Effects of Flushing Diets Containing Whole Flaked Raw and Micronized Rapeseed (Brassica napus) on Reproductive Performance of Mature Kurdish Ewes

Introduction: Dietary supplementation with oilseeds is a widely recognized strategy for enhancing body condition in sheep around the mating period to improve reproductive performance. Rapeseed is the second most prevalent source of oilseeds globally and is known for its favorable profile of unsaturated fatty acids, including high levels of oleic acid, linoleic acid, and alpha-linolenic acid. These fatty acids contribute to improved production and reproductive outcomes in 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 supplement. Micronization as a heat process has the potential of protecting fatty acid from ruminal biohydrogenation and reducing ruminal degradability of protein. We hypothesized that rapeseed supplementation around mating can improve productive and reproductive performance of ewes by supplying the energy and protein. In addition, an increase in unsaturated 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 containing whole flaked raw and micronized rapeseed. 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, and 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 was also measured. The number and diameter of follicles were determined on days of mating and 9 days after mating. Pregnancy was diagnosed at 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 and discussion: The results of this study showed that the weight and body condition score of ewes as well as the lambs birth weight were significantly increased by dietary supplementation with raw and micronized whole flaked rapeseed.Plasma glucose and triglycerides were significantly increased by supplemental flaked rapeseed. Lower BUN concentration was observed for ewes fed diets contained raw and micronized rapeseeds. Plasma estradiol levels at day of mating and progesterone levels at 9 and 30 days after mating were significantly higher in ewes on micronized and raw flaked rapeseed diets, 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 and micronized flaked rapeseeds. The average number and size of large follicles at the day of mating were significantly higher in ewes on micronized and raw flaked rapeseed diets, respectively. The fertility rate and female lamb rate were significantly increased by dietary supplementation with raw and micronized flaked rapeseed. Lambing intervals significantly decreased by dietary supplementation with micronized flaked rapeseed. The lambing rate was significant for both ewes on micronized and raw rapeseed diets. Supplementation diet with micronized rapeseed significantly increased twining rate. Conclusion: Overall, dietary inclusion of rapeseed especially micronized rapeseed around the mating can be an effective nutritional strategy to improve productive and reproductive performance of ewes in traditional sheep production systems.