Effects of dietary carbohydrate sources on degradation kinetics of nitrogen from plant protein sources in the rumen

Guedes, Cristina; Dias‐da‐Silva, A.

doi:10.1002/jsfa.2196

Cited by 3 publications

(1 citation statement)

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“…In addition, the in sacco degradation parameters are typical for these feeds (Guedes and Dias-da-Silva, 2005), with MGF having very high N wash losses, twice those for SFM and SBM. As expected, although the DM degradability of SFM was lower than that of SBM, the degradation rate of insoluble N was much higher for SFM.…”

Section: Protein Sourcesmentioning

confidence: 99%

Effects of protein sources on concentrations of hydrogen sulphide in the rumen headspace gas of dairy cows

Fonseca

Cabrita

Pinho

et al. 2013

Animal

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Two Latin square design experiments investigated the relationship between hydrogen sulphide concentration in the rumen headspace gas of dairy cows and the early stages of protein degradation in the rumen. In Expt 1, three protein sources differing in rumen N (nitrogen) degradability (maize gluten feed (MGF); sunflower meal (SFM); and soyabean meal (SBM)) were used, whereas in Expt 2 four different batches of the same feed (MGF) differing in colour (CIE L*, a*, b* (CIELAB) scale) were used. After allowing the concentration of hydrogen sulphide in rumen gas to decline close to zero, a fixed amount of protein sources was offered to cows and the concentrations of hydrogen sulphide were recorded in rumen headspace gas at 30-min intervals. In Expt 1, the concentration of hydrogen sulphide showed considerable variation between protein sources, with MGF having the highest concentration followed by SFM and SBM resulting in very low concentrations. The N wash losses (zero time measurements with nylon bags) ranked the feeds in the same way, from MGF (highest; 61%) to SBM (lowest; 26%). There were marked differences in the degradation of cystine and methionine between protein sources, although the degradation of cystine was always higher than for methionine. MGF (Expt 2) led to increased concentrations of hydrogen sulphide, with peak concentrations achieved between 1 and 2 h after feeding. The concentrations of hydrogen sulphide were higher for MGF1, intermediate for MGF2 and lower for MGF3 and MGF4, agreeing with colour scale. Differences in the early stages of dietary sulphur degradation corresponded with differences in hydrogen sulphide concentrations in rumen gas. The results suggest that hydrogen sulphide concentrations in the rumen headspace gas could be useful to evaluate nutritional parameters not measured by the in sacco technique, contributing to a better understanding of the response of dairy cows to different protein supplements.Keywords: dairy cow, hydrogen sulphide, rumen, protein sources Implications Differences in rumen headspace gas concentrations of hydrogen sulphide are related to the degradation of sulphur (S) in the rumen. As a high proportion of dietary S is contained within protein, this association offers potential for a new approach to compare protein degradation of different protein sources. This may be particularly useful for studying the early stages of degradation of soluble proteins where the existing nylon bag technique is of limited value.

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Section: Protein Sourcesmentioning

confidence: 99%