Abstract
Two feeding trials with native cattle from Bangladesh were
conducted at the farm attached to the Department of General
Animal Science, Bangladesh Agricultural University, Mymensingh,
in collaboration with the Institute of Animal Science, Royal
Veterinary and Agricultural University, the Development Cooperation Bureau, Royal Veterinary and Agricultural University,
and the Danish International Development Agency (DANIDA),
Ministry of Foreign Affairs.
The objective of the experiments was to determine the level of
supplemented protein required to develop a response curve when
fed with rice straw ammoniated through urea in native, growing
cattle in Bangladesh.
The chemical composition, nylon bag degradability of dry matter
and protein of feed ingredients fed to calves, digestibility of
rations, daily feed intake, and live weight gain were recorded.
The aim of this study also was to investigate the size of the
rumen, gut tissue, NH3-N concentration and pH of the rumen in
native cattle when fed high levels of straw material.
Chemical Composition.
The dry matter, crude protein, crude fibre, ether extract, nitrogen free extract and ash contents in 5% urea-treated rice
straw (ammoniated) varied from 81.9% to 88.8%, 7.21% to 7.51,
30.1% to 33.1%, 1.2% to 1.3%, 38.3% to 41.0% and 19.9% to 20.5%,
respectively. There was a significant increase in the crude
protein content from 3.31 in untreated rice straw to 7.21 in rice
straw ammoniated through urea. Water hyacinths included in rations contained 8.5% to 10.6% dry matter on a fresh sample basis.
The crude protein, crude fibre, ether extract, nitrogen free extract and ash contents of water hyacinths in per cent of dry
matter were found to be 21.87, 9.9, 1.9, 54.9 and 11.5, respectively.
The ration components fishmeal and dried whole milk powder contained 82.1% to 91.6% and 94% of the dry matter, respectively.
Crude protein, crude fibre, ether extract, nitrogen free extract and ash contents of fishmeal and dried whole milk powder in
per cent of dry matter were found to be 53.12 - 55.21% and
28.51%, 3.1 - 4.1% and o.1%, 6.5% and 25.9%, 10.2 - 15.6% and
39.1% and 21.7 - 24.2% and 6.4%, respectively.
Dry Matter and Protein Disappearance from Nylon Bags incubated
in the Rumen of fistulated Cows.
The dry matter disappearance of rice straw, rice straw ammoniated through 5% urea, water hyacinths and fishmeal at 72 hours
of incubation was 43.4, 59.7, 59.5 and 71.8 per cent, respectively. The untreated rice straw showed the slowest rate of
degradation compared to that of other feed ingredients fed to
calves. The protein degradability of water hyacinths and
fishmeal at 72 hours of incubation was 58.2% and 77.5%, respectively. The effective protein degradability (EPD) of water
hyacinths and fishmeal at 72 hours of incubation with the outflow
rate of 2.2, 4.4, 6.6 and 8.8% per hour from the rumen was 55.5%
and 69.0%, 53.7% and 64.0%, 49.8% and 61.2% and 48.7% and 59.3%.
The protein from water hyacinths was found to be less degraded
than that of fishmeal.
Feed Intake.
The dry matter and organic matter intake during the experimental period in per cent of live weight varied from 2.5 to 2.8 and
2.0 to 2.3 with the groups of Experiment A, and 3.5 to 3.8 and
2.8 to 3.1 with the groups of Experiment B, respectively. Dry
matter related to metabolic body size was (g/kg w°.75) was 70
to 88 and 98 to 104 with calves of Experiment A and Experiment
B, respectively. Lower intakes during the experimental period
in Experiment A might be due to the lower initial weight of
the calves as compared to that of animals in Experiment B and
also to differences in the environmental temperature in which
the experiments were conducted.
Digestibility of the Ration.
The apparent digestibility of the basal diet was significantly
lower (P < o.01) than that of the groups receiving fishmeal or
200 g of powdered whole milk with the basal diet. This applied
to both Experiment A and Experiment B. There was no remarkable improvement in the ration digestibility beyond the supplementation of 50 g (8-9% crude protein) fishmeal with the basal
diet.
Experiment_A. The in-vivo dry matter and organic matter
digestibility in per cent was 50 and 55 with the basal diet
of urea-treated straw. For groups receiving basal diet supplemented with fishmeal, figures were 56.6 and 62.6 (50 g),
58.8 and 65.1 (100 g), 59.8 and 66.2 (150 g), 62.0 and 68.0
(200 g) and 59.3 and 66.4 (250 g), respectively. The crude
protein and crude fibre digestibility in per cent was 38.5 and
66.1, 54.3 and 72.0, 54.8 and 71.7, 55.5 and 73.8, 58.5 and 74.1
and 58.9 and 72.7 for basal diets and basal diets supplemented
with 50, 100, 150, 200 and 250 grams of fishmeal, respectively.
