Abstract Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, and the mares would have increased uterine and cervix tone. Therefore, in the present study the effects of hCG administration to induce ovulation, on day 0 (day of ovulation) or day 5 postovulation were evaluated on corpus luteum characteristics, reproductive tract vascularization, and serum progesterone concentration from ovulation until day 15 postovulation. Groups were: G1: (control) - no hCG; G2: 2500 IU of hCG to induce ovulation when a follicle greater than 35mm and uterine edema were detected; G3: 2500 IU hCG on day 0; G4: 2500 IU hCG on day 5 postovulation. Twelve mares were randomly assigned to each group, during consecutive cycles, in a Latin Square experimental design, in a total of 48 cycles. Doppler ultrasound evaluations were performed daily from day 0 until day 15 postovulation, including mesometrial vascularity, endometrial vascularity and corpus luteum vascularity. Blood samples were collected for serum progesterone concentration. Data was analyzed using the Proc Glimmix SAS Procedure for nonparametric variables and Proc Mixed for parametric parameters. There was no treatment effect for all variables studied (P > 0.05). Characteristics were only affected by day (P < 0.05). It can be concluded that hCG administration at the time points suggested in the current study did not alter the characteristics evaluated.

Resumo A placenta é o órgão de ligação entre a égua e o potro e é um dos principais responsáveis pelo desenvolvimento fetal e pelas características morfométricas do neonato. Essa função se torna cada vez mais importante porque os estudos indicam que as características físicas dos potros predizem o seu desenvolvimento na vida adulta. Desta forma, o objetivo do presente estudo foi correlacionar número de partos (1-5) e características maternas de éguas com as características placentárias e o tamanho do potro. As éguas foram categorizadas em grupos de acordo com o número de partos sendo G1: 1 parto (n=4); G2: 2 partos (n=6); G3: 3 partos (n=7); G4: 4 partos (n=5); e G5: 5 partos (n=3). Como principais resultados obtidos, o perímetro torácico e o peso da égua pré- e pós-parto influenciaram positivamente peso (p=0,004/ R= 0,51; p=0,002/ R= 0,55; p=0,01/ R= 0,43), altura (p=0,0005/ R= 0,60; p=0,001/ R= 0,57; p=0,005/ R= 0,50) e perímetro torácico (p=0,0001/ R= 0,65; p≤0,0001/ R= 0,71; p=0,0002/ R= 0,64) dos potros ao nascimento. Éguas com maior peso corporal no pré-parto apresentaram maior peso placentário (p=0,01/R= 0,45) e pariram potros mais pesados (p=0,003/ R= 0,52) com maior perímetro torácico (p=0,01/ R= 0,45). Os neonatos de éguas do G4 foram os mais pesados, indicando que provavelmente o maior tamanho uterino em éguas pluríparas permita uma maior cobertura placentária, maior área de contato materno fetal e provavelmente maior aporte de nutrientes ao feto.

Abstract The placenta connects the mare and the foal and it is one of the main organs responsible for fetal development and newborn’s morphometric characteristics. This function becomes even more important because a number of studies indicates that foals physical characteristics are able to predict their development in adult life. Therefore, the aim of this study was to correlate mares parity (1-5) and maternal characteristics with placental characteristics as well as foals size. Mares were categorized according to parity in G1: 1 parturation (n=4); G2: 2 parturations (n=6); G3: 3 parturations (n=7); G4: 4 parturations (n=5); and G5: 5 parturations (n=3). Results indicate that the mares pre- and post-parturition thoracic perimeter and weight had a positive correlation on foals weight (p=0.004/ R= 0.51; p=0.002/ R= 0.55; p=0.01/ R= 0.43), height (p=0.0005/ R= 0.60; p=0.001/ R= 0.57; p=0.005/ R= 0,50), and thoracic perimeter (p=0.0001/ R= 0.65; p≤0.0001/ R= 0.71; p=0.0002/ R= 0.64) at birth. Mares that were heavier at pre-partum had greater placental weight (p=0.01/R= 0.45) and delivered heavier foals (p=0.003/ R= 0.52) with greater thoracic perimeter (p=0.01/ R= 0.45). Foals of mares in G4 were heavier, probably indicating that the greater uterine size in multiparous mares allows greater placental coverage, greater fetomaternal surface contact and probably greater supply of nutrient to the fetus.

A indústria tem disponibilizado no mercado uma série de substâncias (nutracêuticos) com a intenção de otimizar a utilização de nutrientes em algumas vias metabólicas, influenciando positivamente o desempenho reprodutivo dos animais. No entanto, a resposta ao uso de nutracêuticos varia de acordo com o animal. Como o organismo é altamente complexo e, a fim de alcançar perfeita atividade do eixo hipotálamo-hipófise-gonadal, uma interação ideal na base molecular é necessária, onde os nutracêuticos podem ter sua ação direta. O objetivo neste estudo foi revisar a função e resultados de pesquisas usando os principais nutracêuticos (β-caroteno, vitamina A, L-carnitina, ômegas 3, 6 e 9 e gama-orizanol) sobre as características reprodutivas de touros e garanhões.

The industry has made available in the market a series of substances (nutraceuticals) which intent would be to optimize the use of nutrients in some metabolic paths, influencing positively reproductive performance in animals. However, the response to the use of nutraceuticals varies according to the animal. As the organism is highly complex and in order to achieve a perfect activity of the hypothalamic-pituitary-gonadal axis, an ideal interaction in molecular basis is needed, where the nutraceuticals can have their direct action. The aim of this study was to review the function and research results using the main nutraceuticals (β carotene, vitamin A, L-carnitine, omegas 3, 6 and 9 and Gamma-oryzanol) on reproductive characteristics of bulls and stallions.