Prom the results, it is obvious tint the DC? requirement for maintenance was high in Trial 1 and in the first two periods of Trial 2 but sharply declined during the 5rd and 4th periods of Trial 2. .The stage of growth of the sheep will therefore indicate the DCP requirement for maintenance. A value of 0,74 g/da y / W ^ h ^ "r may be taken as the mean DCP requirement for maintenance over the experimental period,
Tlic factorial method of the Agricultural Research council (1965) was also used to estimate the digestible crude protein (DCP) requirement for maintenance and growth (Table 4*8 )• The equations used were:
DCP requirement for maintenance and growth (g/day)
* 6.25
where UE = Urinary endogenous loss (g/day)
G = Retention of nitrogen in live weight gain, estimated as 2.5 i° of gain for sheep.
BV =s Biological value of protein
i
M F = Metabolic faecal nitrogen estimated as lcD g/day, Where D is dry natter intake in kg/day and k is the metabolic faecal nitrogen, g ll/kg Dry natter intake.
Tho estimates of the DCP requirement for maintenance and
growth arc summarized in Table 4*8. The values of urinary rcndogaaouo#
(UE + C) 100
BV~ H P ( 100
BV" - 1) .(.4.24 )
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The. ostiaate. _of the; digestible crude nrotein requironant for maintenance and -growth, of.
the West African dwarf wether sheep maintained on ha:/- and concentrate supplpaent.3 by. the f notorial method.
TRIALS
• Initial Height of animals
(kg)
Pinal weight of
animals (kg)
__ . _
\
> Moan
| weight i of I animals I (kg)
! i i 1
! I I
live * Mean j Moan weight jweight of|Dry natter
change! animals ' intake
j
( ij
< ^ >!
J ii t
* «
i
« i1 r
_ | __ .'?
l j
EndogenouofMetabolic Urinary N j paGcal
(g/doy) | (s/day)
|
|
Mean Biologica]
value of rations
_ . _ _
Digestible crude protein require
ment for maintenance
(g/day) i
jDigestible
| crude
! protein j requiremen t
, J or
j? mSl+iUGHalxlCG ^
; A / t o y / w ° ; 3"
i _____________
Digestible crude , protein requirement
for maintenance and growth
(g/day )
Digestible crude prortein requirement for growth
(g/day)
“ 1
■ i
19.5+1.3 ! 19.6+1.4
“ !
19.5 2.5 ! 8.9 1 0.48
; *
. ... i .... . . J _____ _
0.21 1.50 | 92.8
6 2.17
k
0.24 2.57
______ __ ___
0.40
2
— 19.6+1.4
— 20.5+1.3
"
20.0 11.3 I
----* ' ■
9.0 0,59 C.21 1.84 95.9
I
1
.33 0.20 3.58 1.75m e a n
--- — +
.... 1 1
1 ---1
—
0.53+0.05 .0.21 U—• —*— 1— - *
1.67+0,17 94.3+1.5 2.00+0.17 ______ ,__
0.22+0,02 3.07+0.50
;
1.08+0.6:
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, 0.734 loss and metabolic faecal nitrogen used were 0.0238g/dayUjCg <and 3 . 1 3 g A g Dry natter intake respectively. The values of DCP require
ment for maintenance wore 2.17 and 1 .83g/day/shoep, or 0,24 and / h ® •734
0.20 g/day/W^g for trials 1 .and 2 respectively, with a mean of 2.00 g DCP per day/shoep or 0.22 g / d n y / W ^ * ^ '. The mean DCP
requirement for naintenance, obtained by the factorial method is much lower than the value of 0.74g/day/t^*7^'r obtained by the nitrogen balance mathod. There was no substantial gain in weight in trial 1 but estimate based on trial 2 gave the value of DCF requirement for
/ / , 0.734
growth as 1.75 g/day per sheep or 0.19g/dny/Wjj.g
4.4 D I S C U S S I O N
The results of comparison of digestibility in fistulated and intact sheep showed no significant differences in the digestibility of dry matter .and protein contents of the feeds. This is in agreement with the reports of Dorori and Loosli (1959) end Hayes, Little and Mitchell (1964). Hayes ot al,(l954) used all hay* all concentrates
and equal parts of hay and concentrate in rumen fistulated and intact steers. Losperanco and Bo ..man (1963) reported that rumen fistulation significantly lowered the apparent digestibility of EM, crude fibre, gross energy and organic natter in four rations.
