INTRODUCTION
The advance in the knowledge of ruminal microbiology and the potential of modification of it is of transcendency in the obtaining of healthy products, safe, environmentally acceptable and that simultaneously contemplate the productivity and profitability of the ruminants production systems (Hassan and Mohammed 2016 and Rossow et al. 2018). Zootechnical additives are one of the groups of greatest interest from this point of view (Patra 2012).
Among the zootechnical additives are yeasts, whose use in ruminant diets has a long history. However, in recent years several researches have been dedicated to clarifying how low levels of yeasts supplemented in the diet can stimulate the ruminants productivity (Chaucheyras-Durand et al. 2008, Bayat et al. 2015, Öztürk et al. 2015 and Zhu et al. 2017).
Similarly, researches has developed with yeast hydrolysates, residues that are obtained in the industry and which can constitute a highly polluting element of the environment, which could be avoided by using it as a supplement for animal feeding. In Cuba, Pérez et al. (2006) described the methodology for obtaining an enzymatic hydrolyzate of Saccharomyces cerevisiae yeast that showed probiotic effects on monogastric animals, with excellent results in immunological, productive and health indicators.
However, there are few studies related to the use of hydrolyzate in ruminant species. Galindo et al. (2010) showed that this product exerts an activating effect on the populations of total viable and cellulolytic bacteria of the rumen, under in vitro conditions. On the other hand, Díaz et al. (2017) with their use obtained modification of the in vitro fermentative pattern towards a more efficient fermentation, due to the increase of the proportion of propionic acid and the reduction of the methane: SCFA ratio.
These antecedents show the possibility that the enzymatic hydrolyzate of S.cerevisiae yeast increases ruminal degradability in animals that intake fibrous diets. However, studies of this nature have not been carried out yet. That is why the objective of this study was to determine the effect of the enzymatic hydrolyzate of S. cerevisiae yeast on the kinetics of in situ ruminal degradation of nutrients from the forage of Cenchrus purpureus cv. OM - 22.
MATERIALS AND METHODS
Experimental procedure. The evaluated material was Cenchrus purpureus cv. OM - 22 (Cenchrus purpureus x Cenchrus americanus), previously established in a forage area of the Institute of Animal Science, located in San José de las Lajas municipality, Mayabeque province, in Ferric Red-eutric soil, of rapid desiccation, clayey and deep on limestones (Hernández et al. 2015), without fertilization or irrigation. A total of 200 samples of 90 days of regrowth were taken, according to a random unrestricted sampling.
Part of the collected material, previously homogenized and dried for 48 hours in a forced air oven at 60ºC, was milled at 1 mm for the determination of the chemical composition and the other part, destined to the studies of in situ ruminal degradability, was milled at 2.5 mm in an Arthur H. Thomas mill, Wiley, USA, model 4.
The chemical composition (dry basis) of the evaluated forage showed values of 9.20 % of CP, 91.99 % of OM, 78.07 % of NDF, 44.50 % of ADF, 31.50 % of cellulose and 7.25 % of lignin.
A total of four Holstein cows of 480 ± 10 kg of live weight were used, cannulated in rumen and housed in individual cubicles with free access to drinking water and food, according to a 4 × 4 Latin square design. The animals intake fresh forage of C. purpureus cv.OM - 22 ad libitum and commercial concentrate for dairy cows, according to treatment, offered once a day (8:00 am).
The treatments were the following:
Treatment 1 (Control). Forage + 2 kg commercial concentrate.day-1
Treatment 2. Forage + 2 kg comercial concentrate + 50 mL of enzymatic hydrolyzate of Saccharomyces cerevisiae yeats .kg de concentrate.day-1
Treatment 3. Forage + 2 kg commercial concentrate + 100 mL of enzymatic hydrolyzate of Saccharomyces cerevisiae yeats .kg of concentrate .day-1
Treatment 4. Forage + 2 kg commercial concentrate + 150 mL of enzymatic hydrolyzate of Saccharomyces cerevisiae yeats .kg of concentrate .day-1
The chemical composition of the offered food is shown in table 1.
Indicators |
|
Commercial concentrate |
---|---|---|
CP | 10.04 ± 0.20 | 17.03 ± 1.33 |
OM | 92.40 ± 0.72 | 92.62± 0.49 |
NDF | 79.99 ± 0.48 | 31.09 ± 9.74 |
ADF | 48.80 ± 1.14 | 11.99 ± 6.63 |
Lignin | 7.50 ± 0.56 | - |
Ash | 7.60 ± 0.72 | 9.38 ± 0.49 |
The mixture of the commercial concentrate and the enzymatic hydrolyzate of S. cerevisiae yeast were daily prepared.
