Rilene Ferreira Diniz Valadares

Comportamento ingestivo de vacas leiteiras alimentadas com dietas à base de cana-de-açúcar ou silagem de milho

Doze vacas da raca Holandesa, puras e mesticas, foram distribuidas em tres quadrados latinos 4 X 4, balanceados de acordo com o periodo de lactacao, com o objetivo de avaliar parâmetros do comportamento ingestivo. As dietas experimentais foram a base de silagem de milho com relacao volumoso:concentrado de 60:40, com base na materia seca, ou a base de cana-de-acucar, com relacao volumoso:concentrado de 60:40 ou 50:50. As vacas foram submetidas a observacao visual para avaliacao do comportamento ingestivo. Os animais foram observados a cada dez minutos, durante 24 horas, para determinacao do tempo despendido em alimentacao, ruminacao e ocio. Nao houve diferenca para os tempos medios despendidos com alimentacao e ruminacao entre as dietas experimentais. Entretanto, na dieta a base de silagem de milho, os animais ficaram menos tempo no ocio, quando comparados aqueles alimentados com cana-de-acucar. Com relacao a eficiencia de alimentacao, expressa em gFDN/h, nao houve diferenca entre as dietas experimentais. A eficiencia de ruminacao, expressa em gMS/h, foi semelhante para as diferentes dietas. A eficiencia de ruminacao, expressa em gFDN/h (ERUFDN) foi maior para a dieta a base de silagem de milho. Nao houve diferenca na ERUFDN entre dietas a base de cana-de-acucar. Vacas alimentadas com dietas a base de cana-de-acucar apresentaram maior tempo despendido em ocio e menor consumo de MS, quando comparadas aquelas alimentadas com dietas a base de silagem de milho

Produção de proteína microbiana e estimativas das excreções de derivados de purinas e de uréia em vacas lactantes alimentadas com rações isoprotéicas contendo diferentes níveis de compostos nitrogenados não-protéicos

The objectives of the present work were to estimate the microbial protein production using the total purine derivatives (PD) excretion, to compare the PD and the urea excretions, obtained from spot urine collection with that observed in the 24 hours collection and to evaluate the plasma and milk N-urea and urea urinary excretion. Sixteen Holstein lactating cows were assigned to four 4X4 Latin Square with 3-wk periods in accordance with the lactation period. The four experimental isoproteic diets were formulated to contain 60% of corn silage and 40% of corn meal, soybean meal, urea and mineral salt mixture as dry matter basis. Crescent levels of urea in the concentrate 0.0, 0.7, 1.4, and 2.1% corresponded to the crude protein of 2.22, 4.18, 5.96 and 8.09% of non protein nitrogen based compounds (NPN), respectively. The urine collection was also estimated with urine samples obtained four hours post fed (spot), by the relation of the daily mean creatinine excretion and the urine spot creatinine concentration. The urinary volume and PD excretion and urea estimated through the urine spot did not differ from that obtained from 24 h urine collection. The N-Microbial production estimated and obtained presenting maximum values of 198.05 and 196.96 g/day with the NPN levels of 5.33 and 4.44%, respectively. The milk allantoin concentration linearly decreased as the NPN increased in the diet and represented 4.5% of total PD excretion. The creatinine excretion was not influenced by the dietary NPN levels (23.41 mg/kg LW), while the estimated and obtained urea excretion, the plasma and milk urea and N-urea concentration linearly increased as the NPN increased in the diet. The plasma and milk N-urea concentration of 19-20 mg/dL and 24-25 mg/dL, respectively, represented the limit values from that would occur nitrogen compounds losses.

Endogenous fraction and urinary recovery of purine derivatives obtained by different methods in Nellore cattle

