Urea and mineral salt in supplements for crossbred dairy cows

Esse estudo teve como objetivo avaliar o uso de suplementos, com diferentes proporções de ureia e sal mineral, para vacas mestiças leiteiras alimentadas com cana-de-açúcar, sobre o consumo e digestibilidade da matéria seca (CMS e DMS, respectivamente) e dos seus constituintes, produção e composição do leite, eficiência alimentar, excreção de compostos nitrogenados e síntese de proteína microbiana. Foram utilizadas dez vacas mestiças, com peso corporal médio de 480 kg (± 30), após o pico de lactação, distribuídas em um delineamento em quadrado latino 5x5, duplicado, com quatro tratamentos de suplementos com diferentes porcentagens de ureia e sal mineral, sendo estas: 10:10; 10:20; 20:10 e 20:20, completados para 100% com fubá de milho, além do quinto tratamento composto somente de sal mineral. Os períodos experimentais tiveram duração de 14 dias cada, sendo os sete primeiros dias para adaptação e os demais para coleta de dados e amostras. Os dados foram analisados utilizando-se o procedimento MIXED do programa SAS, adotando-se um nível de significância de 0,05. O uso de suplemento proporcionou aumento (P0,05) em função da dieta. O uso de suplemento resultou em menores valores (P<0,05) de contagem de células somáticas (CCS) e contagem bacteriana total (CBT) no leite. Os suplementos, quando comparados ao controle ou sal mineral (0:100), apresentaram (P<0,05) menor relação gPBmic/Kg NDT e maior nitrogênio ureico no soro sanguíneo (NUS), nitrogênio ureico na urina (NUU) e nitrogênio ureico no leite (NUL). O aumento do nível de sal mineral não alterou os parâmetros de excreção diária de derivados de purinas, produção de compostos nitrogenados microbianos e concentração de nitrogênio ureico,exceto o nitrogênio ureico na urina, que reduziu. Os suplementos podem ser usados para corrigir as deficiências nutricionais da cana-de-açúcar, resultando em maior consumo, digestibilidade e produção de leite. Os suplementos com 20% de ureia (20:10 e 20:20) em sua composição resultaram em menor consumo com mesmo desempenho dos animais, podendo-se concluir que esses tratamentos apresentaram melhor eficiência de utilização.This study aimed to evaluate the use of supplements with different proportions of urea and mineral salt, for dairy crossbred cows fed with sugarcane on intake and digestibility of dry matter (DMI and DMD respectively) and its constituents ,milk production and composition, feed efficiency , excretion of nitrogenous compounds and microbial protein synthesis . Ten crossbred cows with average body weight of 480 kg (± 30) were used after lactation peak, distributed in a 5x5 Latin square design, duplicate, with four treatments of supplements with different percentages of urea and mineral salt, being these: 10:10; 10:20, 20:10 and 20:20, completed to 100% with corn meal, beyond the fifth treatment consisting only of mineral salt. The experiment lasted 14 days each, with the first seven days for adaptation and the other to collect data and samples. Data were analyzed using the MIXED procedure of SAS, adopting a significance level of 0.05. The use of supplements provided increased (P 0.05) for the diet. The use of supplements resulted in fewer values (P < 0.05) of somatic cell count (SCC) and total bacterial count (TBC) in milk. Supplements, when compared to control or mineral salt (0:100) had (P < 0.05) lower gCP/kgTDN ratio and increased urea nitrogen excretion in urine, blood plasma and milk. The increased level of mineral salt practically did not change the parameters of daily excretion of purine derivatives, microbial N compounds and concentrations of urea nitrogen, except to urinary nitrogen urea that reduced. Supplements can be used to correct nutritional deficiencies of sugarcane, resulting in increased intake, digestibility and milk production. Supplements with 20% urea (20:10 e 20:20) in its composition resulted in lower consumption with the same animal performance and can be concluded that these treatments showed better utilization efficiency.Fundação de Amparo a Pesquisa do Estado de Minas Gerai

