The Effect of Saccharomyces cerevisiae Yeast Enriched with Selenium and Zinc on Some Physiological Traits and Milk Production of Female Shami Goats

Background: Milk production is one of the most important goals pursued by breeders of milk-producing farm animals World Wide. Goats are one of the most important of these animals. This study sought to compare the effect of Saccharomyces cerevisiae yeast (SCY) with or without Selenium and zinc on milk yield and milk nutritional composition and hormones related. Methods : twenty four female Shami goats distributed into 4equal groups (6 goats /group) control group (C) animals fed on standard concentrated diet without adding, T2(SCY) animal dosed with S.Cerevisiae at a concentration of 0.2 g/kg of body weight, T3 (Se + Zn) was fed on Selenium and zinc at a concentration of 0.3 and 0.2 g/kg of body weight, respectively, T4 (SCY+Sc +Zn) was represented by dosing their animals with an S.Cerevisiae 0.2g/kg body weight with selenium and zinc added to ratio at same as T3. Result: there was a significant increase (P  0.05) in the in-milk production, solid-to-fat ratio, milk density and protein level at (SCY+ Sc+Zn) among the transactions, also (SCY+ Sc+ Zn) highlighted a significant increase (P  0.05) in prolactin, thyroxine and cortisol hormones accompanied by a significant decrease (P  0.05) in estrogen and triiodothyronine levels in compared to all treated groups.


INTRODUCTION
The researchers turned to the formation of dietary supplements, a mixture of two or more substances that have an essential vital effect productively and functionally on the animal, including yeast fortified with Selenium and zinc (Tian et al., 2022).Yeasts are one of the growth stimulants that help increase metabolism in ruminants because the ration contains a large percentage of fiber, which can only be digested by microbial digestion (Acharya et al., 2017).The importance of synergy between yeast, Selenium and zinc lies in their physiological role, as yeast improves the stability of rumen fermentation and promotes microbial growth; moreover, complementary yeast provides some nutrients during the digestion process that affect microbial communities and their work, as many studies have shown beneficial effects of yeast on the rumen environment and the number and activity of rumen microbes (Cui et al., 2021) as shown in figure [1].On the other hand, studies using S. Cerevisiae used in dairy goat feed might vary.W hen given goats yeast culture, there were improvements in milk output and milk constituents (Cai et al., 2021).
High-yield dairy goats need feeding plans that ensure the proper contribution of all essential microelements, including Selenium and zinc.Many studies have proven the vital role of Selenium and zinc in stimulating the secretion of the hormone prolactin and increasing milk production in quantity and quality in dairy farm animals (Enjalbert et al., 2006).Although there are few studies (Trinta et al., 2020) available on the effect of baking yeast treated with zinc and Selenium and comparing its effect on milk production with the use of yeast alone or of Selenium and zinc separately and independently, there are signs and hints in some studies, although they do not include female goats, that there is such a synergistic effect (Sun et al., 2021).

Aim of the study
This experiment was accompanied to examine the impact of yeast (Saccharomyces cerevisiae) supplemented with/ without a mixture of Selenium and Zinc on milk yield and milk nutritional composition and monitoring of hormones related, which is closely associated with the ability to milk Shami goats females to produce milk.

MATERIALS AND METHODS
This study was conducted in a private field in the Baybukht area North of Mosul during winter season(from November 2022 to February 2023).Twenty-four female Shami goats, The Effect of Saccharomyces cerevisiae Yeast Enriched with Selenium and Zinc on Some Physiological Traits and Milk Production... aged 1.5 -2 years and weight averaging 35.5±2.5 were used.During the experiment, the female goats were fed collectively concentrated feed (Table 1) with two morning and evening meals of 2% of the live animal's weight.The amount of focused feed was adjusted during the experiment according to the weight developments of the animals, hay, water and provided metal salt briquettes to the animal's ad libitum throughout the investigation.

Experiment design
24 female Shami goats were randomly distributed into four equal groups (6 goats /group).Fed control group (C) animals on the standard concentrated diet without any adding for the second group (SCY) animals were dosed with S. Cerevisiae at a concentration of 0.2 g/kg of body weight.The third group (Se + Zn) was represented by dosing their animals with an elemental mixture of Selenium and zinc at a concentration of 0.3 and 0.2 g/ kg of body weight, respectively.The fourth group (SCY + Sc + Zn) was represented by dosing their animals with an S. Cerevisiae mixture of 0.2 g/ kg body weight with selenium and zinc elements at a concentration of 0.3 and 0.2 g/ kg body weight, respectively.