Two experiments were conducted to assess the endogenous fraction of purine derivative (PD) excretion, urinary recovery, and intestinal digestibility of purines in Nellore heifers. For both experiments, 8 Nellore heifers fitted with ruminal and abomasal cannulas were allocated to two 4 × 4 Latin squares. The diets were based on corn silage and concentrate (60 and 40% DM basis, respectively); feces and urine samples were obtained by total collection, and abomasal DM flow was estimated using indigestible NDF as an internal marker. In Exp. I, 4 of the 8 heifers (BW 258 ± 20 kg) were also fitted with ileal cannula. The planned treatments were 4 different DMI: 1.2, 1.6, 2.0, and 2.4% of BW (DM basis). The endogenous losses and purine recovery as urinary PD were estimated using linear regression between daily urinary PD excretion (Y) and daily abomasal flow of purine bases (X), expressed in millimoles per kilogram of BW(0.75). In Exp. II, the same 8 Nellore heifers (BW of 296 ± 15 kg) were fed at 1.37% BW (DM basis). The treatments were the infusion of purines (RNA from torula yeast, type VI, Sigma) into the abomasum in increasing amounts (0, 33, 66, and 100 mmol/d). All statistical analyses were performed using the PROC MIXED procedure in SAS. In Exp. I, the DMI range was 1.16 to 1.84% of BW and did not affect (P > 0.05) the apparent RNA digestibility in the small intestine, which had a mean of 75.6%, and a true digestibility of 93.0%. The mean ratio of the N-RNA to the total-N in the ruminal bacteria was 0.137. The daily urinary PD excretion (Y, mmol/kg of BW(0.75)) was a function of RNA flow in the abomasum (X, mmol/kg of BW(0.75)): Y = 0.860X + 0.460, where 0.860 and 0.460 were the PD recovery of purines and the endogenous fraction (in mmol/kg of BW(0.75)), respectively. In Exp. II, the daily urinary PD excretion was a function of RNA flow in the abomasum: Y = 0.741X + 0.301, where 0.741 and 0.301 were the recovery of PD in urine of infused purines and the endogenous losses (in mmol/kg of BW(0.75)), respectively. In conclusion, our data suggest that in Nellore heifers the respective values of endogenous PD excretion (mmol/kg of BW(0.75)), urinary recovery of the purines absorbed in the abomasum, and true digestibility of RNA in the small intestine were 0.30, 0.80, and 0.93.

Consumo e digestibilidades aparentes totais e parciais de rações contendo diferentes níveis de concentrado, em novilhos F1 Limousin x Nelore

The objective of this work was to evaluate the effects of five dietary concentrate levels (25.0, 37.5, 50.0, 62.5, and 75.0%) on intake and the total and partial apparent digestibilities of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), total carbohydrates (CHO) and neutral detergent fiber (NDF). Five rumen, abomasum and ileum fistulated F1 Limousin x Nellore bulls, with average initial weight of 279 kg were used, in a 5 x 5 Latin square design, with five treatments, five experimental periods and five animals. Each experimental period lasted 14 days - 10 days for animals adaptation to the diet and four days for feces, and abomasum and ileum digesta collection. Chromium oxide was used as indicator, in two doses of 10 g/day, to measure nutrient flows in the digestive tract. The ether extract and TDN intakes increased and of the NDF linearly decreased with the increase of dietary concentrate levels. The increment of concentrate levels in DM linearly increased the apparent total digestibilities of the DM, OM, CP, and CHO. The apparent total NDF digestibility and the apparent ruminal digestibilities of DM, OM, CP, CHO and FDN were not influenced by the dietary concentrate levels, with means of 45.91, 54.45, 64.67, -9.92, 79.29, and 95.90%, respectively. The increase of dietary concentrate levels did not affect the local of nutrients digestion.

Desempenho produtivo de vacas leiteiras alimentadas com diferentes proporções de cana-de-açúcar e concentrado ou silagem de milho na dieta

Twelve lactating Holstein dairy cows were assigned to three 4x4 Latin squares to evaluate the effects of feeding corn silage or different dietary ratios of sugarcane and concentrate on nutrient intake, apparent digestibility, milk composition and yield, and body weight change. The diets contained 60% corn silage or 60, 50, and 40% of sugarcane supplemented with 1% of urea + ammonium sulphate (9:1). No significant differences were observed between the diet with 60% of corn silage and that with 40% of sugarcane on milk yield (20.81 and 19.78 kg/day), intake of dry matter and almost all remaining nutrients, apparent digestibility of most nutrients, and body weight change. Among sugarcane-based diets, cows fed the diet containing 60% sugarcane had the lowest milk yield (16.90 kg/day), dry matter intake, and body weight change, those fed 50% sugarcane were intermediate, and cows fed the diet with the smallest proportion of sugarcane (40%) had the highest values for these variables. Intake of NDF of cows receiving 50% sugarcane was similar to that of cows fed 40% sugarcane while for apparent digestibilities of NDF and nonfiber carbohydrates similar values were observed for cows fed 60 and 50% sugarcane-based diets. Milk composition did not differ significantly across treatments in the present trial.

