Abstract
The aim of this study was to use estrus synchronization protocols to favor fixed-time artificial insemination and consequently fixed-time embryo collection, and increase embryo production using eCG, in gits. In a cross over design, nine Piau breed gilts were subjected to 18 days of oral progesterone; P4 group did not receive any further; GnRH group received 25µg of GnRH 104 hours after the final application of P4; and eCG+GnRH group received 1000IU of eCG 24 hours after the final P4 in addition to GnRH for subsequent embryo collection, that was performed six days after first AI, by laparotomy. Artificial insemination was performed after 12 and 24 hours of estrus in P4 group, and 128 and 144 hours in GnRH and eCG+GnRH groups. The number of CL (8.6±3.9; 8.3±2.1; 26.7±15.0) and anovulatory follicles (4.3±3.7; 3.9±3.9; 17.2±9.5) was higher in the eCG+GnRH gilts (P<0.05). However, the use of 1000 IU of eCG reduced (P<0.05) the number of total structures (5.2±3.6; 5.1±3.1; 1.7±2.7), viable embryos (5.0±3.5; 4.8±3.3; 0.4±0.7), freezable embryos (3.6±3.4; 3.3±3.8; 0.1±0.3) and recovery rate (63.7±38.9; 58.6±24.7; 5.38±9.5). P4 and GnRH protocols were effective in the production and recovery of embryos. However, the use of 1000 IU of eCG, 24 hours after P4, was not effective in promoting the production of embryos, although the animals had superovulated.
Highlights
At the beginning of the 21st century, there is a change in the demand of the consumer market, mainly for the production of human or animal food, where there is an increase in the demand for food produced with little interference in the natural growth and termination process, making it possible to maintain the animal welfare, reducing breeding stress and indiscriminate use of medicines
The semen was collected on the day of the first insemination of each gilt using the penile massage technique, and diluted in Beltsville Thawing Solution (BTS), so that each insemination dose contained 100 mL and a 3 billion spermatozoa concentration with at least 70% of total motility and 70% of spermatozoa with normal morphology
As the estrus synchronization protocols were effective in inducing estrus, it was possible to perform artificial insemination at a fixed time, the embryo collections occurred at predetermined times and there was recovery of viable embryos
Summary
At the beginning of the 21st century, there is a change in the demand of the consumer market, mainly for the production of human or animal food, where there is an increase in the demand for food produced with little interference in the natural growth and termination process, making it possible to maintain the animal welfare, reducing breeding stress and indiscriminate use of medicines. There is an opportunity for the genetic material of locally adapted breeds to be used in production to obtain more rustic animals and adaptable to the outdoor production system.
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