Relationship between different sources of non-protein nitrogen and supplementation times on performance and metabolism of grazing Nellore cattle during the dry season.

Two experiments were conducted to evaluate the effect of supplementation with two sources of non-protein nitrogen at different feeding times on the performance, ingestive behavior, and rumen metabolism of growing Nellore bulls during the dry season. Exp. 1: One hundred and twenty Nellore bulls, weighing 206 ± 39 kg of initial body weight (BW) and 12 months of age, were divided into 20 paddocks, and they were used in randomized block design in a 2 × 2 factorial arrangement to evaluate performance and ingestive behavior. Exp. 2: 12 rumen cannulated animals with 509 ± 59 BW, divided into 4 paddocks, were used in a triple Latin square 4 × 4 in a 2 × 2 factorial arrangement to evaluate metabolism. The factors were 2 non-protein nitrogen sources (urea or slow-release urea) and 2 feeding times (07:00 or 13:00 at 4 g/kg BW of supplement). There was no influence of non-protein sources, supplementation time, or their interaction on the grazing time or the trough time during daytime, nighttime, or total (P ≥ 0.16). There were no interactions or factor effects on ADG (P ≥ 0.45) or final body weight (P ≥ 0.39). There was an interaction between supplementation time and collection time (P < 0.01) on ruminal pH. Animals supplemented in the morning had greater total SCFA at 18 h after supplementation (P = 0.03). The supplementation time and the non-protein nitrogen sources did not alter the ingestive behavior or animal performance of young Nellore cattle.

Association of ionophores, yeast, and bacterial probiotics alters the abundance of ruminal microbial species of pasture intensively finished beef cattle.

The effect of the association of non-protein nitrogen, yeast, and bacterial probiotics on the ruminal microbiome of beef cattle intensively finished on pasture was evaluated. The experiment was carried out in a completely randomized design with five treatments and four replications. The treatments consisted of a group of animals kept on pasture that received low consumption supplementation (LS) and four groups that received for 98 days, 17.5 g concentrate kg-1 body weight. The supplements were composed of the association of additives: urea (U), slow-release non-protein nitrogen (U+SRN), yeast (Saccharomyces cerevisiae; U+SRN+Y), and bacterial probiotics (live strains of bacteria; U+SRN+Y+BP). All supplements also contained salinomycin and virginiamycin. After slaughtering the animals, samples of ruminal content were collected to quantify groups of fibrolytic bacteria (Ruminococcus albus and Fibrobacter succinogenes), non-fibrolytic (Prevotella ruminicola, Selenomonas ruminantium, and Streptococcus bovis), Archaea, and ciliate protozoa, using the qPCR technique. The abundance of F. succinogenes was the same for the LS animals and those that received the supplement U+SRN+Y (1.42×108 copies mL-1) but higher than the other treatments. Supplementation reduced by 90% the abundance of S. bovis compared to the LS. The inclusion of yeast increased the abundance of fibrolytic bacteria by 2.2-fold. For animals that received the supplement U+SRN+Y+BP and the LS, there was no difference for non-fibrolytic bacteria (3.07×109 copies mL-1). The use of yeasts and sources of non-protein nitrogen in high-concentrate diets for beef cattle stimulates the growth of fibrolytic bacteria, which can contribute to the reduction of digestive disorders and metabolic diseases in animals that receive diets with high concentrate in pasture intensive termination systems.

Analysis of NH3-N Slow Release systems for fiber digestibility of low-quality forage: in vitro approach

Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.

Analysis of NH3-N Slow Release systems for fiber digestibility of low-quality forage: in vitro approach

Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.(AU)

Effects of slow-release urea on in vitro rumen fermentation parameters, growth performance, nutrient digestibility and serum metabolites of beef cattle / Efeitos da uréia de liberação lenta nos parâmetros de fermentaçãono do rúmen em vitro, desempenho de crescimento, digestibilidade dos nutrientes e metabolitos séricos de gado de corte

