Nutrient intake, productive and metabolic parameters of Nellore bulls feed a forage free diet using cottonseed cake as a fiber source.

We hypothesized that cottonseed cake in confined Nellore young bulls' diet as fiber source, could maintain or improve the nutrient intake, and productive and metabolic parameters. It was evaluated the total replacement of whole plant corn silage (WPCS) by cottonseed cake (CSC) as a source of fiber in the diet. A completely randomized design with two treatments and 12 replications was used. The treatments were two experimental diets containing 300 g/kg of WPCS or CSC as roughage. All animals at 0, 15, 30, 60 and 112 days were weighed to monitor productive performance and nutrient intake. Dry matter intakes, organic matter, neutral detergent fiber, physically effective neutral detergent fiber, crude protein and non-fiber carbohydrates of the WPCS treatment cattle were higher (p < 0.05), and the ethereal extract intake of cattle fed CSC diet was higher. The BW of cattle fed WPCS was higher in the two initial periods of confinement (p < 0.05). Animals from both treatments showed linear growth during the confinement period. There was a fiber source × period interaction for total weight gain (TWG), average daily gain (ADG) and feed efficiency (FE) (p < 0.05), with the lowest in the first 15 days and the highest at 30 days, reflecting a compensatory gain in animals fed with CSC. Bulls fed with CSC showed negative TWG and ADG in the first period (p < 0.05), but recovered in the following periods, surpassing that of the SC treatment in the last two periods. There was negative EF of bulls fed with CSC in the first period (P < 0.05), but in the following periods the CSC diet did not differ from the WPCS diet. The animals fed CSC diet showed a higher concentration of cholesterol and glucose in the blood plasma (p < 0.05). The forage-free diet containing cottonseed cake as a source of fiber replacing corn silage promoted better animal performance.

Prediction models of carcass characteristics from non­castrated Nellore cattle finished in the feedlot system under tropical conditions.

Our objective was to use measures of intake and productive performance to adjust prediction models for the carcass traits of non-castrated Nellore cattle finished in a feedlot. Individual data from 168 non-castrated male Nellore steers finished in feedlot between the years 2016-2021 were used. Descriptive statistical analyzes and Pearson correlation coefficients were performed. The outliers were tested by evaluating the studentized residuals in relation to the values predicted by the equations. Residues that were outside the range of -2.5 to 2.5 were removed. The goodness of fit of the developed equations was evaluated by the coefficients of determination (R2) and root mean square error (RMSE). Models for carcass yield, subcutaneous fat thickness, ribeye area, and shear force were adjusted. Means of 53.5% carcass yield, 4.8 mm subcutaneous fat thickness, 73 cm2 loin eye area, and 8.1 kg shear force were observed. The observed average intakes were 9.9 kg/day of dry matter, 3.3 kg/day of neutral detergent fiber content, 1.5 kg/day of crude protein, and 7.1 kg/day of total digestible nutrients. The average confinement time was 113 days, the average total weight gain was 152.2 kg and the average daily gain was 1.35 kg/day. Intake measures significantly correlated with shear force and subcutaneous fat thickness and ribeye area. Carcass yield was significantly correlated with total weight gain, feedlot time, and hot carcass weight. Measures of nutrient intake, performance, and confinement time can be used as predictors of carcass yield, ribeye area, fat thickness, and shear force of non-castrated Nellore cattle finished in a feedlot. The prediction equations for ribeye area, carcass yield, subcutaneous fat thickness, and shear force showed sufficient precision and accuracy for non-castrated Nellore cattle finished in confinement systems under tropical conditions. All equations can be used with caution to estimate carcass traits of cattle finished in a feedlot using measures of intake and productive performance.

Changes in the skin characteristics of Nellore steers during the rearing phase in hot climate pasture supplemented with protein sources.

