Nima Farzaneh

Comparison of the effects of gonadotropin-releasing hormone, human chorionic gonadotropin or progesterone on pregnancy per artificial insemination in repeat-breeder dairy cows

Three different treatments were compared to improve pregnancy per artificial insemination (P/AI) in repeat-breeder (RB) dairy cows. All cows (n=103) were assigned to one of four groups: (1) gonadotropin-releasing hormone (GnRH); (2) human chorionic gonadotropin (hCG); (3) once-used controlled internal drug release (CIDR) device; and (4) control. All treatments performed 5-6days after artificial insemination (AI) and milk samples were collected just before treatment for progesterone assays. There were no significant differences in milk fat progesterone concentration among trial groups. Cows were observed for estrus signs thrice daily. Pregnancy per AI on day 45 in hCG and CIDR groups were significantly higher than GnRH and control groups (60.0% and 56.0% vs. 26.9% and 29.6%, respectively), but there were no differences in P/AI between GnRH and control groups. There were also no significant differences between hCG and CIDR groups. Milk fat progesterone concentrations were compared between pregnant and non-pregnant cows in each group and only in the hCG group it was significantly lower in pregnant cows. In conclusion, treating repeat-breeder cows with hCG or once-used CIDR 5-6days after AI improved P/AI.

Effects of anionic salts supplementation on blood pH and mineral status, energy metabolism, reproduction and production in transition dairy cows.

The objectives of this study were to determine the effects of a pre-partum diet with lower than recommended (DCAD=-82 mEq/kg of dietary DM) amounts of anionic salts on metabolism, health, reproductive performance and milk production in dairy cows. Sixty Holstein multiparous cows were enrolled 21 days prior to expected calving date. The animals were randomly assigned to receive one of two rations: 30 cows received anionic ration [-82 mEq (NA+K-Cl-S)/kg of DM] for 21 d to parturition and the other group (n=30) were fed a usual dry period ration (+192 mEq/kg of DM). Serum samples obtained at days -21, +3 and +21 relative to calving were analyzed for beta-hydroxybutyrate (BHBA), non-esterified fatty acids (NEFA), glucose, calcium (Ca), inorganic phosphorus, magnesium, chloride, sodium, potassium, cholesterol, urea, creatinine, total protein, albumin, and aspartate aminotransferase (AST). Urine pH declined from 8.4 at 21 d before calving (pre-treatment) to 6.2 at day 7 pre-partum in the treatment group. Repeated-measure mixed model analysis indicated that the concentrations of Ca were significantly increased and creatinine, and AST were significantly decreased by lowering DCAD. The concentrations of BHBA, NEFA and glucose were not affected by treatment. The incidence of milk fever and culling were 5 and 11 times higher in the control group in comparison with the treatment group, respectively. The intervals from calving to first breeding and to pregnancy were not influenced by treatment. There was no group effect on average daily milk yield or fat percentage.

Evaluation of five resynchronization methods using different combinations of PGF2α, GnRH, estradiol and an intravaginal progesterone device for insemination in Holstein cows

The aim of this study was to evaluate five methods for the resynchronization of estrus in lactating dairy cows. One hundred and seventy-three Holstein cows were assigned at random to five treatments: Ovsynch-24, IPD+Ovsynch-24, Ovsynch-31, Heatsynch, and IPD+Heatsynch. The start of the resynchronization protocols, and all subsequent procedures, was timed in relation to the pre-enrolment AI (PAI) and ranged over 7 days for each treatment. The pregnancy status of all the animals was evaluated by ultrasound examination on day 31±3 PAI. In all treatments, the resynchronized AI (RAI) was at an observed estrus or at a fixed time after the completion of the resynchronization procedures. Cows were observed for estrus thrice daily and those observed in estrus were inseminated according to the AM-PM rule. Those cows diagnosed as not pregnant and not observed in estrus were inseminated at a fixed time. The average proportion of cows with an active CL was 31.2% (54/173) on day 14 PAI, 22.0% (38/173) on day 21 PAI, and 18.5% (32/173) on day 24 PAI (NS). The incidence of luteolysis averaged 12.7% (22/173) from day 21 to 24, and 28.9% (50/173) from day 14 to 24. The differences between individual treatments were not significant but there was a significantly greater incidence of luteolysis (P<0.0009) from day 14 to 21 for the IPD treatments combined (30.3%; 24/63) than for the non-IPD treatments combined (26.6%; 17/110). Conception rates at day 31 PAI ranged from 16.6% to 42.1% (NS), and at day 61 PAI ranged from 16.6% to 37.1% (NS). Also conception rates at day 31 and 61 RAI ranged from 5% to 25% (NS). Pregnancy losses between days 31 and 61 PAI varied from 0 to 25.0% (NS) between treatments for the pre-enrollment AI but were 0% for all treatments for the resynchronized AI. It was concluded that using IPD, PGF2α, estradiol and GnRH in different resynchronization methods had no effects on conception rate in this study. Also conception rate was not significantly different when resynchronization programs began before ultrasonographic examination for pregnancy diagnosis. Using IPD did not reduce luteolysis during resynchronization programs and estrus detection rates were similar among treatment groups.

