Inseminación artificial a tiempo fijo en vacas con proestro prolongado de 60 y 72 horas

Abstract

Fixed- time artificial insemination (IATF, in Spanish) in beef cattle has provided the use of genetically superior bulls in order to maximize the quality of calves. However, implementing this reproductive technique has proved to be difficult to apply in heifers nursing calves for several months of lactancy. An immediate solution to fertility decline of cattle includes the use of hormones. Some hormonal treatments have been developed which are able to control the moment of the first artificial insemination (IA) and the following inseminations in non- pregnant heifers as well as for the treatment of anestrus. The objective of this work was to evaluate two protocols with prolonged proestrus performing artificial insemination at fixed time at 60 or 72 hours in dual purpose cattle from the Ecuadorian Amazon. The study was held from October 2015 to October 2016. A total of 226 multiparious Brows Swiss cattle with nursing calves were inseminated at 60 (T1, n=115) and at 72 (T2, n=111) hours after removing the progesterone device., The conception rate for T1 was 61% (70/115) and for T2: 47% of pregnancy (52/111), showing significant differences (p≤0.05). The estrus was expressed on average by 70.8%, with no significant difference between the protocols (P = 3.15, p≥0.082), for T1 it was 76% (87/115) and for T2 of 65%. The follicular growth at the withdrawal of the progesterone device (T1: 9.53 ± 0.11 mm, T2: 9.87 ± 0.12 mm), the IATF (T1: 12.3 ± 0.12 mm; T2: 11.9 ± 0.12 mm), and the corpus luteum size (T1: 23.1 0.14±mm; T2:22.8 0.15 ±mm) did not show significant differences p≥0.5 between both protocols. It was concluded that both protocols did not show significant differences regarding follicular development at the time of withdrawal of the IATF device and the size of the corpus luteum size measured at day seven after withdrawal. However, the pregnancy rate was higher for the 60-hour protocol.

Protocolo J-synch con y sin eCG en vacas Brown Swiss y sus cruzas con Bos Indicus en la amazonía ecuatoriana

“…Los resultados de preñez obtenidos en este trabajo con J-Synch con y sin eCG, sobre 448 vacas Brown Swiss y sus cruzas inseminadas, 230 vacas se preñaron representando el 51.3 %, coincidiendo con los resultados reportados por Baruselli y col. 2005y López (2001) en el trópico, también coinciden con encontrados por López y col. (2014) y Quinteros (2009) realizados en la Amazonía Ecuatoriana. Además, concuerdan los porcentajes de preñez con los obtenidos por otros investigadores utilizando similares protocolos de proestros prolongados J-Synch en la Amazonía, cuando se administró eCG y se inseminó a las 60 horas de retirado el dispositivo con el 61 % (70/115) de preñez en comparación al inseminado a las 72 horas adicionando eCG, mostrando un 47 % (52/111) de preñez (López, 2017;Yánez-Avalos y col., 2018).…”