9
• Vol. XIII, Núm. 1 • Enero-Abril 2019 •
Abstract Resumen
Keywords:
organic e inorganic selenium sources, sheep behavior,
Palabras clave:
selenio orgánico e inorgánico, comportamiento en
hair
ewes. Ovinos, ovejas de pelo.
Organic and inorganic selenium
supplementation on the productive and
reproductive performance of hair ewes
Suplementación con selenio orgánico e inorgánico sobre el
comportamiento productivo y reproductivo de ovejas de pelo
LUIS H. DÍAZ-GARCÍA1, FELIPE RODRÍGUEZ-ALMEIDA2, GWENDOLYNE PERAZA-MERCADO3,
F
RANCISCO
C
ASTILLO
-R
ANGEL
2
, O
SCAR
R
UIZ
-B
ARRERA
2
Y
L
EONARDO
C
ARLOS
-V
ALDEZ
2,4
Recibido: Septiembre 10, 2018 Aceptado: Febrero 25, 2019
_________________________________
1 UNIVERSIDAD AUTÓNOMA DE ZACATECAS. Unidad Académica de Medicina Veterinaria y Zootecnia, km 31.5 carretera Panamericana Zacatecas-
Fresnillo, colonia Enrique Estrada, Gral. Enrique Estrada, Zacatecas, México. C.P. 98500
2 UNIVERSIDAD AUTÓNOMA DE CHIHUAHUA. Facultad de Zootecnia y Ecología. Periférico Francisco R. Almada Km. 1, Chihuahua, Chih., México,
31453. Tel. (614) 434-1448.
3 UNIVERSIDAD AUTÓNOMA DE CIUDAD JUÁREZ. Departamento de Ciencias Químico-Biológicas. Ave. Plutarco Elías Calles #1210, Colonia Fovissste
Chamizal, Ciudad Juárez, Chihuahua, México. C.P. 32310
4 Dirección electrónica del autor de correspondencia: lcarlos@uach.mx
Alimentos Artículo arbitrado
The objective of this study was to evaluate the effect of
supplementation with organic and inorganic selenium on the
productive and reproductive performance of ewes and their
offspring. Selenium (Se) is an essential mineral for sheep, studies
have found its intestinal absorption and biodisponibility in the
animal is greater when it comes from an organic source. A total of
18 multiparous and 22 nulliparous ewes Pelibuey breed were used
in this study, averaging 54.8 ± 9.4 kg and 39.7 ± 5.6 kg of body
weight (BW). The experimental units were blocked by the
number of parturitions (none or more than one). Then randomly
assigned to one treatment: basal diet +1.2 ppm of organic Se (OSe,
Sel-Plex®) or basal diet +1.2 ppm inorganic Se (ISe). Using the linear
model PROC MIXED, BW changes were measured in ewes and
average daily gain (ADG) in offspring. Fisher’s test, chi-squared test
and t test were used for analyzing reproductive rates and
production efficiency. No differences (P > 0.05) were found for BW
changes, productive efficiency, and pregnancy rate between
treatments. Prolificacy was higher (P < 0.05) for primiparous ewes
in the OSe group vs the ISe group (66.7 vs 18.2 %). No differences (P
> 0.05) were found for birth weights of lambs. The ADG was higher
(P < 0.05) for the offspring of ISe vs OSe ewes. This indicates that
the OSe supplementation improves reproductive parameters, but
not the productive such as ADG.
El objetivo de este estudio fue evaluar el efecto de la
suplementación con selenio orgánico e inorgánico sobre el
desempeño productivo y reproductivo en ovejas de pelo. El selenio
(Se) es un mineral esencial en ovinos; estudios han encontrado que
su absorción intestinal y biodisponibilidad dentro del animal es
mayor cuando proviene de una fuente orgánica (EFSA, 2014).
