Chemical analyses
The results of the chemical composition of the 3 foods analyzed are presented in Table 1, it shows that the fat content (EE) is very low for all feed and varies between 1.48 to 2.95%. These values are in the recommended range since the fat content exceeding 6-7% reduces fiber digestion and therefore DM intake in dairy ewes (
NRC 2007). The Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) content of date waste and concentrate are almost similar and vary between 32.5-33.8% and 28.1-28.7% respectively, while wheat straw showed the highest value (68 and 37.9%). On the other hand, the date waste analysed presented a low percentage of lignin 6.69%. As for the other parietal compounds, they are moderately low as confirmed by
Boudechiche et al., (2010) and
Boukhris et al., (2017). Crude fiber (CF) content is very low for date waste and concentrate with respectively 6.66% and 8.8% of dry matter, against relatively high content for straw 23.98%. Date wastes is in the range of those reported by
Meradi et al., (2016) and
Abaidia et al., (2020). According to
Chehma et al., (2004), this low content may be due to the fact that the dates are rather a fruit rich in cytoplasmic sugars than in parietal carbohydrates.
On the other hand, these foods are poor in crude proteins, especially for date waste with a value of 4.28%. This result is slightly higher than those reported by
Boudechiche et al., (2010) and
Abaidia et al., (2020) who respectively recorded 3.2% and 2.4% content. Table 2 represents the physico-chemical composition of the five rations distributed to the ewes. The contents of the 5 rations in DM, OM, Ash, EE, NDF, ADF, Cellulose, Hemicellulose and CF, are almost similar. On the other hand, the five rations had a low CP content (7.16% to 5.69%). The 16REBsc ration presented a total nitrogenous matter content of 7.16% with the addition of 2 g/ewe/d
Saccaromyces cerevisiae, similar to the CP content of the 33.3CON ration.
Lesmeister et al., (2004), have recorded the following values of total soluble nitrogenous matter: 16.8% for 0%, 18% for 1% and 17% for 2%, after the addition of
Saccaromyces cerevisiae to 1% and 2% of the starter ration of dairy calves. According to
Hassan and Mohammed (2016), the increase in CP levels is due to
Saccharomyce cervicea stimulating factors, such as amino acids and peptides that increase the number of cellulolytic bacteria and reduce the negative effects associated with high-dose diets.
Analysis of serum biochemical parameters
The results of the biochemical concentrations of lactating ewes according to the distributed rations are presented in Table 3. The average levels of biochemical parameters in this present study are within the range of the results reported in the literature for Ouled Djellel lactating ewes
(Boudebza et al., 2022; Titaouine et al., 2017; Djaalab 2017;
Haffaf et al., 2012 and
Deghnouche et al., 2011). The results indicated that there is a significant difference in aspartate aminotransferase level in early lactation (P<0.05) and creatinine ,urea, aspartate aminotransferase, glucose in late lactation (P<0.05) depending on the addition of date waste and
Saccharomyces cervicea in the rations.
The overall mean serum creatinine values at the beginning and at the end of lactation were (7.85-7.97 mg/l) -(8.86-9.45 mg/l)-(9.81-9.43 mg/l)-(8.31-10.02 mg/l)-(8.97-10.04 mg/l) in the 33.3CON, 8.33REB, 25REB, 16.6REB and 16.6REBsc groups and period respectively. Our results show that in early and late lactation, the serum creatinine levels of ewes supplemented with date wastes at different proportions and/or with the date wastes-
Saccharomyces cervicea mixture tends to be always higher than those observed in the 33.3CON controls. The analysis of variance showed a significant effect (P<0.05) of this parameter only at the end of lactation in the 33CON, the serum creatinine is higher in the ewes of the 16.6REBsc with
Saccharomyce cervicea supplementation and the 16.6REB. According to
Silva et al., (2015), creatinine level in ewes was higher with a concentrate supplementation at 0.5% of BW (69.07 µmol/L) compared to 1.5% of BW (63.14 µmol/L), due eventually to energy deficiency condition and to severe conditions of mobilization of body proteins. Our results agree with those of
Meena et al., (2021), who revealed a non-significant effect on serum creatinine, after supplementation with
Saccharomyce cervicea, with low values varying between 5.89 mg/l and 5.91 mg/l. Nevertheless, the serum creatinine values are mostly within the range of normal serum creatinine values in ewes reported in the literature
(Deghnouche et al., 2011; Titaouine et al., 2017 and
Haffaf et al., 2012).
The concentration of uremia increased in a significant way (P<0.005) at the end of lactation, affected by the 33.3CON ration (0.43 g/l) compared to the other rations (8.33REB (0.17 g/l), 25REB (0.23 g/l), 16.6REB (0.18 g/l) and 16.6REBsc (0.17 g/l)) and in non-significant way in early lactation.
