Dry matter intake
The average DMI of EC goats was significantly increased (P<0.05) by the use of rubber leaves supplemented with probiotics in the diet (Table 2). The DMI ranged from 597.92-890.83 g/head/day, which was higher than that obtained by
Raguati (2016). The high DMI obtained in this study was influenced by the quality, palatability and energy content of the diet with a higher use of rubber leaves.
Wigati et al., (2015) reported that rubber leaves contain up to 21.82% protein and 40.88% non-degradable protein. Meanwhile,
Khattab et al., (2020) reported that supplementation of probiotics in diets increased DMI and milk production and reduced the effect of heat stress.
Feed efficiency
The treatment had no significant effect (P>0.05) on the feed efficiency of EC goats. The average feed efficiency in this study was 37.19-39.87% (Fig 1), however, T3 treatment showed a feed efficiency value of 45%, which tended to be higher than that of the other treatments. The high feed efficiency value in the T3 treatment was due to the role of probiotics, which influence milk production.
Arowolo and He (2018); and
Bain et al. (2022) stated that the use of probiotics effectively increases the digestive process, milk production and milk fat and improves animal health by preventing pathogenic microbes.
Erythrocytes
The results indicated that the treatment significantly affected the total blood erythrocyte levels in EC goats (P<0.05) (Table 3). A higher proportion of rubber leaves supplemented with the probiotic
Bacillus pumilus St. L1 in the diet resulted in an increased production of erythrocytes. The crude protein (CP) content of the feed, which included rubber leaves ranged from 15.40% to 18.22%. This CP is essential for synthesizing microbial proteins in the rumen, which then flow to the small intestine, where they are converted into amino acids that act as precursors for erythrocyte formation, known as erythropoiesis. The mean erythrocyte count ranged from 8.30 to 9.21 million/mm³, indicating good health condition of goats. Normal erythrocyte levels for goats range from 8 to 18 million/mm³ (
Weiss and Waldrop, 2010). These normal levels of erythrocytes suggest that the transport of oxygen and necessary substances in the body is stable. Cases of anemia in cattle occur due to oxidative damage to red blood cells
(Kumar et al., 2018).
Hematocrit/ packed cell volume (PCV)
The treatment had a significant effect on hematocrit levels (P<0.01). The hematocrit levels observed in the T0 treatment were lower than those in T1, T2 and T3 (Table 3). For EC goats fed rubber leaves supplemented with probiotics, the mean hematocrit levels ranged from 26.50% to 34.00%. Including rubber leaves in the diet can enhance hematocrit values because the protein in the feed is effectively utilized by EC goats. The feed protein is utilized optimally in livestock due to the protective effects of tannins found in rubber leaves (
Raguati et al., 2022).
Hematocrit levels observed were within the normal range, indicating that the goats were in good health of goats. The hematocrit value ranged from 16.6% to 19.0%, which is higher than the findings reported by
Hamzaoui et al., (2021). Additionally, the hematocrit levels in livestock are closely related to the levels of erythrocytes and hemoglobin (
Laka et al., 2019). An increase in hematocrit levels typically occurs when there is an increase in blood cell counts or a decrease in blood plasma volume.
Hemoglobin
The blood hemoglobin levels of EC goats were significantly affected by the treatment (P<0.01). The hemoglobin in the T0 treatment was lower than in T1, T2 and T3 (Table 3). Normal hemoglobin levels indicate that the goats are in good health due to a high-protein intake from rubber leaves. The average hemoglobin level of EC goats ranged from 8.13 to 9.50 g/dl, while normal hemoglobin levels in goats ranged from 8 - 12 g/dl (
Weiss and Waldrop, 2010). An increase in blood erythrocyte levels leads to higher hemoglobin, which ensures that the goats blood is sufficiently oxygenated. The elevated hemoglobin is attributed to the protein content in rubber leaves and the action of tannins, which help protect feed protein, making vital nutrients readily available for livestock.
Leukocytes
The treatment had a significant effect on the leukocyte levels of EC goats (P<0.01). Feeding rubber leaves and probiotics resulted in an average decrease of 19.16% in leukocyte levels. In this study, the total leukocyte count ranged from 10.75 - 13.30 x 10³/mm³, which falls within the normal range of 5.1 - 13.3 x 10³/µL (
Mudawamah and Sumartono, 2020)
Fernandez et al., (2021) reported leukocyte counts ranging from 11.6 to 12.11 thousand/mm³ with a basal treatment using sorghum-pea butterfly silage.
The mean leukocyte count in the T0 treatment was notably high at 13.30 thousand/mm³, indicating that the goat was unhealthy. Rubber leaves, which are rich in tannins, have an immunomodulatory effect and are bioactive against inflammation in EC goats, as evidenced by normal leukocyte levels. The addition of rubber leaves along with probiotics (T1, T2, T3) helps normalize leukocyte formation. A normal total leukocyte count reflects the livestock’s ability to defend itself. Probiotic supplementation can enhance nutrient consumption and positively impact the blood metabolism of goats (
Han et al., 2019).
Milk yield and quality
Supplying goats with rubber leaves supplemented with probiotics significantly increased both the yield and quality of milk (P<0.05) (Table 2 and 4). The feed protein level in treatment T3 (CP 18.217%) was higher than in the other treatments. Treatment T3, which consisted of 45% rubber leaves and probiotics, produced the highest milk output. Increased DMI correlated with greater milk production. Milk production relies on quality feed and effective management
(Zucali et al., 2020). The tannins found in rubber leaves can protect degraded protein in the rumen, improving metabolism in the udder glands. This enhanced metabolism contributes to increased milk production and quality. Additionally, introducing varying doses of probiotics into the diets of the experimental groups of pregnant goats resulted in a significant increase in average daily milk yield and milk quality
(Olchowy et al., 2019; Funk et al., 2021).
The average protein content in goat’s milk treated with rubber leaves and supplemented with
Bacillus pumilus St. L1 ranged from 4.17% to 4.29%. The quality of the milk produced in this study is considered premium, meeting the following characteristics: protein greater than 3.7% (
Thai Agriculture, 2008) and above the fresh milk standard of greater than 2.7% (
SNI, 2011). The administration of probiotic-supplemented rubber leaves significantly increased (P<0.05) the fat, total solids and lactose content in the milk of EC goats. The average milk content was found to be as follows: fat 3.76% to 4.56%, solid non-fat (SNF) 8.81% to 9.05%, total solids 12.79% to 13.98% and lactose 3.96% to 4.09% (Table 4). For comparison, the milk quality of dairy goats in Brazil showed moisture content between 89.54% and 90.02%, fat content between 2.51% and 2.72%, protein content between 3.15% and 3.67% and lactose between 4.54% and 4.75% (Costa
et al.,, 2021). These results were higher than those obtained from feeding pineapple peel powder with probiotics, which yielded an average total milk solids content of 12.38% to 12.58% (
Raguati, 2016). Additionally, the SNF content in this study according to previous research, ranges from 12% to 18% and 7.08% to 8.21%
(Marwah et al., 2010; Arief et al., 2020).