The yeast hydrolyzate used was obtained according to the Pérez et al. (2006) methodology from the S. cerevisiae yeast cream from the alcohol distillery plant belonging to the Complejo Agroindustrial "Jesús Rabí”, Calimete, Matanzas province. The hydrolyzate showed DM and OM values of 19.39 and 82.17 %, respectively. The Crude and True Protein was 40.28 and 38.58 % of the DM, respectively. The ash values were in the range of 12.3 %, while the concentration of reducing sugars and total carbohydrates was 7.93 and 6.09 %, respectively.
The experimental periods consisted of 14 adaptation days to the diet and 5 sampling days.
Chemical composition. The content of dry matter (DM), ash, organic matter (OM) and crude protein (CP) according to the techniques described by AOAC (2016) was determined in the samples of the offered food and the evaluated forage in each period. The content of neutral detergent fiber (NDF) and acid detergent fiber (ADF), celluloses, hemicelluloses and lignin was determined by the Goering and Van Soest (1970) method.
In situ ruminal degradability. The determination of the in situ ruminal degradability of the DM, OM, NDF and ADF of C. purpureus cv. OM-22 was performed according to the nylon bag or in situ procedure described by Mehrez and Ørskov (1977).
The bags containing the forage to be evaluated were placed in 25 x 35 cm mesh bags with plastic zipper and were introduced into the ventral compartment of the rumen of the cannulated animals, in reverse order of their incubation time at 12, 24, 48, 72 and 96 h and then were simultaneously removed at 96 hours. Two unincubated bags were left to determine the rapidly soluble fraction (A), which was obtained by incubating the sample in a water bath at 39°C for 30 minutes. After being extracted from the rumen, we proceeded as indicated by Valenciaga et al. (2018) to determine the DM, OM, NDF and ADF degraded in the rumen.
Estimation of degradation. To determine the degradative characteristics, the exponential model proposed by Ørskov and McDonald (1979) was used, assuming that the degradation curves of the DM and the OM over time follow a first order kinetic process that is described in the following way:
And the degradation curves of the NDF and ADF are described according to Dhanoa (1988) by the formula:
Where:
- P: Ruminal degradation. It is the ruminal degradation of the evaluated indicator in the time "t" of permanence in the rumen.
- a: Intercept
- b: Fraction that degrades in time t.
- c: Degradation rate of the fraction “b”.
- t: Incubation time.
- L: Latency time or “lag” (hours). Time spent by the rumen microorganisms to colonize the cell walls of the forages and adhere to them.
- A: Easily soluble fraction.
In order to determine the ruminal Effective Degradability (ED) the McDonald (1981) model was used
Where:
- k: Fractional rate of ruminal passage. It assumes k value (0.044 fraction/h) (NRC 2001)
- B: Insoluble fraction but potentially degradable. (Ørskov 2002)
- c: Degradation rate of fraction B.
Statistical analysis. To determine the effect of enzymatic hydrolyzate of S. cerevisiae yeast in the in situ ruminal degradation of the evaluated forage nutrients, analysis of variance according to 4x4 Latin Square Design was performed. Statistical analyzes were performed for the comparison between the means of each treatment, for each incubation time, using the statistical processor InfoStat (Di Rienzo et al. 2011) and, when necessary, Duncan (1955) test was used for the comparison of means. For the mathematical estimation of the ruminal degradation parameters of the DM, OM, NDF and ADF of the evaluated forage, the NEWAY EXCEL program was used according to Chen (2000).
RESULTS AND DISCUSSION
The lowest DM rumen degradability was verified in each incubation time evaluated, for the control treatment (P <0.0001) (table 2), followed by the treatment of 50 mL of yeast hydrolyzate.kg of concentrate.day-1. In the treatment with 150 mL of yeast hydrolyzate showed the highest ruminal degradability values (P <0.0001), at each incubation time. However, only differed (P <0.0001), from the treatment of 100 mL of hydrolyzate in the first incubation times (12 and 24 hours), after 48 hours the degradability values were similar in both treatments.
