This study was conducted to evaluate the development of the mammary gland in Holstein heifers subjected to different dietary metabolisable protein (MP): metabolisable energy (ME) ratios. Twenty-five Holstein heifers (initial body weight (BW) 213±13·5 kg and initial average age 7·8±0·5 months) were divided into five treatments. The treatments were designed to provide MP:ME ratios equal to 33, 38, 43, 48, and 53 g of MP per Mcal of ME. All diets were formulated to have the same energy content (2·6 Mcal ME/kg dry matter). Actual MP:ME ratios were 36·2, 40·2, 46·2, 47·1, and 50·8 g MP/Mcal ME. The experiment was conducted in a randomised block design, while considering initial BW as a blocking factor to evaluate pre- and post-pubertal periods. Block effect was not observed for all variables evaluated; hence it was considered that the diets had the same influence both on pre- and post-pubertal phases. Dry matter and nutrient intake did not change between treatments, excepting protein intake and digestibility. Serum concentrations of insulin-like growth factor 1 increased linearly across treatments. Changes in the pixel brightness of mammary gland ultrasound images, which are associated with lipid content, were significantly influenced by MP:ME ratios in the diet of heifers that were subjected to accelerated growth rates. It is not recommended to use diets of less than 38 g MP/Mcal ME in diets to heifers allowed to gain more than 1 kg/d.

We evaluated the differences between the supplementation of urea in rumen and/or abomasum on forage digestion, nitrogen (N) metabolism, and urea kinetics in cattle fed a low-quality tropical forage. Five Nellore heifers were fitted with rumen and abomasum fistulas and assigned to a Latin square design. The treatments were: control, continuous infusion of urea in the abomasum (AC), continuous infusion of urea in the rumen, a pulse dose of urea in the rumen every 12 hours (PR), and a combination of PR and AC. The control exhibited the lowest (P<0.10) fecal and urinary N losses, which were, overall, increased by supplementation. The highest urinary N losses (P<0.10) was observed when urea was either totally or partially supplied as a ruminal pulse dose. The rumen N balance was negative for the control and when urea was totally supplied in the abomasum. The greatest microbial N production (P<0.10) was obtained when urea was partially or totally supplied in the abomasum. Urea supplementation increased (P<0.10) the amount of urea recycled to the gastrointestinal tract and the amount of urea-N returned to the ornithine cycle. The greatest (P<0.10) amounts of urea-N used for anabolism was observed when urea was totally and continuously infused in the abomasum. The continuous abomasal infusion also resulted in the highest (P<0.10) assimilation of microbial N from recycling. The continuous releasing of urea throughout day either in the rumen or abomasum is able to improve N accretion in the animal body, despite of mechanism responsible for that being different.

