نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری تغذیه دام، گروه علوم دامی، دانشکده کشاورزی، دانشگاه آزاد اسلامی واحد خوراسگان، اصفهان، ایران
2 گروه علوم دامی، دانشکده کشاورزی، دانشگاه آزاد اسلامی- واحد اصفهان(خوراسگان)
3 استادیار، گروه علوم دامی، دانشکده کشاورزی، دانشگاه آزاد اسلامی واحد خوراسگان، اصفهان، ایران
4 استادیار، فیزیولوژی دام، گروه علوم دامی، دانشکده کشاورزی، دانشگاه آزاد اسلامی واحد خوراسگان، اصفهان، ایران
5 استادیار، گروه بیوشیمی، دانشکده علوم زیستی، دانشگاه آزاد اسلامی واحد خوراسگان، اصفهان، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: The transition period in ewes (3 weeks prepartum to 3 weeks postpartum) is characterized by profound metabolic changes and reduced feed intake, leading to negative energy balance, increased non-esterified fatty acids (NEFA), ketone bodies, and oxidative stress. This condition elevates the risk of ketosis, fatty liver, and impaired immunity. Dietary fat supplementation, as a nutritional strategy, can improve metabolic status by providing a dense energy source and reducing body reserve mobilization; however, its effects on digestion, rumen fermentation, and oxidative stress depend on the type of fat (protected saturated vs. unsaturated). Therefore, the objective of this study was to evaluate the effects of different fat sources on nutrient digestibility, liver enzymes in transition ewes, and selected blood parameters of newborn lambs.
Materials and Methods: The experiment was conducted on 60 pregnant ewes (one month before lambing) at the research farm of Islamic Azad University, Khorasgan Branch. Ewes were randomly assigned, based on body weight and expected lambing date, to five treatments (12 replicates) in a completely randomized design: (1) control (no added fat), (2) 3% calcium salts of omega-9 fatty acids, (3) 3% tallow, (4) 3% canola oil, and (5) 3% rumen-protected saturated fatty acid powder. Diets were formulated according to NRC (2007) and offered as TMR from 21 days prepartum to 21 days postpartum. Blood samples (one week before and three weeks after lambing) were collected to determine liver enzymes. Digestibility was estimated using acid-insoluble ash as an internal marker.
Results: Supplementation with different fat sources had no significant effect on body weight, dry matter intake, or body condition score of the ewes. Feeding rumen-protected saturated fatty acid powder significantly increased ether extract digestibility compared with canola oil and the control group in both pre- and postpartum periods, and showed higher values than animal fat postpartum (P < 0.05). This treatment also improved acid detergent fiber digestibility compared with animal fat and canola oil before lambing and compared with canola oil after lambing. Neutral detergent fiber digestibility was affected by treatments only postpartum, with higher values in the protected saturated fat group than in the canola oil and omega-9 treatments (P < 0.05), while dry matter and crude protein digestibility did not differ among treatments. Liver enzyme activities were influenced by dietary fat source. ALT and AST levels in ewes fed canola oil and animal fat increased significantly postpartum (P < 0.05), whereas values in ewes receiving calcium salts of omega-9 and protected saturated fat remained within the normal range. ALP activity was also affected in both sampling periods, with the highest values observed in the omega-9 and animal fat groups. The type of dietary fat significantly affected blood parameters of newborn lambs (P < 0.05). Lambs born to ewes fed protected saturated fat and omega-9 fatty acids had higher concentrations of glucose, cholesterol, total protein, and immunoglobulin G compared with the control group. Cholesterol, total protein, and IgG concentrations in these treatments were also higher than in the animal fat group, while albumin concentration did not differ significantly among treatments.
Conclusion: Overall, supplementation of transition ewe diets with rumen-protected saturated fatty acid powder improved ether extract digestibility compared with canola oil and the control group and maintained more stable liver enzyme activity postpartum compared with canola oil and animal fat. Although not all traits differed significantly among treatments, these findings suggest that protected saturated fat may contribute to improved digestibility and metabolic status during the transition period compared with some other fat sources.
کلیدواژهها [English]
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