Efeitos da suplementação com Lithothamnium calcareum na nutrição de vacas leiteiras: Impactos na produção, resposta inflamatória e emissão de metano

Abstract

High-starch diets are widely used in intensive dairy farming to increase the energy density of the feed and, consequently, milk production. However, such diets raise the risk of subacute ruminal acidosis (SARA), a fermentative disorder that impairs rumen health and productive performance, and may trigger systemic inflammatory processes. To prevent this condition, nutritional strategies should be adopted, such as the inclusion of physically effective fiber sources and the use of buffering additives. In this context, the present study evaluated the effects of supplementation with Lithothamnium calcareum, a marine algae with buffering properties and rich in minerals, on ruminal pH, productive performance, inflammatory parameters, and estimated enteric methane emissions in dairy cows fed a high-starch diet. The experiment was conducted with 36 multiparous Holstein cows, randomly assigned to two groups (n = 18): control group (CON), supplemented with sodium bicarbonate (1.1% of DM), and the Lithothamnium calcareum group (LITHO), supplemented with Lithothamnium calcareum (0.5% of DM). The experimental period lasted 60 days, and both groups received the same basal diet (TMR with 29.28% starch). The first study aimed to evaluate the impact of Lithothamnium calcareum supplementation on rumen health, feeding and activity behavior, milk yield and composition, as well as the cows’ metabolic status. The second study investigated the effects of Lithothamnium calcareum supplementation on ruminal pH and serum levels of iron and hepcidin, aiming to assess their potential as biomarkers of systemic inflammation. The third study estimated enteric methane production based on the proportions of volatile fatty acids (VFA) in rumen fluid and analyzed its relationship with dry matter intake (DMI) in cows supplemented with Lithothamnium calcareum. Overall, the results indicate that Lithothamnium calcareum is a viable alternative as a buffering additive in highly fermentable diets, promoting ruminal stability and satisfactory productive performance, with no adverse effects on inflammatory biomarkers, metabolism, or behavior. However, its effects on enteric methane mitigation still require further investigation.