The effect of dent versus flint maize genotype on site and the extent of starch and protein digestion, ruminal fermentation and microbial protein synthesis in the rumen of sheep

Abstract

-Ruminal and whole tract digestibility of protein and starch, microbial protein yield in the rumen and molar proportions of volatile fatty acids (VFA) in the rumen fluid and faeces were determined in sheep that were given either maize silage derived from the dent (DTS) or flint type hybrid (FTS). Degradabilities in the rumen were determined by means of the in sacco method using three sheep and microbial protein yield in the rumen by means of urinary purine derivative excretion using four sheep. The extent of starch and protein degradation was significantly (P < 0.001) lower in FTS than in DTS (718 vs. 913 and 704 vs. 767 g·kg -1 respectively). Differences in whole tract starch and protein digestibility were small (986 vs. 997, P < 0.01 and 939 vs. 931 g·kg -1 , P < 0.05 in FTS and DTS respectively). The concentration of VFA in the rumen fluid was not affected by the type of silage (94.5 and 94.7 mmol·L -1 ); however, FTS induced a higher molar proportion of propionate (22.6% vs. 20.7%, P < 0.05) than DTS. The proportion of butyrate was higher in DTS (13.5% vs. 10.8%, P < 0.05). Microbial protein supply in FTS was significantly higher than in DTS (109.7 vs. 96.0 g·kg -1 DM intake, P < 0.05). When expressed in relation to fermentable organic matter (FOM) intake, the differences between hybrids were greater (215.6 vs. 158.6 g of microbial protein per kg FOM, P < 0.01). Lower efficiency of microbial protein synthesis in DTS was probably due to a lower pH value of rumen liquor (6.21 vs. 6.33, P < 0.05). FTS offered better conditions for the degradation of the fibre fraction in the rumen than DTS. The faeces of sheep that were given FTS contained less DM (304 vs. 371 g·kg -1 , P < 0.05) and tended to have a higher concentration of VFA (383 and 235 mmol·kg -1 DM, P < 0.1) indicating that in FTS at least one part of the starch which escaped digestion in the rumen passed through the small intestine undigested and was fermented in the large intestine. It was concluded that FTS could provide about three times more postruminally digested starch and about 20% more metabolisable protein than DTS. Résumé -Effet du génotype de maïs (denté vs. corné) sur le site et le volume de la digestion de l'amidon et des protéines, sur la fermentation ruminale, et sur la synthèse des protéines microbiennes dans le rumen chez les ovins. La digestibilité des protéines, de l'amidon et des constituants pariétaux dans l'ensemble du tractus digestif, le rendement de synthèse des protéines microbiennes dans le rumen et les proportions molaires des acides gras volatils (AGV) dans le jus de rumen et dans les fèces ont été déterminées sur des ovins qui ont reçu de l'ensilage de maïs de type denté (DTS) ou corné (FTS). Les dégradabilités dans le rumen ont été mesurées par la méthode in sacco sur trois ovins alors que le rendement de synthèse des protéines microbiennes a été déterminé à partir de l'excrétion urinaire des dérivés de purines en utilisant quatre ovins. L'importance de la dégradation de l'amidon et des protéines a été significativ...

Effect of maturity and hybrid on ruminal and intestinal digestion of corn silage in dry cows

“…The atypical climate conditions in year 2012 may have enhanced the earliness-related differences in chemical composition between hybrids. The N content of the silages ranged from 1.2 to 1.3% of DM, and was similar among hybrids (as reported by Verbic et al, 2005). In agreement with a review by Khan et al (2015), and as already integrated in INRA (2007) feed tables, starch content increased and NDF and ADF contents decreased with increasing maturity for hybrid FD.…”

“…Fast starch fermentation has been shown to reduce ruminal pH, inhibit fiber digestibility, and thereby increase the risk of digestive disorders (Beauchemin and Yang, 2005). Studies exploring the variability of corn digestion in cattle have investigated the effects of genotype (Taylor and Allen, 2005;Verbic et al, 2005) and grain processing (Huntington, 1997;Johnson et al, 2002;Fernandez et al, 2004) on ruminal starch digestion measured in situ (Lopes et al, 2009;Ali et al, 2014) and in vitro (Tang et al, 2011;Opsi et al, 2013). However, most of the in vivo studies (Bal et al, 1997;Fernandez et al, 2004) available have focused on starch from concentrate-supplemented corn silage diets.…”

The effect of supplementing highly wilted grass silage with maize silage, fodder beet or molasses on degradation of the diets and the efficiency of microbial protein synthesis in the rumen of sheep

“…When compared to GS, a decrease of metabolizable protein concentration in GS-MS was mainly due to a decrease in the supply of postruminally digested dietary protein while GS-FB and in GS-M both, a decrease in the supply of postruminally digested dietary protein as well as a decrease in the supply of digestible true microbial protein, were observed. In absolute terms the metabolizable protein concentrations in diets from the present experiment are higher than those obtained for maize silage (Verbič et al, 2005) and considerably higher than for GS values reported by Verbič et al (1999).…”

“…Higher degradabilities are expected in silages made from dent type grain hybrids than in those characterised by the flint type grain (Verbič et al, 2005). Despite the fact that in the present experiment MS was made of flint type hybrid, EDGCP was closer to the value reported for silage from dent type hybrid (Verbič et al, 2005). The EDGCP of FB was slightly lower than what was reported by Hvelplund and Weisbjerg (2000) (880 g kg -1…”

“…In MS, protein degradation in the rumen depends on the type of grain. Higher degradabilities are expected in silages made from dent type grain hybrids than in those characterised by the flint type grain (Verbič et al, 2005). Despite the fact that in the present experiment MS was made of flint type hybrid, EDGCP was closer to the value reported for silage from dent type hybrid (Verbič et al, 2005).…”