Studies on ruminant saliva. 1. The composition and output of sheep's saliva

Efficacy of combined acid-heat treatments to protect crude protein (CP) against ruminal degradation has not been extensively researched. Four in vitro trials (Daisy technology) with orthophosphoric and malic acids were performed to examine effects on protection of sunflower meal protein. In Trial 1, effects of the solution volume for adding two doses of orthophosphoric acid (0.4 and 1.2 eq/kg sunflower meal) were tested using five dilution volumes (80, 160, 240, 320 and 400 ml/kg of feed) for each acid dose. Samples were heated at 608C. The quantity of CP that remained undegraded after 20 h in vitro (IVUCP) increased with the amount of acid added ( P 5 0.01). Increasing the dilution volume also tended ( P 5 0.065) to increase IVUCP. Therefore, a dilution volume of 400 ml/kg was employed in all further trials. In Trial 2, treatments with solutions of orthophosphoric and malic acids (1.2, 2.4, 3.6 and 4.8 eq/kg) and 608C of drying temperature were used. Increased CP protection with increased acid doses was described. In this and further trials, higher protective effects of malic acid than orthophosphoric acid were also shown. In Trial 3, the effects of both these acids, four acid concentrations (0.6, 1.2, 1.8 and 2.4 eq/kg) and three levels of heat treatment required for drying the samples (100, 150 and 2008C for 60, 30 and 20 min, respectively) were evaluated. An interaction acid type 3 concentration 3 temperature was shown. In addition, interactions concentration 3 temperature was shown in each acid. With heat treatments of 1008C to 1508C, benefits were not obtained after increasing the acid dose over 0.8 eq/kg. The increase of the heat treatments to 2008C and the acid dose up to 1.2 eq/kg increased protection, but to exceed this dose did not improve protection. In Trial 4, available lysine, CP solubility in McDougall buffer and IVUCP were compared after treatment with water or solutions (0.8 eq/kg) of orthophosphoric or malic acids using 1008C and 1508C heat treatments as described in Trial 3. No effects on available lysine were observed. Both CP solubility and IVUCP were reduced to a greater degree by acids than by water treatment. The results showed a high effectiveness of acid-heat treatments. Levels of protection are dependent on the acid dose, its dilution, acid type and drying conditions.

Section: Methodsmentioning

confidence: 99%

In vitro efficiency of combined acid-heat treatments for protecting sunflower meal proteins against ruminal degradation

Arroyo

González

Muñoz

et al. 2011

“…Experimental procedure To begin the experiment, each fermenter was filled with 180 ml of pre-warmed artificial saliva (McDougall, 1948) modified to contain 0.3 g/l of (NH 4 ) 2 SO 4 , and 720 ml of filtered rumen fluid. Solid rumen digesta (20 g), silage (6 g) and concentrate (4 g) for each respective treatment were placed in three separate polyester bags within each fermenter.…”

Section: Experiments 2 Determination Of Efe On Ruminal Digestionmentioning

confidence: 99%

“…Upon removal from the fermenters, solids were squeezed to expel excess liquid from both the silage and concentrate feed bags. Bags were placed together in a plastic bag with 20 ml of McDougall (1948) buffer and processed for 60 s in a Stomacher 400 Laboratory Blender (Seward Medical Ltd, London, England, UK). The processed liquid was squeezed out, poured off and retained.…”

Section: Experiments 2 Determination Of Efe On Ruminal Digestionmentioning

confidence: 99%

Effect of fibrolytic enzymes added to a Andropogon gayanus grass silage-concentrate diet on rumen fermentation in batch cultures and the artificial rumen (Rusitec)

