Browsing by Author "Carrasco, Albert"

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    Administration of Beta-Nerve Growth Factor during the Preovulatory Stage Improves Endocrine and Luteal Function in Dairy Heifers
    (MDPI, 2023) Gajardo, Gonzalo; Paiva, Luis; Ulloa-Leal, Cesar; Valderrama, Ximena; Lopez, Gerardo; Carrasco, Albert; Hidalgo, Alejandra Isabel; Silva, Mauricio E.; Palma, Patricio I.; Ratto, Marcelo H.
    Simple Summary Certain proteins present in semen regulate the reproductive physiology of females. Beta-nerve growth factor (NGF), which is abundantly expressed in the semen of camelids, has a potent ovulatory and luteotrophic effect in llamas after systemic injection. Here, we investigated the effects of intramuscular NGF during the preovulatory stage on endocrine parameters and pregnancy rates after artificial insemination in dairy heifers. Heifers injected with NGF showed enhancement of hormones related to ovulation and gestation maintenance. We also detected the enhancement of genes related to uterine receptivity and higher pregnancy rates. We conclude that the improvement in reproductive hormones related to gestation is possibly linked to the higher pregnancy rate detected here. More research is needed to ensure the NGF effects remain on commercial exploitation farms. The neurotrophin beta-nerve growth factor (NGF), which is present in the semen of different mammals, elicits potent ovulatory and luteotrophic actions in llamas following systemic administration. Here, we determine if purified NGF given intramuscularly (IM) during the preovulatory stage affects the corpus luteum (CL), hormone production, endometrial gene expression, and pregnancy rate of dairy heifers. Holstein-Friesian heifers were estrus-synchronized using estradiol benzoate (EB) plus an intravaginal progesterone (P4) device (DIB). After eight days, the device was removed and cloprostenol was given IM; the next day (day 9), heifers received EB IM plus one of the following: (i) 1 mg of NGF (NGF D9 group), (ii) 1 mg of NGF 32 h after EB (NGF D10 group), or (iii) phosphate buffer saline (control group). To measure pregnancy rates, heifers were treated similarly, then artificially inseminated with sexed semen 48-52 h after DIB removal, then an ultrasound was conducted 30 days after insemination. The females given NGF along with EB (NGF D9) showed significantly higher luteinizing hormone (LH) concentrations, larger CL vascular areas, and higher plasma P4 concentrations than the NGF D10 and control animals. Downregulation of the P4 receptor (PGR), and upregulation of both lipoprotein lipase (LPL) and Solute Carrier Family 6 member 14 (SLC6A14) endometrial genes, were detected in NGF D9 heifers. Furthermore, these heifers had a 10% higher pregnancy rate than the control group. We conclude that the higher P4 output, in response to the early NGF administration, led to the enhanced gene expression of transcripts related to uterine receptivity that may result in enhanced pregnancy rates.
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    Colostrum traits and newborn body weight and growth: comparison between single and twin underfed sheep pregnancies
    (2023) Turin, Jesus; Sales, Francisco; Peralta, Oscar A.; De los Reyes, Monica; Borie, Consuelo; Carrasco, Albert; Gonzalez-Bulnes, Antonio; Parraguez, Victor H.
    Maternal nutrition during gestation plays an important role in colostrum production, postnatal growth, and survival of newborn lambs, especially in twin gestations. This research aimed to investigate the effects of chronic natural undernutrition on colostrum traits and early lamb's postnatal growth born from single and twin sheep pregnancies developed in a restrictive prairie, representative of southern Patagonia. Single- and twin-bearing ewes (n = 20 per group) were maintained grazing in a natural pasture. At 140 days of gestation, ewes were placed in individual pens for lambing control. Colostrum was collected immediately after delivery and at 12, 24, and 36 h postpartum, for determination of yield and composition. Maternal blood was obtained at 140 days of gestation and at lambing for plasma glucose, progesterone, 17 beta-estradiol, and IgG determination. Newborn lamb blood for determining glycaemia and IgG was collected at birth and at 12, 24, 36, and 120 h after birth. Lamb mortality and growth was assessed from birth until 30 days of life. No differences were observed in progesterone and 17 beta-estradiol. There were no differences in colostrum yields and fat components, however single- had higher values of protein and lactose than twin-bearing ewes (p < 0.05 for both). Singletons had higher glycaemia than twins at 12 h postpartum (102.2 +/- 32.8 vs. 73.4 +/- 29.9 mg/dL, p < 0.05). Colostrum IgG content was similar at delivery but higher in single ewes at 12 and 24 h, reaching a similar values at 36 h (4.7 +/- 9.7 and 5.8 +/- 7.7 mg/mL in single and twin pregnancies, respectively). Newborn IgG was higher in singletons compared to twins at least until 48 h of life. Lams body weight was always superior in singleton than twins from birth until 30 days of life. Mortality did not differ during the first week of life, but it increased significantly only in twins until day 30 of life. Undernourishment in pregnant ewes affected colostrum quantity and quality, resulting in a lower postnatal growth and a higher mortality in twins. Alternative managements favoring fetal growth, birth weight and neonatal viability in twin sheep pregnancies are needed, when flocks are breed under harsh environments.