نوع مقاله : مقاله پژوهشی
نویسندگان
گروه علوم دامی، دانشکده کشاورزی، دانشگاه فردوسی مشهد، مشهد، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Objective: Dietary supplementation of oilseeds is a well-known strat-egy of improving body condition in sheep around mating so as to improve the reproductive performance of sheep. Rapeseed is the second most abundant source of oilseeds in the world, and it is known for its desirable unsaturated fatty acids profile with a high proportion of oleic acid, linoleic acid, and alpha-linolenic acid, which improve production and repro-duction performance of animals. The high energy and protein content of rapeseed and its desirable amino acids profile make rapeseed an excellent feed source for ruminants, and there is renewed interest in using it in the rations of high producing animal as a feed sup-plement. Micronization as a heat process has the potential of protecting fatty acid from ru-minal biohydrogenation and reducing ruminal degradability of protein. We hypothesized that rapeseed supplementation around mating can improve productive and reproductive per-formance of ewes by supplying the energy and protein. In addition, an increase in unsaturat-ed fatty acid and protein bypass can induce estrus and increase reproduction performance. Therefore, this study was conducted to investigate the reproductive performance of mature Kurdish ewes to the flushing diets supplemented with whole flaked raw or micronized rape-seed.
Materials and Methods: In this experiment, full-fat rapeseed was micronized at 2.8 micron. The micronized and non-micronized rapeseeds separately flaked by passing between two rotating rollers with a 0.50 mm distance gap. To this end, 55 mature Kurdish ewes were randomly allocated into three treatments: 1) Control (the receivers of basal flushing diet with no rapeseed), 2) basal diet plus supplementation with 0.18 kg/day/ewe raw flaked rapeseed, 3) basal diet plus supplementation with 0.18 kg/day/ewe micronized flaked rapeseed in completely randomized design. Ewes live weight and body condition score measured at the beginning of the experiment and at lambing. The lamb birth weight also measured. The number and diameter of follicles were determined on days of mating and 9 days after mating. Pregnancy was diagnosed 30 days after mating. Blood samples were taken on days of mating, 9 and 30 days after mating. The data obtained from weight and BCS of ewes, lambs birth weight and blood hormones and metabolites were analyzed using GLM procedures of SAS software (9.4 version, SAS Institute Inc.). The data obtained from reproductive performance of ewes were analyzed using chi-square model and Proc Genmod procedures of SAS software. For all results, Least-square means for each treatment are reported in the tables and were compared using adjusted Tukey tests. Statistical significance was accepted at P≤ 0.05.
Results: The results of this study showed that the weight and body condition score of ewes as well as the male and female lamb birth weight were significantly increased by dietary supplementation with raw or micronized whole flaked rapeseed. Plasma glucose, Triglycerides, BUN concentration were significantly increased by supplemental flaked rapeseed. Plasma estradiol at days of mating and progesterone at 9 and 30 days after mating were significantly increased in micronized and raw flaked rapeseed groups, respectively. Plasma insulin also were significantly increased in ewes fed micronized and raw flaked rapeseed, respectively. Dietary treatments had no significant effect on number of small and total follicles as well as the average size of small and medium follicles at the day of mating. The number of medium follicles on the day of mating as well as the carpus luteum size at 9 days after mating were significantly higher for the ewes fed diets contained raw or micronized diets. The mean number and size of large follicles at the day of mating were significantly increased in ewes on micronized and raw rapeseed diets, respectively. The fertility rate and female lamb rate were significantly increased by dietary supplementation with raw or micronized flaked rapeseed. Lambing intervals significantly decreased by dietary supplementation with micronized flaked rapeseed. The rate of pregnancy and lambing as well as the percentage of twinning, male and female lambs were not affected by treatments. The lambing rate was significantly in ewes on micronized and raw rapeseed diets, respectively. Supplementation diet with micronized rapeseed significantly increased twining rate.
Conclusion: Overall, dietary inclusion of rapeseed especially micronized rapeseed around the mating period can be an effective nutritional strategy to improve productive and reproductive performance of ewes in traditional sheep production systems.
کلیدواژهها [English]
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