Blood measurements
Blood samples were taken through the jugular vein at the 1 st month and end of the 3 rd month of the experiment and measured the level of prolactin, estrogen and thyroid hormones.The story of the prolactin, estrogen and thyroid hormones in the blood serum was estimated using a ready-made working kit equipped by the Biotech, Inc. company using the ELISA device technique according to the method of ( Uotila et al., 1981).

Milk measurements
Milk samples were taken at the end of 1 st and 3rd months of the experiment.The goats were milked daily by manual hand milking at seven in the morning at seven in the evening the day before.The amount of production per goat was measured by multiplying the amount of output ×2 to extract the daily milk yield (Icar,1995).The concentration of fat, protein and lactose in the milk was measured and the Eko-milk Analyzer estimated the level of non-fat solids and milk density.
The statistical analysis of the experimental data was carried out according to the completely randomized design; the significance of the differences between the coefficients was tested using Duncan's multiple range tests and used the ready-made statistical analysis program (SAS, 2001).Chemical composition based on dry matter mathematically estimated by (Al-Khawaja ,1978).

RESULTS AND DISCUSSION
The results of the statistical analysis of Tables (2) and ( 3) indicated the same results in all measurements of milk components.At the end of the 1 st and 3 rd months of the experiment, the averages of (SCY + Sc + Zn) recorded the highest increase (P0.05) in milk production, solid-to-fat ratio, milk density and protein level among all transactions.The Effect of Saccharomyces cerevisiae Yeast Enriched with Selenium and Zinc on Some Physiological Traits and Milk Production...In turn, (SCY) and (Se + Zn) groups, recorded their significant superiority (Pde0.05)over the control group in milk production, solid-to-fat ratio, milk density and protein level.While in milk fat ratio, also at the end of the 1 st and 3 rd months, (SCY + Sc + Zn) group gave its lowest rates (Pde0.05)compared to all the experiment transactions, as well as the yeast group (SCY) (Pde0.05)compared to the control, while the decrease was mathematically for the minerals group (Se + Zn) compared to the control.(Gomes et al., 2012;Ferreira et al., 2010) who attributed the improvement in milk production levels, increasing its milk density, the percentage of protein and solid matter in animals that fed on S. Cerevisiae, to the containment of the outer membrane of yeast cells a high protein concentration and high level of solid matter, concurred with the results of the current study.According to ( Dobicki et al., 2006), S. Cerevisiae yeast increased milk production by enhancing microbiota metabolic activity, feed digestibility, energy metabolism and mammary gland health (Milewski and Sobiec, 2009).There is some evidence that S. Cerevisiae influences the composition of milk in ruminants, in addition to some evidence that it has a favorable impact on milk production (Coleman et al., 2023).S. Cerevisiae supplementation dramatically reduced the amount of milk fat in ruminants (Zaworski et al., 2014).Supplementing with S. Cerevisiae also markedly boosted the amount of total protein in ewe milk (Mustafa, 2022).S. Cerevisiae altered the protein content of milk as well.After 70 days of supplementation with S. Cerevisiae at a daily dose of 30 g/ animal during lactation, the concentrations of β-casein were significantly decreased, while k-casein had a significant rise in ewe milk (Milewski et al., 2012).Bioavailable chromium found in S. Cerevisiae may influence insulin-like growth factor 1 and boost milk output (IGF-1).Chromium was reported to upregulate IGF-1 mRNA and IGF-1 When insulin is present, chromium has been shown to increase the levels of IGF-1 mRNA and IGF-1 receptor in skeletal muscle cells (Jia et al., 2018).At the end of the first and third months of the experiment, the goats treated with selenium and zinc produced more milk and milk protein and had less fat, which was consistent with the findings of (Tufarelli and Laudadio, 2011), whose study showed that selenium-fed goats produced the most milk (P0.05) and had higher protein concentrations.Additionally, the findings of the group that combined selenium, zinc and S. Cerevisiae yeast were in line with (Petrera et al., 2009) who observed that milk output was equivalent in Saanen dairy goats fed diets containing selenium-yeast.Selenium-supplemented yeast has been found to have a good impact on dairy goat milk production features and the health of the goat mammary gland (Reczyska et al., 2019).According to (Salama et al., 2003), feeding dairy goats a diet high in zinc improved the levels of milk production and casein protein, increased the Different letters in a row indicate significant differences at (P0.05).
The Effect of Saccharomyces cerevisiae Yeast Enriched with Selenium and Zinc on Some Physiological Traits and Milk Production... concentration of solid-fatty substances and improved the indicators of milk production recipes and their general specification.
The results of the statistical analysis indicated in Table ( 4) of the changes in the levels of hormones in the blood serum showed that there is a significant variation (P0.05) between the coefficients.The treatment of (SCY + Sc + Zn) recorded the highest concentration (P0.05) of the prolactin hormone compared to other groups.In contrast, the estrogen level was decreased (Pde0.05) in the (SCY + Sc + Zn) and (SCY) groups compared to the (Se + Zn) and control groups.While (SCY + Sc + Zn) had recorded the lowest level of T3 hormone, it recorded the highest level of the T4 hormone compared to the rest of the study groups.The (SCY + Sc + Zn) and (SCY) groups also showed higher levels of the hormone cortisol compared to the (Se + Zn) and Control groups.At the same time, one group (Se + Zn) had the lowest cortisol level compared to the other treated groups.
Saccharomyces cerevisiae, which could mobilize nutrients and ensure the supply of chemicals in the body, was given to goats in the current study and these goats had much greater cortisol levels.Strong evidence demonstrates that higher glucocorticoid levels are necessary for increased milk production in order to provide enough energy for galactose synthesis (Mohammed et al., 2018).In addition to stimulating the expression of milk protein genes during lactation, cortisol, the main glucocorticoid in galactose production, also plays a critical role in fostering mammary epithelial cell differentiation (Jia et al., 2021).These results imply that prolactin and cortisol may increase goat milk production.According to our findings, Saccharomyces cerevisiae can make cortisol and prolactin work together in goats to boost production.Here, we discovered that the prolactin level increased together with the cortisol concentration in the treatment group, along with the fact that the combined milk output increased (Du et al., 2022).S. cerevisiae contained an endogenous ligand for the yeast estrogen-binding protein.Estrogen increases blood flow to the uterus and genital system.The endogenous ligand from S. cerevisiae has recently been demonstrated to have estrogenic action in mammalian systems, which is significant (Feldman et al., 1984).Zinc's involvement in enhancing ovarian function and increasing female fertility is thought to be the cause of a large rise in estrogen levels in the (Se + Zn) group compared to yeast-treated groups (Ahmed et al., 2001).This could be the case because selenium stops mature follicles and ovarian tissue from oxidizing, which raises the amount of estrogen released by the follicle.The development of follicles, which are responsible for the release of estrogen, may be stimulated by zinc in the tonic immune system (Shareef et al., 2021).All domesticated animals' growth, development and metabolism are significantly influenced by thyroid hormones, either directly or indirectly.Thyroxine (T4) must be converted into triiodothyronine (T3) in order for the thyroid hormones to operate fully.This process is carried out by a special nuclear receptor protein that may influence the expression of particular regulatory areas of the target genes (Schroede and Privalsky, 2014).After the thyroid hormone receptor was cloned, protein analysis revealed a region that included zinc and selenium ions, which are essential for the receptors' ability to bind to their target genes (Olivieri et al., 1996).As a result, it has been suggested that T3's full biological functioning may depend on its zinc and selenium levels (Shahid, 2022).Since the thyroid gland regulates this rate, increased T4 and T3 release increases body heat production and basal metabolic rate in nursing and lactating goats (Aghwan et al., 2013).In both animals and humans, low selenium or zinc status decreased the T3/T4 ratio mostly through raising T4 levels rather than by lowering T3 levels (Olivieri et al., 1996).

