Impact of Yeast Supplement to the Rations Contained Different Levels of Barley Grain in Milk Production and Components of Awassi Ewes

This study was conducted in the animal field at Department of Agriculture Research, Nineveh Research Department, Ministry of Agriculture, Iraq. Using eighteen Awassi ewes after weaning were used aged 3-5 years, average body weight 55.27 kg, at the period February-2019 to May-2019.  Ewes were allocated randomly according to body weight and milk production into three groups and fed periodically to experimental rations in simple transit design, 1^st ration was control contain 62.5% barley grain, 2^nd ration was similar to the first ration the ewes were dosage with 10 g of yeast (Saccharomyces cerevisiae) per ewe daily after dissolve in warm water, while 3^rd ration contain 35% of barley grain in addition to dosage with yeast (Table 1). Ewes were fed with restricted amount 1.25 kg per ewe daily in three times according to feeding system used in animal research department first at (8:00 am), second (12:00 am) and third (4:00 pm).
 

 
Milk yield was measured for two consecutive days at the end of each period 17 days of the three study periods, milk samples were analyzed to determine milk components using European Eko-milk analyzer.
 
Blood samples were taken from Jugular vein morning after 2hr of feeding and centrifuged for serum separation (3000 r/ hr.) for 15 minute and kept under freezing (-20 C°), then analyzed for glucose, urea, total protein and cholesterol using commercial agent French Biolabo analysis kits.
 
Statistical analysis was done using randomized complete design (CRD) with general linear model (SAS, 2002) by computer and the differences between means was determined by Duncan test (1955).

Table 2 showed that dry matter, protein and energy intake were close between treatments, efficiency of protein and energy utilization improved by 7.57% and 4.48% in T2 when ewes ingested with yeast and fed high barley ration as compared with control T1, while in T3 the improvement in energy utilization increased to 15.15% when ewes fed low barley ration with yeast as compared with T1, this enhance in protein and energy utilization may be due to improvement in dry matter digestibility and increase rumen ammonia utilization as a result of improvement of rumen environment and microbial growth when ewes supplemented with yeast (Habeeb et al., 2017 and Mohammed et al., 2018).
 

 
Results in (Table 3) were indicated no significant differences between treatments in milk yield 554, 575 and 557 g / day respectively, lacking response in milk yield may explain that ewes had requirements of nutrients and the improvement in energy utilization may reflected in increase body weight, this results agreed with the data of (Kattab et al., 2010, Mousa et al., 2012, Al-Ibrahim et al., 2012 and Szues et al., 2013) they did not found  significant effects of yeast supplementation to the rations in ewes milk yield, while others found significant effect of yeast in milk yield (Masek et al., 2008, Ramsing, 2011, De Ondraza et al., 2011 and Fortina et al., 2011) , on other hand (Mikolyunas et al., 2008 and Dosky et al., 2011) observed an increase in milk yield of ewes fed high barley grain, while (Bovera et al., 2003 and Kohestani et al., 2011) indicate that lowering barley grain intake led to increase milk production of ewes (Susin, 1995) was reported a significant increase in milk protein, while fat decreased with increase barley grain intake. However no differences were reported in milk components in ewes fed different levels of barley grain (Bovera et al., 2003 and Aljwari, 2013).
 

 
Table 4 revealed that barley grain and yeast supplement had no significant effect in serum glucose, urea, cholesterol and total protein concentrations, this results were agreed with (Al-Ibrahim, 2012, Helal and Abdelrahman 2010, Hristov et al., 2010 and Yalcin et al., 2011). Moreover (Dosky, 2012) indicated that total protein increased and cholesterol decreased in ewes fed with yeast supplement (Bruno et al., 2009 and Delozal, 2011) found a significant decrease in urea while glucose increased with yeast additive to ewes ration. Therefore (Kohestani et al., 2011, Ranathunga et al., 2010 and Al-Jwari, 2013) were observed no effects of grain levels in blood parameters, otherwise, (Ametaj et al., 2009) was obtained a significant increase in glucose concentration with increase barley grain in cattle diets.
 

Reducing barley grain ewes rations at 3^rd stage of lactation had no effect in milk yield and its components, this economically important as a result to lowered production cost. Also addition of yeast in the low barley grain diet (high fiber) enhance energy utilization.