A comparison between two distinct levels of back fat thickness in open cows, females not becoming pregnant during the previous breeding season, was carried out in order to evaluate their reproductive performance prior...A comparison between two distinct levels of back fat thickness in open cows, females not becoming pregnant during the previous breeding season, was carried out in order to evaluate their reproductive performance prior to the next natural mating in a seasonal breeding program. Thirty open cows from the previous breeding season were divided evenly by age and back fat thickness (BFT) in two groups. HBFT (high back fat thickness ≥ 70 mm) and LBFT (low back fat thickness ≤ 70 mm), values statistically different between groups (P < 0.05). The study was divided into three phases in which the formation of CL and follicular dynamics were recorded by ultrasound and progesterone. Also, serial monitoring of glucose, urea and triglycerides and back fat thickness were studied. A fertile bull previously approved from a breeding soundness evaluation was introduced after the third phase and remained with the herd for 90 days. No differences were found in the follicular dynamics;the number of animals cycling in the two groups and fertility were also similar (80%). Differences in urea and triglycerides were found in cows with high scores of BFT. In conclusion, the decision of keeping open cows to the next breeding season must be based on an economical advantage to the farmer.展开更多
Early pregnancy diagnosis is a very important routine management to identify non-pregnant cows in order to keep an optimum reproductive efficiency both for dairy and beef cows. Ultrasound equipment allows estimating t...Early pregnancy diagnosis is a very important routine management to identify non-pregnant cows in order to keep an optimum reproductive efficiency both for dairy and beef cows. Ultrasound equipment allows estimating the viability and size of the embryo during early gestation. With the aim of assessing age and viability of Bos indicus embryos between 24 and 35 days of gestation, 55 cows were divided into 4 clusters. These clusters were conformed according to the first day that an echogenic structure was seen inside the embryonic vesicle (Group 1: day 24, Group 2: day 26, Group 3: day 27 and Group 4: day 28). The age of the embryos was estimated from the date of AI. Three progressive serial measurements of their length were made within 2 to 5 days. With a model GEE (Generalized Estimating Equations), the effect of days was evaluated to compare the second measurement with the first one and the former with the third observation. No differences in the size of the embryos were observed between the first evaluation (24 days) and the second (28 days) (P = 0.387). Also, simple linear regression analysis found a positive linear association between the size of the embryo and gestation days (R2 = 0.593) with an average growth of 0.078 cm per day (P = 0.001). In conclusion, the variation between measurements at a given time does not allow estimating with precision the exact day of gestation. Nonetheless, serial measurements are useful to estimate the healthy growth of the embryo from day 26 of gestation.展开更多
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-...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.展开更多
文摘A comparison between two distinct levels of back fat thickness in open cows, females not becoming pregnant during the previous breeding season, was carried out in order to evaluate their reproductive performance prior to the next natural mating in a seasonal breeding program. Thirty open cows from the previous breeding season were divided evenly by age and back fat thickness (BFT) in two groups. HBFT (high back fat thickness ≥ 70 mm) and LBFT (low back fat thickness ≤ 70 mm), values statistically different between groups (P < 0.05). The study was divided into three phases in which the formation of CL and follicular dynamics were recorded by ultrasound and progesterone. Also, serial monitoring of glucose, urea and triglycerides and back fat thickness were studied. A fertile bull previously approved from a breeding soundness evaluation was introduced after the third phase and remained with the herd for 90 days. No differences were found in the follicular dynamics;the number of animals cycling in the two groups and fertility were also similar (80%). Differences in urea and triglycerides were found in cows with high scores of BFT. In conclusion, the decision of keeping open cows to the next breeding season must be based on an economical advantage to the farmer.
文摘Early pregnancy diagnosis is a very important routine management to identify non-pregnant cows in order to keep an optimum reproductive efficiency both for dairy and beef cows. Ultrasound equipment allows estimating the viability and size of the embryo during early gestation. With the aim of assessing age and viability of Bos indicus embryos between 24 and 35 days of gestation, 55 cows were divided into 4 clusters. These clusters were conformed according to the first day that an echogenic structure was seen inside the embryonic vesicle (Group 1: day 24, Group 2: day 26, Group 3: day 27 and Group 4: day 28). The age of the embryos was estimated from the date of AI. Three progressive serial measurements of their length were made within 2 to 5 days. With a model GEE (Generalized Estimating Equations), the effect of days was evaluated to compare the second measurement with the first one and the former with the third observation. No differences in the size of the embryos were observed between the first evaluation (24 days) and the second (28 days) (P = 0.387). Also, simple linear regression analysis found a positive linear association between the size of the embryo and gestation days (R2 = 0.593) with an average growth of 0.078 cm per day (P = 0.001). In conclusion, the variation between measurements at a given time does not allow estimating with precision the exact day of gestation. Nonetheless, serial measurements are useful to estimate the healthy growth of the embryo from day 26 of gestation.
文摘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.