Two experiments were conducted to investigate the effects of slow-release urea (SRU) on in vitro rumen fermentation parameters, growth performances, nutrient digestibility, and serum metabolites of beef cattle. The single factor design was applied in both experiments. Three diets with different nitrogen sources including soybean meal (Control group), slow-release urea (SRU group), and common urea (Urea group) was designed (concentrate to forage ratio was 4:6). The diets were formulated to be isoenergetic and isonitrogenous, 75% of the soybean meal in the control diet was replaced by 1.41% SRU and 1.15% urea in SRU group and Urea group, respectively. In experiment 1, five healthy Jinjiang cattle (average body weight (BW) was 380 ± 17.1 kg) with permanent rumen fistulas were used in in vitro ruminal fermentation experiment. The results showed that supplementing SRU increased the dry matter degradation rate (DMD), digestible organic matter (DOM) and propionic acid concentration in cultivated fluid, and SRU supplementation decreased pH, NH3 -N, total volatile fatty acid (TVFA), acetic acid, butyric acid concentration and microbial growth efficiency (MOEFF) in cultivated fluid. In experiment 2, eighteen Simmental crossbred cattle BW= 315 ± 5.2 kg) were stratified by BW and then assigned to the three groups to have equal BW among groups. The results showed that supplementing SRU reduced the average dry matter intake (ADMI), apparent digestibility of ether extract (EE), the activity of glutathione peroxidase (GSH-Px), the levels of IgG and IgA, and the production of thiiodothronine (T3) in serum, SRU supplementation increased the apparent digestibility of dry matter and organic matter (OM) and alanine aminotransferase (ALT) concentration in serum. These results indicated that some soybean meal could be replaced by SRU and urea in the production of beef cattle. In addition, compared with urea, SRU had a good sustained-release effect. The replacement of some soybean meal by SRU in the diet had no adverse impact on rumen fermentation, growth performance, and serum metabolites of beef cattle.(AU)

Os dois experimentos foram conduzidos para investigar os efeitos da uréia de liberação lenta nos parâmetros de fermentaçãono do rúmen em vitro, desempenho de crescimento, digestibilidade dos nutrientes e metabolitos séricos de gado de corte. O design de fator único foi aplicado em ambos os experimentos. As três dietas com diferentes fontes de nitrogênio, incluindo farelo de soja (Grupo de controle), uréia de liberação lenta (Grupo de uréia de liberação lenta) e uréia comum (Grupo de uréia) foi designado (concentre-se em relação forrageira foi de 4: 6). As dietas foram formuladas para serem isoenergéticas e isonitrógenas, 75% da farinha de soja na dieta controle foi substituída por 1,41% de uréia de liberação lenta e 1,15% de uréia no Grupo uréia de liberação lenta e Grupo uréia, respectivamente. No experimento 1, cinco gados Jinjiang saudáveis (peso corporal médio (PC) de 380 ± 17,1 kg) com fístulas ruminais permanentes foram utilizadas no experimento de fermentação do rúmen em vitro. Os resultados mostraram que a suplementação de uréia de liberação lenta aumentou a taxa de degradação da substância seca, substância orgânica digestível e concentração de ácido propiônico no líquido cultivado, e a suplementação de SRU diminuiu o pH, NH3-N, ácido graxo volátil total, ácido acético, concentração de ácido butírico e eficiência de crescimento microbiano no fluido cultivado. No experimento 2, dezoito gados mestiços Simmental (PC = 315 ± 5,2 kg) foram estratificados por PC e, em seguida, atribuído aos três grupos para ter PC igual entre os grupos. Os resultados mostraram que a suplementação de uréia de liberação lenta reduziu a ingestão média da substância seca, digestibilidade aparente do extrato etéreo, a atividade da glutationa peroxidase, os níveis de IgG e IgA, e a produção de tiiodotronina (T3) no soro, a suplementação de uréia de liberação lenta aumentou a digestibilidade aparente da concentração de substância seca e substância orgânica e concentração de alanina aminotransferase no soro. Esses resultados indicaram que algum farelo de soja pode ser substituída por uréia de liberação lenta e uréia na produção de gado de corte. Além disso, comparado com a uréia, uréia de liberação lenta teve um bom efeito de liberação sustentada. A substituição de algum farelo de soja por uréia de liberação lenta na dieta não teve impacto adverso na fermentação ruminal, desempenho de crescimento e metabolitos séricos de gados de corte.(AU)

Effects of partial replacement of soybean meal with other protein sources in diets of lactating cows.

