José Maurício de Souza Campos

Consumo, digestibilidade aparente, produção e composição do leite e variáveis ruminais em vacas leiteiras alimentadas com dietas à base de cana-de-açúcar

Twelve purebred and crossbred Holstein cows were allotted to three 4 x 4 Latin Squares to evaluate the intake, apparent digestibility of nutrients, milk production and composition, ruminal pH and ammonia. The experimental diets were based on corn silage (CS) (AG 1051) with forage:concentrate ratio (F:C) of 60:40, in dry matter (DM) basis, or based on sugar cane (SC) (RB 855536) with F:C of 60:40 with .35 or 1% of urea+ammonium sulfate (AS) mixture or F:C of 50:50 with 1% of urea+AS. DM intake was 17.8, 14.9, 14.4, and 15.8 kg/day, for the diets, respectively. DM intake was higher, resulting in greater nutrient intake for CS based diet, except for the non fiber carbohydrates intake, which showed higher intake for SC based diet with 50% concentrate. Milk production (MP) was higher for the CS based diet, with no difference in MP among the SC based diets, with mean values of 22.0, 19.0, 18.6, and 20.1 kg/day and the 3.5% fat corrected milk production was 23.0, 19.7, 19.4, and 21.3 kg/day for the CS, SC .35%, SC 1% and SC 1% 50:50, respectively. Milk composition was not different among the experimental diets and milk fat contents were 3.8, 3.8, 3.8, and 3.9% for the CS, SC .35%, SC 1% and SC 1% 50:50, respectively. No difference on apparent digestibility of DM, organic matter, crude protein and total carbohydrates among the diets was observed. The neutral detergent fiber (NDF) apparent digestibility was higher for the CS based diet (47). There was no difference in NDF digestibility among SC based diets, 32, 31 and 31%, respectively. Inside each time (before and three hours after the morning feeding) there was no difference of pH values and amonia nitrogen compounds (N-NH3) among the diets.

Estimação da digestibilidade do extrato etéreo em ruminantes a partir dos teores dietéticos: desenvolvimento de um modelo para condições brasileiras

ABSTRACT - The objective of this study was to develop and validate a model to estimate the EE apparently digestiblefraction from different cattle diets. True digestibility coefficients and metabolic fecal contribution were the main parametersfitted to the model. The estimation method for both parameters was based on the Lucas test . The dataset used to build themodel contained 48 and 60 experimental means for lactating cows and growing and finishing cattle, respectively. Data weretaken from 24 experiments (12 experiments for each animal category). Comparison between animal categories was done byusing a Dummy variable. The dataset used for model validation originated from two independent trials with lactating cowsand one trial with growing cattle. The true digestibility coefficient (0.8596) did not differ between animal categories. It wasobserved greater metabolic fecal EE for lactating cows than for growing and finishing cattle. The metabolic fecal EE did notchange with different dietary EE levels (EE%), when expressed as a percentage of dietary EE. Therefore, the EE apparentlydigestible in the diet (EE

Meta-análise do impacto da fibra em detergente neutro sobre o consumo, a digestibilidade e o desempenho de vacas leiteiras em lactação

ABSTRACT - It was evaluated the effects of the chemical characteristics and in vivo NDF digestibility (IVNDFD) onintake, digestibility and performance of dairy cows in fedlot by using a meta-analysis procedure from 285 observations of sixexperiments. It was used data of animals fed diets based on corn silage (n = 213) or sugarcane (n = 72). Despite the lower NDFcontent of sugarcane (45.27% of DM) compared to corn silage (54.48%), it was noted lower intakes of dry matter (DMI) andNDF, which responded with a lower milk yield. It was observed a greater reduction in DMI (kg/day) with the increase of NDFf(NDF forage, % DM) in sugarcane diets (332.4 g of DM for each 1% of NDFf) in relation to corn silage (96 g of DM for each1% of NDFf). The greatest effect of ruminal repletion of sugar cane NDF is caused by the indigestible fraction, majoritary,despite the highest degradation rate of NDF potentially degradable fraction in relation to corn silage. Milk production notcorrected (MP) and MP corrected to 4% fat (MPC) and the content of milk protein decreased linearly with the increase ofNDFf content, regardless of the forage source. However, MP and MPC were not affected by NDFnf (non-forage NDF) level.Intakes of DM, NDF, TDN and milk fat content decreased linearly with increase in the lignin:NDF ratio, with greater amplitudein sugarcane based diets in relation to silage corn. Dry matter intake, MP and MPC reduced linearly and at the same magnitudeamong forage sources, with the increase in NDFD of the diet. The effect of NDF and lignin on intake, digestibility and animalperformance depend upon the source used.Key Words: corn silage, ruminal retention, sugarcane

Estimação da fração digestível da proteína bruta em dietas para bovinos em condições brasileiras