Composição Corporal e Requisitos Energéticos e Protéicos de Bovinos Nelore, Não-Castrados, Alimentados com Rações Contendo Diferentes Níveis de Concentrado e Proteína

Forty Nellore bulls, with average initial live weight (LW) of 240 kg, were used. Four reference bulls and four bulls fed for maintenance were used, and the remaining was assigned to eight treatments, with four different concentrate levels in the diets (20, 40, 60 and 80%) and two (15 and 18%) levels of crude protein (CP). The protein, fat and energy contents retained in the body were estimated by regression equations of the logarithm of protein, fat or energy body content, as a function of the logarithm of empty body weight (EBW). By deriving the prediction equations of body content of protein, fat, or energy, as a function of the EBW logarithm, the net requirements of protein and energy, for gains of 1 kg EBW, were determined. The deriving equation was Y = b. 10a. Xb-1, being a and b intercept and regression coefficient, respectively, of the prediction equations of protein or energy body contents. Net energy requirement for maintenance (NEm) was estimated as the intercept anti-log of the equation obtained by linear regression among the logarithm of heat production and the metabolizable energy intake. The net energy requirement for weight gain of zebu bulls can be obtained by the equation: NEg = 0.0413 x EBW0.75 x gain of EBW0.978. The NEm for these animals was 83.70 kcal/EBW0.75. The following equation was obtained to estimate the retained protein (RP), as a function of EBW gain and retained energy (RE): RP = - 39.0169 + 200.638 gain of EBW + 0.4166 RE. The net protein requirement of Nellore bulls decreased as the LW increased, being 183.22 and 173.72 g/kg of EBW gain for animals with 200 and 400 kg of LW, respectively.

Estimativa da produção de proteína microbiana pelos derivados de purinas na urina em novilhos

O trabalho foi realizado para avaliar a determinacao da producao de proteina microbiana com a utilizacao da excrecao urinaria de derivados de purinas; comparar a producao de proteina microbiana por intermedio dos metodos das bases purinas e da excrecao urinaria de derivados de purinas; determinar a producao de proteina microbiana em funcao do consumo de materia seca e da porcentagem de fibra em detergente neutro da racao; e estabelecer a proporcao de alantoina e acido urico, em relacao a xantina e hipoxantina na urina. Foram realizados cinco experimentos com animais fistulados no rumen, abomaso e ileo para estudos simultâneos de consumo, digestoes totais e parciais de nutrientes e eficiencia de sintese de proteina microbiana. Utilizou-se o delineamento experimental em quadrado latino 5x5, a excecao do experimento IV (4x4). Os dados foram agrupados em todos os experimentos, os que envolveram animais mesticos (I, II e III) e zebuinos (IV e V). Utilizou-se, para todos os dados agrupados, o delineamento inteiramente casualizado, em funcao dos niveis de concentrado da dieta. Da urina total coletada em 24 horas, foram analisados os derivados de purinas (alantoina, acido urico, xantina e hipoxantina) para determinar a producao microbiana. Para todos os experimentos agrupados, as excrecoes de derivados de purinas urinarios, representadas pela alantoina e pelas purinas totais, apresentaram comportamento quadratico em funcao dos niveis de concentrado da racao, acompanhando o comportamento do fluxo de compostos nitrogenados microbianos (N mic) estimado pelos derivados de purinas na urina, usando a relacao N purina:N total de 0,116, e o estimado pelas bases purinas no abomaso, encontrando-se valores maximos de 72,07 e 86,08 g N mic/dia, para niveis de 62,91 e 63,60% de concentrado, respectivamente. A relacao alantoina e acido urico:purinas totais foi de, aproximadamente, 98%, indicando que a concentracao de xantina e hipoxantina seria, em torno, de 2%.

Influence of different levels of concentrate and ruminally undegraded protein on digestive variables in beef heifers.