The protein nutrition of dairy cows is of great importance because of its direct influence on milk production, reproductive efficiency, and feeding cost. Eight first-lactation Holstein cows were randomly assigned to two contemporary 4 × 4 Latin squares in a 2 × 2 factorial design to evaluate the effects of replacing soybean meal with yeast-derived microbial protein (YMP) as a protein source (0% or 1.5% of dry matter (DM)) and its combination with slow-release urea (SRU; 0% or 0.75% of DM) on DM intake and milk production and composition, as well as blood parameters and nitrogen balance. Each experimental period lasted 28 days, with 21 days of adaptation and 7 days of data collection. The diets were formulated to attend the nutritional recommendations of the National Research Council and consisted of 49% forage (47% corn silage and 2% Tifton hay) and 51% concentrate, with 16.8% CP and 1.6 Mcal net energy for lactation/kg DM. For diets without YMP, the inclusion of SRU decreased DM intake, milk production as well as N intake and balance, but did not affect efficiency of production, milk composition or most of blood parameters. On the contrary, for diets with YMP, DM intake and milk production were increased by inclusion of SRU, while minor effects were observed for milk efficiency and composition, blood parameters as well as N intake, excretion and balance. When diets with SRU were compared, the inclusion of YMP increased DM intake, 4% fat-corrected milk, and N intake and balance (P<0.05), with no differences in milk production (kg/day), milk energy, efficiency of milk production or most of the blood parameters. For diets without SRU, YMP inclusion decreased DM intake, milk production, milk energy, N intake, fecal N and N balance (P<0.05), with no effects on milk efficiency and composition, or most of blood parameters. In conclusion, the use of YMP, SRU or both as partial substitutes of soybean meal in the diet of lactating cows has no negative effects on productivity parameters.

Bionutritional efficiency and carcass characteristics of confined steers receiving different nitrogen sources with whole or milled corn / Eficiência bionutricional e características da carcaça de novilhos confinados recebendo distintas fontes nitrogenadas com milho moído ou inteiro

The objective of this study is to evaluate the bionutritional efficiency and carcass characteristics of confined steers receiving different nitrogen sources associated or not with corn grain processing in the diet. The study used a completely randomized design with a 3 × 2 factorial arrangement. Fifty-three Charolais and Nellore crossbred steers were used, with a mean age of 22 ± 0.23 months and initial weight 250 ± 15.80 kg. The animals were randomly divided into the following treatments: soybean meal + whole corn, soybean meal + milled corn, conventional urea + whole corn, conventional urea + milled corn, slow-release urea + whole corn, and slow-release urea + milled corn. A roughage: concentrate ratio of 50: 50 was used. The steers were confined until reaching a weight of 420 kg. The slaughtering occurred according to the schedule of the commercial slaughterhouse. Feed efficiency was lower in animals receiving slow-release urea than those fed true protein. The steers fed soybean meal presented a higher Kleiber ratio and higher nutritional index compared to those receiving conventional or slow-release urea. The provision of soybean meal promoted higher production of rib meat and meat with a higher L* compared to those receiving urea, and better carcass finish compared to those receiving slow-release urea. Diets with milled corn increased warm and cold carcass yields and decreased weight loss during carcass chilling. Total replacement of soybean meal with conventional or slow-release urea reduced the biological efficiency of steers. The supply of milled corn in the concentrated fraction increased carcass yield.(AU)

Objetivou-se avaliar a eficiência bionutricional e as características da carcaça de novilhos confinados, recebendo diferentes fontes nitrogenadas, associadas ao processamento ou não do grão de milho nas dietas. O delineamento experimental foi o inteiramente casualizado, em arranjo fatorial 3 x 2. Foram utilizados 53 novilhos mestiços Charolês e Nelore, com idade e peso médio inicial de 22 ± 0,23 meses e 250 ± 15,80 kg, respectivamente, os quais foram divididos aleatoriamente nos seguintes tratamentos: farelo de soja + milho grão; farelo de soja + milho moído; ureia comum + milho grão; ureia comum + milho moído; ureia de liberação lenta + milho grão e ureia de liberação lenta + milho moído. Utilizou-se relação volumoso:concentrado de 50:50. Os novilhos permaneceram confinados até atingir peso pré-estipulado de 420 kg. O abate transcorreu conforme fluxograma do frigorífico comercial. A eficiência alimentar foi menor nos animais que receberam ureia protegida, em relação aos alimentados com proteína verdadeira. Novilhos alimentados com farelo de soja apresentaram maior Relação de Kleiber e índice nutricional multivariado biológico, que alimentados com ureia protegida ou não. O fornecimento de farelo de soja, promoveu maior participação de costilhar e carne com maior valor de L*, em relação às ureias, além de melhor acabamento de carcaça, em relação à ureia protegida. Dietas com milho moído proporcionaram aumentos nos rendimentos de carcaça quente e fria, com menores perdas de líquidos no resfriamento. A substituição total do farelo de soja por ureia, protegida ou não, reduz a eficiência biológica de novilhos. Maiores rendimentos de carcaça são obtidos quando se fornece milho moído na fração concentrado.(AU)