Connor, Bohman? Losperanco and Kinsingor (1963) found similar results for Dry natter, crude protein, and organic natter in forages but
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154
Ridley, Lesperanco, Jensen and Bohnan (1963) concluded that runen fistulation did not affect pasture digestibility. P eriodic removal of rumen contents from the fistulated animals nay have affected digestion in these pasture trials. When the animals have just boon fed the runen is distended and if the cannula is not well placed, there is a tendency for loss of ruminal digostn. In the present report, the animals were kept in the cage, and the cnnnulao were permanently fired. The problem of leakage of digesta from tho rumen did not occur. Moreover, except on the animals maintained on hay, the ruminal digesta was not fluid but a little semi solid which would also prevent leakage from the animals. The investigators mentioned have all used fistulated steers. There has been no report for shoep but it has always been assumed that it would resemble that of the steer. The present report using fistulated West African Dwarf sheep confirms that runen fistulation particularly if permanently fixed does not have any deleterious effects on the digestibility and metabolism of dry matter and crude protein and on the general well being of the animals.
Tho mean value of DM intake of the sheep in the present report was 49.4 ±.7.8 g/day/W^g^' for hay (7.7 ft0 crude protein).
0.734
This value is lower than 54.6 g/day/w^g obtained for lambs of similar live weight by Elliott and Topps (1963) but similar to the
0.734
value of 49.2 g/day/w^g obtained fa sheep maintained on Dactylic glonerata hay' (crude protein 6.7 ft) by. Crabtree and Millions (1971).
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The supplementation of hay with cassava flour had incroosod total dry natter intake though not significantly (P>0.05), and this agrees with the reports of Elliott and Topps (1963) and of Crabtree and hiIlians (1971) that total DM and digestible energy intake increased when hay was supplononted with energy - rich
concentrates. Dry natter intake in Trial 2 increased with increasing levels of dietary crude protein even though this was not significant
(P>0.05). Elliott and Topps (19 6 3) showed that voluntary intake of low protein feeds by sheep is closely related to the nitrogen content of the feed.
In the present experiment, there were slight increases in DM intake with increasing DM digestibility of rations D, E and F, This relationship was not significant but agrees with the reports of Elliott and Topps (1963) who obtained a low correlation (r = 0.273>
P,>0.05) between DM intake and digestibility. The value of 72.6 + /1
obtained in this report as intake for ration F is , . 0.734
close to 74.5 g/day/tf|£g obtained for a similar ration for sheep by Elliott and Topps
(1963)-The supplementation of hay with concentrate (ration b) mainly cassava flour has resulted in the decrease in hay DM intake.
When the concentrates containing crude protein were- fed in Trial 2, the intake of h a y DM fell progressively as concentrate DM intake increased. This seems to contradict tlx; findings of HI ax ter and Waimnan (1963) that apatite of sheep for hays of low protein content is increaded by supplementation with concentrate feeds. Crabtree and
/ 1 0.' 3.3 g / d a .y / \ g
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156
Williams_(l971) found with hay of a higher digestibility of energy (60.7 f°) t that concentrate feeding reduced hay intake. In the
present report, when the basal hay was supplemented with concentrates, 100g DM of , C2 , C^, Cy and C5 replaced 42.0, 66.8, 55.0, 54.6 and 49«0 g respectively of hay DM., the mean value being 55.1 + 8.0.
Blaster, Wainman ond Wilson (1961) showed that when concentrates wore added to high quality fodder, the HI consumption of fodder fell by slightly .loss than the* amount of DM consumed as concentrates, for instance, that 100g DM of concentrate replaced 79 g of fodder. They showed, however, that when concentrates were added to the ration of poor quality fodder, 100 g of concentrate DM replaced 47 g of poor quality hay.
The value of 55.1 g obtained in the present investigation is slightly higher than 47 g obtained by Blaster ot ■.-.1. (1961).
The intake of concentrate DM increased with increasing levels of crude protein in the concentrate. Similarly intake of concentrate as percentage total DM intake also increased with increasing crude protein content of the concentrate. Tile amount of DM intake by the sheep in the present investigation was estimated as 3$ of body weight or about 6 P> of the metabolic weight, a value used in several fedding experiments (Bergen et al,^ 1968).
