Abstract: (27 Views)
Introduction and Objective: The use of rumen-protected fats, particularly calcium salts of unsaturated fatty acids, is one of the nutritional strategies for increasing dietary energy density and improving the performance of lactating animals during early and mid-lactation. Compared with conventional fat sources, these compounds can provide more energy to animals without causing severe disruption in rumen fermentation and thereby affect milk production and composition, metabolic status, and feed efficiency. Nevertheless, the animal response to fat supplementation depends on factors such as fatty acid type, supplementation level, stage of lactation, diet composition, and species-specific characteristics. In Khuzestani buffaloes, despite their economic importance and high adaptability to the climatic conditions of southern Iran, information regarding the effects of omega-3 fatty acid calcium salts on productive performance, milk composition, digestibility, and blood parameters is limited. Therefore, this study was conducted to investigate the effects of different levels of omega-3 fatty acid calcium salts on feed intake, milk production and composition, apparent nutrient digestibility, and selected blood biochemical indices in lactating Khuzestani buffaloes.
Materials and Methods: This experiment was conducted at the Dezful Buffalo Station using 21 lactating Khuzestani buffaloes in a completely randomized design with three treatments and seven replicates. The mean live body weight of the animals was 585 ± 15 kg, the mean parity was three, the mean days in milk was 100 days, and their age ranged from five to six years. The experimental period lasted 60 days, including a 15-day adaptation period. The treatments consisted of a basal diet without supplementation, a basal diet containing 75 g, and a basal diet containing 150 g of omega-3 fatty acid calcium salts per day. The supplement used, under the trade name Persiaft and produced by Kimia Danesh Alvand Company, was mixed daily with the concentrate. The diets were formulated according to NRC (2001), with a 50:50 forage-to-concentrate ratio, and were offered as total mixed rations twice daily. Drinking water was provided ad libitum. The animals were housed individually so that feed intake and milk production of each animal could be recorded separately. The amount of feed offered and the daily refusals were measured, and samples were collected to determine dry matter intake. Milking was performed at 06:00 and 18:00, and milk samples were collected after homogenization and refrigerated storage for determination of fat, protein, lactose, solids-not-fat, total solids, pH, and freezing point. During the final days of the experimental period, feed, refusal, and fecal samples were collected, dried, ground, and transferred to the laboratory for determination of chemical composition and apparent digestibility of dry matter, organic matter, crude protein, ether extract, and cell wall components. In addition, at the end of the experimental period, blood samples were collected and analyzed for glucose, cholesterol, triglycerides, blood urea nitrogen, creatinine, and the activities of the AST, ALT, and ALP enzymes using Bayer Fars kits and a Mindray BS-200 autoanalyzer. The data were analyzed using the GLM and MIXED procedures of SAS 9.3, and the means were compared at the five-percent level.
Results: The results showed that dry matter intake was not affected by the experimental treatments, and supplementation up to 150 g/day did not cause any noticeable disruption in feed acceptance. Milk production was significantly affected by the supplementation level, with the highest value observed in the 150-g treatment, whereas the 75-g treatment showed only a numerical and nonsignificant decrease compared with the control. Milk fat, protein, and lactose percentages did not differ significantly among the treatments; however, milk solids-not-fat increased significantly following the consumption of 150 g of the supplement. Blood parameters, including glucose, cholesterol, triglycerides, blood urea nitrogen, and creatinine, as well as the activities of Liver enzymes (AST, ALT, and ALP) , were not affected by the treatments and all remained within the normal range. In contrast, dry matter digestibility was significantly higher in the control group than in the supplemented groups, and organic matter digestibility was also higher in the control than in the 75-g treatment. Neutral detergent fiber digestibility showed a decreasing trend with increasing supplementation level and reached its lowest value in the 150-g treatment, although this difference was not significant at the five-percent level. Acid detergent fiber and crude protein digestibility did not differ among the treatments.
Discussion and Conclusion: Omega-3 fatty acid calcium salts, at a level of up to 150 g/day, increased milk production and solids-not-fat (SNF) without reducing dry matter intake in lactating Khuzestani buffaloes. The absence of significant changes in milk fat, protein, and lactose percentages indicates that the increase in SNF was probably attributable to limited and simultaneous changes in the non-fat components of milk. Furthermore, the unchanged concentrations of glucose, cholesterol, triglycerides, blood urea nitrogen, and creatinine, as well as the unchanged activities of the AST, ALT, and ALP enzymes, indicate that supplementation at the 150-g level, under the conditions of this experiment, did not have any evident adverse effect on metabolic status or liver and kidney function. Despite the increase in milk production, the reduction in dry matter and organic matter digestibility and the decreasing trend in NDF digestibility suggest a possible effect of the supplement on the digestion of dietary fiber components. This response may be associated with the activity of rumen fibrolytic microorganisms, the degree of fat protection, the composition of the basal diet, and the uniformity of total mixed ration mixing. However, because fermentation characteristics and rumen microbial populations were not measured in this study, this mechanism should be interpreted cautiously. Overall, the daily consumption of 150 g of omega-3 fatty acid calcium salts may be an appropriate strategy for improving milk production and SNF in lactating Khuzestani buffaloes, provided that forage quality, uniformity of diet mixing, and complete consumption of the supplement are carefully managed. To confirm the commercial applicability of this supplementation level, long-term studies evaluating rumen fermentation, milk fatty acid profiles, reproductive performance indicators, and economic efficiency are recommended.
