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Urea supplementation in rumen and post-rumen for cattle fed a low-quality tropical forage
- Cristhiane V. R. de Oliveira, Tadeu E. Silva, Erick D. Batista, Luciana N. Rennó, Fabyano F. Silva, Isabela P. C. de Carvalho, Javier Martín-Tereso, Edenio Detmann
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- Journal:
- British Journal of Nutrition / Volume 124 / Issue 11 / 14 December 2020
- Published online by Cambridge University Press:
- 25 June 2020, pp. 1166-1178
- Print publication:
- 14 December 2020
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We evaluated the differences between the supplementation of urea in rumen and/or abomasum on forage digestion, N metabolism and urea kinetics in cattle fed a low-quality tropical forage. Five Nellore heifers were fitted with rumen and abomasum fistulas and assigned to a Latin square design. The treatments were control, continuous infusion of urea in the abomasum (AC), continuous infusion of urea in the rumen, a pulse dose of urea in the rumen every 12 h (PR) and a combination of PR and AC. The control exhibited the lowest (P < 0·10) faecal and urinary N losses, which were, overall, increased by supplementation. The highest urinary N losses (P < 0·10) were observed when urea was either totally or partially supplied as a ruminal pulse dose. The rumen N balance was negative for the control and when urea was totally supplied in the abomasum. The greatest microbial N production (P < 0·10) was obtained when urea was partially or totally supplied in the abomasum. Urea supplementation increased (P < 0·10) the amount of urea recycled to the gastrointestinal tract and the amount of urea-N returned to the ornithine cycle. The greatest (P < 0·10) amounts of urea-N used for anabolism were observed when urea was totally and continuously infused in the abomasum. The continuous abomasal infusion also resulted in the highest (P < 0·10) assimilation of microbial N from recycling. The continuous releasing of urea throughout day either in the rumen or abomasum is able to improve N accretion in the animal body, despite mechanism responsible for that being different.
Development of an equation to predict net protein requirements for the growth of Zebu beef cattle
- L. F. Costa e Silva, S. de Campos Valadares Filho, P. Del Bianco Benedeti, E. Detmann, A. C. Baião Menezes, T. Eder Silva, F. A. de Sales Silva
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The accurate estimation of protein requirements for beef cattle is a key factor in increasing livestock profitability and decreasing the environmental impacts of excessive N excretion due to mismatching between assumed requirements and diet formulation. A meta-analysis was conducted to evaluate and validate a new equation to predict the net protein requirements for growth (NPg) of Zebu beef cattle. For the development of the new approach, a database of 552 observations comprised of bulls, steers, and heifers of different genetic groups (Zebu, beef crossbreed, and dairy crossbreed) was assembled. The new approach was evaluated and compared to current models devised by the international nutrient requirements system committees (Agricultural Research Council, 1980; Beef Cattle Nutrient Requirements Model, 2016; BR-CORTE, 2016) to predict NPg. The model evaluation was performed through the model evaluation system (version 3.1.16) using an independent data set (n = 177 observations). An equation was considered the best estimator of NPg if the following conditions were met: (1) the intercept and slope of the regression between ordinary residues and/or predicted NPg values must have been equal to zero and one, respectively; and (2) the greatest concordance correlation coefficient (CCC) and determination coefficient (R), and lowest mean squared error of prediction (MSEP) were attained. Based on the regression models of the observed v. predicted NPg of Zebu beef cattle, both the new approach and that of the ARC (1980) correctly estimated NPg, since the intercept and slope were not different (P > 0.05) from zero and one, respectively. Additionally, the new approach’s determination coefficient was the greatest and the closest to one. The fact that the new model achieved a higher CCC and lower MSEP than the existing models indicated its superior reproducibility and accuracy. The equations proposed by BR-CORTE (2016) and the BCNRM (2016) did not correctly estimate NPg in that the intercept and slope were different (P < 0.01) from zero and one, respectively. Thus, the equations proposed by the new approach and the ARC (1980) accurately and precisely estimated NPg and are recommended for Zebu cattle. Furthermore, the inclusion of equivalent empty BW (EQEBW) in the new approach improves the estimation of NPg. We suggest the use of the following equation to calculate NPg for Zebu beef cattle: NPg = 176.01 × EBG – 0.381 × EQEBW0.75 × EBG1.035 (R = 0.80 and CCC = 0.75); where NPg = net protein requirements for growth, EBG = empty body gain, and EQEBW = equivalent empty BW.
