Administration of estradiol benzoate before insemination could skew secondary sex ratio toward males in Holstein dairy cows.

The present study was conducted to investigate the effect of estradiol benzoate administration before insemination on secondary sex ratio (proportion of male calves at birth) in Holstein dairy cows. Cows (n = 1,647) were randomly assigned to 2 experimental groups by parity over a 1-yr period. Cows in the control group (n = 827; 232 primiparous and 595 multiparous cows) received 2 administrations of PGF2α (500 µg) 14 d apart, started at 30 to 35 d postpartum. Twelve d after the second PGF2α injection, cows received GnRH (100 µg), followed by administration of PGF2α 7 d later. Cows in the treatment group (n = 820; 238 primiparous and 582 multiparous cows) received the same hormonal administrations as the cows in the control group. Additionally, cows in the treatment group received estradiol benzoate (1 mg) 1 d after the third PGF2α injection. Estrus detection by visual observation was started 1 d after the third PGF2α injection and after estradiol administration in the control (for 6 d) and treatment (for 36 h) groups, respectively. Artificial insemination was carried out 12 h after observation of standing estrus. Exposure of cows to heat stress at conception was determined based on temperature-humidity index. Estrus detection rate was lower in primiparous than in multiparous cows (P < 0.05), but conception rate was higher in primiparous vs multiparous cows (P < 0.05). Estradiol administration improved estrus detection rate and fertility (P < 0.05); moreover, it increased secondary sex ratio (adjusted odds ratio: 1.645; P = 0.017). Exposure to heat stress diminished heat detection rate and fertility (P < 0.05), and altered secondary sex ratio toward males (adjusted odds ratio: 2.863; P = 0.012). In conclusion, the present study revealed that estradiol administration before insemination could improve fertility and increase the probability of calves being male in Holstein dairy cows. Moreover, the results showed that cows exposed to heat stress around conception had diminished fertility and increased secondary sex ratio.

Effects of probiotics supplementation in daily milk intake of newborn calves on body weight gain, body height, diarrhea occurrence and health condition.

The effects of probiotic administration were studied in an experiment, using 120 newborn calves. Calves were randomly assigned to two experimental groups (sixty calves for each group) and probiotic (0.25 g h(-1) day(-1)) was added in their daily milk intake until 90 days of age. After the first week, all calves (including control group) received starter ration containing 21.0% crude protein and 3.0% crude fat. Body weight gain, body height and general health condition of all calves were observed at day 30, 60 and 90. Also condition of feces was examined daily and the occurrence of diarrhea was recorded throughout the experiment. Mean values of weight gain during three successive months for treatment and control groups were 57.52 and 50.58 kg, respectively. Body weight gained was not significantly different for first and second mo between treatment and control groups (16.9 and 33.87 vs. 14.49 and 33.07 for fist and second months in treatment and control groups, respectively). However, these values were significantly different (p < 0.001) between treatment (57.52) and control (50.58) groups third months of age. Diarrhea was observed in 35 calves of control group, which was higher than 11 cases in calves treated with probiotic (p < 0.001). The body height values of control and treatment groups in three successive months were 5.49, 10.82 and 15.00 cm for control and 5.44, 9.25 and 15.75 cm for treatment groups in first, second and third mo, respectively, which showed no significant difference between two groups during this study. The results of this study indicated that present probiotic compound have beneficial effects, especially on the third month of age in rearing calves.

Superovulatory response of Sistani cattle to three different doses of FSH during winter and summer.

Objective of the present study was to investigate the effect of season and dose of FSH on superovulatory responses in Iranian Bos indicus beef cattle (Sistani). Cyclic cows, in summer (n=16) and winter (n=16), were assigned randomly to three dose-treatment groups of 120 (n=10), 160 (n=12) and 200 (n=10) total mg of Folltropin-V with injections given twice daily for 4 days in decreasing doses. Estrous cycles were synchronized with two prostaglandin F2alpha injections given 14 days apart. From day 5 after the ensuing cycle, daily ovarian ultrasonography was conducted to determine emergence of the second follicular wave at which time superovulation was initiated. Relative humidity, environmental and rectal temperatures were measured at 08:00, 14:00 and 20:00 h for the 3 days before and 2 days after the estrus of superovulation. Non-surgical embryo recovery was performed on day 7 after estrus. The effects of season, dose, time of estrous expression and all two-way interactions were evaluated on superovulatory responses: total numbers of CL, unovulated follicles (10 mm), ova/embryo, transferable and non-transferable embryos. Season (summer or winter), doses of Folltropin-V (120, 160 or 200 mg NIH) and time of estrous expression (08:00, 14:00 or 20:00 h) did not affect the number of transferable embryos (3.1+/-0.58). When superovulatory estrus was detected at 08:00, a FSH dose effect was detected with the greatest numbers of CL (12.2+/-0.87) and total ova/embryos (12.2+/-1.46) occurring with 200 mg FSH (dosextime of estrous expression; P<0.01).