Laghrour et al., (2020) also recorded an increase in serum urea upon the increase of concentrate level in the ration, they reported a higher level than that found in our study (0.818 g/l). Whereas,
Silva et al., (2015) showed an inversely proportional relationship to concentrate supplementation level. According to
Grizard et al., (1979), there are significant linear relationships between uremia and dietary energy and nitrogenous matter intakes and between uremia and blood glucose levels and those increases in uremia, are due to increased functioning of the urea cycle in the liver, which may have two causes: increased amino acid catabolism and reduced ammonia utilization for bacterial protein synthesis in the rumen.
At the early lactation, the cholesterol level was non-significant in all groups 8.33REB, 25REB, 16.6REB, 16.6REBsc and 33CON respectively (0.64 g/l-0.63 g/l-0.61 g/l-0.57 g/l-0.76 gl) ,even though it tends to be lower in the group of ewes supplemented with date waste and
Saccharomyces cerevisiae (16.6REBsc).
Djaalab (2017) reported lower levels of cholesterol level than those recorded in our study. Further, they observed a significant increase of blood cholesterol level, in females receiving 25% waste dates without
Saccharomyces cervicea (0.63 g/l) in comparison to females ingesting 50% (0.41 g/l). Nevertheless, our results remain lower than those revealed by
Boudebza et al., (2016) in lactating ewes with (1.59 mmol/l).
Laghrour et al., (2020), suggest that the augmentation in cholesterolemia varies with the increase in concentrate in the ration. On the other hand,
Masek et al., (2008) observed that the values of cholesterol tended to be higher in the groups treated with
Saccharomyces cerevisiae. Furthermore,
Dobicki et al., (2005) showed that it reduced the total cholesterol in the blood serum of calves.
Aspartate aminotransferase content in both early and late lactation (p<0.05) is significantly high in ewes ingesting the 33.3CON diet, compared to 8.33REB, 25REB, 16.6REB and 16.6REBsc diets respectively (117. 64-123.78IU/l vs 78.37-77.86IU/l vs 85.33-78.71IU/l vs 85.14-96.09 IU/l vs 86.61-90.66-IU/l). Accordingly, the partial substitution of the concentrate by date waste reduced the serum level of AST, this finding is also confirmed by
Djaalab (2017), who reported a significant decrease in plasma AST (42.80 IU/l in ewes consuming 50% date wastes).
Antunovic et al., (2004) suggested that the high activity of AST could correspond to a protein deficit and an energy supplementation of the ration in relation to a high metabolic activity of the liver. On the other hand, AST was not affected by
Saccharomyces cerevisiae supplementation, which is in agreement with the results of
Masek et al., (2008); Soren et al., (2013).
Plasma albumin and total protein content, in early and late lactation presented non-significant differences in all diets. However, total protein parameter increased proportionally with the increase of the proportion of date wastes in the ration as well as of
Saccharomyces cerevisiae, while comparing the values in the two groups 16.6REBsc and 16.6REB. Hypoproteinemia in 16.6REB group, eventually compensated by the addition of
Saccharomyces cerevisiae in 16.6REBsc.
El-Katcha et al., (2016) showed that there is a positive correlation between total serum protein and protein content of food.
Onochieosita et al. (2020) and
Galip et al. (2006), reported that total proteins were significantly higher, due to
Saccharomyces cerevisiae supplementation, since the addition of yeast of beer in the ration stimulates microbial activity by increasing the incorporation of nitrogen into microbial proteins resulting in an increase in protein digestibility
(Abdel-Khalek et al., 2000). Total protein and total serum albumin values were within physiological limits as reported respectively by
Laghrour et al., (2020) (70.4 g/l, 31.9 g/l) and by
Safsaf et al. (2012) (69.17 g/l, 30.60 g/l) and higher than those reported by
Deghnouche et al. (2011) (64.19 g/l, 24.54 g/l) and by
Djaalab (2017), using a ration containing date wastes (35.60 g/l, 18.76 g/l).
The glycaemia content at the beginning of lactation was significant (p<0.05) in the control group (33.3CON) with a higher content (0.65 g/l) followed by 25REB (0.62 g/l), 16.6REBsc group (0.58 g/l), 8.33REB (0.54 g/l) and 16.6REB group (0.52 g/l). A significant hypoglycaemia of the groups supplemented with date waste compared to the control 33.3CON group is noted, even though it remains within physiological standards
Simpraga et al., (2013) (0.43-0.83 g/l). According to
Chachoua (2015), this decrease is due to the fact that the food ration as a less energy, which can justify the difference in the concentration of glycemia between the rations. On the other hand,
Djaalab (2017), justified the notable hypoglycemia of the ewes supplemented with 25 and 100% date wastes, results as well from an insufficient energy supply in the feed ration, due eventually to the indigestibility of the dietary fibers thus reducing the activity of the ruminal biomass.
El-Tawab et al. (2016) reported a significant increase in glucose concentration in lactating goats and ewes after probiotic supplementation. Furthermore, no change in glycaemia has been reported after yeast supplementation in calves
(Lesmeister et al., 2004).