We hypothesized that the protein source in supplements and the insolation and ambient temperature changes in different seasons could cause changes in the skin of Nellore steers during the rearing phase on warm-climate pasture. The objective of this study was to evaluate the effects of replacing true protein (soybean meal) with NPN (extruded urea) in the supplement on the skin characteristics of steers grazing on Marandu grass pastures. Thirty-six Nellore steers with an average initial weight of 250.0 kg and 15 months of age were used. Skin biopsies were performed at three different times: summer, autumn, and winter. The protein source has effects on the length of the glandular portion, number of follicles, and gland area in steers during the rearing phase at different seasons of the year. In the summer, the skin presented a higher compact structure, while in the autumn and winter, the skin presented a sparser arrangement. Skin from steers that received soybean meal in supplement had a more significant number of follicles in the summer and a smaller area and length of sweat glands. The dermis thickness of steers supplemented with soybean meal was greater than that of urea supplemented. The epidermis thickness and dermis of the steers' skin were greater at the autumn (April). Sweat gland depth was greater in autumn (April) and winter (July) than in summer (December). The protein source in the supplement alters the skin characteristics by increasing of dermis thickness of Nellore steers during the growth phase. The insolation and ambient temperature changes in different seasons alter the skin structure by increasing the epidermis and dermis thickness, sweat glands depth, and glands area of the skin of steers during the growth phase.

Urban sewage sludge stabilization by alkalization-composting-vermicomposting process: Crop-livestock residue use.

Waste management practices are vital for human health and the environment in a world where natural resources stress is expected to increase with the growth of population. Our study aimed to evaluate the potential use of crop-livestock residue as a bulking agent associated with the ideal level of hydrated lime for the stabilization and sanitization of urban sewage sludge through the alkalization-composting process. Therefore, we determined the alkalization efficiency on the heavy metal concentration in urban sewage sludge, quantified the viable eggs of helminths in pure and alkalized sludge, and measured the rate of earthworms (Eisenia fetida) surviving in the vermicomposting process using different levels of alkalized urban sewage sludge associated with crop-livestock residue. Four sequential trials were carried out in a completely randomized design with three replicates. The lime alkalization reduced the levels of Ba, As, Pb, Cu, Cr, Mo, Ni, and Zn compared to the pure urban sewage sludge. Using 30% w/w of lime in the urban sewage sludge (SS-30) for composting process reduced the viable helminth eggs by 71, 72, and 69% for sugarcane bagasse (Saccharum officinarum; SB), fresh chopped Napier-grass (Pennisetum purpureum; NG), and bovine ruminal content (BR), respectively. The ideal level of hydrated lime for stabilization and sanitization of urban sewage sludge was found to be 30%, which was able to reduce the heavy metals. The residues have the potential as a bulking agent for the composting of urban sewage sludge when associated with alkalization. The lime alkalization decreases the total number of helminth eggs and the number of viable eggs. The possibility of starting a vermicomposting using the mixtures is promising, evidenced by the earthworm survival in composting urban sewage sludge mixed with crop-livestock residues after 45 days of composting. The earthworm survival is maintained by an association of at least 80% of the crop-livestock residues.

Mathematical models to predict the lamb weight at birth and at weaning reared in the tropical warm-climate pasture.

