Abstract
To evaluate an artificial insemination program in postpartum Bos indicus cows and by using deterministic models, to estimate the possible economic advantages of insemination by appointment over detected estrus, sixty-three multiparous animals were synchronized using a progestagen device inserted at day 31 and withdrawn after 9 days (average time for withdrawal was 40.9 ± 6.8 days). Cows were observed continuously from 0700 to 1800 during 72 h. The percentage of animals detected positive to estrus by riding behavior was 43.4%, transrectal palpation, 22% and heat detector patches, 4.6%. The percentage of cows ovulating as evidenced by progesterone samples taken at 9 and 11 days after the average estrus response was 73%. The economical assessment by using the values obtained in the present study afforded that the cost of semen, ovulation rate and fertility point to a definitive advantage of using AI at fixed time over a program based on estrus detection.
Highlights
There have been several efforts to evaluate the economical impact of the use of AI, especially in Holstein cows raised under intensive systems where insemination following estrus detection (AIED) or at fixed time (AIFT) are common procedures [1] [2]
Rodgers et al [6] compared the efficacy inseminating at fixed time versus natural mating with the weight of the calves at weaning finding an economical advantage in the former method. This is important in postpartum beef cows in the tropics where the response can be misleading as the development of a corpus luteum (CL) following induced estrus, and has afforded doubts to whether this technique is viable at least under tropical conditions
The objective of the present study was to undertake a field trial to estimate the physiological values on estrus detection efficacy, the formation of a CL indicative of ovulation and the use of external aids to increase the number of animals detected in estrus, in order to assess the convenience of inseminating post partum Bos indicus cows at observed estrus and the data compared with the hypothetical use of AI at fixed time using a modeling procedure to assess the economical value of both procedures
Summary
There have been several efforts to evaluate the economical impact of the use of AI, especially in Holstein cows raised under intensive systems where insemination following estrus detection (AIED) or at fixed time (AIFT) are common procedures [1] [2]. Rodgers et al [6] compared the efficacy inseminating at fixed time versus natural mating with the weight of the calves at weaning finding an economical advantage in the former method. This is important in postpartum beef cows in the tropics where the response can be misleading as the development of a corpus luteum (CL) following induced estrus, and has afforded doubts to whether this technique is viable at least under tropical conditions. Alonso-Alanuza et al [9] in a field trial evaluating fixed AI at 48 and 72 h but observing cows continuously for overt signs of estrus found that eighty-six percent of the pregnancies occurred in cows displaying estrous behavior regardless of the time of fixed AI versus applying this technique by appointment
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