Tadeu Silva de Oliveira

Comparison of growth curves of two genotypes of dairy goats using nonlinear mixed models

The objective of the current study was to assess the use of nonlinear mixed model methodology to fit the growth curves (weight v. time) of two dairy goat genotypes (Alpine, +A and Saanen, +S). The nonlinear functions evaluated included Brody, Von Bertalanffy, Richards, Logistic and Gompertz. The growth curve adjustment was performed using two steps. First, random effects u 1 , u 2 and u 3 were linked to the asymptotic body weight ( β 1 ), constant of integration ( β 2 ) and rate constant of growth ( β 3 ) parameters, respectively. In addition to a traditional fixed-effects model, four combinations of models were evaluated using random variables: all parameters associated with random effects ( u 1 , u 2 and u 3 ), only β 1 and β 2 ( u 1 and u 2 ), only β 1 and β 3 ( u 1 and u 3 ) and only β 1 ( u 1 ). Second, the fit of the best adjusted model was refined by using the power variance and modelling the error structure. Residual variance (

Desempenho produtivo de vacas recebendo dietas com capim-elefante submetido a diferentes adubações e níveis de concentrado

\sigma _e^2

Degradation kinetics and assessment of the prediction equation of indigestible fraction of neutral detergent fiber from agroindustrial byproducts

) and the Akaike information criterion were used to evaluate the models. After the best fitting model was chosen, the genotype curve parameters were compared. The residual variance was reduced in all scenarios for which random effects were considered. The Richards ( u 1 and u 3 ) function had the best fit to the data. This model was reparameterized using two isotropic error structures for unequally spaced data, and the structure known in the literature as SP(MATERN) proved to be a better fit. The growth curve parameters differed between the two genotypes, with the exception of the constant that determines the proportion of the final size at which the inflection point occurs ( β 4 ). The nonlinear mixed model methodology is an efficient tool for evaluating growth curve features, and it is advisable to assign biologically significant parameters with random effects. Moreover, evaluating error structure modelling is recommended to account for possible correlated errors that may be present even when using random effects. Different Richard growth curve parameters should be used for the predominantly Alpine and Saanen genotypes because there are differences in their growth patterns.

Slow-release urea in diets for lactating crossbred cows

Yield performance of cows fed diets with elephant grass subjected to dif ferent fertilization and concentrate levels The objectives of this work were to determine the total diet dry matter (TDDM) intake, milk production and milk composition, net energy for lactation (TNE) and total digestible nutrients (TDN) of elephant grass in the total diet. The elephant grass subjected to chemical (CF) and organic (OF) fertilization was mixed to the concentrate, at levels of 400, 500 and 600 g, in dry matter basis (DM). The treatments were arranged in a 6 x 6 Latin square, in a 2 x 3 factorial design (fertilizer x concentrate level). The average TDDM contents, in fed basis, and NDF, CP, Ca and P of the total diet, in DM basis, were different (P 0,05). Concentrate levels did not influence digestion of TDDM, MO and PB of total diet. NDF digestion decreased (P<.05) with increasing concentrate levels. Digestion of DM, OM

Factors affecting feed efficiency in dairy goats

This study aimed at estimating the kinetic parameters of ruminal degradation of neutral detergent fiber from agroindustrial byproducts of cashew (pulp and cashew nut), passion fruit, melon, pineapple, West Indian cherry, grape, annatto and coconut through the gravimetric technique of nylon bag, and to evaluate the prediction equation of indigestible fraction of neutral detergent fiber suggested by the Cornell Net Carbohydrate and Protein System. Samples of feed crushed to 2 mm were placed in 7 × 14 cm nylon bags with porosity of 50 µm in a ratio of 20 g DM/cm² and incubated in duplicate in the rumen of a heifer at 0, 3, 6, 9, 12, 16, 24, 36, 48, 72, 96 and 144 hours. The incubation residues were analyzed for NDF content and evaluated by a non-linear logistic model. The evaluation process of predicting the indigestible fraction of NDF was carried out through adjustment of linear regression models between predicted and observed values. There was a wide variation in the degradation parameters of NDF among byproducts. The degradation rate of NDF ranged from 0.0267 h-1 to 0.0971 h-1 for grape and West Indian cherry, respectively. The potentially digestible fraction of NDF ranged from 4.17 to 90.67%, respectively, for melon and coconut byproducts. The CNCPS equation was sensitive to predict the indigestible fraction of neutral detergent fiber of the byproducts. However, due to the high value of the mean squared error of prediction, such estimates are very variable; hence the most suitable would be estimation by biological methods.

Simulation of diets for dairy goats and growing doelings using nonlinear optimization procedures

The objective of this study was to evaluate the performance of F1 (Holstein × Zebu) cows in lactation according to different levels of substitution of soybean meal for a protein equivalent non-protein nitrogen originated from slow-release urea (SRU). Eight F1 (Holstein × Zebu) cows in the first third of lactation, with an average milk yield of 12.7 kg (±3.1 kg)/day and a live weight of 552 kg (±30 kg), were used. The experimental design was composed of two simultaneous 4 × 4 Latin squares, with the following treatments: 100% soybean meal and 0% SRU; 66% soybean meal and 34% SRU; 34% soybean meal and 66% SRU; and 0% soybean meal and 100% SRU. Sorghum silage, used as roughage, was supplied together with the concentrate. Feed intake and digestibility as well as milk yield and milk composition were measured. The obtained data were subjected to analysis of variance, adopting a 5% probability level. No intake variable showed significant differences among the treatments, and the mean values for the intakes of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) were 18.35 2.62 and 5.85 kg/day, respectively. The results for apparent digestibility also did not show differences among treatments, with DM, CP and NDF averaging 58.16, 58.64 and 36.21%, respectively. Milk yield and composition were similar among the treatments. The average 4%-fat-corrected milk yield was 13.39 kg/animal day. Intake, digestibility and milk yield and composition variables are not changed according to the substitution of the soy protein for slow-release urea. Thus, for average-milk-yield crossbred.animals, this substitution depends on economic variables only.

