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Cuban Journal of Agricultural Science

versión impresa ISSN 0864-0408versión On-line ISSN 2079-3480

Cuban J. Agric. Sci. vol.52 no.3 Mayabeque jul.-set. 2018  Epub 01-Sep-2018


Animal Science

Characterization of macromineral content in the blood of Blackbelly sheep under free grazing conditions in Ecuadorian Amazon

J.C. Moyano1  7  * 

W. Caicedo1  7 

J.C. López1  7 

J.C. Vargas1  7 

I. Barbona2  7 

P.R. Marini3  4  7 

M.L. Fischman5  6  7 

1Universidad Estatal Amazónica-Centro de Investigación, Posgrado y Conservación Amazónica - Ecuador.

2Facultad de Ciencias Agrarias - Universidad Nacional de Rosario - Argentina

3Facultad de Ciencias Veterinarias-Universidad Nacional de Rosario - Argentina.

4Consejo de Investigaciones (CIC-UNR)

5Universidad de Buenos Aires, Facultad de Ciencias Veterinarias, Cátedra de Física Biológica, Laboratorio de Calidad Espermática y Criopreservación de Gametas, Buenos Aires, Argentina.

6Universidad de Buenos Aires, Facultad de Ciencias Veterinarias, Instituto de Investigación y Tecnología en Reproducción Animal (INITRA), Buenos Aires, Argentina.

7Centro Latinoamericano de Estudios de Problemáticas Lecheras (CLEPL).


The objective of this study was to characterize the serum concentration of macrominerals of Blackbelly sheep under free grazing conditions in Ecuadorian Amazon. Twenty-two Blackbelly sheep, belonging to the Centro de Investigación, Posgrado y Conservación de la Biodiversidad Amazónica (CIPCA) and raised under the same environmental, nutritional and managerial conditions, were studied during the summer period April-June. Blood samples were taken from the coccygeal vein 30 days before lambing, at lambing time and at 30 and 60 days after lambing. Mg2+, Na and P variables showed no significant differences (P>=0.05) with time. However, Ca2+ showed significant differences (P>=0.05), with changes at lambing time and 30 days after. In conclusion, there is a serum deficit of Ca2+ and P in the studied population of Blackbelly sheep under free grazing conditions of Ecuadorian Amazonia during all the period. Supplementation should be selective for these minerals.

Key words: nutrition; sheep; postparturition; blood serum

Blackbelly sheep breed is highly relevant for meat production in Ecuadorian Amazon, because it adapted to extreme conditions without damaging the native flora and fauna of the region, despite it is a non-native introduced species in the East Ecuador. This fact is evidenced in their mortality, precocity and reproductive fertility (multiple parturitions), medium size and productive longevity (Mendives 2007). However, besides environmental adaptation, animals need balanced and adequate levels of all nutrients for their health and good production in any physiological step (Brakat et al. 2013). The nutritional status of this small ruminant influences, in a direct manner, on their reproductive and productive activity (Viñoles et al. 2002). Numerous authors have demonstrated that one of the problems of grazing ruminants is that it does not cover protein, energy and mineral requirements which affect the normal development of metabolic processes (Mc Dowell 2003) because they exclusively depend on the content of forages to satisfy their nutritional requirements (Morales et al. 2007). Imbalance in mineral contents could produce deficiency or toxicity signs (Underwood and Suttly 2003). It is also necessary to consider that forage source normally presents fluctuations in quantity and quality throughout the year.

The importance of the present study was to characterize, through blood analysis, the referential values of the elements in order to determine their concentration during gestation and lactation stages.

The objective of the present study was to characterize serum concentration of macrominerals of Blackbelly sheep under free grazing Ecuadorian Amazon conditions.

Materials and Methods

Design and sheep population. Twenty-two Blackbelly sheep, belonging to the Centro de Investigación, Posgrado y Conservación de la Biodiversidad Amazónica (CIPCA) and raised under the same climate, nutritional and managerial conditions, were studied. This center is located in Arisemena Tola canton of Napo province (Ecuador), kilometer 44 via Puyo-Tena (0.10 14.325' S; O 77o 53.144' W), with an area of 42 ha of grasses. The environment is tropical, with 4000 mm/year of rain, 80 % of mean relative humidity and temperatures between 15 and 25 °C. Its topography is characterized by slightly undulated relief without pronounced slopes, distributed in natural plateaus of great extension. Altitude varied between 380 - 990 m.o.s.l. In general, soils have a diverse composition, but the majority of them were originated from fluvial sediments from the Andes region of the country. The study was conducted during the summer season, in the period between April and July.