Treatments Hours |
mL of enzymatic hydrolyzate of |
SE(±) Signif. | |||
---|---|---|---|---|---|
0 | 50mL | 100mL | 150mL | ||
12 | 24.09d | 35.11c | 42.88b | 44.61a | 0.46 P<0.0001 |
24 | 38.47d | 48.33c | 60.95b | 64.43a | 0.79 P<0.0001 |
48 | 57.81c | 69.31b | 80.91a | 81.69a | 0.44 P<0.0001 |
72 | 66.37c | 74.30b | 82.44a | 83.48a | 0.45 P<0.0001 |
96 | 67.73c | 76.23b | 84.26a | 86.00a | 0.62 P<0.0001 |
AbcdValues with different letter per dow differ at P < 0.05 (Duncan 1955)
The best use of the evaluated forage was obtained in the treatments with 100 and 150 mL of yeast hydrolyzate, where the maximum DM degradation at 96 hours was 84.26 and 86.0 %, respectively, compared to the 50 mL treatment which recorded value of 76.23 % and the control treatment that only increase at 96 hours to 67.63 % of ruminal degradation of the DM (P <0.0001).
On the other hand, the lower ruminal degradability of OM was verified in each incubation time in the control treatment (table 3)
Treatments Hours |
mL of enzymatic hydrolyzate of |
SE(±) Signif. | |||
---|---|---|---|---|---|
0 | 50mL | 100mL | 150mL | ||
12 | 22.50c | 33.92b | 44.79a | 47.96a | 2.74 P=0.0022 |
24 | 37.07c | 47.40b | 62.43a | 66.52a | 2.08 P=0.0002 |
48 | 54.01c | 66.59b | 79.66a | 81.96a | 2.03 P=0.0002 |
72 | 59.57c | 70.60b | 81.72a | 83.33a | 2.51 P=0.0017 |
96 | 60.15c | 71.38b | 82.34a | 84.23a | 2.45 P=0.0015 |
AbcdValues with different letter per dow differ at P < 0.05 (Duncan 1955)
The treatments with 100 and 150 mL of yeast hydrolyzate showed the highest values of the OM degradation in all incubation times, being similar in both treatments and higher (P <0.05), to the rest.
The obtained results coincide with those achieved by other authors in researches of in vitro and in situ ruminal degradation, when evaluating live strains of Saccharomyces cerevisiae as an additive in fibrous diets for ruminants.
Sauvant et al. (2004) observed increase of the in situ ruminal degradability of DM and OM in Holstein cows that received culture of live S. cerevisiae yeast in their diet, with respect to the control group. On the other hand, Fadel El-Seed et al. (2004) showed that supplementation with cultures of this yeast in Nubian kids breed increased the in situ degradability of OM in their diet by 12.1 % with respect to the control diet. While El-Waziry and Ibrahim (2007) found increases in the ruminal degradation of the DM hay of Trifolium alexandrinum with the addition of the yeast in fattening lamb diets.
The highest percentage in the ruminal degradability of the NDF (P <0.0001) of the evaluated forage (table 4), in each incubation time, was obtained with the treatment of 150 mL of yeast hydrolyzate. This did not differ from the treatment with 100 mL of yeast hydrolyzate at 48, 72 and 96 incubation hours.
Treatments Hours |
mL of enzymatic hydrolyzate of |
SE(±) Signif. | |||
---|---|---|---|---|---|
0 | 50mL | 100mL | 150mL | ||
12 | 24.66d | 35.09c | 42.43b | 43.81a | 0.25 P<0.0001 |
24 | 39.58d | 47.78c | 61.18b | 64.00a | 0.51 P<0.0001 |
48 | 58.35c | 69.15b | 80.50a | 82.00a | 0.52 P<0.0001 |
72 | 64.98c | 74.44b | 82.92a | 83.81a | 0.28 P<0.0001 |
96 | 65.53c | 75.34b | 83.44a | 84.29a | 0.43 P<0.0001 |
AbcdValues with different letter per dow differ at P < 0.05 (Duncan 1955)
On the other hand, the lower degradability of the ADF was verified in each incubation time for the control treatment (P <0.0001) (table 5).
Treatments Hours |
mL of enzymatic hydrolyzate of |
SE(±) Signif. | |||
---|---|---|---|---|---|
0 | 50mL | 100mL | 150mL | ||
12 | 16.61d | 27.83c | 38.12b | 39.77a | 0.07 P<0.0001 |
24 | 32.13d | 42.02c | 54.11b | 56.28a | 0.34 P<0.0001 |
48 | 51.91c | 62.84b | 76.75a | 77.41a | 0.26 P<0.0001 |
72 | 57.88c | 69.43b | 79.53a | 80.61a | 0.33 P<0.0001 |
96 | 58.60c | 70.34b | 80.54a | 81.27a | 0.38 P<0.0001 |
AbcdValues with different letter per dow differ at P < 0.05 (Duncan 1955)
The in situ ruminal degradation showed higher use of NDF and ADF of the evaluated forage, with the treatment of 150 mL of yeast hydrolyzate.kg concentrate-1 in all incubation times, since with this treatment the highest degradation values were obtained (P <0.0001). However, after 48 hours similar values were observed with the treatment of 100 mL of the supplement, being higher (P <0.0001) than the rest of the treatments.
