1- Department of Animal and Poultry Nutrition, Faculty of Animal Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
Abstract: (769 Views)
Extended Abstract
Background: The rumen, considered the metabolic center of ruminants, plays a pivotal role in digesting fibrous materials and supplying the animal’s energy and protein requirements. Any dietary change, particularly in the source and physical form of fat, can alter fermentation patterns, microbial populations, and consequently, the efficiency of microbial protein synthesis. Among potential fat sources, Camelina sativa stands out due to its resistance to drought and salinity and its oil, which is rich in unsaturated fatty acids, particularly alpha-linolenic acid (omega-3). This makes it an emerging feed ingredient in livestock nutrition. Palm oil, predominantly composed of saturated fatty acids, exhibits limited effects on ruminal microbial populations. In contrast, camelina oil, rich in unsaturated fatty acids, may alter the volatile fatty acid (VFA) ratio, reduce methane production, and enhance energy utilization efficiency. Furthermore, the form of the product (seed versus oil) can differentially affect ruminal responses. As the direct measurement of microbial populations is challenging and costly, indirect indicators (e.g., urinary purine derivatives) are commonly employed to estimate microbial protein synthesis. Therefore, this study aimed to evaluate the effects of palm oil, camelina oil, and camelina seeds on ruminal fermentation parameters and microbial protein synthesis in fattening lambs.
Methods: Thirty-two male lambs (average age: 3.5 months; initial weight: 23.89 ± 0.48 kg) were randomly assigned to a completely randomized design with four dietary treatments, each replicated eight times, for an 84-day feeding period. The treatments were 1) a basal diet without a fat supplement (Control), 2) a basal diet supplemented with 1.5% palm oil, 3) a basal diet supplemented with 1.5% camelina oil, and 4) a basal diet supplemented with 5% camelina seeds. Diets were formulated according to NRC (2007) recommendations and balanced for energy and crude protein content. Feeds were provided as a total mixed ration (TMR) twice daily (at 07:00 and 16:00). Rumen fluid samples were collected on day 84, four hours post-feeding, via a stomach tube to determine ruminal pH, ammonia nitrogen (NH3-N), and VFAs. Ruminal pH was immediately measured using a portable pH meter. Ammonia nitrogen was analyzed using the phenol-hypochlorite method, and VFA concentrations were determined by gas chromatography. To estimate microbial protein synthesis, 24-hour urine samples were collected on day 80. Purine derivatives (allantoin, uric acid, xanthine, and hypoxanthine) were quantified using standard commercial kits. Microbial nitrogen flow was calculated using the equations of Chen and Gomes (1995). Data were analyzed using the GLM procedure in SAS software (Version 4.9), and means were compared using Duncan’s multiple range test at a 5% significance level.
Results: Ruminal pH was not significantly affected by dietary treatments, remaining within the optimal range of 6.75–7.00 (P > 0.05), indicating a stable ruminal environment. Total VFA concentration was highest in the camelina oil treatment (111.30 mmol/L) and lowest in the palm oil treatment (91.00 mmol/L) (P < 0.0001). The acetate-to-propionate ratio significantly increased in the palm oil group (P < 0.001), whereas the concentrations of acetic acid (62.50 mmol/L) and propionic acid (27.50 mmol/L) were highest in the camelina oil group. Ammonia nitrogen concentration increased significantly in the palm oil treatment (P < 0.001), potentially due to the reduced efficiency of nitrogen utilization by rumen microbes or energy limitation. In contrast, the presence of unsaturated fatty acids in camelina-based diets (oil and seed) likely improved the synchronization of energy and nitrogen availability for microbial growth. Urinary excretion of purine derivatives (allantoin, uric acid, xanthine+hypoxanthine) and estimated microbial protein synthesis were significantly higher in the camelina seed treatment group than in other groups (P < 0.001). Daily microbial protein production was highest in the camelina seed group (46.60 g/day) and lowest in the control group (34.10 g/day) (P < 0.0001). Microbial protein yield per kilogram of dry matter intake was also significantly greater in the camelina seed treatment (1.07 g/kg DMI) compared to the control diet (0.81 g/kg DMI) (P = 0.0007).
Conclusion: Overall, the inclusion of camelina seeds in the diet improved ruminal fermentation patterns and enhanced microbial protein synthesis, whereas palm oil exerted detrimental effects on rumen fermentation. The physical form of the fat source and its fatty acid profile play crucial roles in determining ruminal fermentation and microbial protein synthesis. Owing to the physical protection of oil from rapid ruminal degradation and the simultaneous supply of fermentable energy and protein, feeding camelina seeds maintained rumen pH within the optimal range, increased the propionate-to-acetate ratio, and enhanced microbial protein synthesis. Although camelina oil supplementation at 1.5% of diet dry matter increased total VFA concentration, it did not negatively impact microbial protein synthesis. Based on the findings of this study, including up to 5% camelina seeds in the diet of growing lambs can enhance ruminal fermentation efficiency and microbial protein synthesis, consequently improving overall feed utilization efficiency.
