fed roughage-based diets: Anapproach based on chewing behaviour measurements

Summary in the original language of the document

Chewing behaviour of 23 lactating Swiss Fleckvieh cows was analysed in order to evaluate the predictivepotential for quantitative dry matter intake in a roughage-based indoor cattle feeding system. Cowswere fed total mixed rations (TMR) based on silages and hay with different concentrate supplements.They were kept in a tie stall enabling individual feed intake measurements. Two measurements wereconducted within one month. Chewing behaviour was recorded with RumiWatch®sensor collars, basedon pressure tubes in the collar’s noseband. Cows were equipped with collars for 96 h per measurementperiod. First 24 h were accounted as adaptation time; data of the subsequent 72 h were used for analysis.Data included ruminating, eating (min/day), rumination boli (n per day), chewing frequency and intensityduring ruminating (chews/min and chews/bolus), and activity changes (switching between ruminating,eating and idle; n per h). The constancy of parameters within cows across measurement days was testedwith linear regression models. A linear mixed-effects model was applied to estimate a regression onmeasured feed intake. Average feed intake per day across all measurements was 19.7 kg dry matterper cow, average eating time was 389 min/day and ruminating time was 551 min/day. For most of thechewing behaviour variables, factor ‘cow’ was significant, while ‘day’ was not, indicating a between-animals variance but good consistency of the data within animal. After a stepwise backward procedure inthe mixed-effects model, the remaining significant variable was ‘chewing frequency’ (chews per minuteduring rumination). Inclusion of ‘animal’ as a random factor resulted in an equation with conditionalR2= 0.7. The model without random factor revealed a very low R2. In conclusion, the random factor modelallowed estimation of individual changes in feed intake within animal but not across animals. Chewingbehaviour measurements proved to have a potential for the detection of relative intake alterations withroughage-based TMR diets but data were not sufficient for quantitative estimations.