Our objective was to evaluate the productive parameters of ewes and their lambs in relation to ewe age and to develop models for predicting lamb weight at birth and weaning in a tropical warm-climate pasture. Individual data were collected from 273 ewes and 273 lambs, between 2013 and 2021. During this period all animals were kept on pastures of Brachiaria brizantha cv. Marandu All lambs in the experiments were supplemented in creep-feeding. A descriptive statistical analysis was performed using the PROC SUMMARY procedure in SAS (SAS University Edition, SAS Institute Inc. Cary, CA, USA). Pearson correlation coefficients between variables were estimated using the PROC CORR procedure in SAS (SAS University Edition, SAS Institute Inc. Cary, CA, USA). Model adjustments and variable selection were performed using PROC REG in SAS (SAS University Edition, SAS Institute Inc. Cary, CA, USA). The STEPWISE option and Mallow's C(p) were used to select the variables included in the equations. Outliers were identified by evaluating the studentized residuals based on the predicted values from the equations. Residual analysis was predicted by regression minus observed values and those that fell outside the range of -2.5 to 2.5 were removed. Several statistics were used to assess the predictability of the equations, including the coefficients of determination (r2) and mean standard error (RMSE). The average ewe age at lambing was 3.4 ± 1.7 years, with an average weight of 56.9 ± 8,9 kg and average body condition score (BCS) of 2,4 ± 0.8 points. The average ewe age at weaning was 51.1 ± 7.9, with average BCS of 1.8 ± 0.8 points. The average lamb at birthing was 3.9 ± 0.9 kg. The average lamb at weaning was 21.0 ± 4.9, with daily gain of 0.2 ± 0.1 kg/day and total gain of 17.1 ± 4.7 kg birth to weaning. The lamb produced by ewe at lambing was 5.3 ± 1.7 kg/ewe. The lamb weaned by ewe at weaning was 28.7 ± 10.8 kg/ewe. The ratios of lamb produced per ewe at birth and at weaning were 0.1 ± 0.03 and 0.6 ± 0.2, respectively. The lamb's birth weight showed a positive linear relationship with the age of the ewe, increasing by 115 g per year of age. The regression equations adjusted for ewe age had maximum points ranging from 4.2 to 5.2, occurring at average age of 4,7 years. The other characteristics showed a quadratic tendency. The results suggest the culling of ewes at five years of age to generate lambs with ideal weight at birth and at weaning raised in warm tropical pastures.

Effects of extruded urea levels on the productive performance and carcass and meat characteristics of Nellore cattle.

Because the non-protein nitrogen sources can be an option for a ruminant diet to replace true-protein sources, we hypothesized that using extruded urea in increasing levels by reducing soybean meal in the diet can maintain or improve the productive performance of beef cattle in a feedlot. It was aimed to evaluate the effects of extruded urea levels on the productive performance and carcass and meat characteristics of Nellore steers in feedlot. Twenty-four Nellore steers, with an average age of 22 months and an average initial weight of 333.5 kg, were used. A completely randomized design was used with four treatments: 50, 60, 70, and 80 g/100 kg BW of extruded urea. There was no effect of extruded urea levels on nutrient intake. The final weight and average daily gain were adjusted by a quadratic equation, with maximum estimated values of 479.18 kg and 1.02 kg/day with the inclusion of 59.71, 54.14, and 54.16 g/100 kg BW of extruded urea, respectively. There was no effect (P > 0.05) of extruded urea levels on hot carcass weight (233.3 kg), carcass yield (53.2%), ribeye area (72.7 cm2), and subcutaneous fat thickness (5.3 mm). Likewise, there was no effect (P > 0.05) of extruded urea levels on meat chemical composition, shear force (8.9 KgF), cooking losses (28.2%), pH (5.6), and meat color parameters. We recommended the use of 70 g/100 kg BW of extruded urea in the diet for finishing Nellore steers in confinement.

Effect of physically effective neutral detergent fiber on nutrient intake and digestibility, ruminal and blood parameters, and ingestive behavior of confined beef cattle.

We aimed to evaluate the effect of levels of physically effective neutral detergent fiber from forage (NDFfor) on confined cattle's metabolism and ingestive behavior. Four crossbred steers (514.0 ± 4.54 kg BW) rumen-cannulated were used. The animals were randomly distributed in a 4×4 Latin square design, and the treatments were diets with 9.5%, 5.5%, 2.5%, and 0.0% NDF from whole plant corn silage. The trial was divided into 4 periods of 21 days. The dry matter, organic matter (OM), crude protein, neutral detergent fiber (NDF), physically effective NDF 8mm (peNDF8mm) and NDF1.18mm intakes, and the digestibility of OM and NDF showed a quadratic behavior. The rumen pH values showed a decreasing linear, and the time at pH below 5.8 increased linearly in the diets with lower NDFfor. The production of volatile fatty acids and the proportions of propionate and butyrate showed an increasing quadratic behavior. On the other hand, the proportion of acetate fitted a decreasing quadratic equation. With the lower participation of forage in the diets, the time spent on rumination activity decreased in a quadratic way, and the time spent in idleness increased in a quadratic way. The corn silage can be reduced to 135 g/kg DM in the diet to obtain a minimum of 5.5% of NDF from roughage.

