Effect of urea ammoniation on the nutritional quality of Setaria sphacelata hay in cattle
In the Northeast region of Argentina (NEA), haymaking of tropical grasses at advanced phenological stages frequently results in forages of low nutritional quality, limiting cattle performance. The objective of this study was to evaluate the effect of ammoniation with increasing levels of urea on the...
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| Autores principales: | , , , , , , , |
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| Formato: | Artículo revista |
| Lenguaje: | Español |
| Publicado: |
Universidad Nacional del Nordeste
2026
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| Materias: | |
| Acceso en línea: | https://revistas.unne.edu.ar/index.php/vet/article/view/9222 |
| Aporte de: |
| Sumario: | In the Northeast region of Argentina (NEA), haymaking of tropical grasses at advanced phenological stages frequently results in forages of low nutritional quality, limiting cattle performance. The objective of this study was to evaluate the effect of ammoniation with increasing levels of urea on the nutritional quality of Setaria sphacelata hay and its impact on intake, weight gain, and blood urea nitrogen (BUN) in growing cattle. Low-quality Setaria hay (3.96% CP; 81.48% NDF) was treated with urea on a dry matter basis at levels of 0% (T0-control), 3.5% (T1), 7.0% (T2), and 10.5% (T3), with an incubation period of 28 days. The chemical composition of the hay (n=16 hay bales) was evaluated under a completely randomized design. Subsequently, a feeding trial was conducted with eight cattle (four calves weighing 163 ± 2 kg and four steers weighing 286 ± 3 kg) under a 4×4 Latin square design for 84 days, measuring dry matter intake (DMI), average daily gain (ADG) and BUN. Ammoniation linearly increased crude protein content (from 3.96% in T0 to 12.03% in T3; p<0.001), without significantly affecting fiber fractions (NDF, ADF). DMI showed a quadratic response (p<0.05), with the highest values observed in T1 (3.93 kg d⁻¹ in calves and 5.23 kg d⁻¹ in steers). ADG showed a significant linear effect in calves (p=0.042), with positive values in T0 (+0.23 kg d⁻¹) and T1 (+0.42 kg d⁻¹) and negative values in T2 (-0.19 kg d⁻¹) and T3 (-0.25 kg d⁻¹); in steers, a similar pattern was observed although it did not reach statistical significance. BUN increased linearly (p<0.001) with urea dose, reaching 31.9-32.4 mg dL⁻¹ in T3. These results indicate that ammoniation with 3.5% urea is the optimal strategy to improve the nutritional quality of S. sphacelata hay and maximize intake and weight gain, whereas higher doses lead to excess non-protein nitrogen, evidenced by elevated BUN (>23 mg dL⁻¹) and body weight loss, suggesting an imbalance between nitrogen availability and fermentable energy in the rumen. |
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