Intake and digestibility of silages containing pineapple pulp and coast-cross hay with or without urea and markers recovery in sheep

The objective of this study was to present some factors affecting feed efficiency in dairy goats. To develop our work, individual and average data from performance experiments with lactating goats were used. The following variables were evaluated: gross feed efficiency, adjusted feed efficiency, dry matter intake, milk-yield, 3.5% fat-corrected milk yield, dry matter digestibility, dietary neutral detergent fiber content, different roughage-to-concentrate ratios and body weight. The statistical analyses involved the application of descriptive and dispersion measures besides Pearsons correlation coefficient and linear regression analysis. The analyzed variables were highly correlated with feed efficiency. The feed efficiency of lactating goats was affected by the milk fat correction, dry matter digestibility, dietary fiber content, proportion of roughage in the diet and body weight. Among these factors, standardization of the milk fat appeared to be the most efficient in correcting the feed efficiency in lactating goats. Correction of some of these factors implies greater precision in the measurement of feed efficiency.

Performance and digestibility of steers fed by-product of fresh passion fruit or sorghum silage, with and without concentrate supplementation

The objective of this study was to simulate total dry matter intake and cost of diets optimized by nonlinear programming to meet the nutritional requirements of dairy does and growing doelings. The mathematical model was programmed in a Microsoft Excel(r) spreadsheet. Increasing values of body mass and average daily weight gain for growing doelings and increasing body mass values and milk yield for dairy does were used as inputs for optimizations. Three objective functions were considered: minimization of the dietary cost, dry matter intake maximization, and maximization of the efficiency of use of the ingested crude protein. To solve the proposed problems we used the Excel(r) Solver(r) algorithm. The Excel(r) Solver(r) was able to balance diets containing different objective functions and provided different spaces of feasible solutions. The best solutions are obtained by least-cost formulations; the other two objective functions, namely maximize dry matter intake and maximize crude protein use, do not produce favorable diets in terms of costs.

Sulfur sources in protein supplements for ruminants

The objective of this study was to evaluate the intake and digestibility of silages containing pineapple pulp and coast-cross hay, with or without addition of urea, and the recovery of the markers chromium oxide (Cr2O3), indigestible neutral detergent fiber (iNDF), indigestible acid detergent fiber (iADF), and indigestible dry matter (iDM), in a digestibility assay, in sheep. Treatments were as follows: two levels of pineapple pulp (818 and 758 g kg−1) and two levels of urea (with and without urea), in a completely randomized design. Twelve sheep (three per treatment) were used, kept in metabolic cages. Fecal excreta were determined by total collection or estimated by using the markers. Marker samples were obtained in morning and afternoon collections, with mean concentrations obtained for both daily activities. The level of silage pulp did not affect intake, while addition of urea increased the intake of crude protein (CP), but did not influence the intakes of dry matter, organic matter, neutral detergent fiber, or acid detergent fiber. The digestibility coefficients of all afore-mentioned fractions increased with the increase in pulp, the same happening with the addition of urea. The internal marker with lowest variability among the internal markers was iADF, with mean values near 100%. Mean recovery of Cr2O3 was approximately 107%, but with lower variability among treatments. Inclusion of pineapple pulp in silage does not influence intake, while addition of urea only increases the intake of CP. The levels of pineapple pulp in silage with or without urea increase the digestibility of the silage. Indigestible acid detergent fiber is the marker with lowest variability of recovery, with mean recovery for the four silages used very close to 100%.

Yield, chemical composition, and efficiency of use of nitrogen by Marandu grass

The objective of this study was to evaluate the nutritive value of passion fruit by-product for cattle, contrasting the results with those found with sorghum silage. Four treatments were then constituted, comprising the combinations of the two roughages and the two levels of supplementation (with or without), in a completely randomized design with four animals per treatment. The considered variables included: feed intake, digestibility coefficients of the diets, and live weight gain of the animals. The experimental period lasted 70 days, preceded by a standardization period of 30 days. Chromium oxide was utilized to estimate the fecal output, in the digestibility trial. Treatments were compared by means of three orthogonal contrasts: between the two roughages and between the two concentrate levels within each roughage. Animals fed passion fruit by-product showed higher feed intake (total, per 100 kg of live weight (TLW), and per unit metabolic size) and had higher TLW gain than those fed sorghum silage (1.304 kg vs. 0.134 kg). The coefficients of apparent digestibility of dry matter (DM), organic matter (OM), and crude protein (CP) and the digestibility coefficient of neutral detergent fiber from passion fruit by-product were high, and much higher than those from sorghum silage. The concentrate supplement did not improve the TLW gain of animals fed passion fruit by-product and had a limiting effect on the digestibility coefficients of the diet. The concentrate supplement had a positive associative effect on intake and digestibility coefficients of DM, OM, and CP from sorghum silage. The by-product of fresh passion fruit is an excellent food for growing cattle as it provides high intake levels and weight gains, even when supplied as the only feed.