Early postpartum hormonal therapy improves fertility of dairy cows

A study of 234 Holstein cows was conducted to determine if hormonal treatments of gonadotropin-releasing hormone (GnRH or Cystorelin®) and(or) prostaglandin F2α (PGF or Lutalyse®) given early after calving would improve subsequent fertility of dairy cows. Treatment of cows having abnormal conditions associated with calving (puerperal problems) reduced interval from calving to conception by 43 to 48 days when GnRH was given once between days 10 and 14 postpartum or when PGF was administered once between 20 and 24 days after calving compared with cows given only saline (controls). The reduction in days open was 27 to 29 days overall for all cows (normal and abnormal) treated with either hormone compared with controls. Cows (normal and abnormal) given either hormone required 26 to 41 % fewer inseminations per conception than controls. Reasons for improved fertility are discussed. We conclude that early postpartum treatments with GnRH or PGF improved fertility of dairy cows, especially those that experienced puerperal problems.; Dairy Day, 1985, Kansas State University, Manhattan, KS, 1985;

A study of 234 Holste in cows was conducted to determine if hormonal treatments of gonadotropin-releasing hormone (GnRH or Cystorelin®) and(or) prostaglandin F a (PGF or Lutalyse®) given early after calving would improve subsequent fertdity of dairy cows. Treatment of cows having abnormal conditions associated with calving (puerperal problems) reduced inter val from calving to conception by 43 to 48 days when GnRH was given once between days 10 and 14 postpartum or when PGF was administered once between 20 and 24 days after calving compared with cows given only saline (controls). The reduction in days open was 27 to 29 days overall for all cows (normal and abnormal) treated with either hormone compared with controls. Cows (normal and abnormal) given either hormone required 26 to 41 % fewer inseminations per conception than controls. Reasons for improved fertility are discussed. We conclude that early postpartum .treatments with GnRH or PGF improved fertility of dair y cows, especially those • that experienced puerperal problems.

In troduct ion
Initiating early reestablishment of est;ous cycles after calving is essential for allowing adequate time for cows to be inseminated and maintain a yearly calving interval. Normally, intervals from parturition to first ovulation average about 3 wk. Because not all first ovulations are preceded by estrus, interval to first heat averages about 5 to 6 wk. Both intervals are delayed in cows with periparturient problems such as calving problems, uterine infections, ovarian cysts, injury, or metabolic diseases (ketosis, displaced abomasum, etc.). Gonadotropin-releasing hormone (GnRH or Cystorelin®) is effective for treating ovarian follicular cysts, enhancing uterine involution, and inducing ovulation of ovarian follicles early postpartum. Another hormone, prostaglandin F 20. (PGF), is luteolytic or capable of regressing the corpus luteum and br inging the cow into heat in 2 to 5 days after treatment. PGF has been used effectively to treat ovarian luteal cysts and cows with pyometra or endometritis (if there was a corpus luteum present on the ovary). The objective of our study was to determine if treatments of GnRH and(or) PGF could improve fertility by altering the frequency and occurrence of early postpartum estrus and ovulation. a Days after calving when one intramuscular dose was given.
Cows were examined at calving and between 25 and 40 days postpartum for various abnormalities. Observations at both times determined whether a cow was classified as having a normal or abnormal puerperium. Abnormal classification included any cow that had dystocia, retained placenta, uterine infections, milk fever, ketosis, or unusual enlargement of the uterine horns or cervix.
Blood was collected thrice weekly to monitor blood serum concentrations of progesterone. This allowed us to know when ovula t ions occurred and when a corpus luteum was present.
Intervals to estrus, inseminations, and conception were determined as well as average number of services per conception.

Results and Discussion
Reproductive traits were improved for cows treated with either GnRH or PGF (Table 2).
Cows given GnRH or PGF conceived ear lier after cal ving with fewer services, and tended to have higher conception rates at first service than control cows treated with saline alone. Responses after both hormones were intermediate for the most part,except for reducing services per conception.
An additional benefit of these treatments was the positive effects on cows with an abnormal puerperium. Nearly 30% of the cows had one or more postpartum abnormalities including dystocia, retained placenta, uterine infection, purulent discharge, milk fever, ketosis, or abnormal enlargement of the uterine horns or cervix. At least 77% of the abnormalities observed were of reproductive origin. In all cases, treatment of these cows with GnRH or PGF improved subsequent reproductive performance. Examining various other measurements revealed possible explanations for the improvements in fertility. Gn RH treatment reduced intervals to when cows first ovulated and came into estrus after calving, as well as increasing the proportion of cows with three or more ovula tions before first service from 54% for controls to 83%. Treatment with PGF reduced intervals to second and third ovulations and shortened the duration of the first estrous cycle. Both treatments increased the proportion of cows with estrous cycles of normal duration (18-24 days) before 6 wk postpartum. Therefore, improvement of fertility was associated with increased frequency and occurrence of ovula tion and estrus before first services and the re-establishment of estrous cycles of normal duration. Our work suggests that all cows, especially those with an abnormal pueriperium, had improved fertility when treatment early postpartum with GnRH or PGF.
At present we do not know if such treatments are repeatable in aU dairy herds or if they are economical. We are conduct ing further studies in other herds to verify our present findings. Based on our initial work, it would appear that such treatments (GnRH on days 10,11,12, 13,or 14 or PGF on days 20,21,22,23, or 24) are of economic value for cows that experience postpartum abnormalities because treatments result in improved reproductive performance.