The digestibility of ether extract and nitrogen free extract
was found to be 23.2 and 51.5% for basal diet, and for basal
diets supplemented with fishmeal 40.2 and 57.9% (50 g), 52.8
and 63.3% (100g), 53.2 and 65.0% (150 g), 58.6 and 67.2%
(200 g) and 59.4 and 66.9% (250 g), respectively.
Experiment B. The in-vivo dry matter and organic matter
digestibility in per cent was 57.6 and 62.6 for the basal diet
of urea-treated rice straw and 60.3 and 64.3, 60.9 and 66.1,
61.3 and 66.4, 62.2 and 65.1 for fishmeal supplemented rations
at ratios of 15, 25, 50, and 150 grams, and 60.6 and 66.1 when
200 grams of powdered milk were supplemented to the basal diet.
The crude protein digestibility in per cent was 32.7, 40.7,
44.7, 49.9, 55.5 and 46.7 for the basal diet and diets supplemented with 15, 25, 50 and 150 grams of fishmeal and 200 g of
milk powder to the basal diets, respectively. The crude fibre,
ether extract and nitrogen free extract digestibility in per
cent was 71.6, 42.1 and 61.9 for the basal diet group, 74.1,
42.8 and 65.1 for the 15 g fishmeal, 72.0, 40.6 and 68.2 for
25 g fishmeal, 71.3, 42.4 and 68.8 for 50 g fishmeal, 71.5, 48.5
and 65.1 for 150 g fishmeal and 72.8, 78.3 and 63.9 for the
supplementation of 200 grams of powdered whole milk, respectivel
pH Value and NHz-N Concentration.
Supplementation of fishmeal and water hyacinths to the basal improvement in the ration digestibility beyond the supplementation of 50 g (8-9% crude protein) fishmeal with the basal
diet.
Experiment A. The in-vivo dry matter and organic matter
digestibility in per cent was 50 and 55 with the basal diet
of urea-treated straw. For groups receiving basal diet supplemented with fishmeal, figures were 56.6 and 62.6 (50 g),
58.8 and 65.1 (100 g), 59.8 and 66.2 (150 g), 62.0 and 68.0
(200 g) and 59.3 and 66.4 (250 g), respectively. The crude
protein and crude fibre digestibility in per cent was 38.5 and
66.1, 54.3 and 72.0, 54.8 and 71.7, 55.5 and 73.8, 58.5 and 74.1
and 58.9 and 72.7 for basal diets and basal diets supplemented
with 50, 100, 150, 200 and 250 grams of fishmeal, respectively.
The digestibility of ether extract and nitrogen free extract
was found to be 23.2 and 51.5% for basal diet, and for basal
diets supplemented with fishmeal 40.2 and 57.9% (50 g), 52.8
and 63.3% (100 g), 53.2 and 65.0% (150 g), 58.6 and 67.2%
(200 g) and 59.4 and 66.9% (250 g), respectively.
Experiment B. The in-vivo dry matter and organic matter
digestibility in per cent was 57.6 and 62.6 for the basal diet
of urea-treated rice straw and 60.3 and 64.3, 60.9 and 66.1,
61.3 and 66.4, 62.2 and 65.1 for fishmeal supplemented rations
at ratios of 15, 25, 50, and 150 grams, and 60.6 and 66.1 when
200 grams of powdered milk were supplemented to the basal diet.
The crude protein digestibility in per cent was 32.7, 40.7,
44.7, 49.9, 55.5 and 46.7 for the basal diet and diets supplemented with 15, 25, 50 and 150 grams of fishmeal and 200 g of
milk powder to the basal diets, respectively. The crude fibre,
ether extract and nitrogen free extract digestibility in per
cent was 71.6, 42.1 and 61.9 for the basal diet group, 74.1,
42.8 and 65.1 for the 15 g fishmeal, 72.0, 40.6 and 68.2 for
25 g fishmeal, 71.3, 42.4 and 68.8 for 50 g fishmeal, 71.5, 48.5
and 65.1 for 150 g fishmeal and 72.8, 78.3 and 63.9 for the
supplementation of 200 grams of powdered whole milk, respectively
pH Value and NH₂-N Concentration.