Materials and Methods: This experiment was conducted at the Dezful Buffalo Station using 21 lactating Khuzestani buffaloes in a completely randomized design with three treatments and seven replicates. The mean live body weight of the animals was 585 ± 15 kg, the mean parity was three, the mean days in milk was 100 days, and their age ranged from five to six years. The experimental period lasted 60 days, including a 15-day adaptation period. The treatments consisted of a basal diet without supplementation, a basal diet containing 75 g, and a basal diet containing 150 g of omega-3 fatty acid calcium salts per day. The supplement used, under the trade name Persiaft and produced by Kimia Danesh Alvand Company, was mixed daily with the concentrate. The diets were formulated according to NRC (2001), with a 50:50 forage-to-concentrate ratio, and were offered as total mixed rations twice daily. Drinking water was provided ad libitum. The animals were housed individually so that feed intake and milk production of each animal could be recorded separately. The amount of feed offered and the daily refusals were measured, and samples were collected to determine dry matter intake. Milking was performed at 06:00 and 18:00, and milk samples were collected after homogenization and refrigerated storage for determination of fat, protein, lactose, solids-not-fat, total solids, pH, and freezing point. During the final days of the experimental period, feed, refusal, and fecal samples were collected, dried, ground, and transferred to the laboratory for determination of chemical composition and apparent digestibility of dry matter, organic matter, crude protein, ether extract, and cell wall components. In addition, at the end of the experimental period, blood samples were collected and analyzed for glucose, cholesterol, triglycerides, blood urea nitrogen, creatinine, and the activities of the AST, ALT, and ALP enzymes using Bayer Fars kits and a Mindray BS-200 autoanalyzer. The data were analyzed using the GLM and MIXED procedures of SAS 9.3, and the means were compared at the five-percent level.
Results: The results showed that dry matter intake was not affected by the experimental treatments, and supplementation up to 150 g/day did not cause any noticeable disruption in feed acceptance. Milk production was significantly affected by the supplementation level, with the highest value observed in the 150-g treatment, whereas the 75-g treatment showed only a numerical and nonsignificant decrease compared with the control. Milk fat, protein, and lactose percentages did not differ significantly among the treatments; however, milk solids-not-fat increased significantly following the consumption of 150 g of the supplement. Blood parameters, including glucose, cholesterol, triglycerides, blood urea nitrogen, and creatinine, as well as the activities of Liver enzymes (AST, ALT, and ALP) , were not affected by the treatments and all remained within the normal range. In contrast, dry matter digestibility was significantly higher in the control group than in the supplemented groups, and organic matter digestibility was also higher in the control than in the 75-g treatment. Neutral detergent fiber digestibility showed a decreasing trend with increasing supplementation level and reached its lowest value in the 150-g treatment, although this difference was not significant at the five-percent level. Acid detergent fiber and crude protein digestibility did not differ among the treatments.
Discussion and Conclusion: Omega-3 fatty acid calcium salts, at a level of up to 150 g/day, increased milk production and solids-not-fat (SNF) without reducing dry matter intake in lactating Khuzestani buffaloes. The absence of significant changes in milk fat, protein, and lactose percentages indicates that the increase in SNF was probably attributable to limited and simultaneous changes in the non-fat components of milk. Furthermore, the unchanged concentrations of glucose, cholesterol, triglycerides, blood urea nitrogen, and creatinine, as well as the unchanged activities of the AST, ALT, and ALP enzymes, indicate that supplementation at the 150-g level, under the conditions of this experiment, did not have any evident adverse effect on metabolic status or liver and kidney function. Despite the increase in milk production, the reduction in dry matter and organic matter digestibility and the decreasing trend in NDF digestibility suggest a possible effect of the supplement on the digestion of dietary fiber components. This response may be associated with the activity of rumen fibrolytic microorganisms, the degree of fat protection, the composition of the basal diet, and the uniformity of total mixed ration mixing. However, because fermentation characteristics and rumen microbial populations were not measured in this study, this mechanism should be interpreted cautiously. Overall, the daily consumption of 150 g of omega-3 fatty acid calcium salts may be an appropriate strategy for improving milk production and SNF in lactating Khuzestani buffaloes, provided that forage quality, uniformity of diet mixing, and complete consumption of the supplement are carefully managed. To confirm the commercial applicability of this supplementation level, long-term studies evaluating rumen fermentation, milk fatty acid profiles, reproductive performance indicators, and economic efficiency are recommended.
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