Edward P. Call

Failure of timed inseminations and associated luteal function in dairy cattle after two injections of prostaglandin F2-alpha

Abstract Lactating Holstein cows (n = 235) were used to study changes in luteal function after two injections of prostaglandin F 2 -alpha (PGF 2 -alpha) were administered to induce estrus for timing the first postpartum inseminations. Cows were assigned randomly at parturition to two experimental groups and one control group. Control cows (n = 59) were inseminated at a spontaneous estrus beginning 40 d postpartum. The remaining cows were given two injections of PGF 2 -alpha 11 d apart, beginning 40 to 46 d postpartum. After the second injection (0 h), cows were 1) inseminated once at 80 h (n = 119) or 2) inseminated twice at 72 and 96 h (n = 57). Progesterone was measured in blood serum collected from all cows at 0 and 48 h after each injection of PGF 2 -alpha and from 48 cows throughout the anticipated luteal phase following the second injection. Conception rates of cows inseminated at 80 h (23%) and at 72 and 96 h (30%) after PGF 2 -alpha were lower (P 2 -alpha cows were detected in estrus, conception rate of twice-inseminated cows (55%) was similar to that of controls, whereas the rate of once-inseminated cows (38%) tended to be lower (P = 0.09). Lower conception rates after timed inseminations resulted from failure of PGF 2 -alpha to induce luteolysis (13% of cows) and the presence of low ( 2 -alpha. These results suggest that timed inseminations lowered conception rates after PGF 2 -alpha because of poor timing of insemination relative to estrual events, less than expected induced luteolysis, and to lack of anticipated luteal function at the time of the second injection of PGF 2 -alpha. The latter appeared to be the result of both prolonged postpartum anestrus and ovulatory failure following a previous injection of PGF 2 -alpha.

Conception rates in repeat-breeders and dairy cattle with unobserved estrus after prostaglandin F2 alpha and gonadotropin-releasing hormone

In Experiment 1, cows with a history of at least two previous unsuccessful inseminations were allocated to four groups. At the repeated estrus (third or greater service), some of the cows were inseminated according to the a.m.-p.m. rule (Controls, n = 83), or received i.m. 100 mug gonadotropin-releasing hormone (GnRH, n = 32) within 30 sec after insemination. Ovaries of the remaining cows to be treated were palpated during the anticipated ensuing luteal phase to determine the presence of a corpus luteum. Cows found to have luteal tissue received i.m. 25 mg prostaglandin F(2)-alpha (PGF(2)-alpha) and were inseminated after detected estrus or at 72 and 96 h after PGF(2)-alpha in the absence of estrus. Cows given PGF(2)-alpha either received no further treatment (PGF(2)-alpha, n = 40) or were given i.m. 100 mug GnRH (PGF(2)-alpha + GnRH, n = 29) after insemination or at 72 h after PGF(2)-alpha in the absence of estrus. Conception rate of control cows (39%) was similar to that of cows given PGF(2)-alpha (40%) or PGF(2)-alpha + GnRH (43%), but it tended to be lower (P = 0.13) than that of cows given only GnRH at insemination (54%). In Experiment 2, cows with unobserved estrus and diagnosed not pregnant (palpation) were palpated to detect a corpus luteum. Cows with luteal tissue received i.m. PGF(2)-alpha (n = 52) or PGF(2)-alpha + GnRH (n = 45) and were inseminated as described above. Conception rates were similar (39% vs 33%, respectively). In Experiment 3, cows in a large commercial dairy with (n = 93) or without (n = 420) previous reproductive problems were given i.m. 100 mug GnRH after insemination (n = 169) or were left untreated (n = 344) at repeat services (third and fourth services). Treatment with GnRH improved (P < 0.05) conception in normal (47% vs 36%) and abnormal (25% vs 12%) repeat-breeding cows. Treatment with PGF(2)-alpha alone or in conjunction with GnRH failed to further improve conception rates and only delayed intervals to rebreeding when administered during the luteal phase after the repeated estrus. The use of GnRH failed to reduce intervals from treatment to insemination or improve conception in cows with unobserved estrus compared to treatment with PGF(2)-alpha alone.