Bionutritional efficiency and carcass characteristics of confined steers receiving different nitrogen sources with whole or milled corn / Eficiência bionutricional e características da carcaça de novilhos confinados recebendo distintas fontes nitrogenadas com milho moído ou inteiro

The objective of this study is to evaluate the bionutritional efficiency and carcass characteristics of confined steers receiving different nitrogen sources associated or not with corn grain processing in the diet. The study used a completely randomized design with a 3 × 2 factorial arrangement. Fifty-three Charolais and Nellore crossbred steers were used, with a mean age of 22 ± 0.23 months and initial weight 250 ± 15.80 kg. The animals were randomly divided into the following treatments: soybean meal + whole corn, soybean meal + milled corn, conventional urea + whole corn, conventional urea + milled corn, slow-release urea + whole corn, and slow-release urea + milled corn. A roughage: concentrate ratio of 50: 50 was used. The steers were confined until reaching a weight of 420 kg. The slaughtering occurred according to the schedule of the commercial slaughterhouse. Feed efficiency was lower in animals receiving slow-release urea than those fed true protein. The steers fed soybean meal presented a higher Kleiber ratio and higher nutritional index compared to those receiving conventional or slow-release urea. The provision of soybean meal promoted higher production of rib meat and meat with a higher L* compared to those receiving urea, and better carcass finish compared to those receiving slow-release urea. Diets with milled corn increased warm and cold carcass yields and decreased weight loss during carcass chilling. Total replacement of soybean meal with conventional or slow-release urea reduced the biological efficiency of steers. The supply of milled corn in the concentrated fraction increased carcass yield.

Objetivou-se avaliar a eficiência bionutricional e as características da carcaça de novilhos confinados, recebendo diferentes fontes nitrogenadas, associadas ao processamento ou não do grão de milho nas dietas. O delineamento experimental foi o inteiramente casualizado, em arranjo fatorial 3 x 2. Foram utilizados 53 novilhos mestiços Charolês e Nelore, com idade e peso médio inicial de 22 ± 0,23 meses e 250 ± 15,80 kg, respectivamente, os quais foram divididos aleatoriamente nos seguintes tratamentos: farelo de soja + milho grão; farelo de soja + milho moído; ureia comum + milho grão; ureia comum + milho moído; ureia de liberação lenta + milho grão e ureia de liberação lenta + milho moído. Utilizou-se relação volumoso:concentrado de 50:50. Os novilhos permaneceram confinados até atingir peso pré-estipulado de 420 kg. O abate transcorreu conforme fluxograma do frigorífico comercial. A eficiência alimentar foi menor nos animais que receberam ureia protegida, em relação aos alimentados com proteína verdadeira. Novilhos alimentados com farelo de soja apresentaram maior Relação de Kleiber e índice nutricional multivariado biológico, que alimentados com ureia protegida ou não. O fornecimento de farelo de soja, promoveu maior participação de costilhar e carne com maior valor de L*, em relação às ureias, além de melhor acabamento de carcaça, em relação à ureia protegida. Dietas com milho moído proporcionaram aumentos nos rendimentos de carcaça quente e fria, com menores perdas de líquidos no resfriamento. A substituição total do farelo de soja por ureia, protegida ou não, reduz a eficiência biológica de novilhos. Maiores rendimentos de carcaça são obtidos quando se fornece milho moído na fração concentrado.

Influence of polymer-coated slow-release urea on total tract apparent digestibility, ruminal fermentation and performance of Nellore steers.

