K. El-Shazly

A relationship between thyroid activity, acetate infusion and food intake in rams

Six mature rams were used in a 6 × 6 latin square experiment. They were put on a high concentrate ad lib. diet. Voluntary food intake was measured on the rams which received the following treatments: control, thiouracil, sodium acetate, thyroxine, sodium acetate plus thiouracil and sodium acetate plus thyroxine. Acetate was infused intraruminally at the level of 6·2 g/kg W 0·75 per day for 4 successive days. Thyroxine was injected subcutaneously at the level of 0·3, 0·6, 0·9 and 0·9 mg/kg W 0·75 /day successively. Thiouracil was given orally as the propionyl derivative at a level of 0·03, 0·06, 0·06 and 0·06 g/kg W 0·75 /day successively. Respiration rate, pulse rate and rectal temperature were measured before and 1 h after dosing. A period of at least 25 days was allowed between the trials. All the results were calculated as feed intake (g dry matter)/kg W 0·75 . Injection of thyroxine, sodium acetate and both together inhibited food intake significantly. Thiouracil showed no significant effect on feed intake but it relieved part of the depression caused by acetate. Pulse rate showed significant differences between treatments but rectal temperature and respiration rate did not change significantly. The results are discussed in the text.

A colorimetric technique using chromium-ethylene diamine tetra acetate for measuring rumen volume

A method is described for the determination of rumen volume using Cr-EDTA colour measurement in a spectrophotometer at 550 nm. The results of several determinations of rumen volume comparing this method with Cr-determination as chromate and polyethylene glycol as markers gave similar values with differences ranging from 1 to 14% with an average of 6%. Direct measurements through evacuating rumen contents gave values 20·68% higher than those estimated by the colour method. The values were similar when corrected for dry matter.

A method for determining 2-aminoethane-phosphonic acid in rumen contents

The work described is an attempt to develop a reliable method for determining AEP when mixed with related substances from micro-organisms in the rumen. Hydrochloric acid hydrolysates of rumen contents, rumen bacteria, rumen ciliate protozoa and clarified rumen contents were applied to a column (10 × 1 cm) of Dowex 50–X8, eluted with 0·6 N hydrochloric acid and 2·4-ml fractions collected. Inorganic phosphorus was separated in column fractions 2–10 and AEP appeared in fractions 11–23.When fractions containing AEP were spotted on to Whatman No. 1 filter-paper strips the developed chromatograms showed six ninhydrin-positive spots in addition to that of AEP, which was the slowest acid to migrate (RF= 0·3). The substance giving spot No. 4, another phosphonic acid (RF= 0·59), was present in ciliate protozoa and ciliate-free fractions of rumen contents, whereas AEP was confined to protozoa. A highly significant correlation was found between the AEP concentrations and protozoal counts in samples of rumen contents collected at different intervals. It is therefore suggested that the concentration of AEP can be used as a marker of the protozoal growth in the rumen.

Effect of ruminal infusion of acetic acid and sodium acetate on the concentrations of ciliate protozoa

Two fistulated rams were infused through the rumen cannulae with acetic acid or sodium acetate for 4 consecutive days. This infusion has caused a significant drop in the daily feed intake and in the concentrations of rumen ciliate protozoa. The holotrich protozoa were the most susceptible, whereas entodinia were the least sensitive, to the reducing effect of acetic acid or sodium acetate. Decreasing the daily feed intake by 30% has caused little or no change in the concentrations of rumen ciliate protozoa. The in vitro incubation of sodium acetate and rumen contents has resulted in a remarkable depression in the protozoal numbers. Most of this decrease occurred after 5 h of incubation. The addition of acetic acid or sodium acetate to washed suspensions of mixed populations of rumen ciliate protozoa has decreased the in vitro volatile fatty acid production. It is suggested that both the low pH and acetate, ion were responsible for the reduction in the protozoal numbers in the rumen of rams infused with acetic acid or sodium acetate. The effect of acetate on the ciliate protozoa could be an explanation of the diurnal changes in the concentrations of various protozoal groups usually observed in the rumen of the host animal.

Effect of early weaning on the performance of male buffalo and cattle calves

Forty-eight uncastrated buffalo male calves and 16 male Friesian × Egyptian Native calves were used in two experiments to study the effect of weaning age on the performance of calves fed on a high concentrate ration after the first four months of age. Half of the buffalo calves were weaned at 120 days of age on to 330 kg whole buffalo milk (late-weaned) and the other half were weaned at 45 days of age on to 100 kg whole buffalo milk (early-weaned). Cattle calves were weaned at 31 days of age on to 65 kg whole cow milk. At the age of 7 days the calves were put on a high energy ration of 74% total digestible nutrients and 13·5% digestible protein. After 125 days of age all calves were offered a high concentrate ration (cottonseed cake and rice bran in the ratio of 1:1, plus 2% Ca(OH)2 and 1% common salt). Air-dried roughage was supplied at a level of ½% of the body weight. Buffalo and f-Native calves reached a slaughter weight of 400 kg or more about 540 days of age. Three-quarters Friesian calves reached the same weight at 480 days of age. The high concentrate ration caused a high incidence of bloat in ¾Friesian bulls. The efficiency of feed utilization was better for cow calves than that for buffalo calves. The system of early weaning of buffalo calves proved to be most economical and saved about 26% of the cost per kg live-weight gain. Slaughter experiments indicated that fat deposition was greater in male cattle of 400 kg than in buffalo bulls.