Nonpregnant Hereford cows (n = 70) were used to determine the effect of nutrient intake and body condition on reproductive and thyroid function. Body condition scores (BCS; 1 = emaciated; 9 = obese) of cows averaged 5.0 +/- .2 on July 1, and cows were fed for 4 mo either to lose weight and BCS (thin; n = 22), to maintain weight and BCS (moderate; n = 24), or to gain weight and BCS (fat; n = 24)...

The objective of this study was to determine the effects of two different time of GnRH injection after artificial insemination (A.I) (d 6 and d 12) on reproductive performances of Holstein cows during the warm season. Cows randomly assigned to treatments 1) No GnRH injection (control, n = 300),2) GnRH injection at day 6 after A.I (G6, n=300) and 3) GnRH injection at day 12 after A.I (G12, n=300...

This study was designed to test the treatment with prostaglandin F2α (PGF2α) plus equine chorionic gonadotrophin (eCG) and GnRH 48 h later (PEG protocol) followed by fixed-time AI (FTAI) in dairy cows with silent ovulation (cows with a mature corpus luteum and no signs of estrus detected in the preceding 21 days). In Experiment I, ovulation following the PEG protocol monitored in 24 cows with s...

In the current study, blood samples from 319 cows and heifers were studied. Antibodies against BVDV infections in serum samples and BVDV antigens in leukocytes were present in 203 (148 cows and 55 heifers) and 56 (28 cows and 28 heifers) samples, respectively. Although no significant difference was detected between seropositive ŠBVDV (Ag-/Ab+)1 and uninfected ŠBVDV (Ag-/Ab-)1 cows and heifers a...

Periparturient cows have been found to reveal immunosuppression, frequently associated with increased susceptibility to uterine and mammary infections. To improve understanding of the causes and molecular regulatory mechanisms accounting for this phenomenon around calving, we examined the effect of an antigen challenge on gene expression modulation on cows prior to (BC) or after calving (AC) us...

To compare 2 strategies for systematically resynchronizing ovulation, lactating Holstein cows (n = 763) at various days in milk and prior artificial insemination services were assigned randomly at timed AI (TAI) to receive the first GnRH injection of Ovsynch 26 (D26) or 33 (D33) d after TAI to resynchronize ovulation (Resynch) in cows failing to conceive. Cows in the D26 treatment received GnRH...

Background: Ovarian cysts are among the diseases which cause reproductive failure and economic losses in dairy herds. High yelding dairy cattles are suseptable to reproductive failure caused by ovarian cysts, as a result of their exposure to stressful coditions during lactation. OBJECTIVES: This study aimed to monitor metabolic profile tests in dairy cows with ovarian cysts in comparison with c...

Two experiments were conducted to determine how steroid milieus and pregnancy affect sexual behavior. Experiment 1 was arranged as a Latin square with five ovariectomized cows and five steroid milieus: no steroid (N); progesterone (P4); estradiol benzoate (EB); P4 + EB; and P4 followed by EB (P4:EB). Progesterone was administered via pessary (2 g of P4) for 5 d and EB was injected (1 mg i.m.) o...

The current study was performed to clarify the effects of GHRH treatment on milk production and plasma hormones and metabolites in lactating Japanese Black cows (a beef breed) under negative energy balance (EB). Ten multiparous lactating beef cows were offered a normal-energy diet daily (110% of ME requirements for maintenance and lactation) until 5 d in milk (DIM) to standardize the cows befor...

The objective of this study was to investigate the effect of different body condition score (BCS) at 30 days before calving (-30 days) induced by a differential nutritional management from -100 days until -30 days on productive parameters, the interval to first ovulation and blood parameters in primiparous and multiparous Holstein cows under grazing conditions until 60 days post partum. The exp...