Intensive milk feeding in neonatal calves: Investigations on the development of the intestinal adaptive immune system and the intestinal microbiota and their interaction

• Applicant: Dr. Wendy Liermann
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 531414549

The reduction of calf losses continues to be a major challenge. One of the main causes of calf losses is diarrhoea. Especially the postnatal period is critical for pre-weaning mortality due to diarrhoea. The high incidence in this period results from the low degree of maturity of the neonatal immune repertoire which is prone to inadequately reactions against essential nutrients or insufficient defence against pathogens. Because of the steady cross-talk between the intestinal immune system and the commensals the generation of the intestinal microbiota plays a key role in the establishment of tolerance and defence. However, currently specific mechanisms of the interactions between the intestinal immune system and the microbiota are not fully understood. Previous studies dealing with parenteral feeding or undernutrition show that the nutrients are a crucial stimulus for the establishment of a proper immune system and a beneficial microbial community in the intestine. In practice restrictive pre-weaning milk or milk replacer (MR) feeding is common. With regard to the fact that the nutritional level of this feeding regime is unable to exploit the growth potential of the calves it is also thinkable that a restrictive feeding regime in the neonatal period may impede the establishment of the intestinal immune system and the microbiota due to a low degree of nutritional stimulation. In contrast, an increase of this stimulation by ad libitum milk feeding could support this establishment. With regard to these hypotheses a feeding trial will be conducted with 40 calves fed either restrictively or ad libitum with a high-quality MR. The study will focus on the general animal condition and health. The growth performance of the animals will be documented. Faeces will be analyzed with regard to their physical, chemical and microbiological state. Blood samples will be collected to determine clinical and immunological traits. The animals will be slaughtered on day 8 and day 29 after birth, respectively. During slaughtering especially intestinal tissues and contents will be collected. The T and B cell specific immune response of the calves will be measured by flow cytometry and gene expression analyses. Sequencing analyses will be used to characterize the intestinal microbiota. The investigations allow analyses of the interactions between the microbiota and the T and B cell based immune response especially by studying the short chain fatty acid receptor, FFAR2 expression, on the intestinal immune cells. The focus of the project is the investigation of the poorly explored establishment of the intestinal immune system and the microbiota as well as their interaction in neonatal calves and the feeding regimes as a potential impact factor on this establishment. Therefore, beside the basic research this project contributes to the adjustment of feeding regimes of neonatal calves to their requirements and the reduction of diarrhoeal diseases in the pre-weaning period.

• DFG Programme: Research Grants