Effect of dietary protein content on performance, feed efficiency and carcass traits of feedlot Nellore and Angus × Nellore cross cattle at different growth stages
- P. M. Amaral, L. D. S. Mariz, D. Zanetti, L. F. Prados, M. I. Marcondes, S. A. Santos, E. Detmann, A. P. Faciola, S. C. Valadares Filho
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- Journal:
- The Journal of Agricultural Science / Volume 156 / Issue 1 / January 2018
- Published online by Cambridge University Press:
- 14 January 2018, pp. 110-117
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An experiment was conducted to evaluate whether a reduction in dietary crude protein (CP) and genotype affects animal performance, feed efficiency and carcass traits of beef cattle at different stages of the feedlot. Twenty-two Nellore and 22 crossbred F1 Angus × Nellore (Nellore: 8 months, initial body weight (iBW) = 212.7 kg; Crossbred: 8 months, iBW = 226.1 kg) were used in this experiment. The experiment was conducted in a complete randomized design with six replicates, in a 2 × 3 factorial design. The factors were two genotypes (Nellore and Crossbred) and three CP concentrations (100, 120 and 140 g/kg dry matter [DM]). The experimental period lasted 224 day, being divided into two stages (Backgrounding = 112 day, and Finishing = 112 day). At the end of the experiment, all animals were slaughtered to evaluate their carcass characteristics. Similar patterns were observed during backgrounding and finishing phases on intake and average daily gain (ADG) regarding genotype. Intakes of DM, organic matter, CP, neutral detergent fibre, non-fibre carbohydrates and total digestible nutrients, ADG (kg/day) and feed efficiency were greater in Crossbred animals than Nellore in both phases. During the backgrounding phase, dietary CP did not influence DM intake. However, a linear effect of CP on ADG was observed in the backgrounding phase. During finishing, Nellore cattle fed 100 g CP/kg DM presented lower ADG than Nellore fed 120 and 140 g CP/kg DM. Crossbred animals were heavier than Nellore at the beginning and end of the trial. Crossbred animals also gained more carcass, retained more CP and fat, and had a greater subcutaneous fat thickness during the experiment compared with Nellore. There was a quadratic effect of dietary CP on retained CP and dressing. The current study found that crossbred animals (F1 Angus × Nellore) not only had greater performance, but also better carcass traits compared with Nellore, representing an option for increasing productivity. Also, it is possible to adjust diets according to phase. During the backgrounding stage, 140 g CP/kg DM should be used, being reduced to 120 g CP/kg DM during the finishing stage of feedlot for Nellore and to 100 g CP/kg DM for Crossbred, without affecting performance adversely.
In situ and in vitro estimation of mineral release from common feedstuffs fed to cattle
- D. ZANETTI, A. C. B. MENEZES, F. A. S. SILVA, L. F. COSTA E SILVA, P. P. ROTTA, E. DETMANN, T. E. ENGLE, S. C. VALADARES FILHO
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- Journal:
- The Journal of Agricultural Science / Volume 155 / Issue 7 / September 2017
- Published online by Cambridge University Press:
- 13 June 2017, pp. 1160-1173
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The objective of the current study was to quantify the dry matter (DM) digestibility, and total ash (TA) and mineral release from 12 concentrate and 12 forage feedstuffs commonly fed to cattle using in situ and in vitro methods. Concentrate and forage feedstuffs were incubated in the rumen of ruminally cannulated beef bulls at eight different time points. Two different trials were conducted for concentrates and forages, with maximum incubation time of 72 and 120 h, respectively. The residue from samples incubated for 24 h were treated with pepsin and hydrochloric acid to simulate abomasum digestion in vitro. The initial and residual samples after in situ and in vitro incubations were measured. An asymptotic model was adopted for estimating solubility of minerals, disappearance rate of DM, and TA. Correlations between feedstuff contents and mineral release were evaluated. Residual samples from rumen fermentation after 24 h were incubated in simulated abomasal conditions and mineral release was measured. Cluster analysis was performed to group feedstuffs in relation to TA release. Large variability was observed between concentrate and forage feedstuffs for all constituents analysed. Large variability was observed for the effective ruminal degradation of TA and individual mineral release. When feedstuffs were clustered according to the immediately soluble fraction (‘a’), the insoluble by potentially releasable fraction (‘b’) and the release rate of ‘b’ (‘kd’,/h) estimates of TA ruminal release, four groups were identified. From group ‘1’ to group ‘4’, an increase in the soluble fraction and a reduction in both moderate releasable fraction and release rate was observed. Neutral detergent fibre content had a negative correlation with mineral release in the rumen, while mineral content had a positive correlation. These results demonstrate that mineral solubilization in the digestive tract is not the limiting factor for mineral absorption from the feedstuffs tested.
