ELUCIDATING THE VARIATIONS IN ENTERIC METHANE EMISSION, NUTRIENT UTILIZATION AND MICROBIAL PROTEIN SYNTHESIS ININDIGENEOUS AND CROSSBRED DAIRY CATTLE
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Date
2023
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ICAR-NDRI, KARNAL
Abstract
To determine the difference between indigenous and crossbred cattle under a
similar environment and feeding regimen, 24-hour enteric methane production,
diurnal variation in methane emission, nutrient utilization, and microbial crude protein
(MCP) were estimated in native Sahiwal and composite Karan-Fries cattle. Totaling
16 animals, 8 of each breed, with almost similar parity and days in milk, they were
divided into two groups with a mean body weight of 390.95 and 423 kg, respectively.
Animals of both breeds were fed a conventional diet containing green fodder, wheat
straw, and concentrate in a 50:45:5 ratio for 75 days, followed by a 7-day digestion
trial. During this time, gas emitted by animals was collected and stored in canisters for
12 hours. Separate day and night readings in methane emission were taken in the
morning (before feeding) and evening (after feeding) for 7 days in a row using the SF6
tracer technique. Two gas samples from each animal during the morning and evening
were collected to estimate the diurnal variation in CH4 output. In between digestion
trials, spot urine samples from each animal were collected after 2 to 3 hours of
feeding and were analyzed for purine derivatives to estimate MCP. DMI and nutrient
intake, in terms of per 100 kg BW, and per kg W0.75, were significantly (P<0.01)
higher in Karan-Fries. The digestibility coefficients of DM% (64.33 and 62.65) were
significantly (P<0.05) higher in Sahiwal than Karan-Fries. Day (87.34 and 61.70 g/d),
night (76.23 and 54.11 g/d), and total 24-hour methane (163.58 and 115.81 g/d)
methane levels were higher (P<0.01) in Karan-Fries, while the ratio of Max/Min
value (absolute diurnal variation) and % of day to night variation were nonsignificant.
A linear regression of all data revealed a strong linear relationship
between methane production g/d and DMI kg/d (R2 = 0.984) and NDFI/100Kg BW
(R2 = 0.816), whereas MCP (g/d) showed a negative moderate regression (R2=0.68).
Methane g/kg DDMI (21.38 and 19.94) and CH4 g/Kg FPCM (18.92 and 12.51) were
significantly (P<0.05) lower in Karan-Fries than Sahiwal. In Karan-Fries, the %
methane energy loss per GEI (3.95 and 3.62) was significantly (P<0.05) lower than
Sahiwal. MCP was significantly (P<0.05) higher in Karan-Fries (590.04 g/d) than
Sahiwal (753.75 g/d), while in terms of g/DOMI Kg (125.41 vs. 110.39), a reverse
trend was observed. Feed conversion efficiency in terms of FPCM/CPI (6.37 and
7.46) and FPCM/DE (0.24 and 0.28 Kg/Mcal) was significantly (P<0.05) lower in
Karan-Fries than Sahiwal.