Ribeiro

Gonçalves

Pereira

et al. 2015

In vitro batch cultures were used to screen four fibrolytic enzyme mixtures at two dosages added to a 60 : 40 silage : concentrate diet containing the C 4 tropical grass Andropogon gayanus grass ensiled at two maturities -vegetative stage (VS) and flowering stage (FS). Based on these studies, one enzyme mixture was selected to treat the same diets and evaluate its impact on fermentation using an artificial rumen (Rusitec). In vitro batch cultures were conducted as a completely randomized design with two runs, four replicates per run and 12 treatments in a factorial arrangement (four enzyme mixtures × three doses). Enzyme additives (E1, E2, E3 and E4) were commercial products and contained a range of endoglucanase, exoglucanase and xylanase activities. Enzymes were added to the complete diet 2 h before incubation at 0, 2 and 4 μl/g of dry matter (DM). Gas production (GP) was measured after 3, 6, 12, 24 and 48 h of incubation. Disappearance of DM (DMD), NDF (NDFD) and ADF (ADFD) were determined after 24 and 48 h. For all four enzyme mixtures, a dosage effect (P < 0.05) was observed for NDFD and ADFD after 24 h and for DMD, NDFD and ADFD after 48 h of incubation of the VS diet. For the FS diet, a dosage effect was observed for GP and NDFD after 24 h and for GP, DMD, NDFD and ADFD after 48 h of incubation. There was no difference among enzyme mixtures nor was there an enzyme × dose interaction for the studied parameters. Because of the greatest numerical effect on NDF disappearance and the least cost price, enzyme mixture E2 at 4 µl/g of diet DM was selected for the Rusitec experiment. The enzyme did not impact (P > 0.05) DM, N, NDF or ADF disappearance after 48 h of incubation nor daily ammonia-N, volatile fatty acids or CH 4 production. However, enzyme application increased (P < 0.05) microbial N production in feed particle-associated (loosely-associated) and silage feed particle-bound (firmly associated) fractions. With A. gayanus silage diets, degradation may not be limited by microbial colonization, but rather by the ability of fibrolytic enzymes to degrade plant cell walls within this recalcitrant forage.

“…The latter was replaced by a second feed bag 24 h later. The buffer solution, following McDougall (1948), contained 0.7 mmol NH 4 1 /l from 15 NH 4 Cl (11.5% 15 N abundance) and was infused continuously at an average flow rate of 546 (s.d. 5 29) ml/day.…”

Section: Treatmentsmentioning

confidence: 99%

Effect of maize silage to grass silage ratio and feed particle size on ruminal fermentation in vitro

Hildebrand

Boguhn

Rodehutscord

2011

The effect of the forage source on ruminal fermentation in vitro was investigated for fine (F) and coarse (C) milled diets, using a modified Hohenheim gas production test and a semi-continuous rumen simulation technique (Rusitec). It was hypothesised that the replacement of maize silage by grass silage might lead to associative effects and that interactions related to particle size variation could occur. Five diets with a maize silage to grass silage ratio of 100 : 0, 79 : 21, 52 : 48, 24 : 76 and 0 : 100 differed in their content of CP and carbohydrate fractions, as well as digestible crude nutrients, derived from a digestibility trial with wether sheep. For in vitro investigations, the diets were ground to pass a sieve of either 1 mm (F) or 4 mm (C) perforation. Cumulative gas production was recorded during 93 h of incubation and its capacity decreased with increasing proportion of grass silage in the diet. Across all diets, gas production was delayed in C treatments compared with F treatments. Degradation of crude nutrients and detergent fibre fractions was determined in a Rusitec system. Daily amounts of NH 3 -N and short-chain fatty acids (SCFA) were measured in the effluent. Degradation of organic matter (OM) and fibre fractions, as well as amounts of NH 3 -N, increased with stepwise replacement of maize silage by grass silage. Degradability of CP was unaffected by diet composition, as well as total SCFA production. In contrast to the results of the gas production test, degradation of OM and CP was higher in C than in F treatments, accompanied by higher amounts of NH 3 -N and SCFA. Interactions of silage ratio and particle size were rare. It was concluded that the stepwise replacement of maize silage by grass silage might lead to a linear response of most fermentation characteristics in vitro. This linear effect was also supported by total tract digestibility data. However, further investigations with silages of variable quality seem to be necessary. Keywords: silage, particle size, associative effects, ruminal fermentation, in vitro ImplicationsWhen grass silage and maize silage are incubated together but in different ratios in vitro, the associative effects on criteria of fermentation are unlikely to occur. Fermentation values for the individual silages are additive in these mixtures. However, the effect of variation in silage chemical composition remains to be investigated. The effects of feed particle size should be taken into account when comparing results of studies conducted with a Rusitec system. Further research investigating the effect of feed particle size, larger than particles produced by milling feeds with a 4-mm sieve, on degradation rates measured in rumen simulations is needed.