The aim of the present study was to evaluate the impact of the technological level in small-scale dual-purpose cow-calf <em>Bos indicus</em> female operations on the resumption of the ovarian activity post...The aim of the present study was to evaluate the impact of the technological level in small-scale dual-purpose cow-calf <em>Bos indicus</em> female operations on the resumption of the ovarian activity post-partum. A total of 13 small scale dual-purpose <em>Bos indicus</em> × <em>Bos taurus</em> operations were included in this experiment and they were classified according to their technological status as: high technological status (HT), medium technological status (MT) and low technological status (LT). Ninety-three mature cows were treated with either a CIDR (controlled internal drug release device) with estradiol benzoate (CIDR+EB) or alone (CIDR). At day 9 all animals received intravaginally a CIDR for nine days. At day 0, the CIDR was withdrawn and 24 hours later one dose of estradiol benzoate was administered to 51 cows (17 in HT, 17 in MT and 17 in LT), the remaining animals (n = 42) did not receive the estradiol benzoate administration (14 in HT, 13 in MT and 15 in LT). Comparisons were performed on serum progesterone concentrations after CIDR treatment. By day 7 after implant withdrawal, the proportion of cows that resume ovarian activity detected by progesterone concentration increased in all technological level farms, no statistical main effect was observed within technological level. By day 17 there was a significant main effect of technological level (P = 0.05) on the proportion of animal that resumed the estrous cycles, but neither a main effect of treatment (P = 0.97) nor an interaction between technological level and treatment (P = 0.98). Furthermore, technological level of the farm showed a tendency (P = 0.07) to affect that resume the estrous activity, and a significant effect of treatment was observed (P = 0.005) but no interaction between technological level and treatment. The proportion of cows that showed estrus was different across technological level (P = 0.02), the highest proportion of cows showing estrus regardless of treatment was in the HT: 90% (40% CIDR and 50% CIDR+EB), MT: 50% (13.3% CIDR and 36.7% CIDR+EB) and in the LT: 50% (18.8% CIDR and 31.3% CIDR+EB). In conclusion, the combination of a progestogen and estradiol benzoate resulted in a high proportion of cows that were induced to resume the ovarian activity and this treatment was particularly beneficial in the medium and low technological status of the farms.展开更多
The development of replacement heifers is at the core of cow-calf beef production systems. In 2020, the USDA,National Agricultural Statistics Service reported 5.771 million beef heifers, 500 pounds and over, are under...The development of replacement heifers is at the core of cow-calf beef production systems. In 2020, the USDA,National Agricultural Statistics Service reported 5.771 million beef heifers, 500 pounds and over, are under development for cow replacement. A compilation of data from several studies indicate that between 85% and 95% of these heifers will become pregnant in their first breeding season. Several thousands of heifers being raised for replacement may not deliver a calf on their first breeding season and result in economic losses to cow-calf producers. Many management procedures have been developed to maximize the reproductive potential of beef heifers. Such approaches include, but are not limited to the following: nutritional management for controlled weight gain, identification of reproductive maturity by physiological and morphological indicators, and the implementation of an estrous synchronization program.The implementation of management strategies has important positive impact(s) on the reproductive efficiency of heifers.There are limitations, however, because some heifers deemed ready to enter their first breeding season do not become pregnant. In parallel, genetic selection for fertility-related traits in beef heifers have not promoted major genetic gains on this particular area, most likely due to low heritability of female fertility traits in cattle. Technologies such as antral follicle counting, DNA genotyping and RNA profiling are being investigated as a means to aid in the identification of heifers of low fertility potential. To date, many polymorphisms have been associated with heifer fertility, but no DNA markers have been identified across herds. Antral follicle count is an indication of the ovarian reserve and is an indicator of the reproductive health of a heifer. We have been working on the identification of transcriptome profiles in heifers associated with pregnancy outcome. Our current investigations integrating protein-coding transcript abundance and artificial intelligence have identified the potential for bloodborne transcript abundance to be used as indicators of fertility potential in beef heifers. In summary, there is an ongoing pressure for reducing costs and increasing efficiency in cow-calf production systems, and new technologies can help reduce the long-standing limitations in beef heifer fertility.展开更多
