Treatment with an intravaginal progestagen and estradiol to prevent prolonged anestrus in crossbred zebu cows under tropical conditions

Abstract

To study the effectiveness of a treatment with an intravaginal progestagen in combination with estradiol-17beta (E-17beta) on estrus induction, prevention of prolonged anestrus and fertility in noncycling crossbred zebu cows, a trial was conducted in a farm in Zulia state, Venezuela. Fifty noncycling suckled crossbred cows (B. taurus x B. indicus) with 60 dpp were randomly allotted to one of the following treatments: MAP+E-17beta (n=22), intravaginal device (250 mg of MAP) during 7 days + 50 mg of MAP and 5 mg of E-17beta im (day 0) and 1.5 mg of E-17beta im (day 8) (Pregnaheat-E; VIATECA-Venezuela); CG (n=28), control group without hormonal treatment. The MAP+E-17beta group showed higher (P<0.05) estrus and synchronization rates (59.1 and 36.4 %) than CG (25.0 and 3.5 %). Cows receiving MAP had higher (P<0.05) overall pregnancy rate than CG (45.5 and 17.8 %, respectively). A decreased (P<0.05) anestrus rate was observed in MAP+E-17beta (31.8%) compared to CG (57.1%). Calving-conception interval was shorter (P<0.05) in MAP+E-17beta (132.5+/-16.8 days) than in CG (178.9+/-14.7 days). In conclusion, treatment with MAP+E-17beta at 60 days postpartum was effective to induce estrus, prevent prolonged anestrus, and reduce the calving-conception interval, improving reproductive performance in dual purpose crossbred Zebu cows.

Fertility in Gyr Cows (Bos indicus) with Fixed Time Artificial Insemination and Visual Estrus Detection Using a Classification Table

“…Higher pregnancy rates were found by using the same AI protocol, but without differences with the control treatment inseminated after VO of natural estrus [ 23 – 25 ]. On the other hand, [ 26 ] working with zebu synchronized animals and FTAI at 48 and 72 hours, they classified estrus intensity according to the number of mounts as high (≥20) and low (<20) without estrus by continuous VO; they detected 68.4% of cows in estrus; the overall pregnancy rate was only 25.4%; communicating these authors that 63.8% of the cows that did not show estrus, in fact ovulated, the functional biological phenomenon known as both silent estrus and ovulation occurred; on the other hand, 85.9% of cows with detected estrus ovulated, resulting in a 14% of cows showing the phenomenon known as an-ovulatory estrus which also has been reported for crossbred cows [ 27 ]; it is then possible to assume that the use of the QAM as the only single sign of sexual behavior is not efficient enough to detect cows in estrus in the warm tropics and supports what has recently been reported using rating tables considering other secondary signs as well [ 16 ], in accordance with the highest efficiency using a scale with seven signs, reported by [ 28 ]; and the possibility of more effectively predicting ovulation time by using a scale of points with the estrus signs [ 11 , 14 ].…”

“…Some authors [ 23 – 25 ] have reported a low estrus detection rate for control cows subjected to AI (extreme values: 22.9% to 31.8%), which may be attributable to the traditional estrus detection system based VO of the QAM as the only sign of estrus; the small number and wide separation between two observations in a twelve-hour period; and the lack of trained personnel to recognize, to record, and to rank other secondary and important signs of this natural or induced physiological state, including the detection, recording, and tracking of sexual social events of formation of the active sexual groups, published by [ 3 ] for the DP cattle, which was reported as novel sign of estrus in specialized dairy herds [ 29 ]. System practices for the identification of the cow in estrus for crossbred populations that would indicate an inefficient estrus detection, which is identified as the most important factor limiting fertility of cattle in the world [ 9 ].…”