The impact of vitamin D3 supplementation on the faecal and oral microbiome of dairy calves indoors or at pasture

Abstract Vitamin D (VitD) is emerging as an immune regulator in addition to its established role in metabolism and mineral homeostasis. This study sought to determine if in vivo VitD modulated the oral and faecal microbiome in Holstein–Friesian dairy calves. The experimental model consisted of two control groups (Ctl-In, Ctl-Out) which were fed with a diet containing 6000 IU/Kg of VitD3 in milk replacer and 2000 IU/Kg in feed, and two treatment groups (VitD-In, VitD-Out) with 10,000 IU/Kg of VitD3 in milk replacer and 4000 IU/Kg in feed. One control and one treatment group were moved outdoors post-weaning at approximately 10 weeks of age. Saliva and faecal samples were collected after 7 months of supplementation and analysis of the microbiome was performed using 16S rRNA sequencing. Bray–Curtis dissimilarity analysis identified that both sampling site (oral vs. faecal) and housing (indoor vs. outdoor) had significant influences on the composition of the microbiome. The calves housed outdoors had greater microbial diversity in the faecal samples based on Observed, Chao1, Shannon, Simpson and Fisher measures in comparison to calves housed indoors (P < 0.05). A significant interaction between housing and treatment was observed for the genera Oscillospira, Ruminococcus, CF231 and Paludibacter in faecal samples. The genera Oscillospira and Dorea were increased while Clostridium and Blautia were decreased following VitD supplementation in the faecal samples (P < 0.05). An interaction between VitD supplementation and housing was detected in the abundance of the genera Actinobacillus and Streptococcus in the oral samples. VitD supplementation increased the genera Oscillospira, Helcococcus and reduced the genera Actinobacillus, Ruminococcus, Moraxella, Clostridium, Prevotella, Succinivibrio and Parvimonas. These preliminary data suggest that VitD supplementation alters both the oral and faecal microbiome. Further research will now be conducted to establish the significance of microbial alterations for animal health and performance

Specificity of the tuberculin skin test is modified by use of a protein cocktail containing eSAT-6 and CFP-10 in cattle naturally infected with Mycobacterium bovis

The mycobacterial immunodominant ESAT-6 and CFP-10 antigens are strongly recognizable in tuberculosis-infected cattle, and they do not elicit a response in cattle without infection. In addition, they are absent in most environmental mycobacterial species, and therefore, their use can be an alternative to purified protein derivative (PPD) tuberculin in the development of a more specific skin diagnostic test in cattle. The aim of the current study was to assess the potential of an ESAT-6 and CFP-10 (E6-C10) protein cocktail in a skin test format in naturally tuberculosis-infected and paratuberculosis-infected cattle. We also included MPB83 as a third component in one of the protein cocktail preparations. The protein cocktail was tested at different dose concentrations (5, 10, and 15 μg per protein). The best skin response to the E6-C10 protein cocktail was obtained with 10 μg. Subsequently, this concentration was tested in 2 herds with high and low bovine tuberculosis prevalence, the latter with paratuberculosis coinfection. Our data show that the E6-C10 cocktail allows identification of an important proportion of animals that PPDB is not able to recognize, especially in low-prevalence herds. The protein cocktail did not induce reactions in tuberculosis-free cattle or in paratuberculosis-infected cattle. Addition of MPB83 to the protein cocktail did not make any difference in the skin reaction