F.  Opsi, S.  Tassone, M.  Renna, A.  Mimosi, L.M.  Battaglini, R.  Fortina, 
    Effects of Inactivated Yeast Culture on Rumen Fermentation and Performance of Mid-Lactation Dairy Cows,
    Journal of Animal and Veterinary Advances,
    Volume 10,Issue 5,
    2011,
    Pages 577-580,
    ISSN 1680-5593,
    javaa.2011.577.580,
    (https://makhillpublications.co/view-article.php?doi=javaa.2011.577.580)
    Abstract: The aim of this study was to evaluate the effect of daily supplementation of a devitalized strain of <I>Saccharomyces cerevisiae</I> on milk yield and composition of Friesian-Holstein lactating cows. Average Days In Milk (DIM) and Body Weight (BW) of cows were 98&plusmn;24 days and 619&plusmn;13.2 kg. Prior to the experiment, the effects of the yeast culture added to the diet were investigated in 2 <I>in vitro</I> experiments. In the first experiment, 6 samples of rumen fluid were used to determine the DM, CP and NDF degradability (IVDMD, IVCPD, IVNDFD) of Total Mixed Ration (TMR) at 0 and 48 h with the addition of 0 g (Y<SUB>0</SUB>) and 1 g (Y<SUB>1</SUB>) of yeast culture. In the second experiment, free, total and microbial ATP production were used for the evaluation of microbial activity in rumen fluids after 0, 8, 24 and 48 h incubation. In the 4 weeks trial, 10 multiparous cows were assigned to a Control diet (C) and 10 to the experimental diet (YC = C+35 g/cow/day of yeast culture). TMR on a Dry Matter (DM) basis consisted of corn silage (42.3%), ryegrass hay (14.1%), corn meal (22.1%), soybean meal (17.9%) and a mineral/vitamins mix (3.6%). Crude Protein (CP) and ENl were 14.6% and 1.56 Mcal kg<SUP>-1</SUP> DM, respectively. Cows were individually fed once daily and milked at 7 and 19 h. <I>In vitro</I> experiments showed that the addition of 1 g YC to the rumen fluid increased IVCPD and IVNDFD after 48 h of incubation but did not influence IVDMD. Free, total and microbial ATP values showed a continuous decrease during the 48 h of the trial but the addition of YC proved to be effective in slowing the decrease. Milk yield (31.9 and 33.4 kg day<SUP>-1</SUP>, for the C and YC group), 4% fat corrected milk (FCM: 30.3 and 31.7 kg day<SUP>-1</SUP>) and energy corrected milk (ECM: 32.9 and 34.5 kg day<SUP>-1</SUP>) were significantly different between groups. Dry Matter Intake (DMI), milk fat and protein percentage were similar in both groups. Feed efficiency (ECM kg<SUP>-1</SUP> DMI) was higher in YC group than in C.
    Keywords: rumen fluid;Yeast culture;rumen fermentation;microbial ATP;Italy;milk production