Daiany Íris Gomes

Avaliação dos teores de fibra em detergente neutro em forragens, concentrados e fezes bovinas moídas em diferentes tamanhos e em sacos de diferentes tecidos

Two experiments were carried out to evaluate the effects of particles sizes on contents of neutral detergent fiber (NDF) by using nylon bags F57 (Ankom®) and non-woven textile (NWT 100 g/m2). In the first experiment, to check contents of NDF obtained with each one of the textilles, quantitative filter paper (purified cellulose) was used as analytical standard. The material was processed in a 1 or 2 mm and put in the bags in a ratio of 20 mg of dry matter/cm2 of surface. The analyses were performed in a fiber analyser (Ankom220) and using a heat-stable a-amylase. No effects of particles sizes were found. In the second experiment, it was used samples of forage (signal grass hay, sugar cane, coastcross hay, corn straw, corn silage, and elephant grass at 50 and 250 days of growing after cutting), concentrate feeds (sorghum grain, gluten meal, citrus pulp, cottonseed meal, soybean meal, wheat bran, corn grain, whole soybean, and soybean hulls), and feces of cattle of animals fed diets containing 15 or 50% of concentrate. The samples were prepared, put in bags, and analyzed as described in the previous experiment. In both experiments, the smallest contents of NDF were found by using nylon bags, indicating loss of particles through the bag porosity. It is suggested grind of samples by using 1-mm screen sieve, which provides efficient extraction of cell content by the action of neutral detergent and a greater specific surface by the action of the heat-stable a-amylase enzyme. The use of particles ground at 2-mm overestimates NDF contents.

Effect of protein supplementation on ruminal parameters and microbial community fingerprint of Nellore steers fed tropical forages.

In tropical regions, protein supplementation is a common practice in dairy and beef farming. However, the effect of highly degradable protein in ruminal fermentation and microbial community composition has not yet been investigated in a systematic manner. In this work, we aimed to investigate the impact of casein supplementation on volatile fatty acids (VFA) production, specific activity of deamination (SAD), ammonia concentration and bacterial and archaeal community composition. The experimental design was a 4×4 Latin square balanced for residual effects, with four animals (average initial weight of 280±10 kg) and four experimental periods, each with duration of 29 days. The diet comprised Tifton 85 (Cynodon sp.) hay with an average CP content of 9.8%, on a dry matter basis. Animals received basal forage (control) or infusions of pure casein (230 g) administered direct into the rumen, abomasum or divided (50 : 50 ratio) in the rumen/abomasum. There was no differences (P>0.05) in ruminal pH and microbial protein concentration between supplemented v. non-supplemented animals. However, in steers receiving ruminal infusion of casein the SAD and ruminal ammonia concentration increased 33% and 76%, respectively, compared with the control. The total concentration of VFA increased (P0.05) in species richness and diversity of γ-proteobacteria, firmicutes and archaea between non-supplemented Nellore steers and steers receiving casein supplementation in the rumen. However, species richness and the Shannon-Wiener index were lower (P<0.05) for the phylum bacteroidetes in steers supplemented with casein in the rumen compared with non-supplemented animals. Venn diagrams indicated that the number of unique bands varied considerably among individual animals and was usually higher in number for non-supplemented steers compared with supplemented animals. These results add new knowledge about the effects of ruminal and postruminal protein supplementation on metabolic activities of rumen microbes and the composition of bacterial and archaeal communities in the rumen of steers.

Effect of protein supplementation in the rumen, abomasum, or both on intake, digestibility, and nitrogen utilisation in cattle fed high-quality tropical forage

Effects of differing proportions of ruminal and abomasal protein infusion on intake, digestion, ruminal dynamics and the metabolic parameters of nitrogen (N) compounds were evaluated in beef bulls fed high-quality tropical forage (98.6 g crude protein, CP/kg dry matter) for ad libitum intake. Four Nelore bulls (280 ± 10 kg bodyweight) fitted with ruminal and abomasal cannulas were studied in a 4 × 4 Latin square. Treatments included: Control (no supplement) or 230 g/day of supplemental CP (as casein), with ratios of abomasal : ruminal infusion of 0 : 100, 50 : 50 or 100 : 0. Organic matter intake was not affected by treatments (P ≥ 0.30), though N intake increased by supplementation (P < 0.001). Total CP and organic matter digestibility were increased (P < 0.02) by protein supplementation. Nitrogen balance was 43% greater (P < 0.02) in the treatments with supplementation. Although supplementation did not affect (P = 0.98) the efficiency of absorbed N, a tendency towards a positive linear effect (P = 0.08) was observed when modifying the site of supplementation from the rumen to the abomasum. Supplementation increased (P < 0.01) ruminal ammonia-N, serum urea-N, urinary N and urea-N excretion, which subsequently decreased linearly (P < 0.01) by the displacement of supplementation from the rumen to the abomasum. The results indicate that protein supplementation, either in the rumen or abomasum produces similar effects on N retention. However, the metabolic mechanisms responsible for the improved N retention appear to differ between supplementation sites. Additionally, the efficiency of N utilisation increases with infusion of protein into the abomasum.

