AROEIRA, L. J. M.

BERCHIELLI, T. T.

LEME, P. R.

LIMA, M. L. P.

NOGUEIRA, J. R.

RUGGIERI, A. C.

SALMAN, A. K. D.

SOARES, J. P. G.

English

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ID # 19-19VOLUNTARY INTAKE OF TANZANIA GRASS (Panicum maximum) UNDERROTATIONAL GRAZING BY LACTATING COWS1M.L.P. Lima2,3, T.T. Berchielli2,4, J.R. Nogueira3, A.K.D. Salman2 A.C. Ruggieri3, P.R.Leme4, L.J.M. Aroeira5, J.P.G. Soares21 Project partially supported by FAPESP2 FCAV/ UNESP - Jaboticabal, SP, CNPq Researcher3 Instituto de Zootecnia, C.P. 206, 14001-970, Ribeirão Preto, SP, Brasil4 FZEA/ USP- Pirassununga, SP5 EMBRAPA/CNPGLAbstractThe study was conducted at Nucleo de Pesquisas Zootecnicas Nordeste of the Institutode Zootecnia, Ribeirão Preto, SP, in a rotational grazing area of Tanzania grass (Panicummaximum),  to estimate the dry matter intake by lactanting cows. The estimation of dry matterintake was calculated from the feces production estimated using extrusa Chromium-mordentand the in vitro digestibility of diet. The three treatments were crossbreed cows fed 3 kg.day-1of concentrate, crossbred cows without concentrate suplementation and pure Gir cows alsowithout concentrate supplementation. The milk production was 11.98, 6.53 and 5.46 kg percow per day, the grass intake was 8.26  5.66, 11.01  5.37 and 9.55  2.31 kg of dry matterper day or 2.15%, 2.37% and 2.34% of live weight for the three experimental groupsrespectively. The milk production was higher (P<0.01) for cows fed with concentrate. Nodifference was found for dry matter intake.Keywords: dry matter intake, digestibility, marker indigestedIntroductionThe Tanzania grass is a Panicum maximum variety produced by the Centro Nacionalde Pesquisa com Gado de Corte (EMBRAPA) in 1990. This plant has a high  massproduction, up to 80% of leaves and supported 4,7 animal units (450 kg) per ha (Corsi andSantos, 1995). Also, this plant has a good adaptation and growth on low fertility soil,  and iseasily managed  (Euclides et al., 1999)The pasture dry matter intake affects animal performance because it determinates theintake of nutrients (Gomide, 1993). Studies to estimate the dry matter intake from pastureusing the relation between the fecal production and the indigestible fraction of forage arerecommended. (Aroeira, 1977). Also are recommended the utilization of material taken fromesophageal fistulated animal (extrusa) because of the animal selection during grazing(Aroeira, 1997). The objective of this experiment was to estimate the dry matter intake in arotating grazing area of Tanzania grass (Panicum maximum) by lactating cows.Material and MethodsThe study was conducted at the Nucleo de Pesquisas Zootecnicas Nordeste of theInstituto de Zootecnia, Ribeirao Preto, SP.The experimental area had fourteen 1.13 ha pastures, with Tanzania grass (Panicummaximum), fertilized with 150 kg.ha -1 of nitrogen per year, and managed in rotation withthree days of occupation and 36 days without animals. The mean stocking rate was 2.1 cows.kg.ha -1 .To evaluate the dry matter intake of the pasture 24 lactating cows were  distributed inthree groups as follows: eight pure breed Gir cows, on grass only, eight crossbred Gir xHolstein cows also on grass only and eight crossbred Gir x Holstein cows on grass and fed 3kg of concentrate per day. The experimental design was a  complete block design. Thecomposition of the concentrate was 72.2% corn, 25.3%  soybean meal and 2.5% minerals.The grass dry matter intake was calculated from the estimate of the feces productionand the in vitro dry matter digestibility  using the following equation:where:FP = total of feces produced per cow (kg de MS/day)IVDDM = in vitro dry matter digestibilityFeces production was estimated using extrusa Cr-mordent (treatment with sodiumdichromate, Na2Cr2O7H2O). Each animal received 30 g of extrusa Cr-mordent in thebeginning of the experiment. The feces were collected after 6, 9, 12, 24, 32, 36, 48, 56, 72, 80,96, 104 and 120 hours after the ingestion of marker.The analyses of residual chrome in feces was made according to Willians (1962). Theexcreted feces curves was made from the model proposed by Pond (1989):whereY= marker concentrationK0= initial marker concentrationL1= passage ratet = time after marker ingestion = time until the first apparition of  the marker in the feces.IVDDM1FP)day.DMkg(akeintGrass 159635.0e)t(LKoY)1L(1The  daily total feces (TF) production was calculated