For the master's program in natural resources and environment in arid zones, from the Regional University Unit of Arid Zones, affiliated with Chapingo Autonomous University, Mexico, to give me the opportunity to belong to the second generation of Ph.D. To the postgraduate program in natural resources and sustainable management at the University of Cordoba, Spain, for giving me the opportunity to belong to this program. To my thesis supervisor Ph. lucky enough to be part of the 2017-2020 generation, M.C.
Key role of targeted beta-carotene supplementation on endocrine and reproductive performance in Mexican dryland goats. These results demonstrate for the first time beta-carotene not only as a molecule that regulates AOT, but also as a modulator of the release pattern of GH in adult goats as well as LH in yearling goats with genotypes with a high rate towards highly pronounced seasonal reproduction . Future research should determine the potential site of BC action in relation to hypothalamic-pituitary-gonadal axis function in goats.
EL PAPEL CLAVE DE LA SUPLEMENTACIÓN EXPERIMENTAL DE BETACAROTENO EN EL RENDIMIENTO ENDOCRINO Y REPRODUCTIVO EN CABRAS DE LAS REGIONES ÁRIDAS DE MÉXICO
INTRODUCTION
Goat farming is considered a natural resource of great social importance among residents of rural areas (Arechiga et al., 2008). Reproductive performance is one of the most important economic variables in modern goat production (Haliloglu et al., 2002). Nutritional level influences the processes involved in follicular development and ovulation rate in ruminants, mainly through changes in live weight (BW) and body condition (BC), (Meza-Herrera et al., 2004; Scaramuzzi et al., 2006). ).
These nutritional effects are mediated by changes in the levels of metabolic hormones and the growth factor superfamily (Meza-Herrera et al., 2006). Serum concentrations of growth hormones (GH) fluctuate in response to nutritional status and they can suppress the synthesis and secretion of gonadotropins (FSH and LH) and also reproductive efficiency (Scaramuzzi et al., 2006; Guerra-Garcia et al., 2009). ). 4 range of biological processes, such as cell development, differentiation and morphogenesis via retinoic acid (RA) (Amann et al., 2011).
From a reproductive perspective, BC supplementation was associated with increased steroidogenesis in both corpus luteum and follicular tissue (Lopez-Flores et al., 2018a).
OBJECTIVES
General objective
Specific objectives
To evaluate the effect of supplementation on the reproductive efficiency of female goats bred in the arid areas of Comarca Lagunera, Mexico.
HYPOTHESIS
Beta-carotene supplementation will generate an increase in ovarian function and GH/IGF-1 release pattern in adult female goats. Beta-carotene supplementation will reactivate and improve ovarian function and LH release pattern in yearling anestrous goats.
STATE OF THE ART
- Situation of goat farming in the world
- Goat farming in Mexico
- Environmental impact of goat farming
- Social impact of goat farming
- Economic impact of goat farming
- Reproductive aspects in the female goat
- Reproductive seasonality
- Seasonal Anestrous
- Influence of photoperiod in the female goat to migrate from the anestrous
- Nutrition-reproduction interaction
- Importance of Betacarotene as a modulator of the reproductive function
It is worth noting that 94% of the world's goat population is in developed countries, of which 55% are in arid regions (Arechiga et al., 2008). In addition, due to the selection of the breed groups themselves, an invaluable wealth of germplasm has developed, leading to two interesting situations (Alejandre-Ortiz et al., 2016). It can accommodate 13 producers, especially large milk producers in the central area of the country (El Bajio) and the northern area (Comarca Lagunera).
Rangelands have varying degrees of degradation attributed to the relationship between animal density and the rangeland's ability to serve as food and resist trampling (Barrera et al., 2018). Herbivorous ungulates occupy approximately 47.34% of the surface of this country, as small goat farms are highly represented in the southern and central-northern areas (Alejandre-Ortiz et al., 2016). An example of the low level of diversification in the global goat commercialization chain is the fact that the main commercial product is generally live animals (domestic markets).
Undoubtedly, goat breeding in Mexico is a major challenge for researchers in local livestock biodiversity conservation and sustainable development (Alejandre-Ortiz et al., 2016). In addition, the corpus luteum formed at the beginning of the breeding season has a short half-life, which produces low progesterone levels (Chemineau et al., 1984). This is characteristic of the goat species and has been reported by several authors in various dairy, meat and mohair breeds (Gibbons et al., 1994).
Seasonal anestrus is a consequence of the decrease in the activity of the hypothalamus-pituitary axis, pointing out the reduction of the frequency of GnRH pulses and consequently also the secretion of pituitary hormones. In addition, they induce a negative or positive reaction in the hypothalamus-pituitary axis, preventing an unblocking of the system. In any of the above scenarios, nutritional status is closely related to the function of the hypothalamic-pituitary-gonadal axis (Meza-Herrera & Tena-Sempere, 2012).
With a focused and regulated influence on the ovary, and the beta-carotene as a positive modulator in the activity and hormonal development of the follicle and corpus luteum (CL). Enriquez (2016) proposed that "in the cells of the intestinal mucosa, specific amino acids transfer the beta-carotene to the liver, where it is carried to high-density lipoproteins. These effects will modulate a large part of the physiological system of animals (Scaramuzzi et al et al., 2011).
