The goal of this study was to quantify the organic matter intake (OMI) of Pampinta rams grazing in a Panicum coloratum cv Verde differed pasture. The OMI was compared by two methods: a) the difference between the forage measured in pre and post-grazing condition, and b) the faecal production:digestibility ratio of the diet, estimated by total faecal gathering, and from the quantity of total faecal N in g per 100 g-1 of OMI and the concentration of total faecal N, respectively. The OMI estimated by difference between the forage measured in pre and post-grazing was 9 % higher (P\u3c 0,05) than the one estimated from total faecal gathering and OMD. Interaction was not detected (P\u3e 0,10) between treatments (length of the deferment period) and estimation method. The use of the faecal N can be utilized, considering the time of the year, to estimate the OMD and OMI in grazing condition in P. coloratum deferred pastures

Brizuela, M. A.

Ferri, C. M.

Petruzzi, H. J.

Stritzler, N. P.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XIX International Grassland Congress Intake Estimation of Rams under Grazing Condition in a Deferred Pastures of Panicum coloratum by Two Techniques C. M. Ferri Universidad Nacional de La Pampa, Argentina M. A. Brizuela Universidad Nacional de Mar del Plata, Argentina N. P. Stritzler Universidad Nacional de La Pampa, Argentina H. J. Petruzzi Universidad Nacional de La Pampa, Argentina Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/19/22/8 This collection is currently under construction. The XIX International Grassland Congress took place in São Pedro, São Paulo, Brazil from February 11 through February 21, 2001. Proceedings published by Fundacao de Estudos Agrarios Luiz de Queiroz This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. ID# 22-08INTAKE ESTIMATION OF RAMS UNDER GRAZING CONDITION IN ADEFERRED PASTURES OF PANICUM COLORATUM BY TWO TECHNIQUESC.M. Ferri1, M.A. Brizuela2,3, N.P. Stritzler1,4 and H.J. Petruzzi1,41Facultad de Agronomía, Universidad Nacional de La Pampa, (6300) Santa Rosa, Argentina,vjouve@cpenet.com.ar,2Universidad Nacional de Mar del Plata,3Comisión Investigaciones Científicas Provincia de Buenos Aires.4EEA Ing. Agr. G. Covas, INTAAbstractThe goal of this study was to quantify the organic matter intake (OMI) of Pampintarams grazing in a Panicum coloratum cv Verde differed pasture. The OMI was compared bytwo methods: a) the difference between the forage measured in pre and post-grazingcondition, and b) the faecal production:digestibility ratio of the diet, estimated by total faecalgathering, and from the quantity of total faecal N in g per 100 g-1 of OMI and theconcentration of total faecal N, respectively. The OMI estimated by difference between theforage measured in pre and post-grazing was 9 % higher (P<0,05) than the one estimated fromtotal faecal gathering and OMD.  Interaction was not detected (P>0,10) between treatments(length of the deferment period) and estimation method.  The use of the faecal N can beutilized, considering the time of the year, to estimate the OMD and OMI in grazing conditionin P. coloratum deferred pastures.Keywords: Faecal N, digestibility, intake, rams, grazingIntroductionThe quantification of the intake under grazing condition is a very complex task;however, several methods have been developed. The daily intake of the flock can beconsidered through the difference between the biomass at pre- and post-grazing condition(Meijs et al. 1982). On the other hand, the determination of the individual intake can beestablished through the estimation of the faecal production and the digestibility of the diet. Toobtain a representative diet samples is the main factor limiting the accuracy of estimation ofthe digestibility (Burns et al. 1994). The faecal index technique would eliminate thatlimitation since it doesn't require diet samplings and it only involves routine chemicaldeterminations.During the 90’s, several trials have been carried out with Panicum coloratum L. toevaluate its potential as a winter deferred forage resource in the semi-arid Pampean Region(Stritzler et al., 1996, Ferri et al., 1998ab). The