The objective of this study was to propose and validate a model to estimate the apparently digestible fraction of crude protein (CP) of cattle diets. The theoretical framework for model development was based on true digestibility coefficient and metabolic fecal contribution. The estimation of both parameters was done by using the Lucas test. The dataset for model building was composed by 39 and 54 means from 10 experiments with lactating cows and 23 experiments with growing and finishing cattle, respectively. For comparisons of animal categories a Dummy variable was used. The dataset for model validation came from two trials with lactating cows and two trials with growing and finishing cattle. The true digestibility coefficient, which was estimated as 0.7845 did not differ among animal categories. The greatest metabolic fecal CP was observed on lactating cows but it was not affected by dietary CP level when expressed as percentage of dietary CP. Thus, for animals fed ad libitum the content of apparently digestible CP (CPad%) in the diet can be estimated by the following equations: CPad% = 0.7845CP% - 0.97 for lactating cows and CPad% = 0.7845CP% - 1.61 for growing and finishing cattle. The validation procedure indicated no differences between observed and estimated values of CPad%. It can be concluded that the proposed models will improve the accuracy of TDN prediction using the chemical composition of the diet.

Application of the first canonical variable in the evaluation of animal production trials

The objective of this work was to evaluate the inter treatment discrimination according to feed conversion efficiency in several animal performance experiments. The variables investigated were: feed conversion ratio (FCR = intake: production ratio), feed efficiency index (FEI = production: intake ratio) and bio-nutritional index (BNI). The BNI was constructed from the first canonical variable obtained based on the multivariate analysis of variance of the intake and animal production (weight gain or milk production) variables. The results indicated that FCR and FEI reciprocated each other at experimental plot level but did not reciprocate at animal group or treatment level. This fact implicates distortions on the descriptive levels of probability of type I error for hypotheses tests and compromises the statistical and animal production inferences. On the other hand, the BNI index guarantees the maximum discrimination among experimental groups and allows to identify significant differences, which were not observe with FCR or FEI indexes. This fact can be associated to the incorporation of animal production intensity characteristics using BNI.

Consumo e digestibilidade aparente dos nutrientes da silagem de milho e dos fenos de alfafa e de capim-coastcross, em ovinos

To evaluate the intake, nutrients apparent digestibilities and nitrogen balance of corn silage, alfalfa and coastcross bermudagrass hays a digestibility trial with sheep was conducted. Fifteen crossbred castrated sheeps, with average live weigth 47.5 kg, were used in a randomized blocks design with four repplicates. The dry matter intake, in g/kg0.75, was influenced by feed and the higher value (68.06) was observed in animals fed with alfalfa hay. The ether extract and neutral detergent fiber intakes were smaller for animals fed with corn silage. The total digestible nutrients and crude protein intakes was higher for animals fed with alfalfa hay, both values were 210.97 g/day and 643.42 g/day, respectively. This result is related to the high nutritional value and dry matter content of the alfalfa hay. The crude protein and dry matter apparent digestibilities (56.47 and 73.92%, respectively) were higher on animals fed alfalfa hay. The nitrogen balance was positive only for animals fed alfalfa hays. The average live weight gain were 100.79 and 147.62 g/day for coastcross bermudagrass and alfalfa hays, respectively. The animals fed with corn silage lost live weight (-34.92 g/day). This result could be associated with the fact that the chemical composition of the hays is better than the corn silage.

Comportamento ingestivo, consumo e digestibilidade de nutrientes, produção e composição do leite de vacas alimentadas com silagem de milho ou cana-de-açúcar com caroço de algodão

Doze vacas foram distribuidas em tres quadrados latinos 4 × 4 com o objetivo de avaliar o consumo e a digestibilidade aparente dos nutrientes, a producao e a composicao do leite e o comportamento ingestivo. Os tratamentos consistiram de silagem de milho ou cana-de-acucar contendo 0, 7 ou 14% de caroco de algodao. Na relacao volumoso:concentrado estabelecida, 60:40, o tratamento silagem de milho foi superior na maioria dos parâmetros avaliados, como consumo de MS (20,8 kg/dia), producao de leite e leite corrigida para gordura (25,0 e 27,0 kg/dia) e producoes diarias de gordura e proteina (984 e 772 g/dia). O tratamento cana-de-acucar com 7% de caroco de algodao aumentou o consumo de MS (17,1 vs 15,5 kg/dia) e tanto o tratamento cana-de-acucar com 7% quanto com 14% promoveram aumentos nos consumos de extrato etereo (0,41 e 0,59 vs 0,24 kg/dia), carboidratos nao-fibrosos (7,4 e 7,3 vs 6,7 kg/dia) e NDT (11,6 e 11,9 vs 10,4 kg/dia) em comparacao a cana-de-acucar sem caroco de algodao. Os maiores consumos de nutrientes propiciaram aumentos na producao de leite (19,7 e 20,6 vs 18,6 kg/dia), de leite corrigida para gordura (21,1 e 21,6 vs 18,9 kg/dia) e nas producoes diarias de gordura (771 e 781 vs 664 g/dia) e proteina (602 e 625 vs 565 g/dia) pelos dois niveis de inclusao em comparacao ao tratamento sem caroco de algodao, respectivamente. O tratamento com 14% de caroco algodao apresentou variacao de peso negativa (-0,22 kg/dia), maior tempo em ruminacao que o tratamento cana-de-acucar sem caroco de algodao e tendenica de menores consumos de MS e nutrientes em relacao a cana-de-acucar com 7% de caroco de algodao. Considerando os resultados obtidos nesta pesquisa, o uso e a indicacao de dietas com maiores teores de caroco de algodao devem ser analisados com cautela.