Accuracy of the estimates of ammonia concentration in rumen fluid using different analytical methods

The accuracy of two different methods in measuring the ammonia nitrogen (N-NH3) concentration in rumen fluid were evaluated: a catalyzed indophenol colorimetric reaction (CICR) and the Kjeldahl distillation (KD). Five buffered standard solutions containing volatile fatty acids, true protein, and known ammonia concentrations (0, 3, 6, 12, and 24 N-NH3 mg/dL) were used to simulate rumen fluid. Different ratios (10:1, 7.5:1, 5:1, 2.5:1, 1:1, 1:2.5, 1:5, 1:7.5, and 1:10) of a potassium hydroxide solution (KOH, 2 mol/L) to standard solutions were evaluated by the KD method. The accuracy of each method was evaluated by adjusting a simple linear regression model of the estimated N-NH3 concentrations on the N-NH3 concentrations in the standard solutions. When the KD method was used, N-NH3 was observed to be released from the deamination of true protein (P 0.05). The estimates of the N-NH3 concentration obtained by the CICR method were found to be accurate (P>0.05). After the accuracy evaluation, ninety-three samples of rumen fluid were evaluated by the CICR and KD methods (using the 5:1 ratio of KOH solution to rumen fluid sample), assuming that the CICR estimates would be accurate. The N-NH3 concentrations obtained by the two methods were observed to be different (P<0.05) but strongly correlated (r = 0.9701). Thus, it was concluded that the estimates obtained by the Kjeldahl distillation using a 5:1 ratio of KOH solution to rumen fluid sample can be adjusted to avoid biases. Furthermore, a model to adjust the N-NH3 concentration is suggested.

Evaluation of sodium sulfite and protein correction in analyses of fibrous compounds in tropical forages

The objective of this study was to evaluate the contents of fibrous compounds in tropical grasses and legumes according to utilization of sodium sulfite in the neutral detergent solution or using a procedure for contaminant protein correction. Samples of ten grasses and ten legumes were used. The contents of neutral detergent fiber were decreased when sodium sulfite was used; however, more prominent reductions were verified in legumes. Sodium sulfite decreased the acid detergent fiber content in both forage groups. The contents of neutral and acid detergent insoluble protein and lignin were reduced by sodium sulfite in legumes, but no effect was observed in grasses with regard to these variables. The decrease in fiber contents in legumes could be explained by the solubilization of lignin and decrease in insoluble nitrogen. However, the decreases in fiber in grasses could not be solely explained by the decrease in contaminant protein and solubilization of lignin, and loss of other fibrous compounds probably occurred. The utilization of sodium sulfite compromises the accuracy of the estimates of fibrous compounds contents in tropical forages. The precision of the estimates were not relevantly increased by sodium sulfite. The correction of insoluble fibrous compounds for protein is suggested instead of using sodium sulfite because there are no modifications on neutral detergent solution or undesirable solubilization of fibrous compounds.

Performance and carcass characteristics of young cattle fed with soybean meal treated with tannins

This study aimed to evaluate the effects of replacement of soybean meal (SBM) with soybean meal treated with tannin (SBMT) on the intake, digestibility, performance and characteristics of the carcasses of young cattle fed a high-concentrate diet. Forty-two Nellore bulls with body weight of 244.5 ± 4.99 kg were used. Diets had the inclusion of 7.5% SBM, with a proportion of that SBM (0, 33, 66 or 100%) replaced for SBMT; and other treatment (SBMT + urea) just with 2.5% of SBM which was treated with tannins. Seven animals were randomly selected and slaughtered, and the remaining animals were distributed on treatments and remained for 112 days. After, all animals were slaughtered. There was a linear decline in dry matter intake (P = 0.026) when SBM was replaced with SBMT. No decrease in carcass weight (P > 0.05) was observed. The efficiency of carcass weight gain showed a quadratic function effect (P = 0.049). There were changes in carcass gain composition when SBMT was added (P < 0.05), with an increase in muscle and reduction in fat deposition. The use of SBMT in place of SBM causes changes in body gain composition in animals and reduces DM intake by the animals, achieving a better feed conversion efficiency.

In vitro and in situ activity of carboxymethyl cellulase and glutamate dehydrogenase according to supplementation with different nitrogenous compounds

Two experiments were carried out to evaluate the effect of supplementation with different nitrogenous compounds on the activities of carboxymethil cellulase (CMCase) and glutamate dehydrogenase (GDH). In the first experiment, four treatments were evaluated in vitro: cellulose, cellulose with casein, cellulose with urea, and cellulose with casamino acids. After 6, 12 and 24 hours of incubation, CMCase and GDH activity, pH, and concentrations of ammonia nitrogen (AN) and microbial protein were measured. In the three incubation periods, the concentration of AN was higher when urea was used as a supplemental source of nitrogen. The activity of CMCase was higher with the addition of urea and casamino acids when compared with the control and the casein treatment. Supplementation with casamino acids provided higher GDH activity when compared with the control at 6 hours of incubation. At 12 hours of incubation, the GHD activity was also stimulated by casein. At 24 hours, there was no difference in GHD activity among treatments. In the second experiment, three rumen-fistulated bulls were used for in situ evaluation. Animals were fed Tifton hay (Cynodon sp.) ad libitum. The treatments consisted of control (no supplementation), supplementation with non-protein nitrogenous compounds (urea and ammonium sulphate, 9:1) and supplementation with protein (albumin). In treatments with nitrogenous compound supplementation, 1 g of crude protein/kg of body weight was supplied. The experiment was conducted in a 3 × 3 Latin square design. The measurements were performed at 6, 12 and 24 hours after supplementation. No difference in GDH activity was observed among treatments. The control treatment showed higher CMCase activity when compared with the treatments containing supplemental sources of nitrogen. However, urea supplementation provided higher CMCase activity compared to albumin.