On the other hand, in malnourished animals, puberty is delayed due to weak pulsations.
ARTICLES
The key role of targeted betacarotene supplementation on endocrine and
35 5.2 Precision Beta-carotene supplementation improved ovarian function and LH release pattern in yearling crossbred anestrous goats. Precision beta-carotene supplementation improved ovarian function and LH release pattern in crossbred anestrous yearling goats. THE KEY ROLE OF TARGETED BETA CAROTENE SUPPLEMENTATION ON ENDOCRINE AND REPRODUCTIVE PERFORMANCE IN GOATS IN THE MEXICAN DRY REGIONS.
GENERAL CONCLUSIONS
47 Considering a translational perspective, since GH promotes cell proliferation and angiogenesis while inhibiting apoptosis, the GH/IGF-1 system has been implicated in mammals with the development and/or progression of several cancers (Kopchik et al., 2014). Conversely, GH levels have been associated with signs of premature aging with an extreme reduction in lifespan. Although these premature deaths have been diagnosed as multifactorial in origin, pathological damage to specific organs has been consistently present with an increased incidence of tumors (Bartke et al., 2013; Kopchik et al., 2014).
Furthermore, acting through autocrine/paracrine/endocrine pathways, increased GH levels have been linked to oncogenesis; Therefore, any attempt to reduce the action of GH/IGF-1 in some pathological scenarios may provide remarkable protection against certain types of cancer (Pollack et al., 2001; Kopchik et al., 2014). These findings coupled with our results offer interesting possibilities in the search for potential translational applications, considering the GH-reducing effect of BC supplementation observed in our study; further research considering this approach emerges as an interesting topic. Furthermore, the data found by our research group show that beta-carotene supplementation produces an increase in ovarian activity and ovulation rate, which can be used as a model for adult goats, in particular such a physiological scenario that requires the participation of a decrease in serum GH. however, no effects on IGF-1 levels.
It remains to be determined whether such a decrease in GH secretion may directly affect the hypothalamic centers that modulate the pulsatile release of GnRH or indirectly through peripheral signals that reflect actions of GH/IGF-1 at the ovarian level. However, one study reveals for the first time a potential role for BC as a somatotropin-modulating molecule. However, the precise site of action of BC throughout the HPG axis in females remains to be established; is the latter important for the animal industry and with possible implications of translation from a clinical point of view.
To conclude, the results of our two studies developed in this thesis support the fact that beta-carotene will improve the follicular development during the natural breeding season in adult animals as well as the off-season ovarian function, which changes the pattern of LH release in yearling anestrous goats, without differences in live weight and body condition score. The question remains whether the effects of BC supplementation were exerted by abnormalities in the LH release pattern, whether directly exerted on ovarian physiology or even mediated by upregulation of ovarian LH receptors. Further research designed to uncover the precise endocrine or metabolic effects of BC along the HPG axis will contribute to a better understanding of the positive out-of-season ovarian outcomes observed in BC-supplemented yearling anestrous bucks, particularly with a high degree of genes from highly seasonal goat breeds.
GRAPHICAL ABSTRACT
EL PAPEL CENTRAL DE LA SUPLEMENTACIÓN DIRIGIDA DE BETACAROTENO SOBRE EL COMPORTAMIENTO ENDOCRINO Y REPRODUCTIVO EN CABRAS DE SIETE REGIONES DE MÉXICO. Estudio de aportes de las ciencias sociales a la investigación sobre la agricultura caprina en México. La ingesta a corto plazo de dietas con betacaroteno aumenta la función ovárica y la síntesis de progesterona en las cabras.
Una aproximación para comprender los mecanismos fisiológicos, nutricionales y bioquímicos de las limitaciones reproductivas de origen dietético. Un estudio de los mecanismos implicados en la estacionalidad reproductiva en cabras mediterráneas: el papel de los opioides, las catecolaminas y la serotonina. Universidad de Huelva) Obtenido de. http://rabida.uhu.es/dspace/bitstream/handle Estudio_me canismos_implicados.
La suplementación con β-caroteno aumenta la concentración de progesterona y la actividad de la glutatión peroxidasa siguiendo un protocolo alternativo de sincronización estral de progesterona en cabras. Organización de las Naciones Unidas para la Agricultura y la Alimentación. http://www.fao.org/faostat/es/#data. Evaluación de rasgos de producción en cabras Bóer x Local, Nubia x Local y locales en el trópico seco de Guerrera, México.
Beta-carotene supplementation positively affects selected blood metabolites around the time of onset of puberty in goats. Long-term beta-carotene supplementation positively affects serum triiodothyronine concentrations around the onset of puberty in female goats. The interface between nutrition and reproduction: the very basis of production, In: Astiz S, Gonzalez-Bulnes A (Eds.), Animal reproduction in animals, Encyclopedia of Life Support Systems (EOLSS), UNESCO, Eolss Publishers, Oxford, UK, [http://www.eolss.net].
Efecto del nivel de alimentación sobre la actividad reproductiva en cabras criollas durante la época reproductiva.