This study aimed to evaluate the adequacy of seven non-linear models (France, Orskov and McDonald, Gompertz, exponential, logistic, two-pool exponential and two-pool logistic) in the adjustment of the curve and in the generation of parameters of cumulative gas production from five tropical feedstuffs (rice hulls, sugarcane, cassava chips, turnip by-product, and peach-palm by-product) used in ruminant nutrition. To this end, the feedstuffs were incubated in vitro in graduated glass syringes together with a buffer inoculum solution, in triplicate. Gas production was read at 0, 2, 4, 6, 8, 10, 12, 24, 26, 28, 30, 32, 36, 48, 52, 54, 56, 60 and 72 h of incubation. The data were used to generate the parameters of each model using the SAS statistical package. After the parameters were generated, the gas volume values were obtained at the aforementioned times, for each model, and these were compared with the values observed at incubation by using Model Evaluation System (MES) software. For the comparison, regression parameters were tested using Mayer’s test, in addition to the evaluation of the mean bias (MS), concordance correlation coefficient (CCC), and mean squared prediction error (MSPE). The France, Logistic, and Gompertz models, for rice hulls, and the Orskov and McDonald model, for cassava chips, were significant (P < 0.1) according to Mayer’s test, indicating lack of fit of the model. Besides presenting the lowest MSPE, the models that showed fit according to Mayer’s test were the two-pool logistic for rice hulls and cassava chips, and the two-pool exponential for sugarcane, turnip, and peach palm. Thus, the non-linear two-pool models are the most efficient in adjusting to the curve and in the generation of parameters of cumulative production of gases from the tested feedstuffs.

ResumoA neosporose é uma doença infecciosa, causada pelo Neospora caninum, protozoário intracelular obrigatório, formador de cistos, tendo o cão como principal hospedeiro definitivo. Este pode contaminar água e alimentos destinados a ruminantes, transmitindo assim a doença. Trata-se de uma das principais causas de abortos, gerando expressivos prejuízos econômicos na produção destes animais. A prevalência pode variar bastante em função do sistema de criação. Vários fatores de risco são associados a ocorrência da neosporose em ruminantes, dentre eles está a presença de cães em áreas destinadas a criação desses animais. O diagnóstico pode ser feito por métodos

The Brazilian tannery industry produces annually an enormous amount of scraps and leather shavings impregnated with chromium due to the tanning process. Technologies have been developed to remove chromium from this material. The resultant residue from the chromium removal process is high in protein with a high digestibility, suggesting that this residue may be used to feed monogastric animals. However, due to the nature of this residue, there is a risk of chromium poisoning and the introduction of botulism. The aim of this work was to establish the risks of adding tannery residues to animal feeds, using rats as an experimental model. Forty-eight Wistar rats were placed under eight treatments in a 2 by 4 factorial arrangement. The rats were fed over 60 days with a standard AIN-93 diet and the treatments consisted of replacing part of the diet with 0, 25, 37.5 or 50% of the chromium-tanned leather residue, in natura, known as ‘wet blue’, or the same percentages of this residue after chromium extraction. Industrial processing was able to remove 70–80% of the chromium from the residue. This high chromium level had a negative effect on the weight gain of the animals and caused lesions in the kidneys especially due to the chromium extraction material, suggesting that the removal process increases the biological activity of chromium, making it nefrotoxic. The gravity of this effect was directly proportional to the inclusion level. The results of this study indicate that until industrial processing is refined so that more of the chromium residue is removed, the use of the tannery residues in animal feeds is not safe.

Cannulated cows were allocated to a cross-over design to evaluate the technique for determination of volatile fatty acid (VFA) clearance by infusion of marker solution into intact ruminal digesta, and verify the technique sensibility to the variation in the diet. Animals received diet of forage or forage plus concentrate and infusion of valeric acid and Cr-EDTA solution into intact or evacuated ruminal digesta. The total fractional rate of VFA clearance (FRVFAC) was estimated by the exponential decay of valerate over time. The passage FRVFAC to the omasum was assumed as the decay in ruminal Cr concentration and the absorption FRVFAC was estimated by the difference. The total FRVFAC and absorption did not differ between techniques. The passage FRVFAC, however, was lower when the marker solution was added into the evacuated digesta, probably reflecting the destabilization of the rumen environment during the evacuation and the largest volume of fluid observed in animals with evacuated digesta. In conclusion, the infusion of marker solution into intact digesta with homogenization performed by ruminal motility could be usable for the VFA ruminal clearance determination since it seems to cause lesser disturbance in the ruminal environment.

RESUMOAvaliou-se o efeito do ambiente ruminal sobre a degradação da FDN de 12 cultivares de cana. As dietas continham: 87,1% de cana (Cana) ou 42,0% de cana e 58,0% de concentrado com milho (Milho) ou polpa cítrica (Polpa). Seis vacas com cânula ruminal formaram quadrados latinos 3x3. Por 11 dias de cada período experimental, o consumo de matéria seca foi fixado em 1,2% do peso vivo. No dia 12, baixo pH ruminal foi induzido no Milho e na Polpa por infusão intrarruminal de milho ou polpa cítrica. Simultaneamente, ureia foi adicionada ao rúmen em todos os tratamentos. Sacos de náilon contendo os cultivares foram incubados por 24h nos dias 11 e 12. O pH ruminal no dia 11 foi 7,01 e NH 3 foi 3,4, 4,4 e 6,2mg/dL para Cana, Milho e Polpa, respectivamente. O pH no dia 12 foi 6,98 para Cana, 6,49 para Milho e 6,04 para Polpa, e NH 3 foi 13,0mg/dL. Para Cana, a degradabilidade ruminal da FDN foi 21% no dia 11 e 28% no dia 12; para Milho e Polpa esta foi ao redor de 21% em ambos os dias. O ordenamento dos cultivares por degradabilidade ruminal da FDN foi similar nos ambientes ruminais distintos.Palavras-chave: amido, digestibilidade, efeito associativo, fibra, polpa cítrica A correlação entre o teor de fibra em detergente neutro (FDN) e a digestibilidade da matéria seca no rúmen é negativa e alta na cana-de-açúcar (Pate e Coleman, 1975; Teixeira et al., 2014). Como a digestibilidade da FDN da cana-deaçúcar é baixa (Corrêa et al., 2003) (Pate, 1981). ABSTRACT