Extruded urea levels in lamb supplementation in rainy tropical savanna conditions: the triad host-gastrointestinal nematodes-environment.

The objective of this study was to evaluate the influence of increasing levels of extruded urea (EU, Amireia®) in the diet of lambs naturally infected by gastrointestinal nematodes on the interactions in the host-pasture-soil components in edaphoclimatic conditions of the tropical rainy savanna. A total of 60 Texel lambs with a mean initial weight of 20.7 ± 0.87 and mean age of 2.5 ± 0.70 months were distributed in a completely randomized design, in five treatments consisting of different levels of EU supplementation viz., 0, 6, 12, 18, and 24 g 100 kg-1 live weight (LW). The performance of lambs, parasitological variables, gastrointestinal nematodes (NGIs), and larvae recovery in pasture and soil were evaluated. The highest animal performance was observed in animals that received 0 to 18 g kg-1 LW (146.0 g day-1) and the lowest in animals supplemented with 24 g kg-1 LW (81.0 g day-1) of EU. The body condition score (BCS) was similar in the animals (P > 0.05). Parasitic infection did not differ as a function of EU level (P > 0.05). Eggs of Haemonchus spp., Trichostrongylus spp., Cooperia spp., and Oesophagostomum spp. were found. The largest amount of larvae in the L1/L2 and L3 stages was recovered in the pastures occupied by the animals that received supplementation 0 g kg-1 LW of EU (750 larvae), the smallest in those that the animals received 6 g 100 kg-1 LW of EU (54 larvae). The presence of larvae in the L1/L2 stages changed significantly (P < 0.05) in the soil; in the other stages, it did not differ in the soil. Increasing levels of extruded urea do not influence the eggs per gram of feces (EPG) count. The 0 to 18 g 100 kg-1 LW level maintains animal performance, BCS and FAMACHA©. There is less dispersal of NGI larvae in pasture and soil when EU levels increase in the edaphoclimatic conditions of the rainy tropical savannah, which suggests that this supplement can be implemented in the diet of beef lambs, in addition to to be a lower cost nitrogen source.

Antioxidant action of yerba mate on carcass and meat characteristics and fatty acid profile in meat and fat of lambs finished in tropical pastures.

The objective was to evaluate the effect of the supplementation with natural antioxidants from Yerba mate (Ilex paraguariensis St. Hil.) on the performance, carcass and meat characteristics, and fatty acid profile in meat and fat of Texel × Ile de France lambs kept in Brachiaria-grass pasture. Twenty lambs with a mean age of 90 days and 26.3 kg of BW were distributed in a completely randomized design in two treatments with 10 replicates/treatment: Control-protein-energy supplement based on corn and soybean meal (150 g/kg DM of crude protein) without the addition of natural antioxidant yerba mate and Yerba Mate - energy protein supplement with the addition of yerba mate (110 g/kg DM). There was no treatment effect on animal performance and carcass characteristics. The subcutaneous fat thickness was significantly higher for lambs treated without yerba mate. There was no effect of nutritional treatments on the oxidative markers of lamb meat. The muscle of the animals treated with yerba mate showed a higher concentration of unsaturated and polyunsaturated fatty acids elaidic, linolenic, thymnodonic, docosadienoic, and ceorvonic. The fat of the animals treated with yerba mate showed a higher concentration of palmitoleic acid, linoelaidic acid, heneicosanoic acid, dihomo-γ-linolenic acid, and arachidonic acid. The concentration of polyunsaturated fatty acids was significantly higher in meat and fat of lambs treated with yerba mate. Including yerba mate in the diet of lambs kept on Brachiaria pastures improves the lipid profile of polyunsaturated fatty acids in meat and fat, without altering the performance of the animals.

Prediction models of intake and productive performance of non-castrated Nellore cattle finished in the feedlot system under tropical conditions.

