Nutrient Digestibility and Gas Production of Some Tropical Feeds Used in Ruminant Diets Estimated by the in vivo and in vitro Gas Production Techniques

Janmohammadi Hossein,Taghizadeh Akbar,Moghadam Gholam Ali,Paya Hamid

doi:10.3844/ajavsp.2007.108.113

Abstract

Some feedstuffs which used in ruminants diet (corn grain, soybean meal, wheat bran and alfalfa) were analyzed for chemical composition, apparent in vivo nutrient digestibility, in vitro fermentation gas production and metabolizable energy. Chemical composition of test feeds differed in nutrient contents. Initially apparent in vivo digestibility of alfalfa nutrients were obtained then digestibility of nutrients for the other test feeds were determined by difference method, using 16 Ghezel mature rams (mean weight of 43.9±4 kg). In vivo DM, CP, NDF and OM apparent digestibility were different among the test feeds (p<0.05). Regarding to the results, corn grain had a high DM and OM digestibility between test feeds and soybean meal had a high CP and NDF digestibility between test feeds (p<0.05). Cumulative gas production was recorded at 2, 4, 8, 12, 16, 24, 36, 48, 72 and 96 h of incubation and the equation of p = A (1-e-ct) was used to describe the kinetics of gas production. Potential gas production (A) and rates of gas production (c) differed (p<0.01) among feeds. Corn grain showed higher potential gas production (A) (326.5 mL g -1 DM) and wheat bran had higher rate of gas production (c) (0.097 h -1 ) than the other feeds, inverses alfalfa (257.6 mL g 1 DM) and corn grain (0.048 h -1 ) had lower potential gas production and rate of gas production than the other test feeds, respectively. The metabolizable energy (MJ kg -1 DM) content of feeds was calculated using in vivo organic matter digestibility and gas production data. According to in vivo organic matter digestibility data, the ME values ranged from 9.2 in alfalfa to 13.3 MJ kg 1 DM in corn grain. It was concluded that regarding to different chemical composition of test feeds, the in vivo digestibility, in vitro gas production and ME of feeds showed different values.

Highlights

The nutritive value of a ruminant feed is determined by the concentrations of its chemical components, as well as their rate and extent of digestion
The objective of the present study was to determine apparent in vivo digestibility, gas production function and Metabolizable Energy (ME) of some feedstuffs
Samples of all test feeds for the gas production technique were milled through a 2.0 mm sieve and oven-dried at 80°C until constant weight and for chemical analyses they were milled through a 1.0 mm sieve

Summary

Introduction

The nutritive value of a ruminant feed is determined by the concentrations of its chemical components, as well as their rate and extent of digestion. Determining the digestibility of feeds in vivo is laborious, expensive, requires large quantities of feed and is largely unsuitable for single feedstuffs thereby making it unsuitable for routine feed evaluation. Digestibility may be directly determined in vivo or estimated by using in vitro procedures, which are cheaper and more convenient[5]. There are number of in vitro techniques available to evaluate the nutritive value of feeds at relatively low cost such as in vitro gas production technique. The gas measuring technique was considered to be a routine method of feed evaluation after the work of Menke et al.[26], where a high correlation between gas production in vitro and in vivo apparent digestibility was reported. Gas production techniques are based on the principle that anaerobic microbial digestion of carbohydrates releases gas (primarily CO2 and CH4) and VFA[21]

Objectives

Methods

Results