Involution of the uterus of dairy cattle

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Effect of yearly milk per cow on various reproduction traits

An analysis of 4,334 Holstein dairies confirms the negative genetic correlation that exists between milk production and reproduction. The most obvious traits affected are services per conception and conception rate. When subjected to analysis by the KSU Dairy Herd Analyzer (DHA) program, higher-producing herds have less economic loss because their managers do a better job of controlling factors not under genetic control, such as average days dry and age at calving of first-calf heifers (L-1). Higher-producing herds also have fewer cows that are open and should be bred.

Effect of yearly milk per cow on profitability of dairy herds

An analysis of Kansas Holstein herds in 1992 indicated that the yearly milk production per cow had a significant effect on returns to labor and management. The lowest quartile herds (13,445 lb per cow average) had a negative return to management. Herds averaging 20,614 lb per cow yielded

Effect of yearly milk production on average days open

479 return to management. Records become increasingly important in managing the dairy operation, especially those that are readily analyzed and predict the degree of economic change when management is modified.

Administration of GnRH at insemination in repeat breeding dairy cows: improved pregnancy rates, hormone secretion, and luteal function

Although there is a genetic antagonism between yearly production per cow and reproduction, analysis of Kansas Holstein herds suggests that managers of higher producing herds overcome this inverse relationship. Higher producing herds have fewer cows open at any given time, and those cows that are open average fewer days since last freshening. When open cows are categorized by days open, higher producing herds have fewer cows open more than 60 days, and especially fewer cows open more than 120 days.

Reproductive status of Kansas dairy herds

Administering saline to 14 repeat breeders or 100 μg GnRH to 38 repeat breeders resulted in a greater (P=.07) proportion of pregnancies at 42 to 56 days after third service and fewer (P<.05) lost pregnancies during the 25to 38-day period of placentation. Concentrations of LH in serum of six repeat breeders previously given 100 μg GnRH 12 hr after detected estrus (day 0) were reduced (P<.05) on days 1, 3, and 8 after estrus compared to those in six cows previously given saline at estrus. Concentrations of FSH were similar among treatment groups on days 1 and 3, but were elevated (P<.05) on day 8 in GnRHtreated cows. Furthermore, all six GnRH-treated cows had detectable FSH pulses on day 8 compared to two of six control cows. Concentrations of progesterone in serum were elevated (P<.05) on days 8 to 10 after estrus in GnRH-treated cows, and their corpora lutea obtained on day 10 after estrus and treatment contained a greater (P<.05) proportion (31 vs. 14%) of large-diameter (21 to 37 μm) luteal cells and a lesser (P<.05) proportion (69 vs. 86%) of small-diameter (10 to 17 μm) luteal cells than corpora lutea from control cows. In vitro production of progesterone in response to LH was reduced (P<.05) in luteal tissue obtained on day 10 after estrus from cows previously treated with GnRH at estrus compared to cows given only saline. It appears that pregnancy rates are improved in repeat breeders given GnRH at the time of insemination as a result of increased secretion of progesterone related to alterations in the morphology and function of the corpus luteum, as well as possible influences of FSH secretion from the pituitary gland.

Double inseminations and treatment of repeat breeders with gonadotropin-releasing hormone

There has been no appreciable change in the reproduction status of Kansas dairy herds over the last 25 yr. For example, the average calving interval was 398 days in 1965 and 405 days in 1988. Analysis of other measures show similar results. Although the long-stated management goal for a dairy herd has been a calf-a-year or 365-day calving interval, few herds realize this efficiency. On the positive side, the stability of reproductive performance is noteworthy, since genetic antagonism exists between production and reproduction. From 1965 to 1988, average yearly milk production in production-tested herds (DHI) has increased 41%.; Dairy Day, 1989, Kansas State University, Manhattan, KS, 1989; The 1989 Annual KSU Dairy Day is known as Dairy Day, 1989

Effects of production on reproductive traits in Kansas Holstein herds

This report is brought to you for free and open access by New Prairie Press. It has been accepted for inclusion in Kansas Agricultural Experiment Station Research Reports by an authorized administrator of New Prairie Press. Copyright 1988 Kansas State University Agricultural Experiment Station and Cooperative Extension Service.