Abstract: (13 Views)
Background and objectives: Synbiotics, which combine live microorganisms with selectively utilized substrates, confer significant health benefits to the host. These feed additives can modulate immune signaling pathways, thereby reducing inflammation and enhancing immunity in calves. Furthermore, polyphenol- and tannin-rich compounds can bolster the immune system through their antioxidant properties. Red grape pomace (RGP) is a rich source of plant secondary metabolites with high antioxidant capacity, offering substantial nutritional value in terms of organic matter and crude protein. Therefore, this study was conducted with two main objectives: 1) to determine the chemical composition and nutritional value of RGP, and 2) to evaluate the effects of supplementing RGP with a synbiotic on average daily gain, final body weight, feed and milk intake, feed efficiency, and feeding behavior in Holstein calves.
Materials and methods: Red grape pomace was procured from Khosheh Sorkh Shargh Agricultural and Industrial Company, located in Qaen County, South Khorasan Province, Iran. After being shade-dried for 72 h, the pomace was transferred to the Animal Nutrition Laboratory, Faculty of Agriculture, University of Birjand, to determine its chemical composition and antioxidant activity using standard methods. Four experimental diets were formulated and balanced using NASEM software: 1) basal diet without RGP or synbiotic (CON), 2) basal diet + 0.5% synbiotic (SYN), 3) basal diet with 12% dried RGP substituted (GP12), and 4) basal diet with 12% dried RGP and 0.5% synbiotic (GP12+SYN). The in vitro gas production and three-step in vitro digestion techniques were employed to evaluate fermentation parameters and degradability. For the three-step digestion, 16 polyester bags containing 5 g of RGP were incubated in the rumen of two rumen-fistulated non-lactating Holstein cows (mean body weight: 649 ± 51.6 kg) for 16 h across two consecutive weeks (ruminal step). The residues were subsequently subjected to pepsin-HCl (enzymatic step) and pancreatin-phosphate buffer (intestinal step) incubations to determine the digestibility of dry matter, crude protein, and neutral detergent fiber. For the gas production assay, 500 mg of each diet was incubated in 120-mL vials containing 50 mL of rumen fluid and artificial saliva mixture (2:1, v/v). Vials were sealed with rubber stoppers and aluminum crimps, and connected to a portable digital pressure transducer via a sterile needle. Cumulative gas production was recorded at 2, 4, 6, 8, 12, 16, 24, 36, 48, 72, and 96 h. At 24 and 48 h post-incubation, three vials per treatment were removed to determine culture pH, ammonia-nitrogen concentration, and in vitro dry matter degradability. The gas production assay was conducted with 12 replicates per treatment across two independent runs. The in vivo phase was conducted as a completely randomized design using 40 suckling Holstein calves. Calves were randomly assigned to 4 groups of 10, and each group was fed one of the experimental diets for 60 days. Performance traits were recorded weekly, and feeding behavior was monitored during the last 3 days of the trial.
Results: Laboratory analyses indicated that RGP contained 11.90% crude protein, 7.33% ether extract, and 9.01% ash (on a dry matter [DM] basis), with neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents estimated at 44.35% and 35.04%, respectively. Bioactive compound analysis revealed a total phenolic content of 7.62 ± 0.18 mg gallic acid equivalents/g DM (mg GAE/g DM) and a total tannin content of 6.08 ± 0.06 mg tannic acid equivalents/g DM (mg TAE/g DM). Antioxidant capacity was determined to be 91.72 ± 0.58% using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and 557.3 ± 7.57 µmol Fe²⁺/g DM using the ferric reducing antioxidant power (FRAP) assay. Ruminal and intestinal DM digestibility of RGP was 20.95 and 13.41 g/100 g DM, respectively. In the gas production assay, the GP12+SYN diet exhibited the highest gas production potential (137.85 mL), while the control diet had the lowest (126.29 mL; P < 0.05). The gas production rate was significantly lower in the CON and SYN treatments compared to the GP12 and GP12+SYN diets (P < 0.05). Additionally, synbiotic supplementation significantly increased the lag phase compared to the other treatments (P < 0.05). Cumulative gas production was numerically higher in the GP12 and GP12+SYN treatments than in the CON and SYN groups (P > 0.05). Mean culture pH at 24 and 48 h post-incubation did not differ among treatments (P > 0.05). Ammonia-nitrogen concentration at 48 h was significantly lower in the GP12 treatment (P < 0.05). Although mean in vitro DM degradability was numerically lower in the GP12+SYN treatment, the difference was not statistically significant (P > 0.05). In the in vivo trial, calves fed the GP12+SYN diet showed improved average daily gain and final body weight, along with a reduced feed conversion ratio compared to the control group (P < 0.05). Feed efficiency was similar among treatments during the early period (days 3–18), but the GP12 and GP12+SYN treatments exhibited superior performance from days 18–33 onward (P < 0.05). Finally, feeding behavior was not affected by synbiotic supplementation, 12% RGP replacement, or their combination, with all groups displaying similar behavioral patterns to the control (P > 0.05).
