Effects of solid feed level and roughage-to-concentrate ratio on ruminal drinking and passage kinetics of milk, concentrates, and roughage in veal calves

Research output: Chapter in Book/Report/Conference proceedingAbstract

Abstract

Effects of solid feed (SF) level and roughage-to-concentrate (R:C) ratio on ruminal drinking and passage kinetics of milk, concentrate, and roughage in veal calves were studied. Eighty calves (2 wk of age, 45 kg bodyweight) were divided over 16 pens. Pens were randomly assigned to a low (LSF) or a high (HSF) SF level, and to one of 2 R:C ratios; 20:80 or 50:50 on a DM basis. Roughage was composed of 50% corn silage and 50% chopped straw on a DM basis. During the measurement period at 27 wk of age, SF intake was 1.2 kg DM/d for LSF and 3.0 kg DM/d for HSF, and milk (replacer) intake averaged 2.3 kg DM/d for LSF and 1.3 kg DM/d for HSF. To estimate passage kinetics of milk, concentrate, and straw, indigestible markers (respectively CoEDTA, hexatriacontane C36, Cr-NDF) were supplied with the feed as a single dose at respectively 4, 24, and 48 h before slaughter. At slaughter, marker recovery was quantified in the rumen, abomasum, small intestine, and large intestine. Rumen Co recovery averaged 20% of the last milk meal. Recoveries of milk remained largely unaffected by SF level and R:C ratio. Ruminal recovery of C36 and Cr was unaffected by R:C ratio. Rumen fractional passage rate of concentrate was estimated from recovery of C36 in the rumen and increased (P <0.001) from 3.3%/h for LSF to 4.9%/h for HSF. Rumen fractional passage rate of straw was estimated from Cr recovery in the rumen and increased (P <0.01) from 1.3%/h for LSF to 1.7%/h for HSF. A greater SF level increased (P <0.001) fresh and dry rumen contents. In HSF calves, pH decreased (from 6.9 to 6.0; P <0.01) and VFA concentrations increased (P <0.05) with a lower R:C ratio, indicating increased fermentation. The Cr:C36 ratio was similar in the small and large intestine, indicating that passage of concentrate and straw was mainly determined by rumen and abomasum emptying. In conclusion, SF level rather than R:C ratio influences rumen passage of concentrate and roughage. Our data provide insight in passage kinetics of milk and SF and may contribute to the development of feed evaluation models for veal calves
Original languageEnglish
Title of host publicationBook of abstracts of 2015 Joint Annual Meeting of ADSA-ASAS
Pages869
Volume98
Publication statusPublished - 2015
EventJoint Annual Meeting 2015 ADSA-ASAS - Orlando
Duration: 12 Jul 201516 Jul 2015

Conference

ConferenceJoint Annual Meeting 2015 ADSA-ASAS
CityOrlando
Period12/07/1516/07/15

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