The objective of this study was to understand and predict the intake and performance of Nellore cattle finished in the feedlot. Individual data from 144 non-castrated male Nellore steers finished in the feedlot between the years 2016 and 2020 were used. Descriptive statistical analyses and Pearson's correlation were performed. The outliers were tested by evaluating the studentized residuals in relation to the values predicted by the equations. Residues that were outside the range of - 2.5 to 2.5 were removed. The goodness of fit of the developed equations was evaluated by the coefficients of determination (r2) and root mean square error (RMSE). The mean dry matter intake (DMI) was 10.2 kg/day, neutral detergent fiber intake (NDFI) was 3.4 kg/day, corresponding to 33.3% of DMI, crude protein intake (CPI) was 1.6 kg/day, and total digestible nutrient intake (TDNI) was 7.1 kg/day. The CPI to ADG ratio was 1.3 kg CPI/kg ADG and the TDNI to CPI ratio was 4.5 kg TDNI/kg CPI. The averages of productive performance were 1.3 kg/day for average daily gain (ADG), 152.6 kg for total weight gain (TWG), and 497.8 kg for final body weight (FBW) in average days in the confinement of 115.7 days. The intake measures correlated significantly with the performance measures, except for carcass yield and days in the feedlot. TWG had a high positive correlation with ADG (r = 0.84), while FBW had a positive correlation (r = 0.86) with hot carcass weight (HCW). Measures of intake, performance, and days in the feedlot can be used as predictors of DMI, FBW, HCW, TWG, and ADG. The prediction equations had satisfactory precision and accuracy for non-castrated Nellore cattle finished in feedlot systems under tropical conditions.

Prediction of weaning weight in Santa Inês lambs using the body volume formula.

Weaning weight (WW) is one of the most important information within production systems, as it is a reflection of management during the breastfeeding phase and will influence the performance of animals in subsequent phases. This study aimed to develop and evaluate linear, quadratic, and exponential models to predict WW using the body volume (BV) formula in Santa Inês lambs for meat. Eighty-five lambs at 90 days of age with WW 17.52 ± 3.79 kg and BV 13.29 ± 2.86 dm3 were evaluated. The quality of fit of the models was evaluated using the coefficient of determination (R2), mean squared error (MSE), and root MSE (RMSE). For the external evaluation of the models, an independent dataset from 43 lambs at 90 days of age was used. The first-degree linear model showed the lowest values of MSE (1.02) and RMSE (1.01). In the external evaluation, all models exhibited estimates of mean WW and standard deviation of this weight similar to the external dataset, as well as high values (above 0.89) for the R2 of predicted vs. observed data. Concordance correlation coefficient (CCC) analysis also revealed that all models showed accuracy and precision (CCC > 0.90). There was no difference between the models in terms of accuracy (P > 0.05). The comparison in terms of precision indicated that the linear model is more precise than the exponential model and that the quadratic model is as precise as the linear model. The first-degree linear model should be used due to its simplicity of interpretation and ease of estimation.

Technologies used in ruminant grazing management: an integrative review.

The objective of this study was to identify the main technologies used in the management of ruminant grazing. We developed a review protocol in which the search terms were previously tested and based on the PVO strategy to determine the guiding question (population [P]: domestic ruminants; variables [V] of interest: grazing management technologies; and outcomes [O]: intake, performance, and productivity of animals raised exclusively on pasture). The guiding question was the following: What technologies are used in the grazing management of domestic ruminants on pasture? The databases used were SCOPUS (Elsevier), SciELO Citation Index, Science Direct, and Wiley Online Library, and the search was carried out until October 15, 2021. The search identified 2683 research articles; however, only 43 were considered eligible and included due to their methodological robustness for data extraction. The most commonly used species were Lolium multiflorum and Lolium perenne (20%), Panicum maximum (18%), and Brachiaria brizantha (14%). The most widely used grazing methods were continuous grazing (53.4%) and intermittent grazing (39.5%). Among the technologies, the most widely adopted were pasture height (55.8%) and herbage allowance (11.6%). The most frequent sampling methods were the use of a ruler (37.2%) and measuring stick (13.9%) to measure the height, and clipping with a frame (18.6%) to measure herbage allowance. The animals used in the included studies were cattle (n = 1335), sheep (n = 839), and goats (n = 41). Pasture height and herbage allowance were the most widely used grazing management technologies, with the data concentrated mainly in Brazil, in studies with continuous grazing by cattle.