objective of this study was to compare theintake by grazing rams in P. coloratum deferred pastures using two different approaches: a)the difference between the forage measured in pre- and post-grazing, and b) the faecalproduction:digestibility ratio of the diet.Material and MethodsThe study was carried out in 1997 and 1998 in the Facultad de Agronomía (UNLPam)at Santa Rosa (36°46´S; 64°16´W) using a pasture of Panicum coloratum cv Verde. Themeasurements were made using 60 Pampinta rams with an initial live weight of 49,6±5,1 and45,4±5,2 kg in July of each year, respectively. The organic matter intake (OMI) wasdetermined considering paddocks with different dates of beginning of the defermentprocesses.  During the first growing season (1996/97), the treatments were generated byforage deferment: during the whole season (T1.1), after a harvest by middle of January (T2.1),and of a harvest by the middle of February (T3.1). In the second growing season (1997/98),the treatments were generated by forage deferment produced after harvests carried out: in themiddle of December (T4.2), early in January (T5.2), and early in February (T6.2). In eachseason, the treatments were assigned at random with two replications. Grazing was conductedwith daily strip changes, five rams per paddocks, and an allowance of 40 g DM kg LW-1,which was determined by three harvest of the availabable forage at the beginning of thegrazing (pre-G). To determine the residual forage (post-grazing: post-G) it was made threemeasurements paired to the previous ones.  In the pre-G samples it was determined thechemical composition (ash, crude protein, neutral detergent fiber, acid detergent fiber, andacid detergent lignin) and the in vitro dry matter digestibility (IVDMD). The 8-dayexperimental period was preceded by a period of adaptation of 15 days.The OMI was estimated by two techniques: from the difference between the foragebiomass measured in pre-G and post-G (Meijs et al. 1982), and from the faecal out put /undigestibility ratio: OMI = H / (1 - OMD), where H = daily production of OM of faeces andOMD = digestibility of the OM.  The quantity of H was obtained by two daily gathering, bymeans of harness and collector bags on three animals for treatment.  The OMD wasdetermined according to the equation proposed by Lancaster (1949): OMD= 100 (1-C/FN),where C = the quantity of total N excreted in g per 100 g-1 of OMI, and FN = theconcentration of total N in faeces (g N 100-1 g OM).The estimation with each technique of the mean daily intake of the flock  wasanalyzed using the following model: Yijk = µ+αi+βj+(αβ)ij+δk+(βδ)jk+εijk;  where αi =  therepetition (i = 1..2), βj = the effect of the deferment period (j =1..6), δk = the effect of thetechnique of intake estimation (k = 1..2) and ε = the residual error.Results and DiscussionThe means, standard deviations and ranges of values of the chemical composition andthe IVDMD of forage, and those of the faecal production and daily N excretion are presentedin Table 1. The estimates of mean daily OMI are shown in Table 2.Treatment x estimating method interaction was not significant (P>0,10). The nonsignificant interaction indicates that length of the deferment period does not modify theexcretion of faecal N in g 100-1 per g of OMI (C). According to these results, the time of theyear has an important effect and should be taken into account to establish the value of C. TheOMI estimated from biomass difference between pre- and post-grazing was 9 % higher(P=0,042) than that estimated from the faecal output / undigestibility. The two methods ofintake estimation showed to be sensitive to treatment effects.  However, the technique of thetotal collection of faeces and the OMD allow to make estimations on individual animals.  Theuse of the faecal N to estimate the OMD and OMI in grazing can be applicable when it is notfeasible to get an accurate sample from the animal diet (Corbett 1978).  In monoespecíficpastures it could be useful to improve the knowledge to design pasture utilization systems andto help predicting animal performance.ReferencesBurns, J.C., Pond K.R.  and Fisher D.S. (1994).  