Corn silage supplementation of cows grazing winter oats. Dynamics of digestion and ruminal environment

• Published in: Animal feed science and technology Vol. 38; no. 2; pp. 161 - 174
• Main Authors: Elizalde, J.C., Rearte, D.H., Santini, F.J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.1992; Elsevier
• Subjects: AVENAS; AVOINE; Biological and medical sciences; COMPLEMENT ALIMENTAIRE; COWS; CULTIVOS DE INVIERNO; CULTURE D'HIVER; DIGESTION; ENSILADO; ENSILAGE (PRODUIT); Feed and pet food industries; FEED SUPPLEMENTS; Food industries; Fundamental and applied biological sciences. Psychology; GRAZING; MAIS; MAIZ; MAIZE; OATS; PASTOREO; PATURAGE; RUMEN; SILAGE; SUPLEMENTOS DE PIENSOS; VACA; VACHE; WINTER CROPS; Oat; Bovine; Fodder; Corn; Rumen; Digestion; Grazing; Proteins; Vertebrata; Mammalia; Silage; pH; Complementation; Artiodactyla; Kinetics; Dietary fiber; Ungulata; Feed
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/0377-8401(92)90100-K

The effect of com silage ( Zea mays L.) (CS) supplementation of winter oat (WO) ( Avena sativa L.) in grazing conditions on rumen environment and dynamics of digestion were studied. The trial was designed as a cross-over, for two treatments (T 0, winter oats only; T 1, winter oats and 5 kg of CS (dry matter (DM) basis), two periods and six animals fitted with ruminal cannulae. Animals grazed WO (‘in vitro’ DM digestibility (IVDMD), 71.1%; crude protein content (CP), 12.8% and neutral detergent fiber (NDF), 40.8%). Animals in T 1 ate CS (IVDMD, 64.4%; CP 8.4% and NDF, 50.9%) twice daily (08:00–12:00 and 14:00–20:00 h) and then had a routine similar to T 0. Rumen fluid pH tended to be higher ( P < 0.07) in T 1 (6.31) than in T 0 (6.14). Buffer capacity in the acid range (BC) (Eq. per 100 ml) was higher ( P < 0.05) in T 0 (10.64) than in T 1 (9.42). Ammonia nitrogen concentration and the acetic/propionic ratio were not different while the acetic plus butyrate/propionic ratio tended to be higher ( P < 0.08) inT 0 (T 0: 3.69 and T 1: 3.45). In WO the effective protein degradability (PD) was higher ( P < 0.05) in T 0 (T 0: 79.1% and T 1: 75.3%) and Period I (Period I: 80.6%, Period II: 72.8%). Of NDF degradation kinetics the lag time was higher ( P < 0.05) in T 1 (5.8 h) than in T 0 ( 1.4 h) for WO but not for CS. In WO the actual extent of NDF digestion (AED) was not different between treatments but tended to be higher ( P < 0.10) for Period I (51.6%) than for Period II (36.6%). In CS the AED was low, and tended to be higher ( P < 0.10) in T 0 (T 0: 27.4% and T 1: 23.4%). Corn silage supplementation altered rumen fluid pH and BC but had little effect on NDF digestion of both forages. The smaller AED in corn silage can act as a constraint of total DM intake. The period effect in PD and AED in WO suggests that the chemical and structural variations have an important effect on the digestion process.