Effect of adding low degradable nitrogen and energy to the ration on growth performance and some rumen liquid measurements of Awassi lambs.

• Ayman Fares Mahmood Mohammed Al-Maadeedi¹, Muthanna Ahmed Mohamed Tayeb¹*

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This study was conducted at the Animal Production Fields, College of Agriculture and Forestry, University of Mosul, Iraq, to investigate the effect of supplementing low-degradable nitrogen (slow-release urea) and energy (slow-release glucose) in the diet on growth performance and selected rumen fluid parameters in Awassi lambs. A total of 24 Awassi lambs, aged 5–6 months with an average body weight of 23 ± 1.18 kg, were used in the experiment. The animals were randomly allocated into four groups, each consisting of six lambs.

All lambs were fed a standard diet composed of crushed barley, soybean meal, wheat bran, and wheat straw. A mixture of slow-release urea and slow-release glucose (1:1) was added at levels of 0, 10, 20, and 30 g/animal/day for the four experimental treatments. The results indicated no significant differences in final body weight, total weight gain, or daily weight gain among the treatments. However, a significant difference (P ≤ 0.05) was observed in hot carcass weight in the fourth treatment, which reached 22.41 kg.

Total fat weight was also significantly higher in the fourth and third treatments compared with the first and second treatments, reaching 3.57, 3.22, 4.74, and 4.82 kg for the four treatments, respectively. In addition, significant increases were observed in some edible carcass parts. Liver weight was significantly higher in the fourth treatment compared with the second treatment, averaging 0.75 kg versus 0.52 kg. Similarly, kidney weight showed significant increases in the fourth and third treatments (0.13 and 0.12 kg, respectively) compared with the second treatment and the control group (0.09 and 0.10 kg, respectively).

Chemical analysis of meat samples revealed significant increases in both fat and protein percentages. The fat percentage was higher in the fourth and second treatments (17.90% and 17.92%, respectively) compared with the control group (14.52%). Likewise, protein content was higher in the fourth, third, and second treatments (18.75%, 18.37%, and 19.61%, respectively) compared with the control group (16.10%).

Furthermore, significant differences were observed in bacterial counts two hours after feeding. The fourth treatment recorded the highest bacterial count (260 × 10⁴/ml) compared with the third treatment (120 × 10⁴/ml). The fourth treatment also showed higher concentrations of amino acids in meat samples compared with the control group.

These results suggest that supplementation of diets with higher levels of slow-release urea and slow-release glucose may yield positive outcomes in terms of economic efficiency, carcass characteristics, rumen fluid parameters, and meat palatability, likely due to the increased levels of amino acids

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