Conclusion: Red grape pomace possesses substantial nutritional value due to its rich phenolic profile and high antioxidant capacity, and it can effectively modulate ruminal fermentation parameters. Furthermore, its combined use with a synbiotic improves growth performance and reduces the feed conversion ratio in suckling Holstein calves without adversely affecting their feeding behavior.
Materials and methods: Red grape pomace was procured from Khosheh Sorkh Shargh Agricultural and Industrial Company, located in Qaen County, South Khorasan Province, Iran. After being shade-dried for 72 h, the pomace was transferred to the Animal Nutrition Laboratory, Faculty of Agriculture, University of Birjand, to determine its chemical composition and antioxidant activity using standard methods. Four experimental diets were formulated and balanced using NASEM software: 1) basal diet without RGP or synbiotic (CON), 2) basal diet + 0.5% synbiotic (SYN), 3) basal diet with 12% dried RGP substituted (GP12), and 4) basal diet with 12% dried RGP and 0.5% synbiotic (GP12+SYN). The in vitro gas production and three-step in vitro digestion techniques were employed to evaluate fermentation parameters and degradability. For the three-step digestion, 16 polyester bags containing 5 g of RGP were incubated in the rumen of two rumen-fistulated non-lactating Holstein cows (mean body weight: 649 ± 51.6 kg) for 16 h across two consecutive weeks (ruminal step). The residues were subsequently subjected to pepsin-HCl (enzymatic step) and pancreatin-phosphate buffer (intestinal step) incubations to determine the digestibility of dry matter, crude protein, and neutral detergent fiber. For the gas production assay, 500 mg of each diet was incubated in 120-mL vials containing 50 mL of rumen fluid and artificial saliva mixture (2:1, v/v). Vials were sealed with rubber stoppers and aluminum crimps, and connected to a portable digital pressure transducer via a sterile needle. Cumulative gas production was recorded at 2, 4, 6, 8, 12, 16, 24, 36, 48, 72, and 96 h. At 24 and 48 h post-incubation, three vials per treatment were removed to determine culture pH, ammonia-nitrogen concentration, and in vitro dry matter degradability. The gas production assay was conducted with 12 replicates per treatment across two independent runs. The in vivo phase was conducted as a completely randomized design using 40 suckling Holstein calves. Calves were randomly assigned to 4 groups of 10, and each group was fed one of the experimental diets for 60 days. Performance traits were recorded weekly, and feeding behavior was monitored during the last 3 days of the trial.
Results: Laboratory analyses indicated that RGP contained 11.90% crude protein, 7.33% ether extract, and 9.01% ash (on a dry matter [DM] basis), with neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents estimated at 44.35% and 35.04%, respectively. Bioactive compound analysis revealed a total phenolic content of 7.62 ± 0.18 mg gallic acid equivalents/g DM (mg GAE/g DM) and a total tannin content of 6.08 ± 0.06 mg tannic acid equivalents/g DM (mg TAE/g DM). Antioxidant capacity was determined to be 91.72 ± 0.58% using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and 557.3 ± 7.57 µmol Fe²⁺/g DM using the ferric reducing antioxidant power (FRAP) assay. Ruminal and intestinal DM digestibility of RGP was 20.95 and 13.41 g/100 g DM, respectively. In the gas production assay, the GP12+SYN diet exhibited the highest gas production potential (137.85 mL), while the control diet had the lowest (126.29 mL; P < 0.05). The gas production rate was significantly lower in the CON and SYN treatments compared to the GP12 and GP12+SYN diets (P < 0.05). Additionally, synbiotic supplementation significantly increased the lag phase compared to the other treatments (P < 0.05). Cumulative gas production was numerically higher in the GP12 and GP12+SYN treatments than in the CON and SYN groups (P > 0.05). Mean culture pH at 24 and 48 h post-incubation did not differ among treatments (P > 0.05). Ammonia-nitrogen concentration at 48 h was significantly lower in the GP12 treatment (P < 0.05). Although mean in vitro DM degradability was numerically lower in the GP12+SYN treatment, the difference was not statistically significant (P > 0.05). In the in vivo trial, calves fed the GP12+SYN diet showed improved average daily gain and final body weight, along with a reduced feed conversion ratio compared to the control group (P < 0.05). Feed efficiency was similar among treatments during the early period (days 3–18), but the GP12 and GP12+SYN treatments exhibited superior performance from days 18–33 onward (P < 0.05). Finally, feeding behavior was not affected by synbiotic supplementation, 12% RGP replacement, or their combination, with all groups displaying similar behavioral patterns to the control (P > 0.05).
Conclusion: Red grape pomace possesses substantial nutritional value due to its rich phenolic profile and high antioxidant capacity, and it can effectively modulate ruminal fermentation parameters. Furthermore, its combined use with a synbiotic improves growth performance and reduces the feed conversion ratio in suckling Holstein calves without adversely affecting their feeding behavior.
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