Background: The rumen, considered the metabolic center of ruminants, plays a pivotal role in digesting fibrous materials and supplying the animal’s energy and protein requirements. Any dietary change, particularly in the source and physical form of fat, can alter fermentation patterns, microbial populations, and consequently, the efficiency of microbial protein synthesis. Among potential fat sources, Camelina sativa stands out due to its resistance to drought and salinity and its oil, which is rich in unsaturated fatty acids, particularly alpha-linolenic acid (omega-3). This makes it an emerging feed ingredient in livestock nutrition. Palm oil, predominantly composed of saturated fatty acids, exhibits limited effects on ruminal microbial populations. In contrast, camelina oil, rich in unsaturated fatty acids, may alter the volatile fatty acid (VFA) ratio, reduce methane production, and enhance energy utilization efficiency. Furthermore, the form of the product (seed versus oil) can differentially affect ruminal responses. As the direct measurement of microbial populations is challenging and costly, indirect indicators (e.g., urinary purine derivatives) are commonly employed to estimate microbial protein synthesis. Therefore, this study aimed to evaluate the effects of palm oil, camelina oil, and camelina seeds on ruminal fermentation parameters and microbial protein synthesis in fattening lambs.
Methods: Thirty-two male lambs (average age: 3.5 months; initial weight: 23.89 ± 0.48 kg) were randomly assigned to a completely randomized design with four dietary treatments, each replicated eight times, for an 84-day feeding period. The treatments were 1) a basal diet without a fat supplement (Control), 2) a basal diet supplemented with 1.5% palm oil, 3) a basal diet supplemented with 1.5% camelina oil, and 4) a basal diet supplemented with 5% camelina seeds. Diets were formulated according to NRC (2007) recommendations and balanced for energy and crude protein content. Feeds were provided as a total mixed ration (TMR) twice daily (at 07:00 and 16:00). Rumen fluid samples were collected on day 84, four hours post-feeding, via a stomach tube to determine ruminal pH, ammonia nitrogen (NH3-N), and VFAs. Ruminal pH was immediately measured using a portable pH meter. Ammonia nitrogen was analyzed using the phenol-hypochlorite method, and VFA concentrations were determined by gas chromatography. To estimate microbial protein synthesis, 24-hour urine samples were collected on day 80. Purine derivatives (allantoin, uric acid, xanthine, and hypoxanthine) were quantified using standard commercial kits. Microbial nitrogen flow was calculated using the equations of Chen and Gomes (1995). Data were analyzed using the GLM procedure in SAS software (Version 4.9), and means were compared using Duncan’s multiple range test at a 5% significance level.
Results: Ruminal pH was not significantly affected by dietary treatments, remaining within the optimal range of 6.75–7.00 (P > 0.05), indicating a stable ruminal environment. Total VFA concentration was highest in the camelina oil treatment (111.30 mmol/L) and lowest in the palm oil treatment (91.00 mmol/L) (P < 0.0001). The acetate-to-propionate ratio significantly increased in the palm oil group (P < 0.001), whereas the concentrations of acetic acid (62.50 mmol/L) and propionic acid (27.50 mmol/L) were highest in the camelina oil group. Ammonia nitrogen concentration increased significantly in the palm oil treatment (P < 0.001), potentially due to the reduced efficiency of nitrogen utilization by rumen microbes or energy limitation. In contrast, the presence of unsaturated fatty acids in camelina-based diets (oil and seed) likely improved the synchronization of energy and nitrogen availability for microbial growth. Urinary excretion of purine derivatives (allantoin, uric acid, xanthine+hypoxanthine) and estimated microbial protein synthesis were significantly higher in the camelina seed treatment group than in other groups (P < 0.001). Daily microbial protein production was highest in the camelina seed group (46.60 g/day) and lowest in the control group (34.10 g/day) (P < 0.0001). Microbial protein yield per kilogram of dry matter intake was also significantly greater in the camelina seed treatment (1.07 g/kg DMI) compared to the control diet (0.81 g/kg DMI) (P = 0.0007).
Conclusion: Overall, the inclusion of camelina seeds in the diet improved ruminal fermentation patterns and enhanced microbial protein synthesis, whereas palm oil exerted detrimental effects on rumen fermentation. The physical form of the fat source and its fatty acid profile play crucial roles in determining ruminal fermentation and microbial protein synthesis. Owing to the physical protection of oil from rapid ruminal degradation and the simultaneous supply of fermentable energy and protein, feeding camelina seeds maintained rumen pH within the optimal range, increased the propionate-to-acetate ratio, and enhanced microbial protein synthesis. Although camelina oil supplementation at 1.5% of diet dry matter increased total VFA concentration, it did not negatively impact microbial protein synthesis. Based on the findings of this study, including up to 5% camelina seeds in the diet of growing lambs can enhance ruminal fermentation efficiency and microbial protein synthesis, consequently improving overall feed utilization efficiency.
Keywords: Camelina oil, Camelina seed, Fattening lambs, Microbial protein, Palm oil, Urinary purines, Volatile fatty acids
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