from the relation:Where:K0= initial marker concentrationK1 = passage rate of ruminal solid fractionThe statistical analyses was made using the SAS (1992), program.Results and DiscussionThe total forage mass was 7340 kg.ha-1 at the time turning the cows into the paddocksand 5639 kg.ha-1 after the 3rd day of grazing. The proportion of leaves, stem and dead materialwas 62%, 30% and 8% after the 1st occupation day and 47%, 37% and 16% after the 3rdoccupation day.Table 1 shows the grass (extrusa) and concentrate composition and in vitro dry matterdigestibility.The average of milk production was 11.98, 6.53 and 5.46 kg per cow.day-1 for thecrossbred Gir x Holstein cows fed 3 kg of concentrate, crossbred Gir x Holstein cows andpure breed Gir cows, both without concentrate, respectively. There was a difference (P<0.01)between crossbred cows fed concentrate and other groups but no difference between Gir andcrossbred cows, both without concentrate supplementation.The live weight of the cows (LW), grass and concentrate dry matter intake (DMI) andthe relation between dry matter intake and live weight, in percentage, for the threeexperimental groups are presented in Table 2.24*K)DMg/g(Ko)g(ingestedkermar)day.DMg(TF11Even thought the Gir group produced less milk than the crossbred cows (P<0.01),there was no difference in grass dry matter intake, total dry matter intake and dry matterintake as a percentage of live weight.Similar intake of Tanzania grass without supplementation of concentrate was observedby Euclides et al. (1993b), working with steers. In another experiment, Euclides et al. (1999),also working with steers, measured a dry matter intake of Tanzania grass equivalent to 2.46%of the live weight, also similar to the results presented in this work.ReferencesAroeira, L.J.M. (1997) Estimativas de consumo de gramineas tropicais. In: TEIXEIRA, J.C.(Ed.) Digestibilidade em Ruminantes. Lavras: UFLA/FAEP. p. 127-163Corse, M. e Santos, P. M. (1995). Potencial de Produção do Panicum maximum. Anais do12o Simpósio sobre Manejo da Pastagem tema: O Capim Colonião. Anais.... Escola Superiorde Agricultura “Luiz de Queiroz” FEALQ.  Piracicaba. p.275-304Euclides,V. P B., Thiago,L.R L.S., Oliveira, M.P. (1993). Consumo de forragem pornovilhos pastejando cinco gramíneas. In: Reuniao Anual da Sociedade Brasileira deZootecnia, 30, 1993, Rio de Janeiro, RJ. Anais... p.491Euclides,V. P B., Thiago,L.R .L.S., Macedo, M.C. M., Oliveira, M.P. (1999). Consumovoluntario de forragem de tres cultivares de Panicum maximum sob pastejo. Rev. Soc. Bras.Zootec., 28:1177-1185.Gomide. J. A. (1993). Produção de leite em regime de pasto. Rev. Soc. Bras. Zootec.,22:591-613.Pond, K.R. (1989). Passage of chromium-mordanted and rare earth-labeled fiber: time ofdosing kinetics. J.Anim. Sci., 67:1020-28.SAS users guide: statistics. Cary, SAS Institute Inc., 1992. 965p.Willians, C.H. (1962). The determination of chromic using absorption spectrophotometer.J.Agric.Sci., 59:381-5.Table 1 - Composition of grass collected from esophageal fistulated animal (extrusa), andconcentrate and in vitro dry matter digestibility.% of dry matterDM (%) CP NDF ADF Ash IVDMDExtrusa 13.8 12.1 78.8 42.6 5.9 66.5Concentrate 88.7 19.9 27.0 5.8 - 97.5DM = dry matter, CP = crude protein, NDF = neutral detergent fiber, ADF= acid detergent fiber, IVDMD =extrusa dry matter in vitro digestibility.Table 2 - Live weight of the cows (LW), dry matter intake (DMI) of grass and concentrate(Conc.) and the relation between dry matter intake and live weight, in percentage, for the threeexperimental groups.Treatment      LW                DMI (kg. cow.-1day-1) % LWkg.cow-1        Grass Conc. Total Grass   Conc.     TotalSupplemented crossbredcowsNot supplemented crossbredcowsNot supplemented Gir cows504a495a418b8.26  5.6611.01  5.37  9.55  2.312.59   --10.8511.01  9.55       1.63       0.52        2.15       2.37          -            2.37       2.34          -            2.34a,b Means, in the same column, followed by different letters are different (P<0.01) by the Tukey test.

Voluntary intake of tanzania grass (Panicum maximum) under rotational grazing by lactating cows.

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Voluntary intake of tanzania grass (Panicum maximum) underrotational grazing by lactating cows.

Voluntary intake of tanzania grass (Panicum maximum) underrotational grazing by lactating cows.

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