Preservation of sugarcane silage with urea and calcium oxide: performance and metabolic efficiency of dairy cows / Conservación del ensilaje de caña de azúcar con urea y óxido de calcio: rendimiento y eficiencia metabólica en vacas lecheras / Preservação da silagem de cana-de-açúcar com ureia e óxido de cálcio: desempenho e eficiência metabólica de vacas leiteiras

Abstract Background: Inclusion of urea and calcium oxide (CaO) during sugarcane ensilage has been hypothesized to improve dairy cow performance. Objective: To evaluate the use of urea and calcium oxide as additives to preserve sugarcane silage quality and determine whether they improve dairy cow performance and metabolic efficiency. Methods: Four diets were used: sugarcane silage without additive (SS), sugarcane silage with 10 g/kg urea (SU), sugarcane silage with 5 g/kg urea + 5 g/kg CaO (SUC), and sugarcane silage with 10 g/kg CaO (SC). Eight crossbred cows at approximately 100 days of lactation were distributed in two 4x4 Latin squares, and their diets were formulated to reach an average milk production of 15 kg/day. Results: Dry matter, non-fibrous carbohydrates, organic matter, total carbohydrates, and total digestible nutrient intake were the highest (p<0.05) for the cows fed SC. Urinary excretion of nitrogen was higher (p<0.05) for cows fed diets based on SUC than those fed diets with SC. Milk urea nitrogen content was the highest (p<0.05) in animals fed SU diets. Nitrogen balance was positive in all treatments; however, the microbial protein synthesis was low for all diets. Conclusions: The diet with SU showed the highest nitrogen loss through the milk. Among the evaluated silages, those with SC and SUC are recommended to promote a high intake of nutritional components.

Resumen Antecedentes: La hipótesis fue que una dieta con combinación de urea y óxido de calcio (CaO) para el ensilaje de caña de azúcar, puede mejorar la producción de vacas lecheras cruzadas. Objetivo: Evaluar la urea y el óxido de calcio como aditivos para preservar la calidad del ensilaje de caña de azúcar y determinar si mejoran el rendimento y la eficiencia metabólica de vacas lecheras. Métodos: Cuatro dietas fueron utilizadas: ensilaje de caña de azúcar sin aditivo (SS), ensilaje de caña de azúcar con 10 g/kg de urea (SU), ensilaje de caña de azúcar con 5 g/kg de urea + 5 g/kg de CaO (SUC) y ensilaje de caña de azúcar con 10 g/kg de CaO (SC). Ocho vacas cruzadas fueron evaluadas con una producción media de leche de 15 kg/día y aproximadamente 100 días de lactación, distribuidas en dos cuadrados latinos 4x4. Resultados: El consumo de materia seca, carbohidratos no fibrosos, materia orgánica, carbohidratos totales y nutrientes digestibles totales fue mayor (p<0,05) cuando las vacas fueron alimentadas con dietas conteniendo SC. La excreción de nitrógeno en la orina fue mayor (p<0,05) cuando las vacas fueron alimentadas con dietas basadas en SUC que las alimentadas con dietas SC. El nitrógeno ureico de la leche fue mayor (p<0,05) en animales alimentados con dietas con SU. El balance de nitrógeno fue positivo en todos los tratamientos, sin embargo, la síntesis de proteína microbiana fue baja para todas las dietas. Conclusión: La dieta con SU presentó la mayor pérdida de nitrógeno por medio de la leche. Entre los ensilajes evaluados, aquellos con SC y SUC son recomendados por promover un mayor consumo de componentes nutricionales.

Resumo Antecedentes: A hipótese foi que uma dieta com a mistura de ureia e óxido de cálcio (CaO) para a ensilagem de cana de açúcar, poderia melhorar a produção de vacas leiteiras mestiças. Objetivo: Avaliar ureia e óxido de cálcio como aditivos para preservar a qualidade da silagem de cana de açúcar: melhoria da produção e eficiência metabólica de vacas leiteiras. Métodos: Quatro dietas foram utilizadas: silagem de cana de açúcar sem aditivo (SS), silagem de cana de açúcar com 10 g/kg de ureia (SU), silagem de cana de açúcar com 5 g/kg de ureia + 5 g/kg de CaO (SUC) e silagem de cana de açúcar com 10 g/kg de CaO (SC). Oito vacas mestiças foram avaliadas com uma produção media de 15 kg/dia e aproximadamente 100 dias de lactação, distribuídas em dois quadrados latinos 4x4. Resultados: O consumo de matéria seca, carboidratos não fibrosos, matéria orgânica, carboidratos totais e nutrientes digestíveis totais foi maior (p<0,05) quando as vacas foram alimentadas com dietas contendo SC. A excreção de nitrogênio na urina foi maior (p<0,05) quando as vacas foram alimentadas com dietas baseadas em SUC do que aqueles animais alimentados com dietas SC. O nitrogênio ureico do leite foi maior (p<0,05) em animais alimentados com dietas com SU. O balanço de nitrogênio foi positivo em todos os tratamentos, no entanto, a síntese de proteína microbiana foi baixa para todas as dietas. Conclusão: A dieta com SU apresentou maior perda de nitrogênio por meio do leite. Entre as silagens avaliadas, aquelas com SC e SUC são recomendadas por promover maior consumo de componentes nutricionais.