Dieciocho ovejas multíparas y 22 nulíparas de raza Pelibuey con
54.8 ± 9.4 kg y 39.7 ± 5.6 kg de peso vivo fueron utilizadas para
formar bloques, considerando número de partos (0 o 1 en adelante);
luego asignadas aleatoriamente a un tratamiento: dieta basal +1.2
ppm Se orgánico (OSe, Sel-Plex®) o dieta basal +1.2 ppm Se
inorgánico (ISe). Fue usado un modelo lineal PROC MIXED para
cambios de peso en ovejas y ganancia diaria de peso (GDP) en crías;
y las pruebas de Fisher, chi-cuadrada y t para parámetros
reproductivos y eficiencia de producción. No se encontraron
diferencias (P > 0.05) para cambios de peso, eficiencia productiva,
porcentaje de preñez entre tratamientos. La prolificidad fue mayor
(P < 0.05) para nulíparas bajo OSe vs ISe (66.7 vs 18.2 %). No se
encontraron diferencias (P > 0.05) para pesos al nacimiento en
corderos. La GDP fue mayor (P < 0.05) para corderos hijos de
borregas bajo ISe vs OSe. Es concluyente que el Ose mejora
parámetros reproductivos, pero no los productivos como las GDP.
10
• Vol. XIII, Núm. 1 • Enero-Abril 2019 •
S
Introduction
elenium (Se) is an essential trace mineral for living organisms, and its importance is
mainly related to the glutathione peroxidase enzyme (Libién-Jiménez et al., 2015). This
element could be an effective strategy to improve animal performance and reduce the
negative effects of nutrient restriction to improve oxidative stress (Mousaie et al., 2017).
Selenium supplementation has been reported to
enhance productive and reproductive ewe lamb
performance (Mousaie et al., 2014). In general, Se fed
diet has a positive effect for growth, reproduction,
milk synthesis, and immune system functions in
sheep. The Food and Drug Administration (FDA)
regulations of the EU had authorized the Sel-Plex as a
nutritional additive; produced by Saccharomyces
cerevisiae cultures (EFSA, 2014). The FDA recommend
that Se be supplemented in feed by 0.3 mg/kg (Hall et
al., 2012). However, this recommendation does not
consider the Se source, which is usually classified as
inorganic and organic. The inorganic element is typically
administered through commercial mineral premixes
or injected as Na-selenite or Na-selenate. Organic Se
is associated with the amino acids methionine and
cysteine, which are found in Se-yeast and make it
highly digestible (Stewart et al., 2012; EFSA, 2014).
Therefore, new alternatives for the supplementation
of this mineral are being studied to improve and enhance
animal performance. Sel-Plex (Saccharomyces
cerevisiae cultures) has been demonstrated to have a
higher digestibility compared with inorganic
selenium as feeding additive in animal performance.
However, these are still contradictive results because
the accelerated lambing system demands high
nutritional levels and also the ewes are under continuing
nutritional and management stress. The objective of
this study was to evaluate the effect of feeding
inorganic and organic Se on the productive and repro-
ductive performance of hair ewes and their offspring’s.
Materials and methods
All procedures involving animals were approved
by local official techniques for animal care (NOM–
051–ZOO–1995: Humanitarian care of animals during
mobilization of animals; NOM–024–ZOO–1994:
Animal health stipulations and characteristics during
transportation of animals). Forty Pelibuey non-
pregnant ewes were used in the study (n = 22
nulliparous ewes, and n = 18 multiparous, with one
or more parturitions; averaging 39.7 ± 5.6 and 54.8 ±
9.4 kg of initial body weight [BW], respectively).
Prior to the start of the experiment, all sheep received
1 mL/50 kg BW of Dectomax (0.2 mg/kg BW of
doramectin; Zoetis) and 2.5 mL of Bobact-8® (MSD).
All experimental units were blocked by the number
of parturitions and randomly assigned to one of two
treatments, resulting in two groups of nulliparous and
multiparous ewes. Doses of 1.2 ppm of inorganic Se
(ISe) or organic Se (OSe) Sel-Plex50MR were added to
the basal diet of each group. The basal diet was
prepared every week and consisted of 57% forage
(alfalfa hay and oat hulls) and 43% concentrate
composed of mainly alfalfa and steam-rolled corn grain
to cover nutritional requirements (NRC, 2007; Table 1).
Table 1. Composition of experimental diets and chemical analysis.
