Variability of indigestible NDF in C3 and C4 forages and implications on the resulting feed energy values and potential microbial protein synthesis in dairy cattle

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dc.contributor.author Raffrenato, E.
dc.contributor.author Erasmus, L.J. (Lourens Jacobus)
dc.contributor.editor Muchenje, V.
dc.date.accessioned 2013-10-02T07:03:05Z
dc.date.available 2013-10-02T07:03:05Z
dc.date.issued 2013-08-15
dc.description.abstract Estimation of indigestible neutral detergent fibre (iNDF) is necessary for accurate and precise predictions of feed energy values and potential microbial protein from digested NDF in the rumen. Due to lengthy laboratory procedures, iNDF has been estimated using the formula ADLÃ?2.4 (iNDF2.4). The relationship between iNDF and acid detergent lignin (ADL) is more variable, across and within forage species. The purpose of our study was then to assess the variability of iNDF and respective implications on ration fine-tuning for dairy cattle. Sixty forages, including grasses, maize silages and lucerne hays, were fermented in vitro from 0 to 240 hours. Residual NDF of the fermented samples were obtained at 0, 6, 12, 24, 36, 48, 72, 96, 120, 144, 216 and 240 h, with the last value assumed to represent iNDF (iNDF240).This was used to obtain the potentially digestible NDF fraction (pdNDF). Rates of digestion of pdNDF were obtained assuming a first order decay. Simulations with the Cornell Net Carbohydrate and Protein System (CNCPS v 6.1, 2012) were done to evaluate the effects of the different estimated iNDF and NDF rate of digestion (kd) on energy and microbial protein estimations, assuming the requirements of a high-yielding lactating cow and a standard TMR with at least 50% forage. Results were dependent on the amount of forage and respective NDF and ADL. The iNDF240 values resulted between 1% and 136% higher than the iNDF2.4 values. The reduced pdNDF pool resulted in both lower cell wall linked protein in the rumen and microbial protein of around 5 to 165 g, and, as a consequence, on a total decreased metabolizable protein for milk. Use of iNDF240 showed consistently lower metabolizable energy (ME) between 2 and 10 MJ/day, compared to when using iNDF2.4. The improved metabolizable protein (MP) and ME values would result in 0.3 to 3.2 kg/d less milk when using iNDF2.4. This research demonstrates how points later in the fermentation curve, even if not biologically relevant for the cow, result in a more accurate and precise estimation of the rate of NDF digestibility. Indigestible NDF estimated at 240 h would give better predictions of rumen parameters in models like the CNCPS and better fine-tuning in dairy cow diets, especially when using high forage and/or NDF rations. en_US
dc.description.librarian am2013 en_US
dc.description.uri http://www.sasas.co.za en_US
dc.identifier.citation Raffrenato, E & Erasmus, LJ 2013, 'Variability of indigestible NDF in C3 and C4 forages and implications on the resulting feed energy values and potential microbial protein synthesis in dairy cattle', South African Journal of Animal Science, vol. 43, no. 5, pp. s 93-s97. en_US
dc.identifier.issn 0375-1589 (print)
dc.identifier.issn 222-4062 (online)
dc.identifier.other 10.4314/sajas.v43i5.17
dc.identifier.uri http://hdl.handle.net/2263/31869
dc.language.iso en en_US
dc.publisher South African Society for Animal Science en_US
dc.rights Copyright resides with the authors in terms of the Creative Commons Attribution 2.5 South African Licence. en_US
dc.subject In vitro digestibility en_US
dc.subject ADL en_US
dc.subject Metabolizable energy (ME) en_US
dc.subject Metabolizable protein (MP) en_US
dc.subject Indigestible neutral detergent fibre (iNDF) en_US
dc.subject Acid detergent lignin (ADL) en_US
dc.subject Cornell Net Carbohydrate and Protein System (CNCPS) en_US
dc.title Variability of indigestible NDF in C3 and C4 forages and implications on the resulting feed energy values and potential microbial protein synthesis in dairy cattle en_US
dc.type Article en_US


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