Supplementation offishmeal and water hyacinths to the basal diet of urea-treated rice straw fed ad libitum had little
effect on changes in pH values in the rumen. The pH values
recorded (average of the hours of collection of rumen liquor)
were 7.6, 7.6, 7.7, 7.6, 7.6 and 7.5 for basal diet, supplementation of 15, 25, 50, and 150 g fishmeal and 200 g powdered
whole milk to the basal diet, respectively. The pH values
observed were much higher than values given in literature,
but these values are mostly from exotic breeds fed a low level
of fibrous feed. The higher values may be explained as being
due to feeding of high levels of straw (above 90%) which increase
the rate of rumination and chewing time as well as increasing
the rate of salivation.
The basal diet group maintained a level of NHz-N concentration
of 3.7 mg to 4.7 mg/100 ml rumen liquor throughout the period
of collection. The values obtained for the groups receiving
supplements four hours after feeding were 4.6 to 5.4 mg/100 m1
rumen liquor.
Live Weight Gain and Feed Conversion.
Both in Experiment A and Experiment B supplementation of the
basal diet beyond 50 grams of fishmeal had some benefit on
live weight gain and feed conversion.The fishmeal supplemented
group showed a significant live weight gain (P < o.01) compared
to the group fed basal diet of urea-treated (ammoniated) rice
straw without fishmeal. The initial dramatic response in live
weight gain (142 g/day) with the supplementation of 15 grams of
fishmeal was. significantly different (P < o.01) compared to the
basal diet in Experiment B, but an explanation cannot be given.
Milk poweder as a source of pre-formed protein had no apparent
effect on live weight gain and was no better than the basal diet
group without fishmeal. This might be due to a faster degradability
of milk powder and urea in the rumen compared to that of fishmeal.Experiment A. The initial live weight after the preliminary period and the final live weight of the calves in kg was
48.5 and 57.3, 52.5 and 83.0, 51.5 and 81.8, 52.6 and 83.5,
51.1 and 81.0 and 52.0 and 85.2, respectively. The live weight
gain (g/day) and feed conversion (kg dry matter/kg live weight gain) were 57 and 25, 198 and 9, 197 and 9, 205 and 9, 192
and 9 and 215 and 9 for the basal diet group and with the
grups supplemented with 50, 100, 150, 200 and 250 grams of
fishmeal, respectively.
Experiment_B. The initial live weight after the preliminary period and the final live weight in kg were 55.0 and 64.6,
55.2 and 71.8, 55.0 and 73.0, 56.4 and 81.8, 56.8 and 81.8
and 54.6 and 66.4 with the groups on basal diet and those
receiving 15, 25, 50 and 150 g fishmeal and 200 g powdered milk,
respectively. The live weight gain (g/day) and feed conversion (kg dry matter/kg live weight gain) were 80 and 26, 142
and 15, 151 and 15, 203 and 11, 206 and 12 and 95 and 24 with
the basal diet and groups receiving 15, 25, 50 or 150 fishmeal
and 200 g powdered milk, respectively.
Dressed Carcass and Gut Contents.
Considerable changes in dressed carcass weight and gut contents
of the gastrointestinal tract of ruminants occurred following
changes in the diet. There was little effect on dressed carcass weight beyond supplementation of 50 g of fishmeal to the
basal diet. However, gut contents declined after a level of 50 g
fishmeal in the basal diet. There was a sharp decrease in reticulo-rumen contents and an increasing trend in small intestine contents above supplementation of 150 g fishmeal with the
basal diet of Experiment A. This result may assume a faster
rate of passage from the rumen when the level of fishmeal rises
beyond 150 g with urea-treated straw presumably changing the
site of digestion from the rumen to the lower gut, since all
the groups receiving more than 50 g fishmeal exhibited a more
or less similar total digestibility of rations.
Experiment A. The dressed carcass and gut content in
per cent of live weight were found to be 28.4 and 33.6 with untreated rice straw, 30.5 and 29.7 with basal diet of rice straw
ammoniated through urea, 37.7 and 28.6 with 50 g fishmeal, 36.5
and 27.9 for 100 g fishmeal, 37.6 and 29.1 with 150 g fishmeal,
36.3 and 27.3 with 200 g fishmeal and 37.3 and 26.8 with 250 g
of fishmeal supplemented to the basal diet. Experiment B. The dressed carcass and gut contents in
per cent of live weight were 33.4 and 31.1, 34.5 and 31.4, 36.7
and 32.7, 36.9 and 29.1, 36.5 and 28.3 and 32.7 and 32.5 with
the basal diet of urea-treated straw and 15, 25, 50 and 150
and 200 grams of fishmeal supplemented the basal diet.
There was no significant difference in the gut tissue among
the different groups of calves in Experiments A and B. The
gut tissue in per cent of live weight varied from 5.9 to 7.5
in Experiments A and В.