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

Summary

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.