Productive characteristics, chemical composition, in vitro digestibility, and degradation kinetics of two Brachiaria grasses at different regrowth ages.

The study aimed at the effect of different regrowth ages on chemical, productive, and morphological characteristics, in addition to the kinetics of gas production and in vitro digestibility of grasses of the genus Brachiaria. The treatments consisted of two regrowth ages (21 and 35 days) and two grass species (Brachiaria brizantha and B. ruziziensis), in plat with a dimension of 10 × 10 with four replications, totaling 16 plats in a completely randomized design. The regrowth age did not change the leaf:stem ratio of the grasses. Ruziziensis-grass had higher crude protein (CP) content in leaves than Marandu-grass (14.0% versus 10.9% respectively). Marandu-grass leaf had higher NDF content than Ruziziensis-grass (65.0 and 58.3%, respectively) and ADF content (39.6 and 33.2%, respectively). The accumulation rate is high in Marandu-grass regardless of the age of regrowth; however, the in vitro digestibility of dry matter of Ruziziensis-grass is better both in the leaf and in the stem. The regrowth age did not influence the dry matter (DM) and neutral detergent fiber (NDF) in vitro digestibility (ivD) of the leaves. The ivDNDF of leaves of both types of grass were similar. There was an increase in the ivDDM of stem when the regrowth age was 21 days. The DM degradation rate was higher in Marandu-grass at both regrowth ages, and the total gas production was higher at 21 days. The parameters evaluated in the dual-pool logistic model showed interaction for age and cultivar, except for fractions λ (lag time) and total gas production. Marandu-grass presented a greater volume of gas for the rapidly degradable fraction and a lower degradation rate. There was a significant interaction for the parameters evaluated in the models between ages and grasses. The exponential model showed interaction in all fractions. Grasses had reduced CP content and increased fibrous fraction as a function of age, with no reduction in leaf DM and NDF digestibility. The Ruziziensis-grass has higher digestibility at the regrowth ages evaluated, while Marandu-grass has higher yields. We recommend adjusting the in vitro degradation kinetics by the dual-pool logistic model.

Models to predict live weight from heart girth in crossbred beef heifers.

The objective of this study was to develop and evaluate linear, quadratic, and exponential mathematical models to predict live weight (LW) from heart girth (HG) in crossbred heifers raised in tropical humid conditions in Mexico. Live weight (363.32 ± 150.88 kg) and HG (166.83 ± 24.88 cm) were measured in 400 heifers aged between 3 and 24 months. Linear and non-linear regression was used to construct the prediction models. The goodness of fit of the models was evaluated using the Akaike information criterion (AIC), the Bayesian information criterion (BIC), coefficient of determination (R2), mean squared error (MSE), and root MSE (RMSE). In addition, the developed models were evaluated through internal and external cross-validation (k-folds) using independent data. The ability of the fitted models to predict the observed values was evaluated based on the root mean square error of prediction (RMSEP), R2, and mean absolute error (MAE). The correlation coefficient between LW and HG was r = 0.98 (P < 0.001). The quadratic model showed the lowest values of MAE (736.57), RMSEP (27.13), AIC (3783.95), and BIC (3799.91). Additionally, this model exhibited better goodness-of-fit values regarding external and internal validation criteria (higher R2 and lower RMSEP and MAE), thus having better predictive performance. The RMSE represented about 8% of the observed LW. Heart girth is highly correlated (r = 0.98) with LW. The quadratic model showed a high predictive capacity for crossbred heifers kept in tropical conditions.

Characterization and in vitro evaluations of Baru pulp from almond production waste ensiled with different additives.

