Inter-and intra-individual variability of feeding behaviour in group housed dairy goats
Résumé
The emergence of precision livestock farming (PLF), and with it the increasing capacity to record behaviour and production parameters automatically, makes it possible to monitor feeding behaviour of individual animals over time. This study reports some of the first quantifications of feeding behaviour variables for individual dairy goats whilst group housed. The feeding behaviour of 16 non-lactating goats (NoLact), 32 goats in the middle of their first lactation (MidLact) and 24 goats (including 20 goats from MidLact) at the end of their first lactation (EndLact) from two breeds (Alpine and Saanen) was recorded. The goats were housed in groups of four individuals and each had access to one weight-monitored feeding station where they received a total mixed ration ad libitum twice a day. Following a habituation period, feeding behaviour was measured for nine days (NoLact), 10 days (MidLact) and six days (EndLact). After merging feeder visits into meals (≥8-min inter-meal-interval), six variables were calculated for each individual: meal frequency (number of daily meals, NDM), size (feed intake per meal, FIM) and duration (DUM), as well as feeding rate (FR), daily feeding time (DFT) and daily feed intake (DFI). The inter- and intra-individual variabilities of these six variables were investigated and the intra-class correlation coefficients calculated. Particular attention was paid to the first meal following feed distribution and to the stability of individual feeding behaviour between lactation stages. Effects of body weight, breed, and stage of lactation on the six feeding behaviour variables were analysed using a general linear model. Our study confirmed previous findings from individually housed dairy goats that feeding behaviour variables are relatively stable within an individual but show greater variability between individuals. Although there were differences between the lactation stages studied, the feeding behaviour of individuals tested in two lactation stages (mid- and end of lactation) remained relatively stable. The feeding behaviour variables were normally distributed, and smaller meals were linked with a higher meal frequency and vice versa. The first meal after a feed distribution, in addition to being positively correlated with the DFI, appeared to be stable in size for individual goats with a larger variability among individuals and could potentially be used to characterize the individuals, whereas time-related feeding behaviour variables appeared less useful for this purpose. Characterization of individuals based on their feeding behaviour can potentially be used to refine individual management for disease prevention or as a trait used in genetic selection.
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