1 Commercial mineral premix, each 100 g contains: 1.4% Mg, 0.26%
S, 0.12% Fe, 0.048% Cu, 0.003% Co, 0.072% Mn, 0.42% K, 0.12%
Zn, 0.003% I, 3.936% Na, 6.064% Cl, 14% Ca, and 8% P. DM = dry
matter, OM = organic matter, CP = crude protein, ADF = acid detergent
fiber, NDF = neutral detergent fiber, EE = ether extract.
Source: Author´s own elaboration.
11
• Vol. XIII, Núm. 1 • Enero-Abril 2019 •
The study was performed at the Facultad de
Zootecnia of the Universidad de Chihuahua, from July
1st of 2006 through April 30th of 2007. It began with
the selenium supplementation to the ewes; six weeks
before the breeding season, all through the gestation
period and continued 90 days postpartum until
weaning time. Pregnancy rate, prolificacy, produc-
tion efficiency, and postpartum BW changes were
evaluated for the ewe lambs and ewe groups. The
average daily gain (ADG) of the offspring was also
estimated. The pregnancy rate was determined by
ultrasound imaging using an Aloka SSD-500V with a
3.5 MHz transabdominal probe 60 days after the end
of the breeding period. Prolificacy was determined
after lambing was completed by dividing the total
number of offspring born per group by the number
of ewes lambed within each treatment group.
Productive efficiency was measured by the formula:
(weaned lamb kg/ewe kg) * 100. Body weight
changes in ewes were determined from the beginning
of the experiment using an electronic scale to weigh
individuals every 14 days. The offspring were also
weighed every 14 days from birth to weaning day (at
90 days of age).
Continuous variables of BW changes in ewes and
ADG in offspring were analyzed with PROC MIXED
using a linear model that included treatment, age,
treatment by age, type of lambing, and type of birth
by age (SAS®). The random effects in the model were
the ewes, lambs within treatments, and rams. Fisher’s
and Chi-square test were used to analyze pregnancy
rates and prolificacy, respectively. A t test for
independent samples was used for production
efficiency to observe the effect of treatment on these
variables.
Results and discussion
Pregnancy rate was not different (P > 0.05) by
treatment (OSe vs ISe) among the four groups (81.8%
vs 77.7%; and 72.7% vs 66.6%, nulliparous and
multiparous, respectively). Although it can observe a
higher pregnancy rate for OSe of nulliparous ewe
compare to the multiparous group. Even when no
significant differences were found between organic
or inorganic Se source. Hall et al. (2012) demonstra-
ted high bioavailability of OSe in supplemented ewes.
For other way, Awawdeh et al. (2019) recently found
that multiple injections of vitamin E and Se improve
the pregnancy rate but no the fertility of the ewes.
Then our results are some similar to these studies;
where has been demonstrated that both Se sources
(organic and inorganic) have positive effects on
reproductive performance in ewes. Been numerically
higher when in nulliparous fed with Ose.
The prolificacy rate was higher (P < 0.05) for
the nulliparous OSe group compared with the
nulliparous ISe group (66.7% vs 18.2%, respectively;
Table 2). These results are similar to those of Davis et
al. (2006) and Steen et al. (2008), who reported that
organic Se supplementation increased Se concen-
trations in blood and organ tissues. With positive
effects in tissue metabolism that consequently could
enhance the pregnancy rate and prolificacy. Sanchez
et al. (2008) found a positive effect with Se
supplementation on estrous synchronization inside
and outside the breeding season. However, Sánchez
et al. (2008) reported high embryonic mortality
caused by Se supplementation of the dam previous
mating period. Contrary to our findings fed diet OSe
increases the number of lambs per lambing in the
nulliparous ewes. There were also no differences (P
> 0.05) found between OSe and ISe treatments in the
multiparous groups. These results can be support with
Awawdeh et al. (2019), whom reported increase in
prolificacy in ewes with multiple injections of vitamin
E and Se, pre- and post-mating. Showing that inorganic
or organic Se have a positive effect on prolificacy
rate.
No differences (P > 0.05; Table 2) in BW changes
were found between treatments for nulliparous and
multiparous groups. Similarly, Awawdeh et al. (2019)
reported no positive BW changes in ewes and their
lambs under multiple injections of vitamin E and Se.
