Effects of season on donor and recipient cows and calf performance from birth to weaning in embryo transfer programs in the tropics

The aim of this study was to assess the seasonal effect of an embryo transfer program in the tropics on the donor response, recipient reproductive performance and calf growth from birth to weaning. This study included five-year records from 145 donors, 1149 embryo transfers (ET) and 609 in calves. The effect of the season (dry or wet) was evaluated at the time of embryo flushing, embryo transfer and birth of the calves. There was a seasonal effect on the yield and quality of the embryos. The number of nonfertilized and transferable good quality embryos increased in the wet season. For the recipients, the probability of pregnancy after an ET decreased by 6% for each year of the dam’s age. However, no seasonal effect was found when comparing ET calves with their control group (natural mating—NM), nevertheless, weaning weight was associated with birth body weight, treatment, sex of the calf, season at birth, year of treatment, and dam’s age. Calves born by NM had lower average daily gain (ADG), and male calves registered higher gains than females. Likewise, calves born during the rainy season had lower ADG compared with calves born during the dry season. In conclusion, this study shows that seasonal effect is more apparent in donor and calf performance than in the recipients.El objetivo de este estudio era evaluar el efecto estacional de un programa de transferencia de embriones en sobre la respuesta de los donantes, el rendimiento reproductivo de las receptoras y el crecimiento de los terneros desde el nacimiento hasta el destete. En este estudio se incluyeron los registros de cinco años de 145 donantes, 1149 transferencias de embriones (TE) y 609 en terneros. Se evaluó el efecto de la estación (seca o húmeda) en el momento de la la transferencia de embriones y el nacimiento de los terneros. Hubo un efecto estacional en el rendimiento y la calidad de los embriones. El número de embriones no fecundados y transferibles de buena calidad aumentó en la estación húmeda. Para las receptoras, la probabilidad de preñez tras una TE disminuyó un 6% por cada año de la edad de la madre. Sin embargo, el peso al destete se asoció con el peso corporal al nacer, el tratamiento, el sexo del ternero, la estación del año de nacimiento, el año de tratamiento y la edad de la madre. Los terneros nacidos por NM tuvieron una ganancia media diaria (GD) menor, y los terneros machos registraron ganancias mayores que las hembras. Asimismo, los terneros nacidos durante la estación lluviosa tuvieron un GAD menor en comparación con los nacidos durante la temporada seca. En conclusión, este estudio muestra que el efecto estacional es más evidente en el rendimiento de las donantes y de los terneros que en el de los receptores.Universidad Nacional, Costa RicaEscuela de Medicina Veterinari

Non-toxic freezing media to retain the stem cell reserves in adipose tissues

BACKGROUND: Vitamin A and its metabolite, retinoic acid (RA), are important regulators of cell differentiation and organ morphogenesis. Its impact on beef cattle muscle growth remains undefined. METHOD: Angus steer calves were administrated with 0 (control) or 150,000 IU vitamin A (retinyl palmitate in glycerol, i.m.) per calf at birth and 1 month of age. At 2 months of age, a biopsy of the muscle was obtained to analyze the immediate effects of vitamin A injection on myogenic capacity of muscle cells. The resulting steers were harvested at 14 months of age. RESULTS: Vitamin A administration increased cattle growth at 2 months. At 2 months of age, Vitamin A increased PAX7 positive satellite cells and the expression of myogenic marker genes including , , and . Muscle derived mononuclear cells were further isolated and induced myogenesis in vitro. More myotubes and a higher degree of myogenesis was observed in vitamin A groups. Consistently, vitamin A increased (LD) muscle fiber size at harvest. In addition, vitamin A increased the ratio of oxidative type I and type IIA fibers and reduced the glycolic type IIX fibers. Furthermore, we found that RA, a key bioactive metabolite of vitamin A, activated promoter, which explains the upregulated expression of in skeletal muscle. CONCLUSION: Vitamin A administration to neonatal calves enhanced postnatal muscle growth by promoting myogenesis and increasing satellite cell density, accompanied with a shift to oxidative muscle fibers

Vitamin A administration at birth promotes calf growth and intramuscular fat development in Angus beef cattle

Abstract Background Marbling, or intramuscular fat, is an important factor contributing to the palatability of beef. Vitamin A, through its active metabolite, retinoic acid, promotes the formation of new fat cells (adipogenesis). As intramuscular adipogenesis is active during the neonatal stage, we hypothesized that vitamin A administration during the neonatal stage would enhance intramuscular adipogenesis and marbling. Methods Angus steer calves (n = 30), in a completely randomized design, were randomly allotted to three treatment groups at birth, receiving 0, 150,000, or 300,000 IU of vitamin A at both birth and one month of age. A biopsy of the biceps femoris muscle was collected at two months of age. After weaning at 210 d of age, steers were fed a backgrounding diet in a feedlot until 308 d of age, when they were transitioned to a high concentrate finishing diet and implanted with trenbolone/estradiol/tylosin mixture. Steers were harvested at an average of 438 d of age. All diets were formulated to meet nutrient requirements. Results Weaning weight and weight during the backgrounding phase were linearly increased (P <  0.05) by vitamin A level, though no difference in body weight was observed at harvest. Intramuscular fat of steers at 308 d of age, measured by ultrasound, quadratically increased (P <  0.05) with vitamin A level from 4.0±0.26 % to 4.9±0.26 %. Similarly, carcass marbling score in the ribeye quadratically increased (P < 0.05). Conclusion Administration of vitamin A at birth increased weaning weight and enhanced marbling fat development. Thus, vitamin A administration provides a practical method for increasing marbling and early growth of beef cattle

Neonatal vitamin A injection promotes cattle muscle growth and increases oxidative muscle fibers

Abstract Background Vitamin A and its metabolite, retinoic acid (RA), are important regulators of cell differentiation and organ morphogenesis. Its impact on beef cattle muscle growth remains undefined. Method Angus steer calves were administrated with 0 (control) or 150,000 IU vitamin A (retinyl palmitate in glycerol, i.m.) per calf at birth and 1 month of age. At 2 months of age, a biopsy of the Biceps femoris muscle was obtained to analyze the immediate effects of vitamin A injection on myogenic capacity of muscle cells. The resulting steers were harvested at 14 months of age. Results Vitamin A administration increased cattle growth at 2 months. At 2 months of age, Vitamin A increased PAX7 positive satellite cells and the expression of myogenic marker genes including PAX7, MYF5, MYOD and MYOG. Muscle derived mononuclear cells were further isolated and induced myogenesis in vitro. More myotubes and a higher degree of myogenesis was observed in vitamin A groups. Consistently, vitamin A increased Latissimus dorsi (LD) muscle fiber size at harvest. In addition, vitamin A increased the ratio of oxidative type I and type IIA fibers and reduced the glycolic type IIX fibers. Furthermore, we found that RA, a key bioactive metabolite of vitamin A, activated PPARGC1A promoter, which explains the upregulated expression of PPARGC1A in skeletal muscle. Conclusion Vitamin A administration to neonatal calves enhanced postnatal muscle growth by promoting myogenesis and increasing satellite cell density, accompanied with a shift to oxidative muscle fibers