Respostas de protozoários ciliados e bactérias do rúmen ao excesso de glicose

Rumen microbes hold a central role in ruminant nutrition. They ferment feed components to produce volatile fatty acids (VFA) and grow (synthesize microbial protein), which supplies the greater part of energy and amino acids required by the animals. However, when given excess carbohydrate, microbes growth efficiency becomes low because microbes direct energy to non-growth functions, instead of using it for growth. Different microorganisms respond to this excess in different ways. Certain species respond by storing energy (synthesizing reserve carbohydrate), but other species respond by dissipating the energy as heat (spilling energy). To determine the relative importance of these responses in the microbial community of the rumen, this study aims to quantify how mixed ciliate protozoa and bacteria respond to glucose. It was hypothesized that ciliate protozoa would direct more glucose to synthesis of reserve carbohydrate and less to energy spilling than would bacteria. Ciliates and bacteria were isolated from rumen fluid using filtration and centrifugation, respectively. Posteriorly, ciliates and bacteria were resuspended in nitrogen-free buffer to limit growth and dosed with 5 mM glucose. Samples were collected over time and were subsequently divided in pellet (cells) and supernatant by centrifugation. Pellet samples were analyzed for reserve carbohydrate and protein, while supernatant sample were analyzed for free glucose, D- /L-lactic acid, acetic acid, propionate and butyrate. Additionally, were analyzed heat production and fermentation gases (H 2 , CH 4 and CO 2 ). Endogenous metabolism, reserve carbohydrate synthesis and energy spilling were calculated from the data obtained from the analysis data. Most data were analyzed using PROC GLIMMIX of SAS. Student’s t- test was used to separate means or determine if means differed from 100%. Local regression (LOCFIT package of R; Loader, 1999) was used to fit time-series data to smooth curves. Compared to bacteria, ciliates consumed glucose more than 3-fold faster and synthesized reserve carbohydrate 4-fold faster. They incorporated 53% of glucose carbon into reserve carbohydrate, nearly double the value (27%) for bacteria. Energy spilling was not detected for ciliates, as all heat production was accounted by synthesis of reserve carbohydrate and endogenous metabolism. For bacteria, reserve carbohydrate and endogenous metabolism accounted for only 68% of heat production, thus they spilled large amounts of energy (32% of total heat production). These results suggest that rumen ciliates protozoa alter the course of carbohydrate metabolism in the rumen by consuming glucose more rapidly and outcompeting bacteria for excess carbohydrate. This action of the ciliates in the rumen likely maximizes reserve carbohydrate synthesis while minimizing spilling.Os microrganismos ruminais têm um papel central na nutrição de ruminantes. Eles têm a capacidade de fermentar componentes do alimento para produzir ácidos graxos voláteis (AGV’s) e crescer (sintetizar proteína microbiana), os quais fornecem a maior parte da energia e aminoácidos exigidos pelos animais. No entanto, quando são fornecidos carboidratos em excesso, a eficiência de crescimento dos microrganismos torna-se baixa porque estes direcionam a energia para outras funções, ao invés de a utilizarem para o crescimento. Diferentes microrganismos respondem a esse excesso de maneiras diferentes. Certas espécies respondem armazenando energia (sintetizando carboidratos de reserva), mas outras espécies respondem dissipando a energia na forma de calor. Para determinar a importância relativa dessas respostas na comunidade microbiana do rúmen, este estudo foi cinduzido com o objetivo de quantificar como os protozoários ciliados e as bactérias responderam à glicose. Teve-se como hipótese que os protozoários ciliados direcionariam mais glicose para a síntese de carboidratos de reserva e desperdiçariam menos energia na forma de calor, em relação as bactérias. Ciliados e bactérias foram isolados do líquido ruminal por filtração e centrifugação, respectivamente. Posteriormente, os ciliados e as bactérias foram suspensos em tampão isento de nitrogênio para limitar o crescimento e dosados com 5 mM de glicose. As amostras foram coletadas ao longo do tempo e, posteriormente, divididas por centrifugação em pellets (células) e sobrenadante. Amostras de pellets foram analisadas quanto à reserva de carboidratos e proteínas, enquanto amostras de sobrenadante foram analisadas para glicose livre, ácido D-L lático, ácido acético, propionato e butirato. Adicionalmente, foi analisado a produção de calor e gases de fermentação (H 2 , CH 4 e CO 2 ). O metabolismo endógeno, a síntese de carboidratos de reserva e o desperdício na forma de calor foram calculados a partir dos dados das análises. A maior parte dos dados foi analisada usando o PROC GLIMMIX do SAS. Teste t de Student foi usado para separar as médias ou determinar se as médias diferiam de 100%. Regressão local (pacote LOCFIT de R; Loader, 1999) foi usada para ajustar os dados das séries no tempo. Em comparação com as bactérias, os ciliados consumiram três vezes mais glicose e sintetizaram carboidratos de reserva quatro vezes mais rápido. Eles incorporaram 53% da glicose em carboidratos de reserva, quase o dobro do valor (27%) obtido para as bactérias. Desperdício de energia na forma de calor não foi detectado para os ciliados, uma vez que toda a produção de calor foi contabilizada pela síntese de reserva de carboidratos e pelo metabolismo endógeno. Em bactérias, a síntese de carboidratos de reserva e o metabolismo endógeno representaram apenas 68% da produção total de calor, assim, elas desperdiçaram grande quantidade de energia por meio da produção de calor (32% da produção total de calor). Esses resultados sugerem que os protozoários ciliados ruminais alteram o curso do metabolismo de carboidratos no rúmen, consumindo glicose mais rapidamente, limitando o uso do excesso de carboidratos pelas bactérias. Essa ação dos ciliados no rúmen provavelmente maximiza a síntese carboidratos de reserva, enquanto minimiza a ocorrência de desperdício de energia na forma de calor

