Comparison between two techniques for estimating voluntary intake of female buffaloes under grazing conditions. Technical note

Comparación de dos técnicas para la estimación del consumo voluntario de búfalas en pastoreo. Nota técnica

Odilia Gutiérrez,^I J. Cairo,^I B. Ramírez,^II G. Vasallo,^I M. Varela,^I

ABSTRACT

In order to compare two techniques for estimating dry matter intake of female buffaloes under grazing conditions, 25 pairs of data were used, obtained from the application of the technique of double marking (Cr₂O₃ and IAA) and estimation by the method of metabolizable energy. The analysis of variance for a probability level of 95.0% indicated that there were no differences between the intakes estimated by the methods of double marking (17.20 kg DM/d) and energy (16.84 kg DM/d). There was a high correspondence between the DM intakes estimated by both methods, with determination (R² = 0.94) and correlation coefficient (r = 0.97), and low values of the mean square error. The results demonstrate that the methodology for estimating intake under grazing conditions, proposed by NRC (2001) and adapted by Pérez Infante (2013), can be compared with the traditional technique of double marking, which may be useful for further studies on intake under grazing conditions, destined to buffaloes.

Key words: ingestion, grasses, markers.

RESUMEN

Para establecer comparaciones entre dos  técnicas, con el propósito de estimar el consumo de materia seca de búfalas en pastoreo, se utilizaron 25 pares de datos obtenidos de la aplicación de la técnica de doble marcaje (Cr₂O₃ y CAI) y de  estimación por el método de la energía metabolizable. El análisis de la varianza para  nivel de confianza de 95.0 % indicó que no hubo diferencias entre los consumos estimados por los métodos de doble marcaje (17.20 kg MS/d) y  energía (16.84 kg MS/d). Hubo alta correspondencia entre  el consumo de MS estimado por ambos métodos, con  coeficiente de correlación (r = 0.97) y determinación (R² =0.94) y bajos valores del cuadrado medio del error. Los resultados demuestran que  la metodología para estimar el consumo en pastoreo, propuesta por NRC (2001) y  adaptada por Pérez Infante (2013), es comparable con la tradicional del doble marcaje, lo que  pudiera resultar de gran utilidad para estudios posteriores de consumo en pastoreo, destinados a la especie bubalina.

Palabras clave: ingestión, pastos, marcadores.

INTRODUCTION

NRC (2001) proposes a less complex method for estimating dry matter intake of cows in grazing, which only takes into account the measurable indicators belonging to the animals. Pérez Infante (2013) introduced an adaptation to this methodology, which relates the requirements of metabolizable energy of the animal with that provided by the grass. This method was not used before for estimating dry matter intake of female buffaloes in grazing, so the objective of this study was to establish comparisons between the two techniques for estimating dry matter intake of female buffaloes in grazing.

In order to compare the two methods of intake estimation of female buffaloes in grazing, 25 data of individual intake were taken, determined by the application of the technique of double marking with Cr₂O₃ and insoluble acid ashes (Geerken et al. 1987), and 25 data of intake of the same female buffaloes, estimated by the methodology proposed by Pérez Infante (2013). For estimating intake through the method of metabolizable energy, liveweight, and production and composition of milk from animals was taken into consideration. The tables of nutritional requirements of Méndez and Lima (2011) for lactating female buffaloes were used.

Table 1 shows the data of dry matter intake, estimated by the methods of double marking and metabolizable energy. There were mean intakes of 17.2 and 17.84 kg of DM and there were no differences among them. These results represent figures around 2.4 % of liveweight, and coincide with those of Gutiérrez et al. (2014) for female buffaloes in grazing, under the same conditions of this study.

Figure 1 shows the curve that presents the estimated dry matter intake obtained through the two methods. The analysis of variance, for a probability level of 95.0 %, indicated that there were no differences among the intakes estimated by the methods of double marking and metabolizable energy, with a low mean square of the prediction error.

Analysis of linear regression:

Variable N   R²  R² Aj ECMP  AIC   BIC

          25 0.94  0.93 0.68 60.64 64.30

There was a high correspondence among the intake estimations, after comparing the data obtained by the markers and the estimated by the metabolizable energy with coefficient of correlation (r = 0.94).

Y = a + bx   

a: 4.05  

b: 0.73

R² = 0.94

 Dulau (2011) reported a good correlation between the methods, by cut and by net energy, using the calculation of intake of milking males in grazing, where the measuring method through the pasture measuring underestimated it. Correa et al. (2009) also made comparisons among the estimated intakes with the use of markers (ADFiis/Cr) and the results of the equations from NRC (2001) and from the Cornell net carbohydrates and proteins system (CNCPS) through the analysis of variance and the mean square of the prediction error (ECMP) of each equation. In this case, the coefficients of determination (R²) were low, together with the high values of the mean square of the error, which demonstrated a low prediction of intake.

However, this study showed a great correspondence between the method of double marking (traditional) and the one of metabolizable energy, with a coefficient of correlation of 0.94, and low values of the mean square of the error.

The technique of intake estimation by double marking has demonstrated its reliability, due to the almost total recovery of Cr from the feces (Bargo 2008). In this study, taken as reference, it was closely related to the method of metabolizable energy, which could be faster and simpler due to its principles, with a proper control of the indicators belonging to the animals. Nevertheless, it is necessary to point out that the comparison was performed with female buffaloes in grazing with different intake habits to bovines.

It is important to highlight that the main result of this study is the practical value of the methodology reviewed by Pérez Infante (2013). Its application, under production conditions, is completely feasible and very important because it solves, with a high level of accuracy, the problem of estimating with the best precision dry matter intake of animals.

Nevertheless, it is necessary to increase the number of observations in grazing systems under different conditions to confirm the validity of technology.

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Correa, H. J., Pabón, M. L. & Carulla, J. E. 2009. ‘‘Estimación del consumo de materia seca en vacas Holstein bajo pastoreo en el trópico alto de Antioquia’’. Livestock Research in Rural Development, 21: 207.

Dulau, D. 2011. Estimación del consumo en pastoreo. Comparación de distintos métodos. , Available: <http://www.engormix. com/MA-agricultura/pasturas/articulos/produccion-animal-pastoreo-definiciones-t1439/p0.htm>, [Consulted: November 4, 2012].

Geerken, C. M., Calzadilla, D. & González, R. 1987. ‘‘Aplicación de la técnica de dos marcadores para medir el consumo de pastos y la digestibilidad de la ración en vacas en pastoreo suplementadas con concentrado’’. Pastos y Forrajes, 10: 266.

Gutiérrez, O. J., Cairo, B., Ramírez, N., Dorta, G., Vasallo & Varela, M. 2014. ‘‘Voluntary intake and productive performance of female buffaloes with a new pre-mixture adjusted to their nutritional requirements’’. Cuban Journal of Agricultural Science, 48: 109.

Mendez, A. J. & de Lima, F. 2011. ‘‘Aspectos nutricionales del búfalo’’. Tecnología en Marcha, 24 (5): 105–120.

NRC 2001. The nutrient requirement of dairy cattle. 7th ed., Washington D.C.: National Academy Press, 381 p.

Pérez, I. F. 2013. Nueva ganadería en pastos. Asociación Cubana de Producción Animal, ISBN: 978-959-307-075-1.

Received: January 19, 2015
Accepted: July 28, 2015

Odilia Gutiérrez, Instituto de Ciencia Animal, Apartado Postal 24, San José de las Lajas, Mayabeque, Cuba. Email: ogutirrez@ica.co.cu