No abstract

Background: Production of heart-of-palm from Alexander palm tree generates a waste that could be used as silage for feeding ruminants. Objective: To evaluate the chemical composition, fermentation parameters, and quality of silage made from waste of heart-of-palm production using Alexander palm. Methods: Three types of silage made from waste of heart-of-palm production were evaluated: 1) leaf silage, 2) sheath silage, and 3) compound (leaf + sheath) silage. The processed waste was packed in experimental silos and distributed in a completely randomized design with 10 replications. Means were compared pairwise using Tukey’s test at the 5% significance level. Results: Leaf silage had the highest pH (p<0.05) and the lowest ammonia nitrogen (p<0.05) in relation to the other silages. No difference was observed (p>0.05) for lactic and butyric acids, whereas acetic acid was higher (p<0.05) in the sheath and compound silages. Dry matter and crude protein contents were the highest (p<0.05) in leaf silage. Neutral detergent fiber was higher (p<0.05) in sheath silage, followed by leaf and compound silages, respectively. The highest lignin content (p<0.05) was observed in sheath silage. Conclusions: Based on the fermentative parameters, waste from heart-of-palm from Alexander palm tree has potential for silage production. However, differences in silage composition at the time of feeding ruminants should be considered.Keywords: Archontophoenix alexandrae, byproduct, fermentation, forage, organic acid, pH. ResumenAntecedentes: Los residuos de la producción de palmito de Palma Real podrian utilizarse como ensilaje para alimentación de rumiantes. Objetivo: Determinar la composición, parámetros químicos de fermentación, y calidad del ensilaje elaborado a partir de residuos procedentes de la producción de palmito de Palma Real. Métodos: Tres tipos de ensilaje hechos con los residuos generados a partir de la producción de palmito fueron evaluados: 1) ensilaje de hojas, 2) ensilaje de vainas, y 3) ensilaje compuesto (hojas + vainas). Los residuos tratados fueron empacados en silos experimentales y distribuidos en un diseño completamente al azar con 10 repeticiones. Las medias fueron comparadas mediante la prueba de Tukey, con un nivel de significancia del 5%. Resultados: El ensilaje de hojas mostró el pH más alto (p<0,05) y el nivel más bajo de nitrógeno amoniacal (p<0,05) en comparación con los otros ensilajes. No se observaron diferencias (p>0,05) en los ácidos láctico y butírico, mientras que el ácido acético fue mayor en el ensilaje de vainas y en el compuesto en relación con el otro ensilaje. La materia seca (MS) y el contenido de proteína cruda (PC) fueron mayores (p<0,05) en el ensilaje de hojas. Los contenidos de fibra detergente neutra fueron mayores (p<0,05) en los ensilajes de vainas, seguido por los ensilajes de hojas y compuesto, respectivamente. El contenido de lignina fue más alto (p<0,05) en el ensilaje de vainas. Conclusiones: Según los parámetros fermentativos, los residuos de la producción de palmito de Palma Real tienen potencial para la producción de ensilaje. Sin embargo, se deben considerar las diferencias en la composición de los ensilajes al momento de alimentar rumiantes.Palabras clave: ácidos orgánicos, Archontophoenix alexandrae, fermentación, forraje, pH, subproductos. ResumoAntecedentes: Resíduos da produção de palmito da palmeira Real são um problema para a agroindústria devido sua falta de utilização e o seu uso na forma de silagem pode ser uma alternativa na alimentação de ruminantes. Objetivo: Avaliar a composição química e os parâmetros fermentativos, e verificar a qualidade da silagem produzida a partir do resíduo da produção de palmito da Palmeira Real Australiana. Métodos: Foram avaliadas três tipos de silagem de resíduo da produção de palmito da Palmeira Real: silagem de folha, silagem de bainha e silagem da composta (folha + bainha). O resíduo processado foi acondicionado em silos experimentais e distribuídos em um delineamento inteiramente casualizado com 10 repetições e as médias comparadas pelo teste de Tukey a 5% de significância. Resultados: A silagem de folha apresentou maior pH (p<0,05) em relação as demais silagens, enquanto para o nitrogênio amoniacal (p<0,05), apresentou menor teor em relação as demais silagens. Não observou-se diferença (p>0,05) para os ácidos lático e butírico, enquanto o ácido acético foi maior para as silagens de bainha e composta em relação as demais silagens. O teor de matéria seca (MS), proteína bruta (PB) foi maior (p<0,05) na silagem de folha em relação as demais silagens. A fibra em detergente neutro analisada estimada apresentou maiores valores (p<0,05) para a silagem de bainha, seguida pela silagem de folhas e silagem composta, respectivamente. O teor de lignina foi maior (p<0,05) para a silagem de bainha. Conclusões: De acordo com os parâmetros fermentativos, os resíduos da produção de palmito da Palmeira Real apresentam potencial para a produção de silagem. No entanto, as diferenças na composição das silagens devem ser consideradas quando oferecidas para animais ruminantes.Palavras-chave: ácidos orgânicos, Archontophoenix alexandrae, fermentação, forragem, subprodutos, pH.