Management, feeding and health. Mean animal weight was 37±2 kg (mean ± standard deviatio) and all had simple lambing and consumed only pastures under free grazing conditions (table 1).

Table 1 Chemical composition of pastures 

The health management frequently used for sheep in CIPCA was applied. It includes deworming, ticks and fly control, and aftosa fever, antimicotic and antibacterial vaccination.

Collecting and processing samples. Samples of blood were taken from the coccygeal vein at 30 days before lambing, at lambing time and at 30 and 60 days after lambing, centrifuged (3000 rpm x 15-30 minutes) and the separated plasma was stored at -20 °C until processing. A molecular spectrophotometer (Thermo Scientific spectrophotometer GENESIS 10 UV series; Human commercial kit) was used to determine P and Mg2+ concentration, whereas an electrolytic analyzer (AIDICOM, AC 9801; AUDICOM specific reagents) was used to determine Na+ and Ca2+.

Data analysis. Descriptive statistics of data was applied, calculating mean and standard error of the studied variables. Moreover, graphs of mean profiles were made in order to supervise and LOESS fit to visually analyze the trajectory of variables during time. Analysis of variance and HSD multiple comparison tests of Tukey-Kramertt HSD (p<=0.05) were applied to determine the existence of significant differences between the evaluated periods. All the statistical analysis was carried out with the use of JMP program, version 5.0 for Window (JMP 2003).

Results and Discussion

Recommendations for feeding sheep in tropical and warm regions are generally based on the standards established in temperate climate. Several factors may influence on the nutrient requirements of animals, such as breed, sex, age, body weight, and environmental conditions (NRC 2007). Mineral requirements of ovine have received great attention due to the necessity of precise prediction of their requirements, in order to minimize mineral excretions and environmental contamination. Therefore, it is necessary to study native or naturalized animals, adapted to their original conditions through natural selection, and currently considered as valuable genetic materials (Araujo et al. 2010).

Table 2 shows the results of macromineral content in the blood serum of Blackbelly sheep before, during and after gestation. Regarding Mg2+concentration, there were no differences (P≥0.05) among the different stages. Values obtained are within the normal ranges for Blakbelly breed (2.5 - 3.5 mg/L).

Table 2 Values obtained from the studied macroelements before, during and after gestation Blackbelly sheep 

abDifferent letters in the same line indicate significant differences (P≤0.05)

Figure 1 Fit curve for calcium (Ca) in relation to time 

Ca2+ concentration showed significant differences (P≤0.05) during time, showing changes at the moment of lambing and 30 days after. All values obtained are lower than the normal ranges needed for sheep (11 - 12 mg/L) during the studied period.

The value 0.8 was used as softening parameter. It seems like there is no change of Ca+ values throughout time. Nevertheless, the LOWESS fit is not descriptive, which means that it does not evidence the statistical significance throughout time.

Variable Na+ showed no significant differences (P≥0.05) in the time. The obtained values were normal for sheep population (139-152 mmL/L).

Variable P showed no significant differences (P≥0.05) in the time. The values obtained were lower than normal values in sheep (5-7 mg/L) in all the studied periods.

Minerals are essential nutrients for small ruminants and their concentration in blood should range within reduced intervals, maintaining adequate health state and wellbeing of animals. Proper concentrations of macronutrients favor the correct development of structural, physiological, catalytic and regulatory functions of the organism (Suttle 2000).

In the present study, calcemia of the studied sheep varied between 2.6 and 2.8 mg/L, values lower than those reported by Alonso et al. (1987), Underwood and Suttle (1999) and Quintero-Moreno et al. (2000) . The latter authors reported that normal values of calcium in the blood serum varied between 7 and 8 mg/100 mL in lambs. However, Norton (1994) indicated that Ca is rarely a limiting factor in forage diets. It is possible that the lowest content of Ca2+ in the pastures of Amazonia is due to a natural dilution process, by which dry matter production is higher than minerals absorption (Fleming 1973).