The silage process is an efficient way of storing nutrients for animal nutrition. Our hypothesis was that the Baru pulp can be preserved in the form of silage, regardless of the use of additives to aid the process. Silages of Baru pulp containing different additives were evaluated through in vitro analysis, fermentation parameters, and composition and thermal analysis including differential scanning calorimetry and thermogravimetry. The treatments consisted of (1) silage with Baru pulp (BP) in natura without additive; (2) BP in natura with acetic acid; (3) BP in natura with formic acids; and (4) BP in natura added with microbial inoculums in a randomized experimental design with three replications per treatment and analyzed in duplicate. The ensiled material was kept in anaerobic conditions for a period of 30 days. BP before and after the silage process presented averages of 67.31 and 66.24% for in vitro digestibility of DM (IVDMD). Microbial inoculant additive was the most effective in reducing pH, followed by acetic acid and formic acid. There were effects of additives on silages for all degradation parameters in ruminal liquid in vitro. It was observed that BP before ensiling had the highest A fraction (7.9 mL gas/100 mg DM), without differing from the silage treated with formic acid (7.1 mL gas/100 mg DM). Similar effects were observed on mass loss (TG) and heat flux (DSC) between the silages. Our findings suggest that Baru pulp with formic acid is more efficient in the conservation and preservation of fermentable carbohydrates as well as in silage production.

Ruminal kinetics and nutritive value of Zuri grass silage harvested at different ages and added with powder molasses.

This study aimed to evaluate the effect of regrowth ages and the use of powdered molasses on nutritional characteristics of Zuri grass (Megathyrsus maximus) silages. A completely randomized design was used, in a 3 × 3 factorial scheme: three regrowth ages (65, 80, and 95 days) and three inclusion levels of powdered molasses of sugarcane (0, 20, and 40 g), with four replications. The chemical composition, fermentation parameters, in vitro digestibility, and in vitro degradation kinetics of the silages were evaluated. Greater dry matter (DM) contents were observed in silages with 95 days with 40 g of molasses. The 65 days of regrowth silages with 40 g of molasses had greater in vitro digestibility of dry matter compared to other treatments. However, lower pH values, N-NH3, DM losses, gas losses, and density were observed in silages with 95 days of regrowth with 40 g of molasses. It is recommended to cut the Zuri grass in the range of 80 to 95 days of regrowth with the addition of 40 g/kg of molasses in powders for the production of silages.

A new feed additive composed of urea and soluble carbohydrate coated with wax for controlled release in ruminal fluid.

Urea is a compound widely used as a feed additive for ruminants; however, when used profusely, it can lead animals to intoxication. Another factor that affects the effectiveness of urea is the lack of synchronization between the nitrogen and the availability of carbohydrates, necessary for better development of the ruminal microbiota. In order to circumvent these problems and improve the efficiency in urea use, the present study developed two new nutritional additives (F16 and F17) with different carbohydrate sources. One of the products developed (F16) used sugarcane molasses as a carbohydrate source, while the other (F17) used cassava starch. In addition to the carbohydrate source, both products contained the same amounts of urea, sulfur, calcium carbonate and were coated with carnauba wax. The supplements developed and two other commercial products based on extruded urea (UE) and polymer-coated urea (UP) were tested for solubility and cumulative gas production. The wax used in the coating process of the developed products (F16 and F17) proved to be efficient in reducing the solubility of the ingredients used. During chemical composition analysis it was verified that both supplements developed contained protein equivalent above 150% of crude protein. The cumulative gas production showed a higher production related to the product F17 (p < 0.05). Through thermogravimetric analysis, it was found the chemical integrity of the ingredients that make up the supplements developed. Therefore, is possible to reduce the solubility of urea using carnauba wax as a coating material. The formula with cassava starch associated with urea (F17) had a better synchronization during the degradation of its ingredients.

Biological and economic responses to increasing nitrogen rates in Mombaça guinea grass pastures.