The effect of CP concentration in the diet on urea kinetics and microbial usage of recycled urea in cattle: a meta-analysis
- E. D. Batista, E. Detmann, S. C. Valadares Filho, E. C. Titgemeyer, R. F. D. Valadares
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In ruminants, urea recycling is considered an evolutionary advantage. The amount of urea recycled mainly depends of the nitrogen (N) intake and the amount of organic matter (OM) digested in the rumen. Because recycled N contributes to meeting microbial N requirements, accurate estimates of urea recycling can improve the understanding of efficiency of N utilization and N losses to the environment. The objective of this study was to evaluate urea kinetics and microbial usage of recycled urea N in ruminants using a meta-analytical approach. Treatment mean values were compiled from 25 studies with ruminants (beef cattle, dairy cows and sheep) which were published from 2001 to 2016, totalling 107 treatment means. The data set was analyzed according to meta-analysis techniques using linear or non-linear mixed models, taking into account the random variations among experiments. Urea N synthesized in the liver (UER) and urea N recycled to the gut (GER) linearly increased (P<0.001) as N intake (g/BW0.75) increased, with increases corresponding to 71.5% and 35.2% of N intake, respectively. The UER was positively associated (P<0.05) with dietary CP concentration and the ratio of CP to digestible OM (CP:DOM). Maximum curvature analyses identified 17% dietary CP as the point where there was a prominent increase in hepatic synthesis of urea N, likely due to an excess of dietary N leading to greater ammonia absorption. The GER:UER decreased with increasing dietary CP concentration (P<0.05). At dietary CP⩾19%, GER:UER reached near minimal values. The fraction of UER eliminated as urinary urea N and the contribution of urea N to total urinary N were positively associated with dietary CP (P<0.05), both reaching values near the plateau when dietary CP was 17%. The fractions of GER excreted in the feces and utilized for anabolism decreased, whereas the fraction of GER returned to the ornithine cycle increased with dietary CP concentration (P<0.05). Recycled urea N assimilated by ruminal microbes (as a fraction of GER) decreased as dietary CP and CP:DOM increased (P<0.05). The efficiency of microbial assimilation of recycled urea N was near plateau values at 194 g CP/kg DOM. The models obtained in this study contribute to the knowledge on N utilization, and they could be used in feeding models to predict urea recycling and thus to improve formulation of diets to reduce N losses that contribute to air and water pollution.
Effect of protein supplementation on ruminal parameters and microbial community fingerprint of Nellore steers fed tropical forages
- C. B. P. Bento, A. C. Azevedo, D. I. Gomes, E. D. Batista, L. M. A. Rufino, E. Detmann, H. C. Mantovani
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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 (P<0.05) in steers receiving rumen infusion of casein. SAD and the microbial protein concentration did not vary significantly among treatments during the feeding cycle, but mean SAD values were greater in steers supplemented in the rumen and rumen/abomasum. Ruminal ammonia concentration was positively correlated with SAD in animals receiving ruminal infusion of casein. Polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) analysis revealed low similarity between treatments, animals and time of sample collection. Richness analysis and determination of the Shannon–Wiener index indicated no differences (P>0.05) 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.
Mammary gland development of dairy heifers fed diets containing increasing levels of metabolisable protein: metabolisable energy
- Ronan L Albino, Marcos I Marcondes, Robert M Akers, Edenio Detmann, Bruno C Carvalho, Tadeu E Silva
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- Journal:
- Journal of Dairy Research / Volume 82 / Issue 1 / February 2015
- Published online by Cambridge University Press:
- 16 January 2015, pp. 113-120
- Print publication:
- February 2015
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This study was conducted to evaluate the development of the mammary gland in Holstein heifers subjected to different dietary metabolisable protein (MP): metabolisable energy (ME) ratios. Twenty-five Holstein heifers (initial body weight (BW) 213±13·5 kg and initial average age 7·8±0·5 months) were divided into five treatments. The treatments were designed to provide MP:ME ratios equal to 33, 38, 43, 48, and 53 g of MP per Mcal of ME. All diets were formulated to have the same energy content (2·6 Mcal ME/kg dry matter). Actual MP:ME ratios were 36·2, 40·2, 46·2, 47·1, and 50·8 g MP/Mcal ME. The experiment was conducted in a randomised block design, while considering initial BW as a blocking factor to evaluate pre- and post-pubertal periods. Block effect was not observed for all variables evaluated; hence it was considered that the diets had the same influence both on pre- and post-pubertal phases. Dry matter and nutrient intake did not change between treatments, excepting protein intake and digestibility. Serum concentrations of insulin-like growth factor 1 increased linearly across treatments. Changes in the pixel brightness of mammary gland ultrasound images, which are associated with lipid content, were significantly influenced by MP:ME ratios in the diet of heifers that were subjected to accelerated growth rates. It is not recommended to use diets of less than 38 g MP/Mcal ME in diets to heifers allowed to gain more than 1 kg/d.