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The objective of this study was to determine the effect of supplemental chromium as chromium-L-methionine (Cr-Met) on productive and reproductive performances and some metabolic parameters in late gestation and early lactation of dairy cows. Sixty multiparous Holstein dairy cows according to prior lactation, parity, body mass (682±33 kg), and expected calving date were divided equally (30 cows/treatment) and were randomly allocated to one of the two groups. One group received basal diet without Cr (control group) and another group received Cr-Met supplement added at manufacturer's recommended level (8 mg of "Cr"/head per day) from 21 days before expected calving date until 21 days of lactation. Supplemental Cr tended to increase milk yield (P=0.08) while percentage of lactose and lactose yield increased (P<0.01). Chromium supplementation decreased serum nonesterified fatty acids concentration at 7 days prepartum and 21 days postpartum. Serum insulin concentration for cows receiving Cr was higher than the control group (P=0.05). Serum cortisol concentration decreased (P<0.05) in prepartum period in supplemented group. Chromium did not affect concentrations of metabolic parameters at calving. However, serum glucose concentration increased at 21 days postpartum in the supplemented group (P<0.05). Chromium supplementation increased neutrophil and neutrophil to lymphocyte ratio in prepartum period (P<0.05). Based on serum concentrations of progesterone, days to first ovulation tended (P=0.07) to occur earlier in the supplemented group. Furthermore, days to first service and days to first estrus of the supplemented group occurred earlier than the control group (P<0.05) but days open, services per conception and conception rates at first insemination did not differ between two groups (P>0.05). Percentage of cyclic cows at 36 days postpartum and estrous behavior before AI was higher in the supplemented group.

The object of this study was to determine the effect of prepartum supplementation of vitamin E with or without injective vitamin E and selenium (Se) on productive and reproductive performances and immune function in dairy cows. Sixty multiparous Holstein dairy cows were divided randomly into three groups at the end of gestation. Cows in each group received one of three treatments: (1) a single intramuscular (im) injection of vit. E + selenium 3 weeks prepartum; (2) daily supplementation of oral vit. E given from 3 weeks prepartum to parturition; (3) injective vit. E + Se with daily supplementation of oral vit. E. Blood samples were collected from cows at calving and from calves at 0 and 7 days of age. Concentration of IgG in serum of cows and calves as well as in colostrum was determined. No significant differences among treatments occurred in the concentrations of IgG, animal, and calf production and reproduction performance. Due to the lack of significant difference between injection and oral supplementation, it is recommended to replace the injection with oral supplementation.

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The objective of this study was to evaluate if treatment of equine chorionic gonadotrophin (eCG)-superovulated Sanjabi ewes with repeated administration of human chorionic gonadotropin (hCG) would increase the number of normal corpus luteum (CL) and serum progesterone concentrations and decrease the number of persistent follicles. The superovulated ewes were divided into four groups on day 0 (day of sponge removal); the ewes were treated by an intramuscular administration of 500 IU hCG on day 0 (Group I: n = 10), on days 0 and 1 (Group II: n = 10), or on days 0, 1, and 2 (Group III: n = 10) and no treatment for control group (n = 10). Blood samples were collected on days 0, 1, 2, 5, and 8 (day of slaughter), and serum progesterone concentrations were determined. According to progesterone concentrations, 50 (4/8) and 0 % of the ewes underwent premature luteal regression in the control group and the hCG groups, respectively. There were more CLs in Group III than in Group II and the control group. Ewes treated with hCG had a greater number of normal-looking CL. CL diameter was significantly greater in Group II and Group III than other groups. Total CL weight was significantly (P < 0.05) higher in Group III than in Group I and the control group. Number of persistent follicle and persistent follicle diameter were lower in control group compared to the other groups. Eight days after sponge removal, serum progesterone concentration was significantly higher in Group III than in Group I and the control group. The present results indicate that repeated administration of hCG supported CL formation, increased serum progesterone concentration, and prevented premature luteal regression in eCG-superovulated Sanjabi ewes.

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Objective To compare the effect of human menopausal serum with estrous sheep serum, estrous goat serum, ovine follicular fluid and bovine follicular fluid on in vitro maturation, in vitro fertilization and embryo development of sheep oocytes Method (s) Oocytes were treated in culture with different sera and follicular fluids supplemented media to examine effects on embryo development. Results Basic culture medium supplemented with human menopausal serum, estrous sheep serum and estrous goat serum supported better rates of in vitro maturation, in vitro fertilization and embryo development. Ovine follicular fluid and bovine follicular fluid supplementations supported similar rates of In vitro maturation, In vitro fertilization and embryo development which were lower than those supported by human menopausal serum, estrous sheep serum, estrous goat serum and control medium.Conclusion Human menopausal serum, estrous sheep serum, and estrous goat serum resulted in higher maturation, fertilization and embryo development than ovine follicular fluid, bovine follicular fluid and control media.

The aim of the present study was to evaluate the effects of administration of PGF 2 α on semen characteristics in crossbred rams in the non-breeding season. Twenty crossbred rams (Arkhar-Merino × Moghani and Arkhar-Merino × Ghezel) were randomly allocated into two equal groups. The experimental group received 7.5 mg IM of Estroplan (PGF2α analogue) and the control group received 1 ml of water soluble. A total number of eighteen ejaculates per ram were collected by artificial vagina twice a week 30 min following IM administration. Semen ejaculates were evaluated for volume, sperm concentration, total sperm output, mass and individual motility, methylene blue reduction time-test (MBRT), percentage of live sperm and sperm abnormality rates. The results of the current study shows that PGF 2 α treatment on crossbreed rams improved most semen characteristics including volume, sperm concentration, total sperm output and MBRT in comparison to control group (P < 0.01). However, other semen characteristics show similar values. We concluded that PGF 2 α actually improved semen output without any negative effect on sperm qualities.