Effects of ammoniated pearl millet silage on intake, feeding behavior, and blood metabolites in feedlot lambs.

The aim of this study was to evaluate the effects of urea as an additive in the ensiling of pearl millet on the intake, feeding behavior, and metabolic parameters of feedlot-finished lambs. Thirty-two uncastrated, mixed-breed male lambs were used in the experiment. Diets were composed of pearl millet silage enriched with 0, 2, 4, or 6% urea plus a concentrate containing ground corn, soybean meal, and a mineral mixture. The treatments did not affect feed intake (P > 0.05) but influenced (P < 0.05) eating time (in min/day, in min/kg of dry matter (DM), and in min/kg of neutral detergent fiber (NDF)) and chewing time in min/kg of DM. Eating efficiency (in g DM/h and in g NDFap/h) responded linearly (P < 0.05) to the increasing urea levels in the silages. By contrast, there was no effect (P > 0.05) of diets on the blood protein profile (total proteins and albumin), although the serum urea levels responded quadratically (P < 0.05). Increasing urea levels in the silage did not change the blood energy profile (cholesterol and triglycerides) or blood enzyme activity (alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT); P > 0.05). In conclusion, the treatment of pearl millet silage with urea does not influence the DM intake or metabolic parameters of lambs, but leads to increased eating time and decreased eating efficiency.

Evaluation of days of total collection and use of internal markers in nutritional trials with small ruminants.

Two experiments were conducted to evaluate the number of days required for total fecal collection and the viability of using the indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF), and indigestible acid detergent fiber (iADF) internal markers to determine the fecal excretion of dry matter (FEDM) and digestibility in nutritional trials with small ruminants. Eight sheep in the first experiment and eight goats in the second experiment were distributed into two 4 × 4 Latin square designs. There were no significant differences between days of total fecal collection for FEDM; digestibility of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber corrected for ash and protein (NDFap), and non-fibrous carbohydrates corrected for ash and protein (NFCap); and total digestible nutrients (TDN) in both species. The results suggest that only 1 day of total collection is sufficient to obtain the FEDM and the digestibility of the nutritional components in sheep and goats. The markers are efficient in determining fecal production and digestibility in these animal species.

Intake and ingestive behavior in lambs fed low-digestibility forages.

Ingestive behavior of lambs fed diets consisting of fresh sugarcane with urea, bagasse treated with calcium oxide, and urea ammoniated sugarcane bagasse supplemented with concentrate mixture in 50:50 ratio were evaluated. For this, 34 wethers Santa Inês in their growing phase, with an average age of 3.0 ± 0.6 months and a mean initial live weight of 17.8± 5.2 kg were used. The animals were distributed in a completely randomized design and subjected to visual observation periods of 5 days, for 24 h a day, during the experimental period. Dry matter (DM) intake and intake efficiency of DM were higher (P < 0.05) for animals receiving fresh sugarcane with urea. The animals which were fed with bagasse treated with calcium oxide had higher (P < 0.05) consumption of neutral detergent fiber, longer feeding and chewing time (P < 0.05), and shorter (P < 0.05) idling time. The time spent on chewing the ruminal bolus did not differ from one diet to the other (P > 0.05). Grams of dry matter per ruminated bolus were similar among animals fed with fresh sugarcane and ammoniated bagasse (P > 0.05) but lower (P < 0.05) in animals fed with bagasse treated with calcium oxide. Rumination efficiency values, in grams of dry matter per hour, and grams of neutral detergent fiber per hour for all three diets were similar (P > 0.05) to those found for feeding efficiency. The number of feeding and rumination periods was not affected (P > 0.05) by diet. Based on the intake and ingestive behavior responses, the fresh sugarcane with urea compared to bagasse treated with calcium oxide and ammoniated bagasse was found to be the better alternative feed for use in lamb diets.