Abstract:

The effect of supplementing guinea grass hay with different protein sources on average
body weight gain, feed intake, digestibility, nitrogen balance and feed conversion
efficiency was studied using twenty-four (i.e., twelve females and twelve males) yearling
Mubende goats. The animals, which averaged 15.04±2.1 kg, were assigned to four
treatment diets in a randomized complete block design. The basal diet consisted of
guinea grass hay fed together with 200 g of the maize bran/mineral mixture. The four
protein supplements included lablab hay (LBLB), sweet potato vines (SPV), cassava leaf
meal (CLM) and sunflower meal (SFM). At the end of the feeding trial, all male goats
from each treatment group were used in a three weeks digestion and nitrogen balance trial
after which all goats were sacrificed. The slaughter weight, hot and cold carcass weight,
external and internal organs weights, total bone, total lean and lean: bone ratio were
measured.
Basal dry matter intake was significantly higher (P<0.05) among goats on sunflower meal
CLM and SPV showed higher (P<0.05) total dry matter intake (1141.6 and 1214.8 g
DM/day, respectively) than those on the SFM and LBLB (1019.8 g and 1070.8 g
DM/day, respectively). Dry matter digestibility of 77.91 and 77.58% was exhibited in
animals supplemented with LBLB and SPV, respectively. Energy digestibility followed
similar trend with animals on supplements of LBLB, SPV, SFM and CLM showing
digestibilities of 80.84, 80.11, 73.12 and 71.75 percent, respectively. Supplementing with
CLM gave the highest (P<0.05) nitrogen balance (7.47 g N/day) while animals on the
SFM supplement had the lowest (P<0.05) nitrogen balance of 0.55 g N/day.
Consequently, CLM supplementation resulted in the highest average daily gain (ADG) of
70.33 g/day while animals on LBLB supplement had the lowest (P<0.05) ADG of 38.00
g/day. The most favorable feed conversion ratio of 1:16.23 was observed among goats
on CLM. No significant (P>0.05) differences were observed among the carcass
characteristics for most of the treatment groups except hot carcass weight, cold carcass
weight, head weight, total meat and meat: bone ratio. Consequently, the highest
(P<0.05), gross margin was observed among goats on the CLM treatment of Shs.
18,065.71 and the lowest (P<0.05) was observed among goats on the LBLB treatment of
Shs. 5,604.16. It was concluded that cassava leaf meal is a superior protein supplement,
in terms of animal performance and profitability, for Mubende meat goats fed low quality
roughages with a suitable energy concentrate like maize bran. The results of this study
show that it is profitable to fatten yearling indigenous goats under the feedlot system
especially if supplemented with cassava leaf meal and a maize bran/mineral mixture