Kumar et al. (2009) reported a positive effect on ADG
in feed lot lambs supplemented with Se, been higher
for those receiving organic Se compare to the
inorganic fed. Also, Awadeh et al. (1998) reported that
cows supplemented with Se did not increase their
BW during the experimental period. Most studies
report OSe benefits for reproduction parameters and
immune system, but no improvement in ADG. All
these studies support our results with no positive
effect of Se fed diet on BW changes.
12
• Vol. XIII, Núm. 1 • Enero-Abril 2019 •
Table 2. Productive and reproductive performance in Pelibuey ewes supplemented with organic selenium (OSe) or inorganic
selenium (ISe).
a,b Different literals between columns indicate differences (P < 0.05) between treatments.
* Evaluated within the time of the experiment. OSe = basal diet plus 1.2 ppm organic selenium (Sel-Plex), ISe = basal diet plus 1.2
ppm inorganic selenium.
Source: Author´s own elaboration.
Offspring birth weights were not different (P >
0.05) between treatments. However, ADG was higher
(P < 0.05) for the offspring of nulliparous
supplemented with ISe compared with those
receiving OSe (Figure 1) with regression coefficients
of 3.68 ± 0.75 and 3.21 ± 0.72, respectively. While no
differences (P > 0.05) were found by ADG for the
offspring of multiparous ewes. We believe that the
maximum ADG present in the offspring of ISe
nulliparous group was because had a higher of single
births. Due to the fact that single birth lambs have a
greater advantage (P < 0.05) over twins because they
do not have competition for suckling milk, which
usually results in better performance during the
lactation period. Davis et al. (2006) reported Se
placental transfer from the ewe to the fetus, and
Stewart et al. (2012) reported benefits in ADG for the
offspring of ewes supplemented with supranutritional
Se concentrations. Also, Hefnaway et al. (2008)
reported that subcutaneous or oral sodium selenite
have a positive relationship between maternal plasma,
milk and lamb plasma; improving the body weight
gain of the newborn lambs. Kumar et al. (2009)
reported improved growth rate of lambs fed Se
supplemented diets; being higher when lambs were
under OSe fed diet. Fed Se supplementation diets has
been demonstrated to improve weight gain and
gain:feed (Mahima, 2006). Studies have shown that
OSe is better absorbed and utilized in ruminants when
compared to ISe source (Kumar et al., 2009). These
studies reported a positive effect over ADG of new
born lambs from organic and inorganic Se supple-
mented ewe’s pre-parturition and post-partum. The
results for the present study is similar body weight
gain; although single births could have a potential
effect for this rate.
Figure 1. Body weight (BW) changes of the offspring from
nulliparous ewes.
Source: Author´s own elaboration.
13
• Vol. XIII, Núm. 1 • Enero-Abril 2019 •
Conclusions
Supplementation of 1.2 ppm of OSe at least six
weeks before the breeding season had favorable
effects on pregnancy rates and prolificacy in
nulliparous Pelibuey ewes. However, no beneficial
effects were found on postpartum BW changes. More
studies about OSe supplementation are therefore
recommended because even though there have been
some reports, the results remain inconsistent. Probably
due to the way OSe is supplied, the doses and source of
Se supplementation. We also recommend measurement
of glutathione peroxidase activity, which is the best
indicator of Se metabolic status which could be
associated with animal performance results.
Acknowledgements
This research was partially supported by Facultad
de Zootecnia y Ecologia and by Alltech de Mexico. We
thank Ing. Tabuada, who provided insight and
expertise that greatly assisted in the research. Also,
we thank Robert Tafanelli for assistance as a
reviewer and their comments on earlier version of
the manuscript.
Literature Cited
AWADEH, F. T., R. L. Kincaid, and K. A. Johnson. 1998. Effect of level
and source of dietary selenium on concentrations of thyroid
hormones and immunoglobulins in beef cows and calves.
Journal of Animal Science 76:1204-1215.
