Effects of increasing dietary levels of microalgae rich in docosahexanoic acid on dry matter intake, milk production, composition and fatty acid profile of dairy cows

• Grant number: 17/01570-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2017
• End date: November 30, 2017
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Francisco Palma Rennó
• Grantee: Mauro Sérgio da Silva Dias
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Fat supplementation is one of the most studied strategies, not only for increase dietary energy concentration, but also for potential nutraceutical effects of unsaturated fatty acids (FA). Intake of omega 3 FA (n-3), considered essential, has been associated with different beneficial effects on human health and milk presents as a potential source. However, despite the possibility of direct conversion of ingested FA to milk fat, several processes related with lipid digestion in ruminants, such as biohydrogenation process, alter the digesta FA profile. In addition, fat supplementation has been associated with decreased on dry matter intake and milk fat content. Some factors, such as the lipid source, the inclusion and the profile of the supplemented lipids seem to be determinants for the results. The objective of this study is to evaluate the effect of increasing levels of dietary DHA-rich microalgae on dry matter intake, milk production, composition and FA profile. Twenty-four Holstein cows will be used, which will be distributed in a replicated Latin square, for to receive the following treatments: control (CON), basal diet without supplements; And supplementation of 50g, 100g or 150g of a commercial source of dehydrated whole-cell DHA-rich microalgae. Each experimental period will last 21 days, with 14 days of adaptation and 7 days of sampling. Samples of refusel and feeds will be sampled during the collection period. These samples will be evaluated for dry matter content to determine DM intake. The milk will be weighed during the last seven days of each trial period. Milk samples will be collected three days to evaluate the composition and FA profile. Data will be analyzed using PROC MIXED of SAS 9.3 (AU)