RESUMEN

The objective of this study was to evaluate the effect of replacing ground corn (402 g kg−1 of dry matter) with rehydrated corn grain silage (RCGS; 425 g kg−1 of dry matter) in a flushing diet on follicular development in tropical Santa Inês ewes. Fifteen ewes were randomly assigned to one of two treatment groups: a diet with ground corn (control, n = 7) or a diet with RCGS (n = 8). The first day of the diets was designated d0, and the diets were fed for 30 days, up to two days after the end of the estrus synchronization protocol. The estrus synchronization protocol (intravaginal progestogen sponge for 11 days plus 300 IU eCG and 37.5 µg d-cloprostenol IM two days before sponge removal) started on d17 of the diets. The number and diameters of ovarian follicles ≥3 mm were assessed by ultrasound on the day before the diets were provided (d−1), on d14, and then daily from two days before sponge removal until ovulation or up to the eighth day after sponge removal. Blood samples were collected on days −1, 0, 6, 12, 18, 24, and 30 for glucose and urea analyses. There was no effect of the treatments on dry matter intake, plasma glucose, and urea nitrogen concentrations, or on the percentage of ewes that ovulated and on the number of ovulations. The number of follicles ≥3 mm did not differ between treatment groups; the number increased between d−1 and d14 and did not differ between d14 and d28. The diameter of ovulatory follicles at sponge removal, the interval from sponge removal to estrus, and the growth rate of the ovulatory follicles were greater in the RCGS group than in the control group, resulting in larger follicles at ovulation. Replacement of ground corn by RCGS in the flushing diet does not increase the number of ovulations but results in delayed onset of estrus and ovulation of larger follicles.(AU)

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RESUMEN

To evaluate the effects of moderate dietary restriction and lipid supplementation on ovarian follicular development, hormonal and metabolic profile, thirty-five prepuberal ewe lambs were blocked by body weight and randomly assigned to treatments: ALUS (control) - unsupplemented-diet ad libitum (3.5% ether extract, n = 9); R-US - intake restricted to 85% of the ALUS diet (n = 9); AL-LS - lipid-supplemented-diet ad libitum (9.8% ether extract, n = 8); R-LS - intake restricted to 85% of the ALLS diet (n = 9), from 95 ± 8 days of age until estrus or 7 months of age. Lipid supplementation did not reduce dry matter intake. Daily weight gain was greater in lambs fed ad libitum. Plasma glucose was greater in the RLS treatment group, while serum insulin was less with lipid supplementation. There was a treatment by age interaction on total cholesterol, HDL cholesterol and triglyceride serum concentrations. Estrus was detected in 43% of the animals and the overall ovulation rate was 60%. The number of follicles, diameter of the largest follicle, body weight, age and serum progesterone at puberty did not differ among treatment groups. The mean diameter of the largest follicle was greater in lambs having than in those not having ovulations and increased with age in both groups. There was an interaction between the effects of occurrence of ovulation and age on the number of follicles between 3 and 5 mm and > 5 mm. Lipid supplementation and dietary restriction altered the metabolic profile in ewe lambs with no concomitant changes in values for reproductive variables.

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RESUMEN

A number of studies have shown that dietary omega-6 and omega-3 long-chain fatty acids can be incorporated into muscle tissue of ruminants despite the biohydrogenation of dietary fatty acids in the rumen. The main focus of this review is on eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) fatty acids because health authorities around the world consider the sum of these fatty acids as the basis of classifying a food as a source or good source of omega-3 polyunsaturated fatty acids (PUFAs). A high proportion of polyunsaturated fatty acids are hydrogenated in the rumen, leading to a higher concentration of 18:0, but some escapes the rumen to be absorbed intact by the small intestine. Feeding strategies for ruminants have been successfully applied to increase the absorption of PUFAs in the small intestine and therefore to increase the levels of PUFAs in muscle tissue. Protected fats and algae are strong candidates to improve the nutritional value of red meat in ruminants in terms of health-claimable omega-3 fatty acids. Efforts to understand the genetic basis of fatty acid metabolism have been underway. The knowledge of the main genes which control the output of omega-3 fatty acids is still lacking, but gene expression studies have helped to explain the deposition of these acids in muscle, liver, and subcutaneous fat.