Nitrogen fertilization has been recognized as an essential tool towards the establishment of sustainable intensification of pasture-based livestock systems using tropical perennial grasses if, for a given ecosystem it is capable of increasing forage growth, stocking rates and animal performance. This study assessed pasture growth traits, nutritive value, animal and economic responses of Panicum maximum cv. Mombaça guinea grass pastures subjected to different levels of N fertilization (100 (N100), 200 (N200), and 300 (N300) kg N ha-1 yr-1). Pastures were managed under rotational stocking to maintain similar pre (80-90 cm) and post-grazing (45 cm) canopy heights. A partial budget and a Benefit-Cost Analysis were used to assess the economic returns on increasing N fertilization. N300 resulted in greater post-grazing herbage mass. A slightly higher neutral fiber and acid lignin detergent was observed at N100 (P < 0.05); crude protein increased linearly, and in vitro digestible organic matter reached maximum value at 265.4 kg N ha-1 yr-1. Annual averages of animal weight gain were 515, 590 and 660 g d-1, respectively, for N100, N200 and N300. There was a decrease from 3.7 to 1.9 kg of body weight gain per kg of additional N applied when increasing N rates from 100 to 200 and from 100 to 300 kg ha-1. The net profit improved with increasing N levels, but at reducing rates, reaching its maximum at the N300 level. The change from 100 to 200 kg N ha-1 presented the best return, with USD 3.73 for each additional dollar invested, while the change from 200 kg N ha-1 to 300 kg N ha-1 was economically less than optimal, recouping only USD 1.60 for each dollar. The N300 rate presented the highest net profit per hectare (accounting profit), even in a pessimist scenario (25% reduction in production). Despite being profitable, the N300 rate was less than optimal from an economic standpoint, since an additional 100 kg of Nitrogen ha-1 to change from N200 to N300 level reduced both the net returns and the Benefit-Cost ratio. Our results suggest that the economically optimal level of N fertilization for Mombaça guinea grass pasture should be between 200 and 300 kg ha-1.

Cotton cake as an economically viable alternative fibre source of forage in a high-concentrate diet for finishing beef cattle in feedlots.

Cotton cake can be a sustainable and economically viable alternative to maize silage as an effective fibre source in the finishing diet of feedlot beef cattle. Thus, the objective was to evaluate the economic viability and the productive performance of Nellore steers finished in feedlots using cotton cake as a source of fibre, replacing maize silage in the diet. Twenty-four non-castrated Nellore steers, with an average weight of 377.8 kg and an age of approximately 24 months, kept in individual pens, were used. The diet was 30% roughage, in the form of maize silage, and a diet without forage containing 30% cotton cake as an effective fibre source, based on dry matter. The design used was completely randomised with two treatments and 12 replications. Effects (p < 0.05) of the dietary fibre source were observed for final body weight (BW), total weight gain, hot carcass weight (HCW) and carcass yield (CY). Revenue and net margin were higher for the treatment with cotton cake. The corn silage diet promoted higher total costs per animal (U$ 408.41 vs. U$ 336.06) and daily costs (U$ 3.65 vs. U$ 3.00). Greater differences were observed between fibre sources for the concentrate cost, and the maize silage diet had a cost U$ 98.29 higher than the treatment with cotton cake (U$ 314.04 vs. U$ 215.75). The cotton cake treatment had a higher cost of U$106.98/animal for the net margin. Cotton cake is a viable alternative and can be used as a source of fibre in forage-free diets without affecting production performance, promoting benefits in economic performance for finishing beef steers in feedlots.

The influence of protected fat in supplements on the performance and carcass characteristics of Nellore beef bulls in tropical pasture.

The finishing stages for uncastrated Nellore beef cattle on tropical pasture often produce high yielding carcasses with minimal fat cover. This study aimed to evaluate the performance and carcass characteristics of uncastrated Nellore beef bulls fed a diet containing rumen-protected fat during the rainy period for 210 days. Eighty Nellore beef bulls with 28 months of age, and an initial live weight of 416 kg ± 16 kg, were allocated into eight paddocks (7.0 ha), totaling 56 ha, at 10 animals/paddock, in a continuous-grazing system. The pasture characteristics, performance production, loin-eye area (cm2), subcutaneous fat thickness (mm), and rump fat thickness were evaluated. There was no effect (P > 0.05) on the average total weight gain (203.00 kg) and average daily gain (0.98 kg/day). On the other hand, the subcutaneous fat thickness and rump fat thickness were 42.8% and 49.5% greater, respectively, when the animals were fed a diet containing rumen-protected fat inclusion (P < 0.05). Supplementation with rumen-protected fat provided a thicker fat layer in the carcass of Nellore beef bulls grazing on tropical pasture during the rainy period.