OBJECTIVE: Two experiments were performed to evaluate the effects of coated slow-release urea on nutrient digestion, ruminal fermentation, nitrogen utilization, blood glucose and urea concentration (Exp 1), and average daily gain (ADG; Exp 2) of steers. METHODS: Exp 1: Eight ruminally fistulated steers [503±28.5 kg body weight (BW)] were distributed into a d 4×4 Latin square design and assigned to treatments: control (CON), feed grade urea (U2), polymer-coated slow-release urea A (SRA2), and polymer-coated slow-release urea B (SRB2). Dietary urea sources were set at 20 g/kg DM. Exp 2: 84 steers (350.5±26.5 kg initial BW) were distributed to treatments: CON, FGU at 10 or 20 g/kg diet DM (U1 and U2, respectively), coated SRA2 at 10 or 20 g/kg diet DM (SRA1 and SRA2, respectively), and coated SRB at 10 or 20 g/kg diet DM (SRB1 and SRB2, respectively). RESULTS: Exp 1: Urea treatments (U2+SRA2+SRB2) decreased (7.4%, p = 0.03) the DM intake and increased (11.4%, p<0.01) crude protein digestibility. Coated slow-release urea (SRA2+SRB2) showed similar nutrient digestibility compwared to feed grade urea (FGU). However, steers fed SRB2 had higher (p = 0.02) DM digestibility compared to those fed SRA2. Urea sources did not affect ruminal fermentation when compared to CON. Although, coated slow-release urea showed lower (p = 0.01) concentration of NH3-N (-10.4%) and acetate to propionate ratio than U2. Coated slow-release urea showed lower (p = 0.02) urinary N and blood urea concentration compared to FGU. Exp 2: Urea sources decreased (p = 0.01) the ADG in relation to CON. Animals fed urea sources at 10 g/kg DM showed higher (12.33%, p = 0.01) ADG compared to those fed urea at 20 g/kg DM. CONCLUSION: Feeding urea decreased the nutrient intake without largely affected the nutrient digestibility. In addition, polymer-coated slow-release urea sources decreased ruminal ammonia concentration and increased ruminal propionate production. Urea at 20 g/kg DM, regardless of source, decreased ADG compared both to CON and diets with urea at 10 g/kg DM.

Replacement of soybean meal by conventional and coated urea indairy cows: intake, digestibility, production and composition of milk / Substituição do farelo de soja por uréia convencional e protegida em vacas leiteiras:consumo, digestibilidade, produção e composição do leite

This study evaluated the effect of dairy cows diets containing two different sources of ureaon dry matter intake, nutrient apparent digestibility, and milk production and composition. Eight crossbred cows (Holandês x Zebu) were confined and randomly assigned to four sequential diets distributed in two4 x 4 Latin: SM = soybean meal; SRU 0 = conventional urea (CU) 100%/slow release urea (SRU) 0%;SRU 44 = CU 56%/SRU 44%; SRU 88 = CU 12%/SRU 88%. Experimental periods consisted of 21 days,with total duration of 84 days. Dry matter intake, neutral detergent fiber, organic matter, crude protein, and total digestible nutrients were not affected by experimental diets. Dry matter and neutral detergent fiber digestibility coefficient presented average values of 69.43 and 51.07%, respectively. Average digestibility ofcrude protein was 65.43%. Average milk production was 9.609 kg. The partial replacement of soybean mealby conventional urea and slow release urea, at 2.1% of the diet dry matter, showed that these sources of urea can be offered without production impairment for dairy cows.(AU)

Objetivou-se, avaliar o efeito de duas diferentes fontes de ureia em dietas de vacas lactantes sobre consumo, digestibilidade aparente, produção e composição do leite. Utilizaram-se oito vacas mestiças Holandês x Zebu, sendo confinadas e distribuídas aleatoriamente, alocadas a uma sequência de quatro dietas experimentais, em delineamento distribuído em dois quadrados latino 4 x 4. FS - farelo de soja; ULL0 = ureia convencional (UC) 100% / ureia de liberação lenta (ULL) 0%; ULL 44 = UC 56% / ULL 44%;ULL 88 = UC 12% / ULL 88%. Os períodos experimentais foram de 21 dias, com duração total de 84 dias.Não houve efeito significativo nas dietas experimentais, para os coeficientes de consumo de matéria seca,fibra em detergente neutro, matéria orgânica, proteína bruta e nutrientes digestíveis totais. O coeficiente de digestibilidade da matéria seca apresentou valor 69,43% e o da fibra em detergente neutro de 51,07%.A digestibilidade da proteína bruta obteve média de 65,43%. A média de produção de leite foi de 9,609 kg.A substituição parcial de farelo de soja por ureia em 2,1% da matéria seca da dieta, mostra que as fontes de ureias utilizadas podem ser oferecidas, sem que haja prejuízos produtivos para as vacas lactantes.(AU)