Effects of monensin on metabolism and production in dairy saanen goats in periparturient period.

This trial evaluated the effects of dietary supplementation with monensin sodium on dry matter intake, metabolic parameters and milk yield and milk composition of dairy Saanen goats in the periparturient period. Twelve Saanen pregnant dairy goats were assigned to a treatment and a control group. Saanen goats were fed monensin as its 10% sodium salt in the amount of 33 mg/kg of total dry matter intake during 30 d before parturition till d 42 in milk. Blood samples were collected from each goat at d 30, 15 and 7 before expected kidding time and also in d 1, 7, 13, 19, 21, 28, 35 and 42 postpartum. The serum concentrations of β-Hydroxybutyrate (BHBA), non-esterifed fatty acid (NEFA), calcium, magnesium, inorganic phosphorus, cholesterol, triglyceride, urea, total protein, albumin and glucose and aspartate aminotransferase (AST) activity were determined. The BHBA concentration significantly decreased in goats, which received monensin in comparison to controls in the postpartum period (p = 0.049). The concentration of sodium (Na) was significantly influenced by monensin treatment in the postpartum period (p = 0.048). In addition, the difference in dry matter intake was highly significant between the two groups during the pre-partum period. Controls had more dry matter intake (DMI) than treatment goats (p = 0.0001). Mean 3.5% fat corrected milk production was not influenced by monensin treatment. However, milk fat percentage was significantly decreased in monensin treated goats (p = 0.0017).

Expression of endogenous retroviruses in pre-implantation stages of bovine embryo

Endogenous retroviruses (ERVs) are involved in cellular proliferation, pluripotency, tissue-specific remodelling and regulation of developmental processes. These elements are transcriptionally active in mouse and human pre-implantation embryos. Empirical evidence indicates that regulatory networks involved with ERV transcripts are responsible for pluripotency and totipotency at certain stages of mouse and human pre-implantation development. Yet, the expression in pre-implantation bovine embryo remains unidentified. To determine whether two members of bovine endogenous retroviruses, BERV-K1 and BERV-K2, are expressed in the pre-implantation bovine embryo, each embryonic stage developed in vitro and was subjected to RNA release, reverse transcription and quantitative PCR. We found that BERV-K1 and BERV-K2 are expressed throughout different stages of pre-implantation development. The higher level of expression was detected in embryonic blastomeres with totipotent/pluripotent status (two-cell to 16-cell stages), while the more differentiated blastocyst stage showed significantly lower levels of ERVs expression. These findings suggest a possible role for endogenous retroviruses in the establishment of totipotent and pluripotent states in pre-implantation bovine embryo, similar to functions which have been suggested for these elements in human and mouse embryos.

Evaluation of Levamisole Administration at Dry Period for Controlling Postpartum Bovine Mastitis

Bovine respiratory syncytial virus has been identified as an important pathogen associated with acute respiratory disease in calves. An infection model has been developed reflecting the clinical course and the development of pathological signs during a natural BRSV-infection. Calves were infected at age 15-20 weeks and reinfected 14 weeks later. Clinical signs and virus excretion were monitored daily. Blood samples were obtained in the whole period and investigated for the acute phase proteins: haptoglobin and serum amyloid A (SAA) and for the cytokines: interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-6 (IL-6) and interferon-gamma (IFN(). Haptoglobin and SAA were measured by ELISA and cytokine expression (mRNA) were determined by a quantitative real time RT-PCR (Taq-Man technology). The results showed an induction of IL-6, haptoglobin, SAA and IFNγ, to the first experimental infection, whereas there was a smaller induction of IFNγ, and no induction of IL-6, haptoglobin and SAA in the reinfection. Indication of a correlation was found between IL-6 expression and clinical signs and also acute phase protein induction and clinical signs. Another correlation was found between IFNγ and virus excretion. In conclusion, it seems that early mediators are important for the clinical outcome of infection, and that cytokines and acute phase proteins can be useful as clinical parameters reflecting the establishment, development and severity of the infection.