AWAWDEH, M. S., A. H. Eljarah, M. M. Ababneh. 2019. Multiple
injections of vitamin E and selenium improve reproductive
performance od estrus-syncronized Awassi ewes. Tropical
Animal Health and Production. https://www.ncbi.nlm.nih.gov/
pubmed/30706332. Consulted, 15th of March of 2019.
DAVIS, P. A., L. R. McDowell, N. S. Wilkinson, C. D. Buergelt, R. Van
Alstyne, R. N. Weldon, and T. T. Marshall. 2006. Effects of
selenium levels in ewe diets on selenium in milk and the plasma
and tissue selenium concentrations of lambs. Small Ruminant
Research 65:14-23.
EFSA Panel on Additives and Products or Substances used in
Animal Feed (FEEDAP); Scientific Opinion on Safety and
efficacy of Sel-Plex® (organic form of selenium produced by
Saccharomyces cerevisiae CNCM I- 3060) for all species. EFSA
Journal 2014;9(4):2110. [52 pp.] doi:10.2903/j.efsa.2011.2110.
Available online: www.efsa.europa.eu/efsajournal
GUYOT, H, P. Spring, S. Andrrieu, F. Rollin. 2007. Comparative
responses to sodium selenite and organic selenium
supplements in Belgium Blue cows and calves. Livest. Sci.
111:259-263.
HALL, J. A., R. J. Van Saun, G. Bobe, W. C. Stewart, W. R. Vorachek, W.
D. Mosher, T. Nichols, N. E. Forsberg, and G. J. Pirelli. 2012.
Organic and inorganic selenium: I. Oral bioavailability in ewes.
Journal of Animal Science 90:958-576.
HEFNAWY, A. E., R. López-Arellano, A. Revilla-Vázquez, E. Ramírez-
Bribiesca and J. Tortora-Pérez. 2008. Effect of pre- and
pospartum selenium supplementation in shee. J. of Animal
and Veterinary Advances 7:61-67.
KOYUNCU, M. and H. Yerlikaya. 2007. Effect of selenium-vitamin E
injections of ewes on reproduction and growth of their lambs.
South African Journal of Animal Science 37:233-236.
KUMAR, N., A. K. Garg, R.S. Dass, V. K. Chaturvedi, V. Mudgal, V. P.
Warshney. 2009. Selenium supplementation growth
performance, antioxidant status and immune response in
lambs. Animal Feed Science and Technology 153:77-87.
MOUSAIE, A., R. Valizadeh and M. Chamsaz. 2017. Selenium-
methionine and chromium-methionine supplementation of
sheep around parturition: impacts on dam and offspring
performance. Archives of Animal Nutrition 71:134-149.
MOUSAIE, A., R. Valizadeh, A. A. Naserian, M. Heidarpour, H. Kazemi-
Mehrerdi. 2014. Impacts of feeding selenium-methionine and
chromium-methionine on performance, serum components,
antioxidant status and physiological response to transportation
stress of Baluchi ewe lambs. Biol Trace Elem Res. 162:113-123.
LIBIÉN-JIMENÉZ, Y., M. D. Mariezcuerrena-Berasanin, J. Lugo de la
Fuente, A. Z. M. Salem, A. E. Kholif, R. Vaca-Paulin and M. A.
Mariezcurrena-Berasain. 2015. Effect of organic selenium
supplementation in the diets of finishing sheep on meat color
and pH during shelf life. Indian J. Anim. Res. 49:652-657.
NATIONAL RESEARCH COUNCIL (NRC). 2007. Nutrient requirements of
small ruminants: sheep, goats, cervids, and new world camelids.
Washington, D.C., USA. National Academy Press.
SÁNCHEZ, J., A. Jiménez, S. Regodón, and S. Andrés. 2008. Inhibitory
effect of selenium supplementation on the reproductive
performance in synchronized Merino sheep at range
conditions in a selenium-deficient area. Reproduction of
Domestic Animals 43:328-332.
STEEN, A., T. Strøm, and A. Bernhoft. 2008. Organic selenium
supplementation increased selenium concentrations in ewe
and newborn lamb blood and in slaughter lamb meat
compared to inorganic selenium supplementation. Acta
Veterinaria Scandinavia 50:1-6.
