Pre-weaning calf rearing options for organic dairy producers

Abstract

The objective of this research was to investigate different calf-rearing strategies for pre-weaned dairy calves in organic and pasture-based systems. The first study compared the health, growth, and behavior of dairy pre-weaned heifer calves housed individually, in pairs, in groups, or with their dams. A randomized study involving a total of 350 dairy heifer calves was conducted at the University of Minnesota West Central Research and Outreach Center in Morris, MN (WCROC). At 3d after birth, calves were assigned to a treatment: Individual-control (IND, n=87), Pair (PAIR, 90 calves, n = 45), Group (GRP, 85 calves, n = 14 (6 calves per group), or Dam-raised (DAM, 88 cow-calf pairs, in groups of six cow-calf pairs, n =14). The results show that dam-raised calves had a higher average daily gain than other treatments. Overall calf mortality was low (0.8%, 3/350), but calves raised by dams and housed in groups presented higher odds of showing soft stools than those raised in pairs or individually. The second study investigated the impacts of calf-calf and cow-calf contact on the gut microbiome of dairy pre-weaned heifer calves around the time of weaning. Fecal samples were collected before and three days after weaning from a subset of the IND (n =18); GRP (n=21); and DAM (n=15) calves from the first season of the first study. Samples were sent for 16S rRNA short amplicon sequencing (V4 region). The results show that calves raised in a cow-calf contact system may develop a distinct gut microbiome. Additionally, we found the presence of beneficial bacteria in all treatments. For instance, dam-raised calves had an enrichment of bacteria associated with gut health. In contrast, calves separated from their dams, especially those in group housing, showed an enrichment of bacteria that may facilitate the weaning transition. The third study examined pre-weaned calf management practices in organic and pasture-based dairy farms located in the Midwest of the United States. In-person interviews (n=12) and telephone interviews (n=5) were conducted. The results revealed a wide range of calf management practices among organic and pasture-based dairy farms. In many farms, calf-rearing practices were adaptable to the grazing season and labor availability. Most farms promoted naturalness and the expression of social and affiliative behaviors.