These results coincide with those obtained by Biricik and Türkmen (2001), who reported increases in the ruminal degradability of NDF and ADF, both in vivo and in vitro, in diets with different proportion of forage: concentrate and S. cerevisae yeast. On the other hand, Kholif and Khorshed (2006) observed a positive effect of yeast supplementation on the ruminal degradation of NDF, ADF, cellulose and hemicellulose in buffaloes diets.
El-Waziry and Ibrahim (2007) found increases in the ruminal degradation of the NDF and ADF of Trifolium alexandrinum hay with the addition of S. cerevisiae yeast in fattening lambs diets, while Olmedo et al. (2015) showed increases in the in situ ruminal degradability of NDF in fibrous diets for sheep when was supplemented with strain S. cerevisae yeast. Recently, Martínez et al. (2017) obtained improvements in the ruminal degradation of the NDF of different forages with the addition of yeasts in finished steer diets, by providing sufficient energy and protein, which was reflected in an increase in the concentration of SCFA.
The increase of the rumen degradability of the forage nutrients evaluated, with the increase of the amount of yeast enzymatic hydrolyzate added to the diet, could be related to what is stated in the scientific literature about the activating effect of the yeast strains on the populations of total viable bacteria and of cellulolytic bacteria, when these strains are used as additives in ruminants diets (Chiquette 2009, Herrera-Torres et al.2014, Zhu et al. 2017 and Casas Rodríguez 2018).
Many mechanisms have been described by which small doses of yeast added to the diet can stimulate microbial growth in the rumen. One of them explains that the activating effect has its origin in the growth factors that the yeasts have for the ruminal microorganisms, such as the B complex vitamins, the short chain fatty acids (SCFA) and the branched chain, the provitamins and micronutrients (Newbold et al. 1996, Dawson and Girard 1997, Fonty and Chaucheyras-Durand 2006).
Dawson and Girard (1997) suggested that the stimulation of microbial growth may be associated with the presence of two growth factors located in the different cellular fractions of the yeast, one of them thermolabile of lipid origin and the other thermostable with a possible peptide origin. Subsequently, Rossi et al. (2004) isolated from S. cerevisiae two peptide fractions rich in lysine and histidine, which were effective in stimulating the growth of ruminal bacteria Megasphaera elsdenii.
On the other hand, Chaucheyras-Durand et al. (2008) showed the effectiveness of yeasts to influence on the growth and enzymatic activity of fiber-degrading microorganisms in the rumen and reported the in vitro stimulation of the fungus Neocallimastix frontalis, by the thiamine supplied by yeasts, which is a vitamin required by the rumen fungi for zoosporogenesis. In addition, these authors showed that yeasts stimulate the growth and enzymatic activity of glycosidases and hydrolases enzymes in bacteria responsible for the digestion of fiber such as Fibrobacter succinogens, Ruminococcus spp. and Butyrivibrio fibrosolven, for the supply of nutrients and vitamins they make for this fibrolytic population.
In general, few studies have analyzed the effect of yeast hydrolysates on ruminant animals. The specific mechanisms of action of these have not been clearly defined. Galindo et al. (2010) when evaluating the effect of two levels of enzymatic hydrolyzate of the S. cerevisiae yeast on the ruminal microbial population of animals that intake C. purpureum cv. Cuba CT-115 observed an increase in the populations of total viable bacteria and of cellulolytic bacteria under in vitro conditions. The level of 100 mL. kg of concentrate. day-1 was the one that allowed to obtain the highest increase of the population of total viable bacteria.
Kettunen et al. (2016) and Oeztuerk et al. (2016) reported the efficacy of two hydrolysates of S. cerevisiae yeast, which stimulated the in vitro fermentation of different substrates and increased the production of SCFA. Recently, Díaz et al. (2017) evaluated the effect of supplementation with hydrolyzate of S. cerevisiae yeast on the fermentative parameters in RUSITEC fermenters that received alfalfa hay and concentrate in a 1: 1 ratio. These authors found increases in the microbial growth in rumen, especially of cellulolytic bacteria, with the addition of the hydrolyzate in the diet.
