Optimising Microbial Protein Synthesis Through Dietary Manipulations In Forage Based Diet Of Mecheri Sheep
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Date
2008
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Tamil Nadu Veterinary and Animal Sciences University
Abstract
This study to optmise rumen microbial protein synthesis through dietary
manipulation by evolving suitable grazing strategy for sheep was conducted in
Mecheri track of Tamil Nadu. The study included of one survey and a series of five
experiments. Survey on the grazing pattern adopted in this area revealed that
majority of sheep farmers (58.33%) first allowed their sheep to graze for three hours
in hillock grazing land followed three hours of roadside grazing land and finally one
and half hours of grazing at fallow grazing land.
Based on the survey results, experiment I was designed to document basic
information on the palatable floral statistics by assessing the herbage biomass, and
its composition, diet composition, preference index of herbage species and its
chemical composition during two season viz., summer and monsoon. The overall
herbage biomass in hillock grazing land was 743.05 g/m^2 during monsoon and
735.48
g/m^2 during summer, in fallow grazing land it was 107.16
g/m^2 during
monsoon and 57.08 g/m^2 during summer and in roadside grazing land it was 187.29
g/m^2 during monsoon and 161.12 g/m^2 during summer.
The experiment II focused on fermentation and degradation characteristics of
individual herbage species and diet of Mecheri sheep at three different grazing
lands. Securinega leucopyrus and Bothriochloa pertusa in Hillock grazing land,
Dactyloctenium aegyptiacum in fallow grazing land and Crotoloria sp and Indigofera
linnaei in roadside grazing land produced highest microbial biomass in the in vitro
studies. Analysis of CP in the diet during monsoon in the three grazing land
indicated similar CP, reflecting the animal’s ability to choose various herbages to
meet its protein requirement. The Phosphorus content was found to be below the
critical level hillock grazing land indicating the necessity for rotational grazing. This
study also revealed that the microbial biomass production was highest in the diet ofhillock grazing land and fallow grazing land indicating their significance in the sheep
diet.
The experiment III was undertaken to determine the optimum duration of
grazing in each grazing land in order to maximize the microbial protein synthesis. Six
diets were formulated having different proportion of hillock diet, fallow diet and
roadside diet. Results of this study indicated that the microbial biomass production
was highest in D5 (Hillock diet: Fallow diet: Roadside diet 3:3:1.5) followed by D6
(Hillock diet: Fallow diet: Roadside diet 4.5:1.5:1.5). The widely adopted grazing
sequence of grazing the animal first at hillock grazing land for 3 hours, then grazing
at roadside grazing land for 3 hours and grazing at fallow grazing land for 1.5 hours
was found to be an inefficient grazing strategy.
The experiment IV aimed to evaluate the simulated grazing sequence for their
efficiency in synthesizing rumen microbial protein in semi continuous culture to
identify promising grazing strategy. The selected diets (Diet 5 and diet 6) through in
vitro studies were subjected to various sequences to examine their efficacy in
enhancing microbial protein synthesis through synchronized nutrient delivery. This
study was conducted in TANUVAS RUSITEC and it revealed that grazing the
animals at sequence of fallow grazing land 3 hours, followed by roadside grazing
land 1.5 hours and concluding the grazing at hillock grazing land for 3.0 hours was
found to be the best rotational grazing management system.
The experiment V was carried out to validate the in vitro finding by comparing
the selected grazing period and sequence with existing practice for optimum
microbial protein synthesis in growing male lambs. Results revealed that the total
purine derivatives (PD) was significantly (P<0.05) higher in treatment lambs (1.21
g/d and 7.66 mmol/d) than the control lambs (1.06 g/d and 6.75 mmol/d). The
microbial protein nitrogen calculated from purine derivative was significantly higher in
treatment groups than the control groups. Similarly, the microbial crude protein
calculated from purine derivative was significantly higher in treatment (40.84 g/day)
groups than the control (35.76) groups.
It may be concluded from the results that in vitro results obtained in
TANUVAS RUSITEC was comparable to the in vivo experiment results. It is
advocated to adopt the grazing strategy of allowing sheep at Mecheri to first graze at
fallow grazing land for 3 hours, followed by road side grazing land 1.5 hours and
concluding grazing at hillock grazing land for 3.0 hours as it yields highest microbial
protein synthesis and in turn will promote body weight gain.
Description
Keywords
Sheep, Grazing, Hillock, Fallow, Roadside land