STEWART, W. C., G. Bobe, W. R. Vorachek, G. J. Pirelli, W. D. Mosher, T.
Nichols, R. J. Van Saun, N. E. Forsberg, and J. A. Hal. 2012.
Organic and inorganic selenium: II. Transfer efficiency from
ewes to lambs. Journal of Animal Science 90:577–584.
Este artículo es citado así:
Díaz-García, L. H., F. Rodríguez-Almeida, G. Peraza-Mercado, F. Castillo-Rangel, O. Ruiz-Barrera y L. Carlos-Valdez. 2019. Organic and
inorganic selenium supplementation on the productive and reproductive performance of hair ewes. TECNOCIENCIA Chihuahua
13(1):9-14. DOI: https://doi.org/10.54167/tch.v13i1.303
14
• Vol. XIII, Núm. 1 • Enero-Abril 2019 •
Resumen curricular del autor y coautores
LUIS HUMBERTO DÍAZ GARCÍA. Terminó su licenciatura en el año 2000, año que le fue otorgado el título de Médico Veterinario Zootecnista
por la Facultad de Medicina Veterinaria y Zootecnia de la Universidad Autónoma de Zacatecas (UAZ). Realizó su Maestría en
Producción Animal con Área Mayor en Nutrición en la Universidad Autónoma de Chihuahua, obteniendo el grado de Maestro en
Ciencias en 2004. Desde 2003 a la fecha es Docente Investigador Asociado C en la Unidad Académica de Medicina Veterinaria y
Zootecnia de la Universidad Autónoma de Zacatecas. Es perfil PRODEP de 2011 a la fecha. Ha dirigido más de 23 tesis de licenciatura
y 3 de maestría. Es autor y coautor de 5 artículos científicos y más de 25 ponencias, de las cuales más de 10 han sido por invitación
en congresos y eventos nacionales e internacionales. Cuenta con más de 30 memorias en extenso en congresos nacionales e
internacionales y la publicación de un manual en producción de ovinos. Su área de especialización es la Nutrición de Rumiantes y
Parasitología Veterinaria. Ha dirigido un proyecto financiado con recursos externos.
FELIPE ALONSO RODRÍGUEZ ALMEIDA. Es Ingeniero Zootecnista (1988) y Maestro en Ciencias en Producción Animal con área mayor en
Reproducción y Genética por la Universidad Autónoma de Chihuahua (1990). Obtuvo su doctorado en la Universidad de Nebraska-
Lincoln (1994) en el área de Mejoramiento Animal, su disertación se orientó al desarrollo de modelos para la evaluación genética
de bovinos carne en poblaciones multirraciales. Su trabajo de investigación en México lo ha enfocado principalmente al desarrollo
de evaluaciones genéticas nacionales, la evaluación de cruzas para la producción de carne de ovino y bovino, con énfasis especial en
la eficiencia biológica y los factores que influyen en la misma, y la incorporación de la genética molecular y la genómica en los
programas de mejora genética de ovinos en México. Es autor y coautor de más de 45 artículos en revistas indizadas y arbitradas, tres
capítulos en libro, y más de 60 trabajos presentados en congresos nacionales e internacionales. Se ha desempeñado como académico
en la Facultad de Zootecnia y Ecología de la Universidad Autónoma de Chihuahua desde 1990 y ha sido Miembro del Sistema
Nacional de Investigadores desde 1993 (Candidato 1993-1996, Nivel I 1996-2002, 2008-2022).