Influência de Rumensin®, óleo de soja e níveis de concentrado sobre o consumo e os parâmetros fermentativos ruminais em bovinos

The objective of this research was to evaluate the effects of soybean oil (500 mL/animal/day), Rumensin® (3g/animal/day) and levels of concentrate (0, 25, 50 and 75%) in the diet of bovines, and sugarcane as a forage source, in some ruminal parameters and dry matter intake. There were used four rumen fistulated 7/8 holstein-zebu steers, at 400 kg of live weight. The experiment consisted of four periods of 15 days, in which 12 were for adaptation to the diets and three for sampling. It was used one level of concentrate in each period and oil and Rumensin were distributed in a latin square, as 2x2 factorial design. Ammonia, pH and VFA analysis in the rumen fluid were measured in samples collected at 0, 3 and 6 hours after feeding. The pH was immediately measured by glass electrode, ammonia was analysed by colorimetry and VFA by gas chromatography. Acetate, acetate to propionate ratio and pH were decreased, but isobutyrate, isovalerate, and ruminal ammonia were increased in high concentrate levels. Propionate was increased and acetate to propionate ratio was decreased with Rumensin. Butyrate was increased with oil in the forage diet, but decreased with increasing concentrate. Ruminal ammonia and pH were decreased during sampling time. In vitro deamination activity by the mixed ruminal bacteria decreased by increasing concentrate and increased by adding oil. Dry matter intake increased by increasing concentrate level and decreased with Rumensin and oil. All other main effects and interactions were not significant.

Produção de leite, consumo e digestibilidade aparente dos nutrientes, pH e concentração de amônia ruminal em vacas lactantes recebendo rações contendo silagem de milho e fenos de alfafa e de capim-coastcross

Ten lactating cows (Holtein and H*Z crossbreed) after 55d calving, with average weigth of 540 kg alloted to a switch-back design, were used in order to evaluate the intake and apparent digestibilities of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), crude protein (CP), total carbohydrates (TC) and ether extract (EE), the pH and ruminal ammonia concentration and milk yield and composition. The animals were fed ad libitum with diets containing alfalfa hay (AH), coastcross bermudagrass hay (CCH), corn silage (CS), ½ AH + ½ CS and and ½ CCH + ½ CS in 60% of the total diet (dry matter basis). The nutrients intake were not affected by the diets. The dry matter, crude protein and neutral detergent fiber apparent digestibilities were higher for diets with corn silage. The experimental diets did not affect pH and the ruminal ammonia concentration, however quadratic effect was observed for collection time. The highest milk productions were observed for the animals that received CS and ½ AH + ½ CS diets. The diets did not affect the crude protein and fat milk contents.

Estimate of the optimal level of concentrates for dairy cows on tropical pastures by using the concept of marginal analysis

It was adopted in this work a methodology to estimate the optimal level of concentrate food for dairy cows on tropical pastures based on the theory of marginal analysis. An empiric model was developed and validated for application of the methodology using a database composed of 62 means of treatments from 32 studies in which milk production was evaluated regarded to the levels of concentrate feeding. Milk production (MP) showed quadratic behavior in response to concentrate intake (CI): MP (kg/cow/day) = 10.554 + 1.5855CI - 0.0552CI2. Evaluation of the MP values observed over the predicted ones pointed the non-rejection of the null hypothesis, indicating that the model can be applied on the prediction of milk production, and consequently, on the optimal level of supplementation. However, evaluation of the partition of mean square error of prediction indicated the need for adjustments. The marginal production response (MPR) presented decreasing linear effect at CI level: MPR (kg milk/kg concentrate added) = 1.5855 - 0.1104CI. The intake of concentrate that maximizes profit per animal (CIoptimum) is estimated by the following equation: CIoptimum (kg/cow/day, as fed basis) = (1.5855 - (Px/Py))/0.1104; in which Px and Py are, respectively, the prices of concentrate feeds (