文摘The aim of the present study was to evaluate the impact of the technological level in small-scale dual-purpose cow-calf <em>Bos indicus</em> female operations on the resumption of the ovarian activity post-partum. A total of 13 small scale dual-purpose <em>Bos indicus</em> × <em>Bos taurus</em> operations were included in this experiment and they were classified according to their technological status as: high technological status (HT), medium technological status (MT) and low technological status (LT). Ninety-three mature cows were treated with either a CIDR (controlled internal drug release device) with estradiol benzoate (CIDR+EB) or alone (CIDR). At day 9 all animals received intravaginally a CIDR for nine days. At day 0, the CIDR was withdrawn and 24 hours later one dose of estradiol benzoate was administered to 51 cows (17 in HT, 17 in MT and 17 in LT), the remaining animals (n = 42) did not receive the estradiol benzoate administration (14 in HT, 13 in MT and 15 in LT). Comparisons were performed on serum progesterone concentrations after CIDR treatment. By day 7 after implant withdrawal, the proportion of cows that resume ovarian activity detected by progesterone concentration increased in all technological level farms, no statistical main effect was observed within technological level. By day 17 there was a significant main effect of technological level (P = 0.05) on the proportion of animal that resumed the estrous cycles, but neither a main effect of treatment (P = 0.97) nor an interaction between technological level and treatment (P = 0.98). Furthermore, technological level of the farm showed a tendency (P = 0.07) to affect that resume the estrous activity, and a significant effect of treatment was observed (P = 0.005) but no interaction between technological level and treatment. The proportion of cows that showed estrus was different across technological level (P = 0.02), the highest proportion of cows showing estrus regardless of treatment was in the HT: 90% (40% CIDR and 50% CIDR+EB), MT: 50% (13.3% CIDR and 36.7% CIDR+EB) and in the LT: 50% (18.8% CIDR and 31.3% CIDR+EB). In conclusion, the combination of a progestogen and estradiol benzoate resulted in a high proportion of cows that were induced to resume the ovarian activity and this treatment was particularly beneficial in the medium and low technological status of the farms.
基金The Virginia Tech Open Access Subvention Fund contributed to the fee for article-processing charges。
文摘The development of replacement heifers is at the core of cow-calf beef production systems. In 2020, the USDA,National Agricultural Statistics Service reported 5.771 million beef heifers, 500 pounds and over, are under development for cow replacement. A compilation of data from several studies indicate that between 85% and 95% of these heifers will become pregnant in their first breeding season. Several thousands of heifers being raised for replacement may not deliver a calf on their first breeding season and result in economic losses to cow-calf producers. Many management procedures have been developed to maximize the reproductive potential of beef heifers. Such approaches include, but are not limited to the following: nutritional management for controlled weight gain, identification of reproductive maturity by physiological and morphological indicators, and the implementation of an estrous synchronization program.The implementation of management strategies has important positive impact(s) on the reproductive efficiency of heifers.There are limitations, however, because some heifers deemed ready to enter their first breeding season do not become pregnant. In parallel, genetic selection for fertility-related traits in beef heifers have not promoted major genetic gains on this particular area, most likely due to low heritability of female fertility traits in cattle. Technologies such as antral follicle counting, DNA genotyping and RNA profiling are being investigated as a means to aid in the identification of heifers of low fertility potential. To date, many polymorphisms have been associated with heifer fertility, but no DNA markers have been identified across herds. Antral follicle count is an indication of the ovarian reserve and is an indicator of the reproductive health of a heifer. We have been working on the identification of transcriptome profiles in heifers associated with pregnancy outcome. Our current investigations integrating protein-coding transcript abundance and artificial intelligence have identified the potential for bloodborne transcript abundance to be used as indicators of fertility potential in beef heifers. In summary, there is an ongoing pressure for reducing costs and increasing efficiency in cow-calf production systems, and new technologies can help reduce the long-standing limitations in beef heifer fertility.