GWENDOLYNE PERAZA MERCADO. Terminó la licenciatura en Química Industrial en 1997, título otorgado por la Facultad de Ingeniería
Química de la Universidad Autónoma de Yucatán (UADY). Realizó su posgrado en Yucatán, donde obtuvo el grado de Maestro en
Ciencia y Tecnología de Alimentos en 2000 por la Universidad Autónoma de Yucatán, y el grado de Philosophy Doctor in Animal
Production en el área de Ciencias de la Carne en 2010 por la Universidad Autónoma de Chihuahua. Desde 2001 labora en el
Instituto de Ciencias Biomédicas de la Universidad Autónoma de Ciudad Juárez. Su área de especialización son los alimentos de
origen animal y vegetal, y la tecnología de alimentos. Ha participado con más de 30 trabajos de investigación en congresos nacionales
e internacionales, como autor principal y coautor. Ha dirigido 7 proyectos de investigación financiados por fuentes externas y
fondos propios. Tiene más de 24 publicaciones científicas arbitradas, así como capítulos de libros. Actualmente es Secretaria del
Comité Institucional de Ética y Bioética de la Universidad Autónoma de Ciudad Juárez y es Quinto Vocal de la Mesa Directiva del
CONAECQ (Consejo Nacional para la Evaluación de Programas de Ciencias Químicas) de COPAES. En cuanto a lenguas extranjeras,
posee un 100% de inglés y español y 85% en francés e italiano.
FRANCISCO CASTILLO RANGEL. Terminó su licenciatura en 2005, año en que le fue otorgado el título de Médico Veterinario Zootecnista por
la Unidad Académica de Medicina Veterinaria y Zootecnia de la Universidad Autónoma de Zacatecas (UAZ). Realizó su posgrado en
Chihuahua, donde obtuvo el grado de Maestro en Ciencias en el área de Nutrición Animal en 2007 por la Universidad Autónoma de
Chihuahua (UACH), y el grado de Doctor in Philosophia también en el área de nutrición animal, en 2011 por la Universidad
Autónoma de Chihuahua. Desde diciembre de 2013 labora en la Facultad de Zootecnia y Ecología de la UACH y posee la categoría de
Académico titular B. Ha sido miembro del Sistema Nacional de Investigadores desde enero de 2019 a la fecha. Su área de especialización
se basa en el uso de aditivos en los sistemas de alimentación animal y su impacto ambiental. Ha dirigido 2 tesis de licenciatura y 2
de maestría. Es autor de más de 15 artículos científicos, ha participado en 2 ponencias en congresos internacionales, y ha sido
coautor de 1 libro; además ha dirigido 3 proyectos de investigación financiados por fuentes externas. Ha fungido como evaluador
PRODEP en los últimos dos años. Es árbitro de una revista científica de circulación internacional.
OSCAR RUIZ BARRERA. Es Ingeniero Zootecnista por la Universidad Autónoma de Chihuahua (Chihuahua, México), Maestro en Ciencias
(Forrajes) por el Colegio Superior de Agricultura Tropical (Tabasco, México) y doctorado (Nutrición Animal) por La Universidad de
Reading (Berks, Inglaterra). Es el maestro decano de la Facultad de Zootecnia y Ecología, con una antigüedad de 43 años y posee la
categoría de Académico Titular C. Ha titulado 10 estudiantes de doctorado, 5 de maestría y 10 de licenciatura. Es el coordinador del
Cuerpo Académico consolidado CA-1 (UACH). Desde el año 2000 ha publicado 60 artículos científicos como autor y coautor en
revistas indizadas nacionales e internacionales, 4 capítulos de libros y más de 70 ponencias en congresos nacionales e internacionales.
Miembro del Sistema Nacional de Investigadores (CONACYT) Nivel I y evaluador acreditado del CONACYT (RCEA).
LEONARDO CARLOS VALDEZ. Terminó su licenciatura en 1995, año en que le fue otorgado el título de Médico Veterinario Zootecnista por
la Facultad de Medicina Veterinaria y Zootecnia de la Universidad Autónoma de Zacatecas (UAZ). Realizó su posgrado en Chihuahua,
donde obtuvo el grado de Maestro en Ciencias en Producción Animal en 1998 por la Universidad Autónoma de Chihuahua (UACH),
y el grado de Philosophy Doctor en el área de nutrición animal en 2009 por Oklahoma State University. Desde 1998 labora en la
Facultad de Zootecnia y Ecología de la UACH. Su área de especialización es la nutrición y reproducción de ovinos. Ha participado con
más de 20 trabajos de investigación en congresos nacionales e internacionales, como autor principal y coautor. Ha dirigido más de
4 proyectos de investigación financiados por fuentes externas. Tiene más de 12 publicaciones científicas arbitradas y memoria en
extenso en congresos internacionales y nacionales.