Lara Toledo Henriques

Digestibilidade total e parcial e balanço nitrogenado em bovinos em pastejo no período das águas recebendo suplementos com nitrogênio não-proteico e/ou proteína verdadeira

The objective of this study was to evaluate the effect of different true protein:non-protein nitrogen ratios in supplements on digestibility, microbial protein synthesis and nitrogen balance in grazing cattle during rainy season. Five crossbred Holstein × Zebu steers, averaging 335±35 kg of body weight and fitted with rumen and abomasum canullae were used. The treatments were: control (only pasture), and supplements based on urea, 2/3 of nitrogenous compounds from urea and 1/3 of nitrogenous compounds from albumin, 1/3 of nitrogenous compounds from urea and 2/3 of nitrogenous compounds from albumin, and albumin. Two hundred grams of crude protein (CP) were daily supplied from supplements. The experiment was carried out according to a 5 × 5 Latin square design, with five 15-day experimental periods. Supplementation did not affect the total digestibility coefficients or the diet content of total digestible nutrients. Supplementation increased ruminal apparent digestibility coefficient of CP, which moved from negative for the control treatment to positive, but not different from zero, for treatments involving supplementation. Supplementation increased the rumen ammonia nitrogen concentration. Nitrogen balance was enhanced by supplementation. The replacement of urea by albumin caused a cubic effect on the nitrogen balance, with the higher value obtained at 1/3 of supplemental CP as urea. The efficiency of microbial protein synthesis was not influenced by supplementation or supplement composition. Supplementation with ruminal degradable nitrogenous compounds for grazing cattle during the rainy season increases the efficiency of use of pasture mainly by improving the body nitrogenous compounds retention.

Consumo e dinâmica ruminal da fibra em detergente neutro em bovinos em pastejo no período das águas recebendo suplementação com nitrogênio não-proteico e/ou proteína verdadeira

The objective of this study was to evaluate the effect of different true protein:non-protein nitrogen ratios in supplements on intake and ruminal transit and degradation dynamics of neutral detergent fiber (NDF) in grazing cattle during rainy season. Five crossbred Holstein × Zebu steers, averaging 335±35 kg of body weight and fitted with rumen and abomasum canullaes were used. The treatments were: control (only pasture), and supplements based on urea, 2/3 of nitrogenous compounds from urea and 1/3 of nitrogenous compounds from albumin, 1/3 of nitrogenous compounds from urea and 2/3 of nitrogenous compounds from albumin, and albumin. Two hundred grams/d of crude protein (CP) were supplied from supplements. The experiment was carried out according to a 5 × 5 Latin square design, with five 15-day experimental periods. There were no effects of supplementation on voluntary intake, except for CP intake, which was increased by supplementation. The replacement of urea by albumin in the supplements caused linear effect on the CP intake. The intakes of the other diet components were not affected by the supplement composition. There was no effect on ruminal rate of passage of fibrous compounds. Supplementation increased the estimates of common rate of lag and degradation of NDF. However, no effect of supplement composition alteration was observed on this parameter. Supplementation of cattle with rumen degradable (protein or non-protein) nitrogenous compounds for grazing cattle during rainy season does not affect voluntary intake of pasture.

Exigências nutricionais de bezerros nelores lactentes

This experiment was carried out to evaluate the nutritional requirements of protein, energy and macro minerals for Nellore calves from birth to 180 days. A total of 20 calves, 10 males (M) and 10 females (F) with average body weight (BW) of 30±3 kg were used. Soon after birth, four (2 males and 2 females) calves were slaughtered to estimate initial body composition of animals that remained in the trial. At 90 days, another eight calves were slaughtered (4 males and 4 females), and the remaining animals were slaughtered at 180 days. Besides milk, the calves were fed with corn silage ad libitum and commercial concentrate set at a maximum of 0.5 kg/animal/day. Two digestibility assay were conducted at 30 and 90 days to estimate the energy intake of the calves. After slaughtered all calves had their right half-carcasses dissected. The content of protein, energy and minerals were estimated by the equation Y = a. EBWb, where EBW is the empty body weight. The relationship EBW/BW of calves was 0.9622 and EBWG/BWG was 0.958, where G is the gain. The net requirements of protein and energy increased with increasing body weight, while calcium decreased. The metabolizable protein requirements for gain of 1 kg BW were 216.96 and 261.98 g for calves with 100 and 200 kg respectively. The following equations are recommended to estimate the body content of preweaning Nellore calves: protein (g/day) = 0.135 × EBW1.0351; energy (Mcal/day) = 1.1798 × EBW1.1805; calcium (g/day) = 0.091 × EBW0.6019; phosphorus (g/day) = 0.00894 × EBW0.9629; sodium (g/day) = 0.00126 × EBW0.9791; magnesium (g/day) = 0.000405 × EBW0.9827; potassium (g/day) = 0.00165 × EBW0.9364.

