Some quantitative data on the role of the ruminant proventriculi in the digestion and absorption of nitrogen-free organic matter

Fourteen cows and five young bulls were fed with hay uniformly during 10 days. After slaughtering, the ingesta of the abomasum were removed and sampled. From the hay, from the contents of the abomasum, and from the feces lignin, N-free organic matter, and N-free non-lignin organic matter were determined. Using the lignin ratio principle, the digestibility of the two N-free fractions was calculated both for the proventriculi and for the whole digestive tract. It appeared that of the total amount of the N-free non-lignin organic matter digested in the whole digestive tract, 76—99 % was digested in the proventriculi. If the results for two of the cows are discarded, the limits in the cows are 85 and 91 %. On the basis of this investigation it can be concluded that in cattle carbohydrates are digested mainly in the proventriculi and their degradation products are absorbed principally from these stomachs

Digestibility by Sheep of the Constituents of the Nitrogen-Free Extract of Feeds.

15 p

The nutritional value of oat forages for dairy cows

Three studies were conducted to evaluate the nutritional value of different oat (Avena sativa) forage cultivars (Assiniboia, Bell and Baler) that were newly emerged cultivars as a result of extensive oat growing conditions in western Canada. A total tract digestibility trial using 24 sheep (n=6) in a completely random design was conducted to assess apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), crude fat (EE), acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, non-structural carbohydrate, acid detergent lignin (ADL), soluble crude protein (SCP), non-protein nitrogen (NPN) and neutral detergent insoluble crude protein (NDICP) in Assiniboia silage, Bell hay, Baler hay and Rosser (barley- Hordeum vulgare) silage. Rumen in situ degradability characteristics of DM, OM, CP, ADF and NDF were determined on Assiniboia silage, Bell hay, Baler hay and Rosser silage at 96 to 0 h using a Holstein cow fitted with a rumen fistula. A dairy production trial using 8 multiparous Holstein cows at 90±20 DIM averaging 41 kg d-1 milk yield, in a 2 × 3 switch-back design was conducted to compare the production response of the cows fed either 48 percent Assiniboia silage or Rosser silage (DM basis) in total mixed rations with the concentrate portion consisting mainly of rolled barley, canola meal and soy meal. Digestibility of DM, OM, NDF, NPN, NDICP and EE were not different for Assiniboia and Rosser silages. Digestibility of DM, NDF and ADF were similar for Baler hay and Rosser silage. Digestibility of hemicellulose, NSC and ADL were similar for all forages. Sheep voluntary intakes of DM, OM, NDF, ADF and EE, except CP were similar across the forages. Assiniboia silage provided more nutrients to the rumen than the hays due to the higher rumen disappearance and effective degradabilities of DM and CP, and lesser undegradable DM, CP, NDF and ADF (

Ruminal Degradabilities and Intestinal Digestibilities of Canola Meals and the Production Response of Cows Fed Canola Meal With Varying Concentration of Starch Sources

