AVALIAÇÃO DE BIOTÉCNICAS DA REPRODUÇÃO SOB O FOCO AMBIENTAL

O aumento da produção de alimentos sem comprometer o meio ambiente é uma preocupação mundial. Pesquisadores da cadeia produtiva da carne bovina vêm buscando tecnologias na tentativa de sanar esta preocupação, desenvolvendo pesquisas relacionadas ao manejo, sanidade, alimentação e reprodução. As biotecnologias da reprodução são ferramentas capazes de contribuir positivamente com este cenário. Este trabalho teve como objetivo analisar o efeito das duas principais biotecnologias da reprodução animal, a IATF e TETF sobre a taxa de gestação, taxa de concepção e sexagem fetal em bovinos e comprovar se, o emprego destas biotécnicas pode favorecer a sustentabilidade desta cadeia produtiva.  Foram utilizadas vacas da raça Nelore, distribuídas, aleatoriamente, em dois tratamentos: IATF-Inseminação Artificial em Tempo Fixo e TETF-Transferência de Embriões em Tempo Fixo. O delineamento experimental foi inteiramente casualizado e as variáveis foram analisadas pelo procedimento PROC, utilizando-se distribuição binomial e função de ligação identidade. Os resultados mostraram que, apesar das menores taxas de concepção e de gestação alcançadas com o emprego da TETF, esta técnica apresenta mérito sob o ponto de vista da sustentabilidade ambiental, visto que, permite a produção de descendentes de melhor qualidade genética e apresenta maiores resultados de gestação de sexados de machos, que, sabidamente, levam a uma maior produção de carne por hectare

Discharge of embryos from in vitro bovine production: a sustainable vision of the process

Brazil is the world's largest producer of in vitro embryos, so breeders in the country have strong interest in increasing the sustainability of the production process of this biotechnology. In vitro embryo production (IVP) leads to large waste of good quality embryos, so studies that aim to detect real losses of IVP embryos are important due to the need to develop more sustainable reproductive processes. The objective of this work was to ascertain the disposal rate of viable embryos from the bovine IVP database and present proposals to reduce production losses. The survey was carried out in a laboratory database that contains information about 2,399 aspirations performed between 2013 and 2016. The in vitro embryo production was carried out in the laboratory using processes such as maturation, fertilization and in vitro culture. On the seventh day of culture, the embryos were evaluated for viability for transfer, with some used and others discarded. Data were analyzed using descriptive statistics and showed the following rates of viable embryos and viable embryos wasted, respectively: in 2013 - 29% (2312/7905) and 7% (167/2312); in 2014 - 34.4% (1824/5308) and 11% (195/1824); in 2015 - 37.1% (3100/8355) and 21% (559/3100); and in 2016 - 30.1% (2165/7192) and 32% (530/2165). In four years of studies the total embryo production was 32% (9401/28760), with 15% (1451/9401) waste. This waste occurred because the average production of embryos exceeded the number of available synchronized receivers. Analyzed economically, this practice of discarding viable in vitro embryos generates a lower profit. From an environmental standpoint, this discarding wastes materials and consumes unnecessary energy. Thus, the best solution would be freezing these embryos. However, so far the most limiting factors are the vulnerability to cryopreservation, which exists possibly due to the accumulation of lipids in the cytoplasm. To summarize, the total loss of in vitro embryos was 15%. We propose a plan to count the number of synchronized recipients, taking into account breed, population and donor's history of aspiration (short term resolution). In the long term, a solution would be to establish an efficient embryonic cryopreservation technique

Effect of progesterone supplementation on pregnancy rate and resynchronization of nelore breed recipients: preliminary data

Animal reproduction uses biotechniques to promote sustainable farming. One of these techniques, called in vitro production (IVP) is known to increase herd productivity by allowing production of more animals in smaller areas. Despite many efforts to improve pregnancy rates, birth efficiency of IVP embryos is usually 10% less compared to other techniques, due two main issues: quality of embryos and efficiency of the synchronization protocols of the recipients. In light of this problem, studies of hormonal protocols that aim to increase circulating levels of progesterone (P4) in embryo recipients can lead to both a reduction in embryo losses and faster preparation of non-pregnant recipients for new transfers. This can be achieved due to the inhibitory action of progesterone in luteinizing hormone (LH) peaks and negative feedback in the hypothalamic pituitary gonadal axis. The objective of this study was to evaluate a hormonal protocol with reusable P4 implants in IVP embryo recipient cows regarding gestation rate and resynchronization rate of non-pregnant recipients. A first experiment was carried out in a farm situated in northwestern Paraná from May to August 2017. Fifteen Wagyu breeders and 70 Nellore breeders were used and recipients were divided into two treatments of 35 animals each. In the control group (GC1), 2.0 mg of IM plus an intravaginal device (CIDR®; Zoetis, São Paulo, SP) were applied on first use (D0) and then on the seventh day PGF2a (Lutalyse®; Zoetis, São Paulo, SP) was applied. The implant removal occurred nine days after insertion along with 0.5 mL of ECP (ECP®; Zoetis, São Paulo, SP) and 1.5 mL of ECG (Novormon®, Zoetis, São Paulo, SP). The treated animals (GT1) received the same protocol, but on transfer of the embryo they received a CIDR implant in the 2nd or 3rd use as well, which was withdrawn on D31. The transfer of the embryo into the recipient cow occurred in D19 in both groups. On the 23rd day after embryo transfer, gestation diagnoses were performed. Experiment 2 occurred on the same farm along with another transfer of an IVP embryo in non-pregnant recipients with corpus luteum from experiment 1, resulting in in two groups: GC2 (from GC1) and GT2 (from GT1). Diagnosis of gestation was performed using GC2 and GT2 on the 23rd after embryo transfer. In experiment 1, the gestation rate was 44% (15/34) in GC1 and 25% (9/36) in GT1. Of the 46 non-pregnant animals from experiment 1, 24 presented negative diagnoses and the presence of luteal bodies, so they received a new embryo (starting the second experiment). Experiment 2 showed positive gestation diagnosis of 18% (2/11) for GC2 and 45% (6/13) for GT2. Preliminary results from experiment 1 suggest that P4 implantation in PIV embryo recipients does not influence the pregnancy rate. However, the results of experiment 2 suggest that the P4 implant is efficient for resynchronization of recipients, increasing the pregnancy rates of the negative cows in the first examination