الفهرس 
Introduction
Effect of yeast culture supplementation onOnly 14 pages are availabe for public view
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Abstract
The main objectives of the present study were to investigate the effects of Rumi yeast (RY) supplementation at two roughage : concentrate ratios of corn silage (CS) : concentrate feed mixture (CFM) in diets of lactating Zaraibi goats on nutrient digestibilities, some rumen liquor parameters, some blood constituents, milk yield and its composition, feed conversion and economic efficiency.
Methods & Results:
The experimental work of this study was carried out at El-Serw Experimental Research Station, Animal Production Research Institute, Agriculture Research Center and Animal Production Department, Faculty of Agriculture, Mansoura University during summer 2011. Twelve mature Zaraibi bucks weighing 60.0±0.4 kg were divided into 4 equal groups (3 bucks in each) for running the digestibility trials for the nutritional evaluation of the tested diets before starting the performance trial. In addition, Twenty-four lactating Zaraibi goats (36.5±0. 5 kg) were used to study the effects of feeding tested diets on their productive performance. The experimental period lasted for 120 days. The tested diets were as follows::
Diet 1: CFM, 70% + 30% CS with RY, Diet 2: CFM, 70% + 30% CS without RY, Diet 3: CFM, 30% + 70% CS with RY, Diet 4: CFM, 30% + 70% CS without RY. Three g RY /head/day was chosen as recommended dose suggested by the (Multi Vita) company for small dairy ruminants in rations of lactating goats, since this level was found to be economical in feeding practices.
The addition of RY significantly (p˂0.05) enhanced all nutrients digestibility coefficients, as well as digestibility of cell wall constituents (NDF, ADF, ADL, cellulose, hemicelluloses). RY ddition improved nutritive values as total digestible nutrients (TDN) and digestible crude protein (DCP %). Rumen parameters (pH values, TVFA’S and ammonia-N concentrations) were improved with HC diets compared with HR ones. The average daily milk yield (ADMY) was significantly (P<0.05) the highest when goats were fed HC diet compared with those fed HR diet. Rumi yeast supplementation had significant (P<0.05) effect on ADMY. Milk fat, protein, total solids (TS) and solids non fat (SNF) contents were significantly affected by R : C ratio during lactation period. While, lactose and ash contents in milk of tested treatments were not significantly affected by R:C ratio estimated biweekly. Milk fat, total solids (TS%) percentage was significantly (P < 0.05) higher with RY supplemented (RYS) diet than unsupplemented one (USRY). Milk protein, Lactose and ash content were not significantly affected by RYS during the experimental period. The R:C ratio did not significantly affect most of blood parameters, e.g. ALT, AST, cholesterol, glucose, total protein, globulin, albumin concentrations and A/G ratio, but total lipids, triglyceride and urea concentrations were significantly (P<0.05) higher by about 14.9, 4.41 % and 2.78% for HC than HR diet, respectively. RY supplementation had no significant effect on total protein, globulin, A/G ratio, cholesterol, triglyceride, glucose, AST and urea- N concentration.The albumin and blood total lipids concentration and the activity of ALT concentrations were significantly (P<0.05) higher with RY supplementation than unsupplemented one. The economic feed efficiency (EFE) was the highest for goats fed HR supplemented with RY (202.62%) than those fed HR unsupplemented with RY (197.65%), followed by those fed HC supplemented with RY (171.11%), while the lowest daily feed cost was recorded with goats fed HC without RY (164.87%).
Conclusion:
It could be concluded that concentrate: roughage ratio had remarkable effect on animal performance. Nutrients digestibility coefficients, feeding values, rumen parameters and animal performance were improved with HC diet compared with HR. RY supplementation had positive effect on digestibility coefficients, feeding values and rumen parameters. While, animal performance was slightly improved by rumi yeast supplementation.