When equation 4.2,
= aWb C
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is used to estinate DM intake, ’b* was obtained as 0.668 in the present report. This shows that DM consumption of these rations is related to the live weight of the sheep raised to the power of 0.668. Blaxter et a l . (1961) showed that DM consumption is
influenced by tile nature of the ration; consequently, the value of the exponent *b* will also be influenced by the ration.
Blaxter et al. (1961) obtained 0.70 as the value of 1V for rations of hay.
The present report with the value of 0.668 + 0.026 is not different from 0.66, the exponent which relates body weight to body surface area, and slightly lower than 0.734, also the exponent relating basal energy metabolism to body weight (Brody, 1945),
The indication in the present report of a value of 'b! similar to 0.67 which confirms the reports of other investigators n a y perhaps be attributed to the necessity for the sheep under tropical conditions to maintain homoeothorny by heat loss through the body surfo.ce and hence to a closer relationship between metabolism (in this case as indicated by intake) and body surface, than between intake and body weight (Butterworth, 1966).
The West African dwarf wether sheep used consumed slightly less nitrogen in ration B (basal hay + Supplement ) than in
ration A (basal hay); concentrate contained little protein (1.57/&) but the concentrate served mainly as a source of energy. Since
intake of this concentrate did net improve the intake of hay, the
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158
pajor ■ source of dietary nitrogen, it is expected that reduction in hay intake with supplementation with concentrate C-| will lead to sone reduction in total intake of nitrogen. In Trial 2, nitrogen' intake increased with increasing level of c rude protein in the
concentrate, which is in agreorient with the findings of Robinson and Forbes (1970) who used weaned lambs. From this, it is seen that lanbs are likely to take low m o u n t of nitrogen in a ration of low crude protein content, which nay not be sufficient to maintain then in nitrogen equilibria^ In the present investigation, all the animals were in positive nitrogen balance indicating that nitrogen intake was adequate at least for maintenance since the
animals did not,put on nuch weight. The fact that supplomentati/o■i of hay (7.7 crude protein) with energy did not significantly reduce total nitrogen intake offers an advantage in animal feeding.
In places where the crude protein level in herbage is just adequate (about 8 fo) , supplementation of herbage with energy while removing the limitation to animal growth due to energy, would not introduce shortage of crude protein. It is likely that the animals would consume sufficient energy for their requirement hut not too much as to significantly reduce their intake of harbage, the major source of crude protein. This situation may not, however, apply if the crude protein content of herbage is very low (about 4/^).
In this case, nitrogen intake may be so low as to make nitrogen limiting to the growth of the anirils.
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Robinson and Forbes (1970) showed with lambs fed on so y a boon meal that the nitrogen intake per metabolic size were 0.53* 1.03,
1.60 and 1.81 g when the rations contained 7.3% , 13.3$, 19.8$ and 23.1 $ crude protein respectively which, in the present studies, the values of 0.84, 0.91, 1.28 and 1.55 g per Ityg*^rwere obtained.
Hie HI digestibility of ration B was significantly (P<.0.0l) higher than that of ration A. This is in agreement with the results of Crabtree and Williams (1971) who showed higher DM digestibility of nixed rations than for hay alone. Hie DM digestibility of rations B to F were high, no doubt, due to the presence of concentrate
supplements. The supplementation cf hay of low DM digestibilitjr with a concentrate of high DM digestibility is expected to lead to higher DM digestibility of the nixed ration. There was no marked effect of level of dietary ©ru.de protein on DM digestibility oven though slight CM digestibility increases wore ob&orvod with rations D, E and F. Robinson and Forbes (1970) had observed-linear increase in DM digestibility with increasing crude protein'intake. ' •
In the present report, there was a. slight increase in Dli digestibility with increasing DM i: take especially for rations D, E and F. The present report that DM digestibility of a ration increases with increasing proportion of concentrate in the ration, is in
agreement with the findings of Crabtree and Williams (1971).
The lower digestibility of DM in period 1 than periods 2 to
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160
4 of Crial 2 reflects the higher intake of highly digestible
concentrate fraction during periods 2 to 4 than in period 1 (.Robinson and Forbes (1970).
Similarly, supplementation of the basal hay (7.7$ crude protein) with the concentrate (C-j) did not significantly affect its digestibility. Campbell, Sherrod and Ishizaki (1969) found that supplementation of Kikuyu grass (Pennisoturn Clandestinum).