Effects of urea and soybean meal supplementation on rates of plasma leucine turnover and protein synthesis in sheep fed concentrate-based diets

Feeding Thai Native Sheep Molasses Either Alone or in Combination with Urea-Fermented Sugarcane Bagasse: The Effects on Nutrient Digestibility, Rumen Fermentation, and Hematological Parameters

The purpose of this study was to find out how adding molasses to fermented sugarcane bagasse (FSB) alone or in combination with urea affected sheep’s rumen fermentation, hematological parameters, and ability to digest nutrients. Four Thai native sheep with an initial body weight (BW) of 20.87 ± 1.95 kg and 11 ± 1.0 months old were assigned to a 4 × 4 Latin square design with 4 periods of 14-d adaptation and 7 d of sample collection. Each treatment received a different combination of experimental roughage as follows: FSB without additives (T1), FSB + 10% molasses (T2), FSB + 20% molasses (T3), and FSB + 10% molasses + 3% urea (T4). The concentrate diet was fed twice daily at 2% BW, while roughage sources were provided ad libitum for each treatment. The crude protein (CP) digestibility in the T2 and T3 groups was higher (p < 0.05) than in the FSB group without additions, with the T4 group having the highest (p < 0.05). Although there were no significant differences in blood glucose, packed cell volume, ruminal pH, ammonia−nitrogen (NH3-N), propionic acid, or acetic acid, the plasma urea nitrogen (PUN) at 0 h was highest in the T4 group (p < 0.05) compared with the other groups. However, the proportion of butyric acid tended to be higher in all FSB groups with additives. Thus, the current experiment concluded that the addition of molasses alone or in combination with urea had positive effects on pH and LAB population, and including both together in FSB improved the CP digestibility of sheep. In conclusion, FSB with 10% molasses and 3% urea might be used as an alternate roughage source for ruminants without affecting the animal’s ruminal fermentation or hematological parameters.

Effects of urea supplementation on ruminal fermentation characteristics, nutrient intake, digestibility, and performance in sheep: A meta-analysis

Background and Aim:

As a non-protein nitrogen source, urea is a popular, low cost, and easily obtained protein supplement. The objective of the present study was to perform a meta-analysis of the effects of urea supplementation on rumen fermentation and sheep performance.

Materials and Methods:

A total of 32 experiments from 21 articles were compiled into a dataset. The levels of dietary urea varied from 0 to 31 g/kg of dry matter (DM). Parameters observed were rumen fermentation product, nutrient intake, nutrient digestibility, and sheep performance. This dataset was analyzed using a mixed model methodology, with urea supplementation levels as fixed effects and the different experiments as random effects.

Results:

Increasing levels of urea were associated with increases (p=0.008) in rumen pH, butyrate (C₄) production, and ammonia (NH₃–N) concentration. Urea supplementation had minor effects on total volatile fatty acids (p=0.242), total protozoa (p=0.429), and the microbial N supply (p=0.619), but tended to increase methane production (CH₄; p<0.001). Supplementation of urea increased the intake of dry matter (DM; p=0.004) and crude protein (CP; p=0.001). Digestibility parameters, such as DM digestibility (DMD) and CP digestibility (CPD), also increased (p<0.01) as a result of urea supplementation. Retained N (p=0.042) and N intake (p<0.001) were higher with increasing levels of urea supplementation. In terms of animal performance, supplementation of urea increased average daily gain (ADG; p=0.024), but decreased the hot carcass weight percentage (p=0.017).

Conclusion:

This meta-analysis reports the positive effects of urea supplementation on rumen fermentation products (i.e., pH, C₄, and NH₃–N), intake (DM, CP, and N), digestibility (DMD and CPD), and ADG in sheep.