Replacement of soybean meal by conventional and coated urea indairy cows: intake, digestibility, production and composition of milk / Substituição do farelo de soja por uréia convencional e protegida em vacas leiteiras:consumo, digestibilidade, produção e composição do leite

This study evaluated the effect of dairy cows’ diets containing two different sources of ureaon dry matter intake, nutrient apparent digestibility, and milk production and composition. Eight crossbred cows (Holandês x Zebu) were confined and randomly assigned to four sequential diets distributed in two4 x 4 Latin: SM = soybean meal; SRU 0 = conventional urea (CU) 100%/slow release urea (SRU) 0%;SRU 44 = CU 56%/SRU 44%; SRU 88 = CU 12%/SRU 88%. Experimental periods consisted of 21 days,with total duration of 84 days. Dry matter intake, neutral detergent fiber, organic matter, crude protein, and total digestible nutrients were not affected by experimental diets. Dry matter and neutral detergent fiber digestibility coefficient presented average values of 69.43 and 51.07%, respectively. Average digestibility ofcrude protein was 65.43%. Average milk production was 9.609 kg. The partial replacement of soybean mealby conventional urea and slow release urea, at 2.1% of the diet dry matter, showed that these sources of urea can be offered without production impairment for dairy cows.

Objetivou-se, avaliar o efeito de duas diferentes fontes de ureia em dietas de vacas lactantes sobre consumo, digestibilidade aparente, produção e composição do leite. Utilizaram-se oito vacas mestiças Holandês x Zebu, sendo confinadas e distribuídas aleatoriamente, alocadas a uma sequência de quatro dietas experimentais, em delineamento distribuído em dois quadrados latino 4 x 4. FS - farelo de soja; ULL0 = ureia convencional (UC) 100% / ureia de liberação lenta (ULL) 0%; ULL 44 = UC 56% / ULL 44%;ULL 88 = UC 12% / ULL 88%. Os períodos experimentais foram de 21 dias, com duração total de 84 dias.Não houve efeito significativo nas dietas experimentais, para os coeficientes de consumo de matéria seca,fibra em detergente neutro, matéria orgânica, proteína bruta e nutrientes digestíveis totais. O coeficiente de digestibilidade da matéria seca apresentou valor 69,43% e o da fibra em detergente neutro de 51,07%.A digestibilidade da proteína bruta obteve média de 65,43%. A média de produção de leite foi de 9,609 kg.A substituição parcial de farelo de soja por ureia em 2,1% da matéria seca da dieta, mostra que as fontes de ureias utilizadas podem ser oferecidas, sem que haja prejuízos produtivos para as vacas lactantes.

Utilização de uréia encapsulada de liberação lenta na alimentação de novilhos Nelore / Use of polymer-coated slow release urea in the feeding of beef Nellore

O presente estudo foi desenvolvido à partir de dois experimentos. No primeiro objetivou-se foi avaliar a utilização de uréia encapsulada de liberação lenta em dietas de novilhos Nelore canulados no rúmen e seus efeitos sobre o consumo e digestibilidade dos nutrientes, fermentação e produção microbiana ruminal, balanço de nitrogênio, e as concentrações de parâmetros sangüíneos. Foram utilizados 8 novilhos canulados da raça Nelore, mantidos em regime de confinamento, alocados em baias individuais cobertas, tipo tie stall. Os animais foram distribuídos aleatoriamente em 2 quadrados latinos 4 x 4 balanceados e contemporâneos, para receber as seguintes rações experimentais: 1) Controle (C), composta por ração sem a inclusão de uréia; 2) Uréia pecuária (Reforce N) (U), com a utilização de 2,0% de uréia pecuária na ração, baseada na matéria seca; 3) Uréia encapsulada 1 (UE-1), a utilização de 2,0% de uréia encapsulada com o polímero 1 na ração, baseada na matéria seca; e 4) Uréia encapsulada 2 (UE-2), com a utilização de 2,0% de uréia encapsulada com o polímero 2 na ração, baseada na matéria seca. O volumoso foi a silagem de milho, sendo a proporção volumoso: concentrado da dieta de 50:50. Foi observado maior consumo de MS, MO, PB, EE, CNF, FDN, FDN e consumo de MS em relação a %PV nos animais controle em relação aos alimentados com uréia. Foi observado menor digestibilidade da PB nos animais controle em relação aos alimentados com uréia. Maiores concentrações de N-NH3 ruminal foram observadas nos animais alimentados com uréia comum em relação aos alimentados com uréia encapsulada e maiores concentrações de propionato foram encontradas nos animais alimentados com uréia encapsulada em relação aos com uréia comum. Foi observado maior consumo de energia bruta, energia digestível, energia líquida, produção de energia líquida de ganho e eficiência energia líquida de produção nos animais submetidos a dieta controle em relação aos alimentados com uréia. Também foi observado maior consumo de nitrogênio (N) (g/dia) nos animais controle em relação aos com uréia, ainda maior quantidade de N e %N total nas fezes nos animais controle em relação aos alimentados com uréia e maior quantidade de N e %N urinário nos animais alimentados com uréia comum em relação aos com uréia encapsulada. Observou-se maiores concentrações de colesterol sérico nos animais controle em relação aos com uréia e maiores concentrações de uréia e N-ureico séricos nos animais alimentados com uréia em relação aos com uréia encapsulada. A utilização de uréia encapsulada alterou positivamente a fermentação ruminal,...