In the case of phosphorus, Underwood and Suttle (1999) indicated as critical level of deficiency of this element in blood concentrations lower than 4.03 units. The low content of P in the soil could explain the low content of P in blood serum (Masters et al. 1999). The variation of these elements (Ca2+ and P) may be explained by the fluctuation of climatic conditions (Orden et al. 1999).

Mg2+ concentration in blood serum varied between 2.5 to 2.7 mg/L. Magnesium should have values in blood between 1.45 and 1.82 mg/100 mL, establishing concentrations inferior to 1 mg/100 mL as critical level. The organic deficit of Mg produces low growing and development of animals. Mc Dowell et al. (1993) state that Mg is an enzymatic activator involved in the metabolism of carbohydrates and lipids because it is a catalyzer of great varieties of enzymes. In addition, Mg participates in protein synthesis through its activity in ribosomal aggregation. There is no homeostatic control for magnesium. Therefore, its concentration in blood directly shows the level in the diet (Moallem et al. 2007).

In the present study, Na+ concentration in blood of studied sheep varied between 136 and 146 mg/L. This element is the most abundant metabolite in the extracellular liquid. The small ruminants require Na+ supplementation because, in general, plants have low content of calcium. Moreover, according to ARC (1980), animals raised under tropical conditions, have higher requirements of this element because losses through the skin are superior than those of animals raised in temperate climate. High intakes of Na+ can increase K+ excretion (NRC 2007). Tropical forages have higher concentration of minerals, which justifies the need to evaluate their requirements in animals raised under warm conditions.

Improving animal yield, through the increase of biodiversity, may be a sustainable path towards a superior feed supply (Pereira et al. 2016). Hair sheep are important for global agriculture and management of natural resources in tropical areas (Pereira et al. 2017). The advance of ruminant nutrition in tropical environment requires a high understanding of mineral requirements (Regadas Filho et al. 2013), taking into account the diverse factors that have affected mineral concentration in animals (Salah et al. 2014).


It is concluded that there is a serum deficit of Ca2+ and P in the studied population of Blackbelly sheep under free grazing conditions of the Ecuadorian Amazonia during all the period. Supplementation should be selective for these minerals.


Alonso, A., Orden, M.A., Benedito, J.I., Tejón, D. & García Partida, P. 1987. Ionograma y enzimas séricas en ovinos merinos trashumantes. An. Vet. (Murcia) 3: 103-106. [ Links ]

Araújo, M. J., Medeiros, A. N., Teixeira, I. A. M. A., Costa, R. G., Marques, C. A. T., Resende, K. T. & Melo, G. M. P. 2010. Mineral requirements for growth of Moxotó goats grazing in the semi-arid region of Brazil. Small Ruminant Research 93,1-9. [ Links ]

ARC. 1980. The Nutrient Requirement of Ruminant Livestock. Agricultural [ Links ]

Barakat, N.A., Laudadio, V., Cazzato, E. & Tufarelli, V. 2013. Potential contribution of retamaraetam(Forssk.) Webb &Berthel as a forage shrubin Sinai, Egypt. Arid Land Res Manag. 27(3):257-271. [ Links ]

Fleming, G.A. 1973. Mineral composition of herbage. In: G.W Butler and W. Bailey (eds). Chemistry and biochemistry of herbage. Academic Press, London. p. 529-566. [ Links ]

JMP. 2003ón-jmp-2011Links ]

Masters, D.G., Purser, D.B., Yu, S.X., Wang, Z.S., Yang, R.Z., Liu, N., Lu, D.X., Wu, L.H., Ren, J.K. & Li, G.H. 1993. Mineral nutrition of grazing sheep in Northern China. 1 Macro-minerals on pasture feed supplement and sheep. Asian-Aust. J. Anim. Sci. 6: 99-105 [ Links ]

McDowell, L. R. 2003. Minerals in Animal and Human Nutrition.2 edition. Elsevier Science B.V., Amsterdam, The Netherlands. 644 p. [ Links ]

