A comparison of the rumen degradability of some protein and energy concentrates using the artificial fibre bag technique.

Abstract

Proc. Aust. Soc. Anim. Prod. THE NUTRITIVE VALUE OF WHOLE CROP SILAGE FROM IRRIGATED MAIZE J.B. MORAN Dairy farmers in the irrigated areas of northern Victoria and southern N.S.W. have recently commenced growing high yielding summer fodder crops for inclusion as silage in their pasture based production systems. Silages from four consecutive maize crops (1981 to 1984), harvested at the hard dent stage at were fed to wether sheep in metabolism cages to assess their Kyabram, digestibilities. Silage dry matter, organic matter and protein contents were 30 - 36%, 89 - 95% and 6.4 - 8.1% respectively. Differences in organic matter digestibilities of the four crops were values were 68.5, 68.5, 69.5 and 65.0%. The mean value, 67.9%, was equivalent to a metabolizable energy content of 9.8 MJ/kg DM. This value is lower than that reported from England or Holland(10.8 - 10.9 MJ/kgDM) where whole crop maize silage is traditionally made from varieties with a shorter small; yields (24 - 26 tonne DM/ha) but they could also lead to decreases in nutritive value of the ensiled product through increased fibre deposition. Therefore production levels of milk or meat obtained from diets based on local maize maturation period and ensiled at a lower dry matter content (ie., 20 - 25%). At Kyabram, the high summer temperatures during maturation of the maize give high silages may not be as high as those reported overseas, particularly from Europe. Kyabram Research Institute, Kyabram, Vic. 3620 A COMPARISON OF THE RUMEN DEGRADABILITY OF SOME PROTEIN AND ENERGY CONCENTRATES USING THE ARTIFICIAL FI BRE BAG TECHN IQUE R.J. MOSS*, P.R. MARTIN**, 1-K. BUCHANAN* and N. STANDFAST** One characteristic of the concentrate which affects the relative amounts of energy and protein absorbed from the gut is the extent of degradation in the rumen (Leng et al, 1977)In these studies the artificial fibre bag technique was used to estimate the rumen degradability of twenty-two meals in five experimental runs. These included eight different protein meals, three grains, and two formaldehyde treated proteins (casein and cottonseed meal). A mixture of protein meals was examined (80% treated CSM, 10% fishmeal, 10% meatmeal) and the effect of heating on rate of breakdown of soybean meal was studied. Rate of breakdown of animal proteins (meatmeal, fishmeal) was slower than for vegetable proteins, with 37% DM and 53% CP lost from bags in 24 hours, Soybean meal was most rapidly degraded with 93% DM and 95% CP lost over 24 hours. Mechanically extracted cottonseed meal (CSM-Bacal) and solvent extracted CSM (Norwest) were similar in their rate and extent of degradation with 74% DM and 86% CP lost in 24 hours. Formaldehyde treatment (1%) reduced degradation of Bacal CSM to 29% CP lost in 24 hours, and gave total protection of casein against rumen degradation. Heat treatment of soybean meal caused a small reduction in breakdownGrains (sorghum, maize and wheat Pollard) were degraded at a similar rate to the vegetable protein meals. The results suggest the major difference to rumen degradability of concentrate supplements is between animal and vegetable products. LENG, R.A., KEMPTON, T.J. and NOLAN, J.V. (1977). AMRC Review 33 : l-22. * QDPI # Mutdap illy Resea rch Station, M-S. 8 25, Ipswich, Qld. 4305 ** QDPI , Animal Research Institute, Yeerongp illy , Qld, 4105 42 3