Abstract :
One hundred and sixty Alpine kids (16 kg BW) were studied for 150 days with two diets, evaluating in situ DM disappearance,
VDMI, OMI, rumen degradation, rate of passage, ammonia (NH3) and volatile fatty acids (VFA) concentrations,
apparent digestibility, pH, total fermentable carbohydrates (FC), andBWgains. Group 1, designated as CS/SIUS (n = 80 plus
two cannulated goats) was offered corn stubble (CS) 800 g per day and alfalfa hay (AH) 100 g per day, with 150 g per day of a
slow-intake urea supplement (SIUS) consisting of 16.5% molasses,5%urea,4%fishmeal,2%limestone,16%cottonseed meal,
17.5% rice polishing, 14.5% corn, 9.5% poultry litter, 4.1% commercial mineral salt, 0.9% orthophosphate, 2% ammonium
sulfate, 1.5% cement kiln dust, and 6.5% animal lard. Group 2, designated as AH/BC (n = 80 plus two cannulated goats) were
fed 550 gAHper day supplemented with 450 g of a balanced concentrate (BC) per day, consisting of 1.1% mineral salt, 1.2% orthophosphate,
40.0% corn, 25.9% wheat bran, 25.8% barley, and 6.0% soybean meal.VDMIandOMIwere similar for 150 days
for the two experimental diets fed to goats. NH3 concentration and degradation of potential non-degradableDMfractions were
augmented by SIUS (P < 0.05). RumenpHrose to 6.9 by 2 h after CS/SIUSwas offered and stayed above 6.6 for 12 h, while the
rumen pH in AH/BC goats decreased to 5.57 by 6 h and rose again to 6.50 after 12 h.Nintakewith CS/SIUSwas 18.60 g per day
versus 14.57 g per day with AH/BC (P < 0.05). In vivoNdigestibililtywas 76.63% in the CS/SIUS diet and 54.16% in AH/BC
(P < 0.05). In vivo digestibility ofNDFwas greater for CS/SIUS (P < 0.05) (77.14% versus 65.11% for AH/BC). Degradation
rate constant (kd) of NDF also favored the CS/SIUS diet (P < 0.05) and non-degradable fiberwas less (P < 0.05) (35.18% versus
63.32% for AH/BC). Half-time (t1/2, h) disappearance of cellulose and hemicellulose in the CS/SIUS diet were 29.34 and
29.14 compared to 16.54 and 20.16 in the AH/BC diet, respectively (P < 0.05) and passage rates differed similarly (P < 0.05).
True digestibility of cellulose in CS/SIUS at 46.24%was higher (P < 0.5) than that ofAHat 33.22%. Growth in 150 days averaged
112±23 g gain per day for CS/SIUS compared to 86±21 g per day for theAH/BCdiet (P < 0.05). SIUS supplement intake
per kgBWranged from 6.57 to 3.12 g per day for the CS fed goats and 21.02 to 11.80 g per day for the AH/BC fed control goat
kids (P < 0.05). Rumen NH3 was higher for CS/SIUS (12.3 mg per 100 ml versus 6.8 mg per 100 ml for AH/BC) (P < 0.01).
Rumen acetic and butyric acids increased with the CS/SIUS diet (P < 0.05), while propionic acid was less and total VFA were
not different. Supplementation of a high fiber diet with a slow-intake NPN supplement improved rumen fermentation. SIUS
supplied critical nutrients to the rumen microflora, improved rate of passage, ruminal pH, NH3 contents, and resulted in higher
weight gain than the AH/BC fed control goat kids. Results showed that high fiber forages like CS can be used efficiently by
growing goats, when conditions for ruminal microorganisms are improved with a continuous slow-intake N supplementation.
© 2003 Elsevier B.V. All rights reserved
Keywords :
goat kids , Non-protein N supplementation , Corn stubble , Rumen fermentation , growth
