RESUMO
Since 2018, when a process hygiene criterion for Campylobacter in broilers at the slaughterhouse was implemented across Europe, efforts to reduce Campylobacter at farm level have increased. Despite numerous studies aiming to reduce Campylobacter colonization in broilers, no efficient control strategy has been identified so far. The present work assessed first the efficacy of a commercial litter treatment to reduce Campylobacter colonization in broilers during two in-vivo trials and second, its impact on cecal microbiota. The treatment does not affect broiler growth and no effect on Campylobacter counts was observed during the in-vivo trials. Nevertheless, cecal microbiota were affected by the treatment. Alpha and beta diversity were significantly different for the control and litter-treated groups on day 35. In addition, several taxa were identified as significantly associated with the different experimental groups. Further work is needed to find a suitable control measure combining different strategies in order to reduce Campylobacter.
RESUMO
To meet the demands of the beef cattle sector in France, weaned beef calves are transported to sorting facilities and sorted into batches composed of animals of similar body weight (BW) before the beginning of the fattening period. This procedure aims to facilitate animal management. However, it leads to practices that affect animal welfare, health and performance, such as transporting weaned beef calves over long distances and mixing animals originating from different cow/calf farms. In contrast, other potentially beneficial practices, such as pre-weaning vaccination against bovine respiratory diseases (BRD), are seldom taken into consideration when batches are formed. This observational study, based on field data from 15,735 Charolais bulls, aimed to investigate which criteria should be favored for batch constitution by quantifying the effect of batch characteristics on the growth performance of young bulls during the fattening period. Clustering analysis was used to group young bulls exhibiting similar batch characteristics and define batch types. Associations between batch characteristics/batch types and individual growth performance/homogeneity of growth performance (mean and standard deviation (SD) of average daily gain (ADG) and fattening period duration) were studied using linear mixed models. The mean BW and the percentage of animals vaccinated against BRD before weaning were positively associated with ADG (+35 g/d for each additional 50 kg and +28 g/d for a high percentage of vaccinated animals, P < 0.05). In contrast, transportation distance was negatively associated with ADG (-12 g/d for each additional 120 km travelled). Mixing animals and BW homogeneity did not affect growth performance (P > 0.05). Only the mean BW and mixing animals negatively influenced the homogeneity of ADG (P < 0.01). The clustering analysis revealed that batches with the most BW heterogeneity, the least mixing, the shortest transportation distance and a high percentage of pre-weaning animals vaccinated against BRD had better growth performance compared to batches with the opposite characteristics (+61 g/d, P < 0.001). Our results suggest that major improvements of growth performance of fattening young bulls could be obtained by minimizing transportation distance, providing vaccination programs against BRD before weaning, and maintaining groups from the same cow/calf farm instead of constituting groups of animals with similar BW at the beginning of fattening.