McDowell, L.R., Conrad, J.H. & Hembry, F.G. 1993. Minerals for grazing ruminants in tropical regions 2º Ed. University of Florida, Gainesville, USA.Animal Science Department Centre for Tropical Agriculture 53-55. [ Links ]

Mendives, J. A. Importancia de los ovinos tropicales intoducidos al país: Características productivas y reproductivas. 2007. Latinoam. Prod. Anim. 15(1): 310-315. Available: [ Links ]

Moallem, U., Katz, M., Arieli, A., & Lehrer, H. (2007). Effects of peripartum propylene glycol or fats differing in fattys acid profiles on feed intake production, and plasma metabolites in dairy cows. Journal Dairy Science. 90(8): 3846-3856. [ Links ]

Morales A., E., I. Domínguez V., M. González Ronquillo, G. Jaramillo E., O. Castelán O., N. Pescador S. & M. Huerta B. 2007. Diagnóstico mineral en forraje y suero sanguíneo de bovinos lecheros en dos épocas en el valle central de México. Técnica Pecuaria México 45:329-344 [ Links ]

Norton, B.W. 1994. The nutritive value of tree legumes. In: R.C. Gutteridge and H. M. Shelton (eds). Forage tree legumes in tropical agriculture. CAB International. Oxon. UK. p. 177-191. [ Links ]

NRC, 2007. Nutrient Requirements of Small Ruminants: Sheep, Goats, Cervids and New World Camelids, 1st edn. National Research Council. National Academy Press, Washington, DC. [ Links ]

Orden, E.A., Serra, A.B., Serra, S.D., Aganon, C.P., Cruz, L.C. & Fujihara, T. 1999. Mineral concentration in blood of grazing goats and some forage in Lahar-Laden area of Central Luzon, Philippines. Asian- Aust. J. Anim. Sci.12: 422-428 [ Links ]

Pereira, E.S., Fontenele, R.M., Medeiros, A.N., Lopes, R.O., Campos, A.C.N., Heinzen, E.L. & Bezerra, L.R. 2016. Requirements of protein for maintenance and growth in ram hair lambs. Tropical Animal Health and Production 48: 1323-1330. [ Links ]

Pereira, E. S, Lima1, F. W. R., Marcondes, M. I., Rodrigues, J. P. P., Campos, A. C. N., Silva, L. P., Bezerra, L. R., Pereira, M. W. F. & Oliveira, R. L. 2017. Energy and protein requirements of Santa Ines lambs, a breed of hair sheep. Animal 11:12, 2165-2174 [ Links ]

Quintero-Moreno, A., Miranda, S., López, R., Dean, D., Rojas, N., González, A., Palomares, R. & Boscan, J. 2000. Crecimiento, niveles de calcio, fósforo y magnesio y perfiles séricos de progesterona en corderas prepúberes mestizas west african suplementadas con tres fuentes de minerales. Revista Científica FCV-LUZ 10 (3):205-211. [ Links ]

Regadas Filho, J.G.L., Pereira, E.S., Pimentel, P.G., Villarroel, A.B.S., Medeiros, N.A. & Fontenele, R.M. 2013. Body composition and net energy requirements for Santa Ines lambs. Small Ruminant Research 109: 107-112. [ Links ]

Salah, N., Sauvant, D. & Archimède, H. 2014. Nutritional requirements of sheep, goats and cattle in warm climates: a meta-analysis. Animal 8, 1439-1447 [ Links ]

Suttle, N. F. 2010. Mineral Nutrition of Livestock. 4. H Edition. CABI Publishing, UK. 595 p. [ Links ]

Underwood, E. J. & N. F. Suttle. 1999. The Mineral Nutrition of Livestock. 3 Edition. CABI Publishing. UK. 624p [ Links ]

Underwood, E. J . & N. F. Suttle 2003. Los minerales en la nutrición del ganado.3 edición. Editorial ACRIBIA, S.A.,Zaragoza, España. 637 p. [ Links ]

Viñoles, C., G. Forsberg, G. Banchero & E. Rubianes. 2002. Ovarian folliculardynamics and endocrine profi les in Polwarth ewes with high and low body condition. Animal Science 74: 539-545 [ Links ]

Received: August 22, 2017; Accepted: June 28, 2018

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