Resumen

SANCHEZ-SALAS, Jeffry; ELIZONDO SALAZAR, Jorge Alberto; VIQUEZ MATEI, Evelio  y  OROZCO-VIDAORRETA, Carlos. Supplementation with organic seleniumand its effect on productive and reproductiveperformance in grazing dairy cows in Costa Rica. Agron. Costarricense [online]. 2014, vol.38, n.1, pp.29-41. ISSN 0377-9424.

The objective was to evaluate the effectof supplementation with selenized yeast, derivedfrom a specific strain of Saccharomyces cerevisiae(CNCM I-3060), on productive and reproductiveperformance and on selenium concentrations in milk of grazing dairy cows. MultiparousHolstein cows (n=40), with an average bodyweight of 607±62 kg and a body condition scoreof 2.9±0.2 before parturition, were randomlyassigned to 1 of 2 treatments. Control treatmentconsisted of a basal diet supplying 0.7 mgof Se.kg^-1 dry matter. Experimental treatmentconsisted of the same basal diet supplementedwith 3.0 mg of Se, from day 5 to 56 of lactation.Milk production, milk composition, SCC, andSe content of milk were determined at day 5, 14,28, 42, and 56 of lactation. Blood samples fromeach cow were also taken during the same days,to measure glutathione peroxidase (GSH-Px)and Se concentration. To evaluate reproductiveperformance, the ovaries were examined bytransrectal ultrasonography at days 22 and 57 postpartum. Days open, days to first service andservices per conception were also recorded. Milkproduction, milk composition, and SCC did notdiffer between treatments during the trial. Seleniumsupplementation did not alter GSH-Px concentration (199.0 vs. 220.3 U.g^-1 Hb) or Se concentration inblood (166.4 vs. 184.2 µg.l^-1). However, organic selenium supplementation increased (p<0.01) Se apparent efficiency of transfer into milk (7.9 vs. 9.9%) and Se content of milk (12.7 vs.20.5 µg.l^-1); therefore, milk derived from cowssupplemented with selenized yeast could be auseful way to contribute to daily intake of Sein humans, allowing to reach the daily dietaryrecommendations and helping as a functionalfood to solve problems related to Se deficiency.

Palabras clave : Trace minerals; milk; enriched milk; nutrition; dairy cattle.

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