The present study was developed from two experiments. At first the aim was to evaluate the use of polymer-coatedslow release urea in rations of Nelore bulls with ruminal cannulas and its effect on consumption and nutrient digestibility, rumen fermentation and microbial production, nitrogen balance, and blood parameters concentrations. Eight Nelore bulls with ruminal cannulas, kept in individual tie stalls, were assigned to two 4 x 4 contemporary Latin squares balanced to receive the following experimental diets: 1) Control (C), consisting of diet without the addition of urea, 2) Feed-grade Urea (FGU) with 2,0% urea in ration, based on dry matter (DM), 3) Polymer-coated urea1 (PCU-1), with 2.0% PCU1 in the ration, based on DM, and 4) Polymer-coated urea 2 (PCU-2) with 2.0% PCU2 in the ration based on DM. The forage source was corn silage, and the proportion forage:concentrate diet was 50:50. There was higher dry matter intake (DMI), original matter intake (OMI), crude protein (PB), ether extract (EE), non-fiber carbohydrates (NFC) and neutral detergent fiber (NDF) in relation to percentage of body weight (BW%) in control animals compared with those fed urea. Lower digestibility of CP was observed in control animals compared with those fed urea. Higher concentrations of ruminal NH3-N were found in animals fed urea compared to those fed PCU and higher concentrations of propionate were found in animals fed PCU compared to those fed FGU. There was a higher consumption of gross energy, digestible energy, net energy, net energy production and efficiency gains net energy production in animals receiving control diet than those fed urea. There was a greater consumption of nitrogen (N) (g/day) in animals receiving control diet compared to urea fed groups, even greater amount of N and total % N in feces in control animals than urea fed groups and higher N and % urinary Nin ureafed animals compared to those fed PCU. Higher concentrations were observed in serum cholesterol in the control group compared urea fed groups and higher concentrations of urea and serum urea-N in FGU group compared to PCU group. The use of PCU positively affected ruminal fermentation, however inclusion levels of 2% decreases the intake of animals. In the second experiment, to evaluate the use of PCU in diets of bull calves in confinement and its effect on intake, animal performance, carcass quality and blood parameters. Animals were used 84 whole steers, Nellore, aged approximately 18 months and initial weight of 350 kg. The animals were confined for a period of 84 days, preceded by an adaptation ph r...

Utilização de ureia encapsulada de liberação lenta na alimentação de vacas em lactação / Use of Polymer-coatted slow-relase urea on Feeding Dairy Cows