CONCLUSION
According to the results obtained from the study, we concluded that Organic form (Saccharomyces cerevisiae yeast supplemented with selenium/ zinc) credited to maximum milk production and the best results for the indicators of milk qualities as measured by the experimental groups for the duration of the study, also measurements of hormones related to the physiological functions of milk production showed their best indicators in the two treatment groups, including on yeast with or without the mixture of mineral elements.

ACKNOWLEDGMENT
The authors are very grateful to the University of Mosul/ College of Agriculture and Forestry provided facilities, which helped improve the quality of this work.They also

Fig 1 :
Fig 1: The potential mechanism of Saccharomyces cerevisiae yeast-based supplements (SCYSs) on milk production and composition (JIA et al. 2021).

Table 3 :
The effect of S. Cerevisiae dosing with or without minerals on milk production and its components at the end of 3 rd month.
Different letters in a row indicate significant differences at (P0.05).

Table 1 :
Ingredients and chemical composition of the essential diet(NRC, 2007).

Table 2 :
The effect of S. Cerevisiae dosing with or without minerals on milk production and its components at the end of 1 st month.

Table 4 :
The effect of S. Cerevisiae dosing with or without minerals on Prolactin, Estrogen, Cortisol and Thyroid hormones at the end of the study.Different letters in a row indicate significant differences at (P0.05).The Effect of Saccharomyces cerevisiae Yeast Enriched with Selenium and Zinc on Some Physiological Traits and Milk Production... thank Dr. Dheyaa mohamed for her assistant work , College of Veterinary Medicine, University of Mosul.