Estimação por aproximação química dos teores de proteína indegradável insolúvel em detergente neutro em forragens tropicais

A mathematical model was developed to predict the content of undegradable neutral detergent insoluble protein (UNDIP) from chemical characteristics of tropical forages. This study was based on a biological limitation of a previous model, which restricts the UNDIP estimates to values equals or higher than 1.34% of dry matter. The databank was formed by 540 samples of tropical forages used in cattle feeding (fresh forage and hay). The ratio of UNDIP on neutral detergent insoluble protein (NDIP) was chosen as response variable and the acid detergent insoluble protein (ADIP) as independent variable. The mathematical model was found to be exponential, assuming the formula: UNDIP = NDIP x e-(0,818+0.16764DIP) , in which all values are expressed on dry matter basis. It was observed that biological limitation of the previous model was eliminated, even though a low statistical improvement was obtained. The prediction of a biological parameter (UNDIP) from a chemical characteristic (ADIP) still have some restrictions and the estimates should be applied with caution in some situations. The main application of the model described above is estimate UNDIP contents when biological methods are not available.

Exigências nutricionais de vacas nelores primíparas lactantes

This study was conducted to evaluate the nutritional requirements of protein and energy of primiparous lactating Nellore cows from 0 to 180 days after calving. A total of 20 lactating primiparous cows with average body weight at calving of 362±25 kg were used. Four cows were slaughtered soon after calving and were considered as reference group. From calving to 90 days post partum four cows were fed restricted at 1.5% of body weight (BW) in dry matter (DM) basis and 12 were fed ad libitum. At 90 days post partum eight cows were slaughtered (four from each feeding system). From 90 to 180 days, four cows were realocated for maintenance (1.8% BW in DM) and four remained in voluntary intake, and all were slaughtered at the end of the period. The contents of protein and energy were estimated by the equation Y = a. Xb, in which X is the empty body weight (EBW), and a and b are the parameters of the allometric equation. Ratios obtained for empty body weight (EBW)/BW and empty body gain (EBWG)/BWG were 0.894 and 0.936, respectively. The net energy for maintenance (NEm) were 97.84 kcal/EBW0.75 and the metabolizable energy for maintenance (MEm) were 140.17 kcal/EBW0.75. The efficiencies of energy use for maintenance and gain were 0.70 and 0.44, respectively. The content of protein and minerals, except calcium, decreased with the increase in BW while the energy increased. The milk of cows had average contents of 3.71, 3.88 and 4.74%, respectively, for crude protein, fat and lactose. The NEm requirement for lactating Nellore cows is 97.84 kcal/EBW0,75, while MEm is 140.17 kcal/EBW0,75 and metabolizable protein requirement is 52.8 g. To produce 1 kg of milk with 4% fat Nellore cows need 0.300 kg TDN.

Forage cactus associated with different fiber sources for lactating Sindhi cows: production and composition of milk and ingestive behavior

The objective of this study was to evaluate the association of forage cactus with different fiber sources (elephant grass hay - EGH; corn straw - CS, hay of cassava shoots - HCS; fresh sugarcane bagasse - FSB; and hydrolyzed sugarcane bagasse - HSB) on the milk yield and composition and the feeding behavior of lactating Sindhi cows. Five cows with average body weight, average daily milk yield, and average daily 4%-fat-corrected milk yield of 265, 4.95 and 5.22 kg, respectively, were used in a 5 × 5 Latin square design. The effect of experimental diets on milk yield and composition, feeding time (FT), rumination time (RT), idle time, mean values of total chewing time (TCT), number of ruminal boli (NRB), number of rumination chews (NRC), and feed efficiency (FE) and rumination efficiency (RE) expressed as a function of DM and NDF were analyzed. Milk yield in kg/day and corrected to 4.0% fat from the animals that received cactus associated with CS were higher as compared with the treatment with hydrolyzed sugarcane bagasse. The milk composition variables were not influenced by the treatments, and nor were FT, RT, TCT, NRB and NC. Two patterns were observed for FE and RE, with higher efficiency of the diets with EGH, CS and HCS and lower efficiency for diets containing sugarcane bagasse. In this context, Sindhi cows fed forage cactus associated with corn straw, elephant grass hay, and hay of cassava shoots present better performance, feeding efficiency, and rumination responses than those fed forage cactus associated with fresh sugarcane bagasse and hydrolyzed sugarcane bagasse.

Forage cactus associated with different fiber sources for lactating Sindhi cows: intake, digestibility and microbial protein production

This experiment was carried to evaluate the effect of forage cactus with different fiber sources (elephant grass hay [EGH], corn straw [CS], hay of cassava shoots [HCS], fresh sugarcane bagasse [FSB], and hydrolyzed sugarcane bagasse [HSB]) on intake, apparent digestibility and macrobiotic protein production of cows. Five cows with 265 kg average body weight, 4.95 kg average daily milk yield and 5.22 kg 4% fat-corrected milk yield were randomly allocated to a 5 × 5 Latin square design. The animals fed cactus associated with CS, EGH and HCS showed higher intake of DM and nutrients. However, regarding the digestibility, diets with sugarcane bagasse showed higher digestibility compared with those with CS and hay. For microbial protein, the excretion of purine derivatives, synthesis of microbial N and microbial protein production were higher in the treatment with CS than in the treatment with sugarcane bagasse. On the other hand, the treatment with EGH and HCS did not have statistical differences compared with the other cases. The mean efficiency of microbial protein synthesis of the experiment was 131 g microbial crude protein/kg of TDN. The treatment with CS showed better efficiency; however, it was statistically superior only compared with FSB. The other treatments did not show statistical difference compared with the other cases. Diets with cactus associated with corn straw, hay of elephant grass or hay of cassava shoots provide higher intake of dry matter and nutrients and better metabolic response compared with diets with cactus associated with sugarcane bagasse for lactating Sindhi cows.