If it is take into account that the enzymatic hydrolyzate of Saccharomyces cerevisiae consists mainly of low molecular weight peptides, oligosaccharides of glucans and mananes, vitamins, amino acids, nitrogenous bases, nucleosides and nucleotides, among other components (Barton et al. 2010), then it is evident that it can exert a stimulating effect on the ruminal microbial population as well as live yeast strains, due to the presence of these substances in the enzymatic hydrolyzate, which could directly affect the increase of the ruminal degradability of the forage nutrients evaluated in this research.
With respect to the parameters of the ruminal degradation of the DM and OM of the evaluated forage (table 6), it should be highlighted that the model used had high goodness of fit, since R2 was high, ranging between 0.99 and 0.96 for all treatments, which shows that this model explains a high variation percentage of the real data of ruminal degradability.
Treatments | ||||
---|---|---|---|---|
Parameter | mL of enzymatic hydrolyzate of |
|||
0 | 50 mL | 100 mL | 150 mL | |
DM | ||||
A (%) | 17.60 | 17.60 | 17.60 | 17.60 |
B (%) | 53.80 | 61.30 | 67.30 | 68.30 |
(A+B)(%) | 71.40 | 78.90 | 84.90 | 85.90 |
C (Fraction/ h-1) | 0.035 | 0.037 | 0.052 | 0.058 |
RSD | 1.09 | 1.35 | 1.49 | 1.15 |
R2 | 0.98 | 0.97 | 0.96 | 0.99 |
ED (%)k= 0.044 | 41.44 | 45.60 | 54.05 | 56.44 |
OM | ||||
A (%) | 16.60 | 16.60 | 16.60 | 16.60 |
B (%) | 45.60 | 56.90 | 66.70 | 68.10 |
(A+B)(%) | 62.10 | 73.50 | 83.30 | 84.70 |
C (Fraction/ h-1) | 0.042 | 0.043 | 0.056 | 0.063 |
RSD | 1.12 | 1.04 | 1.41 | 1.02 |
R2 | 0.96 | 0.98 | 0.97 | 0.99 |
ED (%)k= 0.044 | 38.87 | 44.39 | 53.95 | 56.70 |
RSD: Residual standard deviation
R2: Coefficient of determination belonging to the model
The same value of fraction A was considered for each treatment, taking into account that the incubated substrate was the same in all, while a tendency to increase fraction B and the potential degradability of DM and OM of the evaluated forage was observed, with the increase of the amount of enzymatic hydrolyzate added to the diet.
In the case of DM, there was a tendency to increase the degradation rate with the increase in the amount of enzymatic hydrolyzate (0.035, 0.037, 0.052 and 0.058fraction% h-1 for the treatments of 0, 50, 100 and 150 mL of enzymatic hydrolyzate of yeasts, respectively). Similar performance had this parameter for the OM that increased from 0.042 to 0.063 fraction % h-1 with the increase of enzymatic hydrolyzate of yeasts in the diet.
On the other hand, when analyzing the parameters of the ruminal degradation of the NDF and ADF of the evaluated forage (table 7), it was verified that the addition of increasing levels of enzymatic hydrolyzate of yeast in the concentrate resulted in an improvement in both indicators and a tendency to increase fraction B and the potential degradability of both indicators was observed.
Treatments | ||||
---|---|---|---|---|
Parameter | mL of enzymatic hydrolyzate of |
|||
0 | 50 mL | 100 mL | 150 mL | |
NDF | ||||
A (%) | 16.10 | 16.10 | 16.10 | 16.10 |
B (%) | 52.10 | 62.40 | 68.60 | 69.10 |
(A+B)(%) | 68.20 | 78.50 | 84.70 | 85.20 |
C (Fraction/ h-1) | 0.038 | 0.040 | 0.055 | 0.060 |
L (h) | 7.70 | 4.30 | 3.30 | 3.30 |
RSD | 1.46 | 2.29 | 1.71 | 1.41 |
R2 | 0.98 | 0.97 | 0.99 | 0.97 |
ED (%)k= 0.044 | 33.55 | 41.31 | 48.92 | 49.02 |
ADF | ||||
A (%) | 7.50 | 7.50 | 7.50 | 7.50 |
B (%) | 53.50 | 66.00 | 75.10 | 77.00 |
(A+B)(%) | 61.00 | 73.70 | 82.60 | 84.50 |
c(Fraction/ h-1) | 0.037 | 0.041 | 0.045 | 0.045 |
L (h) | 7.80 | 4.60 | 2.60 | 2.40 |
RSD | 1.59 | 2.00 | 1.30 | 1.04 |
R2 | 0.97 | 0.99 | 0.98 | 0.99 |
ED (%)k= 0.044 | 25.79 | 34.61 | 44.44 | 44.40 |
RSD: Residual standard deviation
R2: Coefficient of determination belonging to the model
In the case of NDF, the degradation rate increased from 0.038 to 0.060 fraction %h-1 with the increase of the enzymatic hydrolyzate of yeasts and for the ADF increased from 0.037 to 0.045 fraction %h-1. A shorter latency period (L) was observed for 100 and 150 mL treatments of yeast hydrolyzate. kg concentrate.day-1, being similar between both treatments and lower to the rest.