Measurement of forage intake. p. 494-531.In: G.C. Fahey, Jr. (ed.). Forage quality, evaluation, and utilization. American Society ofAgronomy. Madison, WI., USA.Corbett, J.L. (1978). Measuring animal performance. p. 163-231. In: t’Mannetje (ed.)Measurement of grassland vegetation and animal production. CAB, UK.Ferri, C.M., Jouve V.V., Stritzler N.P. and Petruzzi H.J. (1998a). Estimation of intake andapparent digestibility of kleingrass from in situ parameters measured in sheep. AnimalScience 97:535-540.Ferri, C.M., Petruzzi H.J., Stritzler N.P. and Jouve V.V. (1998b). Consumo voluntario,digestibilidad in vivo y proteína bruta dietaria en distintas épocas de utilización de Panicumcoloratum diferido. Revista Argentina de Producción Animal 18:163-170.Lancaster, R.J. (1949).  Estimation of digestibility of grazed pasture from faeces nitrogen.Nature 163:330-331.Meijs, J.A.C., Walters R.J.K.  and Keen A. (1982). Sward methods. p. 11-36. In: J.D..Leaver (ed.) Herbage Intake Handbook. British Grassland Society. Hurley, Maidenhead,England.Stritzler, N.P., Pagella J.H., Jouve V.V.  and Ferri C.M. (1996).  Semi-arid warm-seasongrass yield and nutritive value in Argentina. Journal of Range Management 49:121-125. Table 1 - Mean, standard deviation (s.d.) and range of values of (a) chemical compositionand in vitro dry matter digestibility (g kg-1 DM) of deferred Panicum coloratum; and (b) totaldaily faecal production and daily N excretion by grazing rams .Variable† Mean s.d. Range(a) Chemical composition and dry matter digestibilityASH   88 18   72-135CP   26   5 20-35NDF 702 22 656-738ADF 450   9 434-466ADL   61   8 49-74IVDMD 369 23 342-423(b) Total daily faecal production and daily N excretionOM faecal(g kg-1 LW d-1)       9.41     1.39 6.17-11,90Total faecal N(g 100 g-1 OM) 1.180 0.117 1.020-1,451(g kg LW-1 d-1) 0.111 0.020 0.074-0,154† CP: crude protein, NDF: neutral detergent fiber, ADF: acid detergent fiber, ADL: acid detergent lignin,IVDMD: in vitro dry matter digestibility.Table 2 - Means daily organic matter intake (OMI; g kg LW-1) of Panicum coloratum underdifferent treatments as estimated by two techniques: A – agronomic difference and B –indirect technique based on faecal output and organic matter undigestibilityTreatmentsTechniques T1.1 T2.1 T3.1 T4.2 T5.2 T6.2 Means A 18.2 18.4 21.8 14.2 15.9 17.9 17.9ª B 15.2 15.5 18.3 14.8 16.8 19.1 16.4bMeans: 16,7bc 16,9bc 20,0a 14,5c 16,4bc 18,5aba, b, c  Means with different superscripts are significantly different (P<0.05).Table 1 - Mean, standard deviation (s.d.) and range of values of (a) chemical composition andin vitro dry matter digestibility (g kg-1 DM) of deferred Panicum coloratum; and (b) totaldaily faecal production and daily N excretion by grazing rams .Variable† Mean s.d. Range(a) Chemical composition and dry matter digestibilityASH   88 18   72-135CP   26   5 20-35NDF 702 22 656-738ADF 450   9 434-466ADL   61   8 49-74IVDMD 369 23 342-423(b) Total daily faecal production and daily N excretionOM faecal(g kg-1 LW d-1)       9.41     1.39 6.17-11,90Total faecal N(g 100 g-1 OM) 1.180 0.117 1.020-1,451(g kg LW-1 d-1) 0.111 0.020 0.074-0,154† CP: crude protein, NDF: neutral detergent fiber, ADF: acid detergent fiber, ADL: aciddetergent lignin, IVDMD: in vitro dry matter digestibility.Table 2 - Means daily organic matter intake (OMI; g kg LW-1) of Panicum coloratum underdifferent treatments as estimated by two techniques: A – agronomic difference and B –indirect technique based on faecal output and organic matter undigestibilityTreatmentsTechniques T1.1 T2.1 T3.1 T4.2 T5.2 T6.2 Means A 18.2 18.4 21.8 14.2 15.9 17.9 17.9ª B 15.2 15.5 18.3 14.8 16.8 19.1 16.4bMeans: 16,7bc 16,9bc 20,0a 14,5c 16,4bc 18,5aba, b, c  Means with different superscripts are significantly different (P<0.05).

Intake Estimation of Rams under Grazing Condition in a Deferred Pastures of \u3ci\u3ePanicum coloratum\u3c/i\u3e by Two Techniques

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Intake Estimation of Rams under Grazing Condition in a Deferred Pastures of \u3ci\u3ePanicum coloratum\u3c/i\u3e by Two Techniques

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