This experiment evaluated the effect of 2 levels of diet concentrate (20 and 40% of DM) and 2 levels of ruminally undegraded protein (RUP: 25 and 40% of CP) on nutrient intake, total and partial apparent nutrient digestibility, microbial protein synthesis, and ruminal and physiological variables. Eight Nellore heifers (233 +/- 14 kg of BW) fitted with ruminal, abomasal, and ileal cannulas were used. The animals were held in individual sheltered pens of approximately 15 m(2) and fed twice daily at 0800 and 1600 h for ad libitum intake. Heifers were allocated in two 4 x 4 Latin square designs, containing 8 heifers, 4 experimental periods, and 4 treatments in a 2 x 2 factorial arrangement. All statistical analyses were performed using PROC MIXED of SAS. Titanium dioxide (TiO(2)) and chromic oxide (Cr(2)O(3)) were used to estimate digesta fluxes and fecal excretion. Purine derivative (PD) excretion and abomasal purine bases were used to estimate the microbial N (MN) synthesis. No significant interaction (P > 0.10) between dietary levels of RUP and concentrate was observed. There was no effect of treatment (P = 0.24) on DMI. Both markers led to the same estimates of fecal, abomasal, and ileal DM fluxes, and digestibilities of DM and individual nutrients. Ruminal pH was affected by sampling time (P < 0.001), but no interaction between treatment and sampling time was observed (P = 0.71). There was an interaction between treatment and sampling time (P < 0.001) for ruminal NH(3)-N concentration. A linear decrease (P = 0.04) over sampling time was observed for the higher level of RUP, whereas a quadratic effect (P < 0.001) of sampling time was observed for the lower level of RUP. The higher level of dietary concentrate led to greater MN yield regardless of the level of RUP. The MN yield and the efficiency of microbial yield estimated from urinary PD excretion produced greater (P < 0.01) values than those estimated by either TiO(2) or Cr(2)O(3), which did not differ (P = 0.63) from each other. However, all methods yielded values that were within the range reported in the literature. In conclusion, no interactions between dietary levels of RUP and concentrate were observed for ruminal and digestive parameters. Neither RUP nor concentrate level affected DMI. Titanium dioxide showed to be similar to Cr(2)O(3) as an external marker to measure digestibility and nutrient fluxes in cattle.

Comparação de Indicadores e Metodologia de Coleta para Estimativas de Produção Fecal e Fluxo de Digesta em Bovinos

It was aimed to compare the internal markers, indigestible neutral detergent (NDFi) and acid fiber (ADFi), and ADFi with oxide chromic to esteem the dry matter fecal production and nutrients digestibility of diets of bovine, in two outlines of collections (2 or 6 days). For the comparison among internal markers, 32 Nelore growing bulls, with 240 kg, were maintained under feedlot, receiving diets with different concentrate levels (20, 40, 60 and 80%). For the comparison among internal and external marker, five 165 kg Nelore growing bulls, rumen, abomasum and ileum fistulated, were used. The design was in blocks with four treatments and 5 collection periods. The treatments consisted of four concentrate levels (20, 40, 60 and 80%). The roughage used was Tifton 85 hay. The apparent digestibility of dry matter (DM) was smaller, when was estimated by oxide chromic, however the DM digestibility in the rumen and intestines did not differ among markers. When the collection methodology was compared (6 days vs. 2 days), there was not difference in all the studied variables, demonstrating the suggested alternative methodology as soon as can be used with safety for the estimates of fecal production and DM flows in the abomasum and ileum.

Consumo, digestibilidade e excreção de uréia e derivados de purinas em vacas de diferentes níveis de produção de leite

The objective of this trial was to evaluate the effect of milk production level on intake, digestibility of nutrients, microbial protein synthesis, and nitrogen (N) metabolism in Holstein cows. It was also of particular interest to compare spot urine sampling and total urine collection as methodologies to quantify yield of microbial N using purine derivatives (PD) as indirect microbial markers. Fifteen Holstein cows were grouped by milk yield (5.88 kg/day: LOW treatment; 18.54 kg/day: MEDIUM treatment; and 32.6 kg/day: HIGH treatment) and data analyzed as a completely randomized design. Animals were fed ad libitum corn silage plus one kg of concentrate per each three kg of milk produced. Except for NDF corrected for ash and protein (NDFap), intake of all remaining nutrients was increased by milk yield. Digestibilities of DM and OM and dietary TDN content did not differ among treatments. However, digestibility of CP was higher and that of NDFap was lower on the greatest milk yielding cows (HIGH treatment). Concentrations of milk urea N and serum urea N as well as urinary N excretion were all greatest in the HIGH treatment and were also highly correlated with milk yield. Microbial protein synthesis estimated by PD was lowest on cows in the LOW treatment and did not differ when either spot urine sampling or total urine collection was used. Therefore, spot urine sampling can be used to estimate urinary excretion of nitrogenous compounds and microbial protein synthesis in Holstein cows with different production levels.