On the other hand, an increase in ED was observed with the increase in the amount of the supplement evaluated in the diet for all the nutrients under study (table 6 and 7). This result is of great importance since the feeding strategies of ruminants in the tropics have to be based on the capacity of this species to efficiently use the grasses and forages and, to take advantage of fibrous resources, optimizing the efficiency of the ruminal fermentative activity, with a view to increase the intake and use of the staple food, and only to supplement with those nutrients that are deficient for the host animal (Barahona Rosales and Sanchez Pinzón 2005). It is evident that the addition of 100 and 150 mL of enzymatic hydrolyzate of yeast /kg concentrate/day increase the use of the C. purpureus vc.OM - 22 forage.
The increase in the population of bacteria and cellulolytic fungi in the rumen and their fermentative patterns, with the addition of the enzymatic hydrolyzate, could explain the increase in the degradability of nutrients, as well as the degradation rate and the ED which has been verified in the research. However, it is probable that the polysaccharides components of the cell wall of S. cerevisiae yeast also exert stimulatory effects on the ruminal microbial population by certain mechanisms that should be studied in future researches.
The cell walls of the yeasts can constitute approximately 30 % of the cell dry matter. On a structural scale, the cell wall of the yeasts is constituted by three groups of polysaccharides: mannose polymers or manane-protein, up to 50 % of the DM; polymers of glucose or β-glucans (1.3/1.6), up to 55 % of the DM; and to a lower extent, polymers of N-acetyl-glucosamine or chitin in 6 % of the DM of the yeast cell wall (Aguilar-Uscanga and Francois 2003 and Díaz et al. 2017)
Since the past decade there has been increasing interest in the use of yeast cell wall fractions diet as sources of polysaccharides of β-glucans and manane-oligosaccharide (OSM). This type of polysaccharides are recognized as natural additives able of exerting beneficial effects on the health and productivity of animals (Hooge 2004 and Pérez et al. 2016), mainly because they stimulate the immune response and prevent infectious diseases due to their great antibacterial potential (Rodríguez et al. 2015).
However, there are very few studies that have analyzed the effect of these components on ruminant animals and the specific mechanisms of action have not been clearly defined. In spite of this, the benefits obtained in the health and productivity of animals by their application in the diet are well documented.
Gomez-Basauri et al. (2001) observed an increase in milk production and a lower DM intake in cows that intake OSM in their diet, which generated higher efficiency in the foods conversion, showing possible positive effect of OSM on the ruminal microflora. In dairy cattle, supplementation with polysaccharides β-glucans and OSM has been associated with the reduction of the negative impact of heat stress in cattle, with increases in milk production, improvements in immune status, and decrease in incidence of mastitis, reducing the somatic cell count (Salinas-Chavira et al. 2015)
However, studies to evaluate the impact of these fractions of yeast cell walls in the fermentation and kinetics of ruminal degradation were not found in the available consulted literature, so it is of great interest to continue the studies to elucidate the action mechanisms of these components, which can constitute nutrients able of stimulating the microbial populations of the rumen and directly influence on the fermentative processes, with the consequent positive effect on the ruminal degradation of nutrients from animals that intake fibrous diets.
The obtained results allow to concluding that the addition of enzymatic hydrolyzate of Saccharomyces cerevisiae yeast in the diet had a positive effect on the kinetics of ruminal degradation of nutrients of C. purpureus vc.OM - 22 forage. It is recommended to use the level 100 mL of enzymatic hydrolyzate /kg concentrate/day in ruminants that intake diets with high fiber content and it is suggested to continue the studies to clarify the action mechanisms of polysaccharides β-glucan and manane-oligosaccharides of yeast cell walls, in the kinetics of ruminal degradation of low quality forages.