the aim of this study was to consider reproductive performance parameters and blood progesterone concentration changes in high-producing dairy cows (39±2 kg per day) after artificial insemination, in summer and winter. 270 heads of holstein dairy cattle were choose in three big dairy farms, and blood samples were collected at days seven, ten and fourteen after artificial insemination. temperatu...

No report has been published on the economical losses associated with errors in oestrus detection in cows under Iranian intensive dairy management. The following study was carried out to determine the accuracy of oestrus detection by farmers using artificial insemination in Shiraz dairy farms. Milk samples were collected from 179 Holstein milking cows at the time of artificial insemination. Mil...

no report has been published on the economical losses associated with errors in oestrus detection in cows under iranian intensive dairy management. the following study was carried out to determine the accuracy of oestrus detection by farmers using artificial insemination in shiraz dairy farms. milk samples were collected from 179 holstein milking cows at the time of artificial insemination. mil...

BACKGROUND Results regarding the use of bovine somatotropin for enhancing fertility in dairy cattle are variable. Here, the hypothesis was tested that a single injection of a sustained-release preparation of bovine somatotropin (bST) during the preovulatory period would improve pregnancy success of lactating dairy cows at first service. RESULTS The first experiment was conducted in a temperat...

The present study aimed to determine the effect of administrating prostaglandin F2α (PGF2α) and GnRH at the time of artificial insemination (AI) on the pregnancy per artificial insemination (P/AI) and the pregnancy survival rate of dairy cows. A number of 830 lactating Holstein cows were randomly divided into four groups. Cows in group 1 (n=200) treated with 150 µg d-cloprostenol. In group 2 (n...

The aim of the present study was to investigate inline lactate dehydrogenase (LDH) dynamic changes based on different cow factors - number and stages lactation, milk yield, status reproduction in clinically healthy dairy cows. In Herd Navigator system, LDH activity levels (μmol/min per litre) were measured using dry-stick technology. A total 378 cows selected. According their reproductive statu...

Infertility has been linked to numerous factors in high producing dairy cattle in the last decades. The detection of estrus continues to present difficulties and, although progress has been made in regards to estrus synchronization and artificial insemination, the reproductive performance of dairy cows has not improved substantially. Moreover, in warm countries, summer heat stress is a major fa...

Effects of twinning on lactation and days open in Holsteins were studied from calving records compiled by member surveys of Eastern Artificial Insemination Cooperative. Records of cows with 305-day mature-equivalent records from the Northeast Dairy Records Processing Laboratory were grouped according to whether the twin calving was associated with dystocia. Records of each cow that had a twin c...