Steroid priming shortens prostaglandin-based estrus synchronization program from 14 to 7 days in cattle.

Single injection of estrogen and progesterone before prostaglandin (steroid priming) was used to shorten the prostaglandin-based estrus synchronization program. Sixty-five cyclic Sistani cattle, with parity ranging from 1 to 4 and postpartum period of >80 days were selected at unknown stages of the estrous cycle and assigned to 2 groups according to their age, weight and parity. Females in the control group (n=33; 58.4 +/- 4.3 months; 277 +/- 8 kg LW) received two consecutive injections of prostaglandin F2alpha analogue (500 microg; Cloprostenol, PG) 14 days apart (Day 0 = First PG injection). On Day 7, treated females (n=32; 60 +/- 4.8 months; 292 +/- 9 kg LW) were given an intramuscular injection of 100 mg progesterone and 2 mg estradiol benzoate followed by prostaglandin 7 days later, concurrent with the second PG injection of the control group. Estrus detection was carried out every 6 hours for 7 days, commencing from 24 hours after the last PG injection. Females that allowed to be mounted were identified (standing estrus) and inseminated with frozen semen 12 hours later. Pregnancy was diagnosed on Day 50 after AI through palpation per rectum. Data were analyzed using Chi-squared and t-test. The tightness of estrus synchrony (%), the interval from the end of treatment to estrus (h) and conception rates (%) were similar (P > 0.05) between control (69.6%, 77.7 +/- 5.96 h and 56.5%) and treatment (68.2%, 82.6 +/- 7.64 h and 54.5%) groups. In conclusion, steroid priming is an efficient way to shorten the prostaglandin-based estrus synchronization program from 14 to 7 days without compromising estrous response and fertility.

Factors associated with rectovaginal injuries in Holstein dairy cows in a herd in Tehran, Iran.

Rectovaginal injuries can result in subsequent infertility in cows. In a retrospective study, records of 147 Holstein cows with evidence of rectovaginal injuries were reviewed to determine the odds ratio (OR) of these injuries and their related risk factors. The study was conducted in a large dairy (typical herd size 1420 cows) in Tehran between the years 1993 and 1996. Period prevalences were 0.4% fistula, 1.9% laceration (third degree), 5.7% pneumovagina, 1.5% urovagina and 0.8% mixed injuries. The highest risk occurred among first-calf heifers. Animals with dystocia, first-calf heifers and male calves were at higher risk for rectovaginal injuries. We concluded that (1) handling dystocia with care might have a substantial role in reducing rectovaginal injuries, (2) first-calf heifers are to be under close observation and care during calving, and (3) because rectovaginal injuries reoccur in the next calving, cows with the history of these injuries should be monitored at the next labor.

Effective dose to the public from 226Ra in drinking water supplies of Iran.

One of the most important and prevalent isotopes of radium (Ra) in the human food chain, and especially in drinking water, is 226Ra. To determine the contribution of this radionuclide to the annual effective dose to the public in Iran, a national program for determination of this radionuclide was established. Over 500 water samples from different surface and ground water supplies including wells, rivers and springs, as well as hot springs and sea water from the Caspian Sea and Persian Gulf have been analyzed. An emanation method with a minimum detection limit of less than 2 mBq L(-1) was developed and applied in this study. Unweighted mean concentrations of 3.3 mBq L(-1) and 8.0 mBq L(-1) were determined in surface and ground drinking water supplies, respectively. Based on such values, mean unweighted annual intakes of 226Ra were found to be 0.85 Bq for an infant, 1.97 Bq for a child, and 2.82 Bq for an adult, which correspond to mean unweighted annual effective doses of 0.17 microSv y(-1), 0.39 microSv y(-1), and 0.56 microSv y(-1), respectively. The mean 226Ra concentrations in hot springs were higher with a maximum of 146.5 Bq L(-1) measured in the Ab-e-Siah hot spring in Ramsar, a town on the coast of the Caspian Sea in Iran.