Objetivou-se avaliar a utilização de ureia encapsulada de liberação Lenta nas dietas de vacas em lactação e seus efeitos sobre o consumo e digestibilidade aparente total da matéria seca e dos nutrientes, fermentação ruminal, produção microbiana ruminal, produção e composição do leite, e as concentrações de parâmetros sangüíneos. Foram utilizadas 16 vacas da raça Holandesa com produção média de 30,0 kg/dia, agrupadas em 4 quadrados latinos 4x4 balanceados e contemporâneos, recebendo as dietas experimentais: 1) Controle (CT), ração sem a inclusão de ureia; 2) Ureia pecuária (UP), com a utilização de 1,0% de UP na ração, baseada na matéria seca (MS); 3) Ureia encapsulada 1 (UE1), com a utilização de 1,0% de UE1 na ração, baseada na MS; e 4) Ureia encapsulada 2 (UE2), com a utilização de 1,0% de UE2 na ração, baseada na MS. O volumoso utilizado foi a silagem de milho, em relação de 50:50 (relação volumoso:concentrado). A produção de leite e o consumo de matéria seca foram mensurados diariamente durante todo o período experimental. As amostras utilizadas para análise da composição do leite foram coletadas no 16º dia de cada período experimental, sendo provenientes das duas ordenhas diárias. As amostras de sangue foram coletadas em tubos vacuolizados por punção da veia e/ou artéria coccígea. As amostras de líquido ruminal foram coletadas com a utilização de sonda esofágica três horas após a alimentação matinal. A digestibilidade foi determinada por meio de indicador interno FDAi. Não houve diferença para consumo de matéria seca, matéria orgânica, proteína bruta, extrato etéreo, fibra em detergente neutro e nutrientes digestíveis totais. Foi observado aumento na digestibilidade da proteína bruta e nos nutrientes digestíveis totais observados nos animais submetidos às dietas contendo ureia quando comparados aos animais alimentados com a dieta controle. Não houve efeito das dietas experimentais sobre o pH e concentração de amônia ruminal. Foi observado aumento nas concentrações totais de ácidos graxos de cadeia curta e do ácido propiônico nos animais tratados com a dieta controle quando comparados aos animais alimentados com as dietas com inclusão de ureia, mas não foi observada alteração na relação acetato:propionato e na proporção molar dos ácidos graxos de cadeia curta. Também não foi observada diferença na síntese e na eficiência de síntese de proteína microbiana. Não houve diferença para o consumo de compostos nitrogenados totais, e nas excreções de compostos nitrogenados na urina, no balanço de nitrogênio e na eficiência de utilização do nitrogênio. Foi observado aumento na excreção de compostos nitrogenados no leite e nas fezes nos animais tratados com a ração controle quando comparados aos animais tratados co...

The aim was to evaluate the use of polymer-coated slow release urea (PCU) in rations for lactating cows by evaluating its effects on consumption and nutrient digestibility, ruminal fermentation, rumen microbial yield, production and milk composition, and concentrations of blood parameters. To perform this experiment were used 16 Holstein cows with average production of 30.0 kg/day, divided into four 4x4 balanced and contemporary latin squares, receiving the experimental diets: 1) Control (CT) diet without the addition of urea, 2) Feedgrade Urea (FGU), with the use of PCU 1.0% in the diet based on dry matter (DM), 3) PCU 1, with the use of PCU1 1.0% of the diet, based on DM, and 4) PCU 2 , with the use of 1.0% PCU2 in the diet, based on DM. The forage used was corn silage in a ratio of 50:50 (forage:concentrate ratio). Milk production (MP) and dry matter intake (DMI) were measured daily throughout the experimental period. The samples used to analyze the composition of milk were collected on the 16th day of each experimental period, and from the two daily milkings. Blood samples were collected in tubes vacuolated by vein puncture and/or coccygeal artery. The rumen fluid samples were collected with the use of esophageal probe three hours after the morning feeding. The digestibility was determined by means of the internal marker indigestible acid detergent fiber. There was no difference for DMI, organic matter, crude protein, ether extract, neutral detergent fiber and total digestible nutrients. There was a increase in the digestibility of crude protein and total digestible nutrients in animals treated with urea diets compared to animals fed the control diet. There was no effect on pH and ruminal ammonia. An increase in concentrations of total short-chain fatty acid and propionic acid was observed in animals treated with the control diet compared to animals fed diets with inclusion of urea. There was no change in acetate: propionate ratio and the molar ratio of short-chain fatty acids. There was no difference in the synthesis and efficiency of synthesis of microbial proteins. There was no difference in consumption of total nitrogen compounds, and nitrogen compounds excretion in urine, nitrogen balance and nitrogen use efficiency. There was an increase in the excretion of nitrogenous compounds in milk and feces in animals treated with the control diet compared to animals treated with urea rations. Was observed an increase in milk production and total fat and lactose production in animals treated with the control diets compared to animals treated with urea rations. There was no difference in blood concentrations of glucose, urea and urea nitrogen. The use of urea in the feeding of dairy cows, despite the lower mil...