Canola meal (CM) is a by-product in the manufacturing process of canola oil which can be performed with or without using solvent extraction. It is a protein supplement which has grown its importance in dairy cattle feeding competing with soybean meal (SBM). However, final quality of the feed depends on the oil extraction process and the production conditions used by the individual processing plant. Two studies were conducted to investigate: 1) the variability among the CM produced in different processing plants and 2) the best starch source or the most suitable proportion of corn and barley to be fed with CM, in order to optimize dairy cattle performance. The first study consisted of an in situ and in vitro experiment where ruminal disappearance kinetics and intestinal digestibility parameters were estimated in seven CM samples obtained from different processing plants located in Canada. Canola meal 5, 6, 7, 9, 10, and 11 were obtained from processing plants using solvent extraction and CM12 was from a plant using mechanically extraction. Disappearance and digestibility parameters for CM were compared with SBM. Ruminal degradation and intestinal digestibility varied significantly among treatments. However, values obtained for degradability and digestibility parameters were in agreement with NRC with slight variations. Data from this study suggests that, variabilities in the chemical composition of CM may be because of the production variabilities occurring during CM manufacturing process in different processing plants. In the second experiment, CM was used as the primarily protein supplement with four different ratios of corn and barley 1) 100:0, 2) 67:33, 3) 33:67, and 4) 0:100. Sixteen multiparous Holstein cows were used in 4×4 Latin square design. Production parameters were not significantly different among treatments. Milk production was averaged for 41.2 kg/d and the efficiency of milk production averaged 1.53. There were no significant differences between the milk protein fractions among treatments. However, ruminal propionate and acetate to propionate ratio varied quadratically. Ruminal pH, NH3-N, and plasma glucose concentration were similar to all treatments. Apparent total tract digestibilities of nutrients (except starch) were linearly decreased as the proportion of barley starch increased in the diet. However, total tract starch digestibility averaged 95.5% and was not affected by varying proportions of corn and barley in the diet. Results of this study concludes that there is no significant effect of starch source on animal performances when CM was used as the major protein source, and similar production responses of feeding corn can be obtained by feeding barley or by mixing corn and barley in different proportions

Factors influencing the flow of fluid, saliva and some cations through the reticulo-omasal orifice of the cow

vokKirjasto Aj-kTekijöitä, jotka vaikuttavat nesteen, syljen ja eräiden kationien kulkuun lehmän verkkomaha-satakerta-aukost

Evaluation of several chemical analyses as indicators of the productive value of forages

An investigation was undertaken in which dry matter digestibility and voluntary dry matter intake data were used to compare the following chemical constituents of forages as predictors of digestibility and intake of dry matters acid detergent fiber (ADP), lignin, lignin in ADP, cell wall constituents (CWC) and crude protein. Two experiments were conducted: (1) with alfalfa hays harvested at six stages of maturity and (2) with three forage species: alfalfa, red clover and Lindsey 77F, The relationships of stage of maturity and forage species with forage composition, digestibility and intake were investigated. As forage advanced in growth the fibrous fractions - ADP and CWC, increased and crude protein decreased, also in Experiment II ADP and CWC were lowest in alfalfa, intermediate in red clover and highest in Lindsey 77F, A highly significant negative correlation between the fibrous fractions and crude protein was obtained. Dry matter digestibility, dry matter intake and nutritive value index (NVl) were significantly lower with advance in stage of maturity in Experiment I and in Experiment II were highest on alfalfa, intermediate on red clover and lowest on Lindsay 77F. Lignin digestibility was quite variable and some negative digestibility of lignin was observed. Heat damage to feces and/or the presence of hemicellulose in lignin determination might be the factors contributory to artifact lignin values. There was a decreasing trend in CWC digestibility as influenced by stage of maturity; alfalfa was significantly higher than red clover in digestibility of CWC, while alfalfa and Lindsey 77F were similar. Digestibility of cell contents ranged from 85 to 44 cent. Low digestibility of cell contents might be due to the non-cell-wall matter in feces, which comprises bacterial and endogenous excretions. Increase in butyrate (rumen VPA) was associated with higher protein content of forages. Acetate:propionate ratios were significantly lower at the bud stage than at the half bloom; this ratio with red clover and Lindsey 77P was significantly higher than that for alfalfa. Dry matter digestibility (DDM) showed highly significant positive correlations with voluntary dry matter intake, digestibilities of crude protein, ADF, CWC, cell contents and per cent of lignin in ADP, crude protein content and NVI. Highly significant negative correlations between DDM and ADP or CWC, dry matter intake and ADF or CWC were observed. These results indicated that with an increase in the forage fibrous fractions digestibility and intake of dry matter decreased significantly. In this study Availability Index and Summative Equation were poorly related to dry matter digestibility and intake and would be poor expressions of the value of feeds. NVI being dependent on energy digestibility and dry matter intake appears to be an excellent measure of feeding value. Highly significant negative correlations between ADF and CWC with either DDM or intake and NVI would indicate that the chemical components ADF and CWC, have real value for predicting the value of a feed