Performance of Holstein-Gyr crossbred heifers on pasture of Brachiaria decumbens supplemented with multiple supplement or proteined salt

 This study aimed to evaluate the performance, efficiency and economic viability of different supplements for dairy heifers on Brachiaria decumbens pasture. Twelve heifers with 186 ± 30.5 kg average weight were divided in three groups of four animals. The treatments were mineral salt ad libitum; 0.4 kg animal-1 day-1 proteined salt and 1.0 kg animal-1 day-1 multiple supplement. The experimental design was randomized blocks, with the contrasts considered significant at 5% probability. There was greater (p 0.05) in any of the performance parameters between proteined salt and multiple supplement. The use efficiency was 1.31 and 0.61 for proteined salt and multiple supplement, respectively. The cost per kg weight gain in treatments with mineral salt, proteined salt and multiple supplement was R$0.67, R$ 0.68 and R$ 1.25, respectively. The use of proteined salt or multiple supplement provides superior performance than mineral salt in crossbred heifers. However, the proteined salt has higher utilization efficiency and economic advantage.

Protected fat and variable level of protein in diets of crossbreed cows in early lactation

Current study evaluated the inclusion of protected fat and different levels of crude protein (CP) in the diet of crossbreed cows in early lactation. Twelve cows were distributed in a 4 x 4 factorial design, with four treatments (12 or 16% CP, with or without MEGALAC-E®). Statistical analyzes with ANOVA and Pearson’s linear correlation procedures were performed. Protected fat did not affect intake of dry matter (DM) and organic matter (OM) (p > 0.05). Increased CP raised consumption of CP and EE and decreased the non-fiber carbohydrates (NFC; p 0.05) on milk yield and composition due to protected fat or CP rates. Since the inclusion of protected fat and higher content of CP (16%) in the diet did not benefit the production and composition of milk in crossbreed cows, diets with 12% CP without the inclusion of protected fat are recommended.

Urea and salt as supplementary diet for crossbreed milk cows

This study aimed to evaluate the use of supplementary feed with different percentages of urea and mineral salt for crossbred milk cows. Ten animals were used, mean body weight 480 kg ± 9,7, distributed in a 5 x 5 double Latin square, with treatments of supplements with different urea and mineral salt percentages, namely, 10:10; 10:20; 20:10 and 20:20, completed to 100% with corn meal. Data underwent statistical analysis by SAS at 0.05 significance level. The use of supplements increased (p < 0.05) the total dry matter (DM) intake of diet. The increase in the level of urea in the supplement decreased DM intake of supplement. The use of supplements increased (p < 0.05) DM digestibility. The treatments with presence of supplement showed higher (p < 0.05) milk production. Supplemented diets may be used to correct nutritional deficiencies of sugar cane, with higher intake, digestibility and milk production. Treatments with 20% urea in the composition of the supplement caused a lower DM consumption with the same performance in the animals. The above-mentioned treatments had the best efficiency

Soybean meal replaced by slow release urea in finishing diets for beef cattle

Eight crossbred steers (average body weight of 418 kg) fitted with ruminal and abomasal cannula were used to evaluate the effects of replacing soybean meal (SBM) with slow-release urea (SRU) in beef cattle diets containing two concentrate levels. The experimental design included two 4×4 Latin squares, which were run simultaneously. Each Latin square received one level of concentrate [400 or 800 g/kg on a dry matter (DM) basis]. Within each Latin square, the four replacement levels of soybean meal protein with slow-release urea were applied to the animals (0%, 33%, 66% and 100% of substitution on N basis). The DM intake as well as organic matter (OM) intake and crude protein (CP) intake decreased linearly (P0.10). A lower intake of DM, OM, and CP was observed when cattle were fed SRU compared to SBM. However, the use of SRU did not change the digestibility and digestion rate (kd) and kp of DM, OM, CP and neutral detergent fiber corrected for ash and protein (NDFap). In summary, SRU provides higher concentrations of NH3–N throughout a day than SBM in cattle fed low concentrate diets